Microprocessor controlled idle ECU

[Bitsyncmaster]

While the forum was down, here is the status of my project.

I shipped an ECU to another owner. He put it on his car and his engine had a deceleration difference than my car. So I wrote some new software (I'm glad I rewrote that software because it's really improved on my car.) Anyway I shipped him a programmer and emailed him the new software. He will be testing it this weekend (I dying to hear results). This is going to be a good way to test the unit (shipped with a programmer). My goal is to get a few users running it all with one software revision then I will offer it for selling. The big problem is I only have three units. One on my car, I carry a spare unit, and the one I shipped. I have populated 15 boards in all but spare old ECUs are hard to come by.

[DeloreanJoshQ]

While the forum was down, here is the status of my project.

I shipped an ECU to another owner. He put it on his car and his engine had a deceleration difference than my car. So I wrote some new software (I'm glad I rewrote that software because it's really improved on my car.) Anyway I shipped him a programmer and emailed him the new software. He will be testing it this weekend (I dying to hear results). This is going to be a good way to test the unit (shipped with a programmer). My goal is to get a few users running it all with one software revision then I will offer it for selling. The big problem is I only have three units. One on my car, I carry a spare unit, and the one I shipped. I have populated 15 boards in all but spare old ECUs are hard to come by.

Dave, what and how does the microprocessor controlled idle ECU work? I missed your original posts....

[Bitsyncmaster]

Dave, what and how does the microprocessor controlled idle ECU work? I missed your original posts....

It's a plug and play unit. I update your old one my installing a new circuit board into your old case and use the connector.

Some advantages of mine:

1) You can program the idle RPM via a switch. 775 to 1000 RPM in 25 RPM steps.
2) Crystal controlled so the RPM you program is exactly the the RPM you get.
3) Saves power. I shut down the idle motor power if the engine is not running. And I shut down the power above 1300 RPM. This is when the idle motor is fully closed.
4) You can remove your idle switch if you desire. If you do this you must remove the diode (bypass it) in the harness near the idle ECU. Then I control your advance solenoid.
5) You can program the unit delay. This is for help with idle hunting or the user with the Volvo idle motor. With my car using the stock idle motor I have no delay programmed. I think my ECU will help with cold start hunting but hunting caused by the lambda ECU will probably not be curred.
6) I have a test mode you can enable to test your idle motor. You set this mode and it opens and shuts your idle motor slowly. You then look into the idle motor and see if the valve is sticking in any position.
7) There is an LED on the board that lights when the idle motor is fully closed. This is to help you trouble shooting an idle problem and setting your curb idle.
8) An air conditioning idle speed bump can be wired onto the board. This will bump the selected idle speed up 100 RPM if that signal is +12 volts.

See instructions on my web site that are in progress (still editing them).

[DeloreanJoshQ]

It's a plug and play unit. I update your old one my installing a new circuit board into your old case and use the connector.

Some advantages of mine:

1) You can program the idle RPM via a switch. 775 to 1000 RPM in 25 RPM steps.
2) Crystal controlled so the RPM you program is exactly the the RPM you get.
3) Saves power. I shut down the idle motor power if the engine is not running. And I shut down the power above 1300 RPM. This is when the idle motor is fully closed.
4) You can remove your idle switch if you desire. If you do this you must remove the diode (bypass it) in the harness near the idle ECU. Then I control your advance solenoid.
5) You can program the unit delay. This is for help with idle hunting or the user with the Volvo idle motor. With my car using the stock idle motor I have no delay programmed. I think my ECU will help with cold start hunting but hunting caused by the lambda ECU will probably not be curred.
6) I have a test mode you can enable to test your idle motor. You set this mode and it opens and shuts your idle motor slowly. You then look into the idle motor and see if the valve is sticking in any position.
7) There is an LED on the board that lights when the idle motor is fully closed. This is to help you trouble shooting an idle problem and setting your curb idle.
8) An air conditioning idle speed bump can be wired onto the board. This will bump the selected idle speed up 100 RPM if that signal is +12 volts.

See instructions on my web site that are in progress (still editing them).

That is pretty cool! The website is also very informative. However, I was unsuccessful in downloading the prototype part links...

Great job! Keep on upgrading! I will have to help finance the cause once I get some other things taken care of..

[Bitsyncmaster]

That is pretty cool! The website is also very informative. However, I was unsuccessful in downloading the prototype part links...

Great job! Keep on upgrading! I will have to help finance the cause once I get some other things taken care of..

Yes those links were to the old fourm. Guess I'll have to remove them.

[Bitsyncmaster]

I'm back making software changes. I'm making the software save the PWM settings at different temperature readings when the engine has a stable idle. That way I can instantly load that value when I detect your foot is off the gas. Doing this because I was able to get my engine into a hunting mode by punching the gas before I let it get to a stable idle after starting the engine.

So when you select a new idle RPM, change the curb idle setting or replace the idle motor the unit will self calibrate for those differences.

So it would be best to start your car cold and let it warmup to normal temp without touching the gas after a major change. That would calibrate all the values for each temperature reading.

[Bitsyncmaster]

Boy I'm getting good at writing code ;) . I wrote all that calibration code and did not have any bugs first time.

It now saves 32 values for 32 temperatures.

So far I can not break my ECU into hunting no matter how hard I try. I preload the values with what I got but they get updated anytime your engine is at a stable idle. Of course to get all 32 values updated you would need to idle your engine at 40 below zero.

[Elvis]

Where's the "I like it" Button ? :-)

and where are the people that told me back then that
they like the hunting because so they know the car is
misadjusted or alive... ?

[Bitsyncmaster]

Well that last change I made for first start on a hot day worked good for starting the car but today a hot restart started good but would not keep running without giving it some gas. Once it ran a few seconds it was fine. So I have to modify my "fast idle" routine.

Guess I knew anyway this project was going to be a big software effort.

[dhaney]

While the forum was down, here is the status of my project.

I shipped an ECU to another owner. He put it on his car and his engine had a deceleration difference than my car. So I wrote some new software (I'm glad I rewrote that software because it's really improved on my car.) Anyway I shipped him a programmer and emailed him the new software. He will be testing it this weekend (I dying to hear results). This is going to be a good way to test the unit (shipped with a programmer). My goal is to get a few users running it all with one software revision then I will offer it for selling. The big problem is I only have three units. One on my car, I carry a spare unit, and the one I shipped. I have populated 15 boards in all but spare old ECUs are hard to come by.

Have you gotten any results from the other owner yet?

Dan

[Bitsyncmaster]

Have you gotten any results from the other owner yet?

Dan

I should let him comment but his stalling problem seems fixed but he had a hunting issue one time. We have not found why his car is so different from mine yet. I'm thinking his idle motor may be sticking so he will try another one. He can load new software as I fix things and hopefully read some data I'm saving in EEPROM to help debug things.

I did put one in another owner's car and it seemed to run like my car but only did a quick hot engine test.

I'm still working on perfecting the engine start at all engine temperatures. Not that the start is a problem but gives me something to do meantime. It's interesting what the WUR does to the start of a hot engine. It seems to take about 2 or 3 seconds and then it quickly swings the control pressure to normal. You don't see this only with a hot engine start.

[robvanderveer]

At what point in time can we expect this ECU to be marketed, and at what price?
Are there any other benefits that better stability, replacement of old stuff, and lower power consumption?

[Bitsyncmaster]

At what point in time can we expect this ECU to be marketed, and at what price?
Are there any other benefits that better stability, replacement of old stuff, and lower power consumption?

Allows you to set your idle RPM. Usually those with high lift cams want higher idle.

I think you should get better city MPG since I keep the idle motor closed when decelerating.

It may fix cold start hunting. This remains to be test with one that hunts cold.

Has ability to bump idle up with an AC signal wired to it. This has only been bench tested.

You don't need to use the idle micro switch. This lets the idle drop slower since the advance stays on until below 1300 RPM. That also should aid MPG.

I shut down the idle motor power above 1300 RPM. I do bump it on every 5 to 10 seconds in case it creeps off of the closed position. That keeps the idle motor cool and saves up to one amp of load. I also shut down the idle motor power when the engine stops.

The price will be $125 but you have to ship me your old ECU since I need the connector and case. It's just the testing and software changes to improve what that testing finds that will determine the release time. It's not a big deal to load new software but you would need to ship it to me or someone that has the programmer. The programmer retails for $35 which plugs into a windows USB port. The programming software comes on a CD or you can download it free on the INTERNET. It takes about 5 seconds to load a new program from the ".HEX" file I provide.

[robvanderveer]

Because I am living in the Netherlands, shipping my ECU to the States may not be an option. Other than that, I am seriously interested. If the housing and/or connector is an issue, we might be able to construct a new housing and connector perhaps. I am aware that this might raise the price a little, but it will allow me to restore the original ECU module at any point in time.

[Chris 16409]

Because I am living in the Netherlands, shipping my ECU to the States may not be an option. Other than that, I am seriously interested. If the housing and/or connector is an issue, we might be able to construct a new housing and connector perhaps. I am aware that this might raise the price a little, but it will allow me to restore the original ECU module at any point in time.

Here's what you could do. There are currently three Volvo idle ECUs on eBay. You can buy one and have it shipped directally to Dave. I'm sure he wouldn't mind. Then he can ship you the converted ECU when he's ready. That's probably the cheapest method.

[Bitsyncmaster]

Here's what you could do. There are currently three Volvo idle ECUs on eBay. You can buy one and have it shipped directally to Dave. I'm sure he wouldn't mind. Then he can ship you the converted ECU when he's ready. That's probably the cheapest method.

I've had someone do that with an RPM relay.

Another option is to find someone over there that can open, unsolder and solder the connector onto populated boards I supply. Opening the unit is a PITA so far but the more I do makes me think of other ideas to do the job easier. Unsoldering the connector can be done in 30 seconds with a vacuum powered solder sucker but even solder wick would not take much effort. Soldering the 9 pins on the board is also real easy.

[Bitsyncmaster]

I've had two starts that point to my idle motor sticking. It's always the first start of the day. The software sets the idle motor at the same position the OEM unit sets on power up. Then after I see ignition pulses it goes to a closed loop at 1050 RPM (fast idle) for about 5 seconds.

One start seemed to stick at the preset start position (800 RPM) and then suddenly jumped to about 1300 RPM. It then quickly came back down to 1050 RPM.

The second time it would not stay running unless I gave it gas. After a few seconds of running all was back to normal.

So I'm making the software open the idle motor full open on power up for 0.1 seconds and then close to the correct start position. That will give the idle motor full torque to get it moving if it was stuck. Even if this problem turns out to be a software bug, I like this software change since it would help when the idle motor gets sticky.

After I get the software ready for release, I do plan to install the Volvo idle motor I have. I like the way the Volvo idle motor runs more linear and smother than the OEM motors but my early testing suggested they were slower.

I also forgot to list a new function of my unit. You can set a test mode (DIP switch) so when you turn the key to on, it will slowly run the idle motor back and forth full open to full closed. That was done to let the owner evaluate his idle motor for sticky operation. You have to pull the idle motor out of the mount and look inside to see the valve moving. Of course you do not want to run the engine with this test mode set.

[DMCH James]

If I could make one suggestion from an "ease of service" point of view, I would suggest including TWO labels with each unit. One attached to the ECU, and the other perhaps to put on the access board on the rear shelf. That way, if at some point down the road someone is trying troubleshoot or diagnose a problem with the car, it may not be easily discernible that this new unit is installed, especially if the idle switch is removed.

James

[Bitsyncmaster]

If I could make one suggestion from an "ease of service" point of view, I would suggest including TWO labels with each unit. One attached to the ECU, and the other perhaps to put on the access board on the rear shelf. That way, if at some point down the road someone is trying troubleshoot or diagnose a problem with the car, it may not be easily discernible that this new unit is installed, especially if the idle switch is removed.

James

Alway welcome suggestions. Thanks. I will label the unit on top of the case. Not sure if people will want a label showing on the rear shelf.

[Bitsyncmaster]

Well it looks as though that bump to full open (idle motor) for 100 ms when I start the engine, fixed my occasional start problem. So I removed the extra setting I was doing that the OEM unit did not do and that makes the hot starts even better. Looks like they got those settings correct on the OEM unit.

So it appears my idle motor is a little sticky after setting not used for a day or two.

I'm not doing much to the software these days. Just minor tweaks to perfect things I find. I think I will try dropping my 1300 RPM set point (where I close the idle motor and turn on ignition advance), to 1200 RPM and see if that helps or hurts anything.

When I get time, I'm thinking of adding software for the AC on signal to keep a separate table of calibration values. Not that the AC makes much change to RPM when it switches on or off but since I've only used half my micro memory I may as well write the code.

I also will try the Volvo idle motor again. I really want to keep the Volvo unit since it runs so much smoother than the two OEM idle motors I have checked.

[jmrydholm]

Very cool!

[Bitsyncmaster]

I put the Volvo idle motor in and so far I only had to increase the delay one switch setting. I did discover one thing I need to change but don't think the idle motor change has anything to do with it.

What I saw today was like a sticking return of the throttle plates. It would drop fine if I punched the throttle but if I let off slowly it would hang up around 1300 RPM.

What I think my problem is the advance is still on and not letting the idle drop to my new 1200 RPM setting where I turn the advance off. You would only see this if you remove the idle switch. So I think I need to turn the advance off when it drops below 1500 RPM just to make sure your idle returns to normal.

It maybe that I just need to reduce the curb idle with this new idle motor but I still think the safe thing to do is change the advance RPM.

[Bitsyncmaster]

My beta tester is getting good results now. He installed a different idle motor and downloaded my latest software. Now we are just looking for bugs and minor adjustments to the software.

I'm getting ready to try added the "AC bump" into my car.

There is another thread about idle hunting. Just an FYI on how my ECU may prevent hunting caused by the OEM idle ECU. It will not fix hunting caused by the lambda ECU. As I stated in that other thread, if you increase the delay before you make an idle adjustment it should prevent ECU caused hunting. I did choose a longer delay with my unit and the end user can adjust that delay with four choices via a DIP switch on the board. I was able to run the shortest delay with the OEM idle motor and not have any hunting. With the Volvo idle motor I'm running the next delay (little bit longer).

So with the slower close loop response time, I have to have it faster when you take your foot off the gas and the engine RPMs drop. I detect when RPM is falling past 1500 RPM and instantly load the last good idle value that held the idle correctly. This results in no undershoot of the set idle speed. It just drops cleanly to the idle speed and holds it there. The other condition is going down hill in gear below 1500 RPM. Well just like the OEM unit, my ECU also closes the idle motor fully. So my software loads that same correct value instantly when the RPMs are below the (set idle speed - 100 RPM). So you do see the idle undershoot in that condition but it recovers so quickly unless your looking for it on the tach, you will not notice.

[Bitsyncmaster]

Just added an LED flashing code to display to the user what Revision level the software is at loaded into the ECU. The code flashes one time after you turn the key on and don't start the engine. You don't need to wait for it to flash only if you want to read the code.

I did this because I plan to offer field updating to the latest software.

Now the user will be able to tell if his unit has the latest code.

The first released code will be Revision #1 so you would see one flash.

[Bitsyncmaster]

I hooked up the AC bump wire. Pretty easy to do. Just connect (splice) to the pink (mine looks light brown) wire on the diode on the right side of your relay compartment harness.

I'm going to include this wire that will have a one terminal connector on it. I will drill a hole in the center of the connector housing and install the wire.

I was not going to do this on my car but I'm going to keep another calibration table when the AC is on so you should never have any engine deceleration problems (undershoot). Just ran down to the bank and was sitting in a long line for the drive up and the AC keep me cool sitting at idle speed. I have the normal RPM set for 800 so when the AC is running it bumps it up 100 RPM (900 RPM).

[Farrar]

I have the normal RPM set for 800 so when the AC is running it bumps it up 100 RPM (900 RPM).

Perfect!

Great work as always!

Farrar

[Ryan King]

When the units are done, are you planning on including instructions on how to install the ECU and how to tune it correctly?

[Bitsyncmaster]

When the units are done, are you planning on including instructions on how to install the ECU and how to tune it correctly?

My web site already has the instructions. It's a work in progress document.

[Bitsyncmaster]

Well I'm really excited with something I came up with on my latest software. My new change will really make it hard to get into that mode where you get an undershoot of the set RPM value. Even though I've got that mode working very good in that it recovers so fast you would only see if you were watching the tach for it.

First, as I found I have to turn the ignition advance off below 1500 RPM. If you turn it off lower than that you risk your RPMs won't drop enough to control. This only takes effect if you remove the idle switch and diode so I'm controlling the advance.

I now close the idle motor fully above 1200 RPM. I keep the idle motor closed until RPM drops to the set RPM value +100 RPM. Then it instantly loads the correct value that is recorded in the calibration table. This works perfectly with the AC off but I think I may move that +100 value up to +150 so with the AC on it won't dip any. The AC causes the engine RPMs to drop faster than without it.

So to get into that one undershoot mode you can only do it by not running the RPM above 1200.:devil:

[Bitsyncmaster]

It took loading the idle PWM value at 300 RPM above the set idle speed to stop undershoot when decelerating with the AC running. So now I have to work my software to do this. This is running the Volvo idle motor which I think is slower so it should work better with the OEM idle motor.

[Bitsyncmaster]

Here is how I open the case on the idle ECU.

1). I sand the sides on the end with the connector flush with the sides of the case. I think this will let the two latches on the side of the case flex a little easier so I can pop the connector and PCB out of the case.

2) I take a screwdriver and lift the center of the top (wide) of the case and pry the connector outward. You will see that lifts the two latches on the top clear of the case and your forcing the two side latches to give way.

3) Once you get one of the short sides free it pulls out easy.

4) I cut the two latches on the short side of the case off with an exacto knife.

5) I trim the overlap of plastic off the case.

All this work is done on the case (box) and nothing is done to the connector. Then it's easy to open in the future to look at the LED or change the switch setting. I guess you could also cut some holes in the case if you wanted to always see the LED and or modify the switches but it's just so easy to pop it out after you cut the two side latches.

[Bitsyncmaster]

Here is how I open the case on the idle ECU.

1). I sand the sides on the end with the connector flush with the sides of the case. I think this will let the two latches on the side of the case flex a little easier so I can pop the connector and PCB out of the case.

2) I take a screwdriver and lift the center of the top (wide) of the case and pry the connector outward. You will see that lifts the two latches on the top clear of the case and your forcing the two side latches to give way.

3) Once you get one of the short sides free it pulls out easy.

4) I cut the two latches on the short side of the case off with an exacto knife.

5) I trim the overlap of plastic off the case.

All this work is done on the case (box) and nothing is done to the connector. Then it's easy to open in the future to look at the LED or change the switch setting. I guess you could also cut some holes in the case if you wanted to always see the LED and or modify the switches but it's just so easy to pop it out after you cut the two side latches.

Edit:
The photos attached I could not load yesterday.

[Bitsyncmaster]

Here is my solution to connecting the AC on signal.

What connecting the AC signal gains you is:
Your idle speed is increased 100 RPM higher so you get more cooling stuck in traffic or at a stop light.
It also keeps a separate table of values so you get more consistent idle without it dropping under your set idle speed when you take your foot off the gas.

[jmpdmc]

Just wanted to bump this to see if Dave has any updates to the project.


Jeff

[Bitsyncmaster]

My first beta tester is still having occasional hunting issues. I think it's the way he drives which makes his show the problem and not mine. I'm making some more software changes for him to try.

[Bitsyncmaster]

I've been bench testing some new units and my test idle motor seems very sticky. As a matter of fact, I’ve never seen an OEM idle motor that does not stick somewhere in its motion. The only smooth one I've see is the Volvo unit.

The talk of the GM idle "solenoid" got me thinking this unit will not have a sticking problem. I'm assuming it open wide open and then fully closed with the timing changing to control the average.

Now I just thought I could do the same with the stock ISM just by lowering the PWM frequency. I'm going to try that soon and send that change to my beta tester that is having a hunting problem.

[bigmac]

Hi Dave,

Are these available for sale yet?

Thanks

Fred

[Bitsyncmaster]

Hi Dave,

Are these available for sale yet?

Thanks

Fred

I'm still fine tuning the software but if you need an idle ECU now, I can sell them. My plan is to offer free software updates if you pay the return shipping (about $4 first class mail in US). Of course you would want to wait till your car is not used to ship your unit to me.

I've been picking up some EBay units to have ready to exchange in person but updating your OEM returned unit is pretty quick since I have boards built and ready.

[bigmac]

Being in New Zealand shipping back and forth could be a problem.

Can i add your board to my ecu with instructions from you?

thanks

[Bitsyncmaster]

Being in New Zealand shipping back and forth could be a problem.

Can i add your board to my ecu with instructions from you?

thanks

Opening the OEM box it a pain. I'm a little better at it now that I've done 10 or more. You can try to open yours. Then you need to unsolder the connector and solder it on to the new board.

Probably better if you can buy a spare ECU here in the US and have it shipped to me to update. You can update the software with a $50 tool and a windows PC with a USB port. The tool is a PICKIT-2, programming software is free to download and I would send you the updated .HEX file via email.

[bigmac]

Looked all over but nothing.

Where are you finding all of yours?

[Bitsyncmaster]

Looked all over but nothing.

Where are you finding all of yours?

Volvo units at junk yards. The junk yards sell on EBay also. I think these Volvo units will start selling cheaper now that not many 30 year old Volvo's are around.

[elfking]

Volvo units at junk yards. The junk yards sell on EBay also. I think these Volvo units will start selling cheaper now that not many 30 year old Volvo's are around.

I will for sure be either sending you my ECU or finding a spare to send to you only since I am in good 'ol California. I doubt any of your upgrades would flop my smog test, but if I could track down another ECU to ship to you for the upgrade I would do it in a heart beat!

That said, do I just need to keep my eyes open for a Volvo unit that had the similar engine in it I suppose or is there a certain model number I should be searching for? I haven't pulled my ECU out yet to see if there are some numbers on it for me to search for...

Then I suppose the last question is how much do you want for the Replacement/ECU upgrade!

[Bitsyncmaster]

I will for sure be either sending you my ECU or finding a spare to send to you only since I am in good 'ol California. I doubt any of your upgrades would flop my smog test, but if I could track down another ECU to ship to you for the upgrade I would do it in a heart beat!

That said, do I just need to keep my eyes open for a Volvo unit that had the similar engine in it I suppose or is there a certain model number I should be searching for? I haven't pulled my ECU out yet to see if there are some numbers on it for me to search for...

Then I suppose the last question is how much do you want for the Replacement/ECU upgrade!

Our ECU is a 9 pin unit but if you can find the 11 pin unit all the better. I have an AC bump circuit that increased the set RPM 100 when the AC compressor is running. With the 9 pin units I add a wire for the AC. With the 11 pin units I supply a wire with a pin you install in your harness. You have to remove the two connector "keys" with an exacto knife to use the 11 pin unit. The Volvo units are the same case and connector as ours so look at yours and see what it looks like.

To upgrade your returned unit I plan to charge $125.

I have been picking up some spare units that sell on EBay. Expect to pay from $30 if your lucky to $90 for one. I have a bunch of 11 pin units but would have to charge a premium if you want one returning your stock 9 pin unit. They are harder to get.

[elfking]

Fantastic,
Thank you for that info, so if I track down an ECU to send in, it doesn't need to work since your only after the case and pins? Or do you need a working core?? Just is of course hit and miss in the junk yards is all depending on the rainy weather and location..



Our ECU is a 9 pin unit but if you can find the 11 pin unit all the better. I have an AC bump circuit that increased the set RPM 100 when the AC compressor is running. With the 9 pin units I add a wire for the AC. With the 11 pin units I supply a wire with a pin you install in your harness. You have to remove the two connector "keys" with an exacto knife to use the 11 pin unit. The Volvo units are the same case and connector as ours so look at yours and see what it looks like.

To upgrade your returned unit I plan to charge $125.

I have been picking up some spare units that sell on EBay. Expect to pay from $30 if your lucky to $90 for one. I have a bunch of 11 pin units but would have to charge a premium if you want one returning your stock 9 pin unit. They are harder to get.

[Bitsyncmaster]

Yes, all I use is the case and connector. I will clean the pins up on the connector so don't worry if they look dirty.

9 pin unit:
0 280 220 009

11 pin unit
0 280 220 005

I think there are other numbers that will work but I have a few of those already done.

[DMC5180]

I thought the 9-PIN was a 0 280 220 003

[Bitsyncmaster]

I thought the 9-PIN was a 0 280 220 003

I think there are a few numbers with the 9 pin. Those two numbers are on the case of units I have now. The 005 11 pin unit is for a 4 cyl, turbo.

[Bitsyncmaster]

Last night I parked my car outside to test a cold start. The air temp was 30 deg.F. It started like always and did not need the CSV to run.

I've been playing with the software to try to get the hunting eliminated with a cold start. My car has a wideband O2 system so it goes closed loop mixture after about 15 seconds from a cold start. Without software modifying some values it would hunt at about 25 second to 60 seconds. If I pulled the lambda input before the cold start and put it back at 120 seconds to simulate the stock O2 then I did not get any hunting on the cold start. To fix the wideband hunt, I make finer adjustments to the idle motor change and increase the delay a little. Now I just need to find what temp reading to enable and disable those modifications.

Anyway, I've added some new functions to the unit and will have to update my instruction manual. I've got two switches (dip switch on my board) to help debug and setup the unit. Switch 8 when switched on will stop the closed loop idle changes and hold the idle motor where it is. If that stops hunting or unstable RPM then you need to select more delay. Switch 7 when switched on will close the idle motor and hold it there. That lets you set your curb idle which has to be below your set idle speed. I have my curb idle set at 650-700 RPM. Setting switches 1 to 4 on before start will put the idle motor into a slow swinging test mode. That lets you look at the idle motor (you need to pull it out) and see if there are any sticking locations as it swings from full closed to full open. That test keeps running until you turn the unit off. I now flash the LED at power up with the revision code of the software that is loaded. Right now you get one flash. Next released code will have two flashes, etc.

I have a second programmer on loan to one of my beta testers. If I have a new revision of software, I can loan that to someone at a tech meet and you can all update your software.

Things really improved when I reduced the PWM frequency from 122 Hz to 61 Hz. Believe it or not, that really speeded up the closed loop control. It reduced the delay required by half. It must be because it reduces the sticking of the idle motor.

[Bitsyncmaster]

I sent my demo unit to another user and we found using the stock idle speed motor (ISM), I need to use some different engine start values. The problem is you would need to give it some throttle to start the engine with air temp above 50 deg. F.

I think the three cars running my unit all have the Volvo ISM. So I may have to have a DIP switch setting to indicate which ISM you are using. So a new Revision of the software is being worked on.

[thirdmanj]

0 280 220 003

If I understand correctly, this part number is NOT what you're looking for?

[Bitsyncmaster]

0 280 220 003

If I understand correctly, this part number is NOT what you're looking for?

I have not seen every part number that would be compatable. Just as long as the connectors and case look the same it should work. I just use the connector and case and install my new circuit board to them. If you get the 11 pin connectors, you will need to pull the two nylon keys from one connector in your harness.

[Bitsyncmaster]

Well I made one value change to the amount the ISM opens at engine start above 50 deg F. That change runs the ISM about 10% wider open at start. It now works great with the OEM ISM and seems to also work great with the Volvo ISM. I will keep running my car with this change for more testing time.

Just for your info. The start position is adjusted wider open according to the engine temp. But that only affects starts colder than 50 deg. F. Above that temp the start position is fixed just a little wider than half open. This is also the way the OEM ECU works. So if you have the ISM removed but plugged in, you should see it jump to half open when you first turn the key to on.

[jmpdmc]

Dave,

I saw in an Orlando thread you are offering these for sale. Is all the testing done that the beta testers were doing? I am just wondering about the status and if you are releasing the final product now. I have followed this thread and I am interested in one.


Jeff

[Bitsyncmaster]

Dave,

I saw in an Orlando thread you are offering these for sale. Is all the testing done that the beta testers were doing? I am just wondering about the status and if you are releasing the final product now. I have followed this thread and I am interested in one.


Jeff

I still need to do some "tweaks" to the software when I can get some time. But the other users are happy with the results. But nothing is ever perfected. My car has been running fine with it until a drive the other day (was 93 degrees) showed a 3 or 4 cycle hunt sometimes went I hit the clutch. Since I'm busy with DCS right now, I just set the DIP switch to add one extra delay time and will see if that corrects that problem. I run the Volvo idle motor which is a slower than the OEM idle motor.

[jmpdmc]

Thanks, Dave. I know how you mean nothing is perfect but your standards are high so that is good enough for me. I have the OEM idle motor but I think you have the ECU figured out for both units. Keep us updated about all of your findings.


Jeff

[Bitsyncmaster]

Well running with the added delay of one seems to have fixed that hunt condition I had seen. I don't see anything got hurt adding that delay. I do think I will reduce the value I have in my software which adds a little higher RPM to the idle for the first few seconds after you take your foot off the throttle. That may have aggravated that hunt problem but I think it would be better to lower it anyway.

So far it looks like if your running the Volvo idle motor, you may find it better to use one delay (DIP switch selection).

[Bitsyncmaster]

I was getting an idle hunt on some real hot days after running the car for an hour or more. The hunt started showing up sooner on cooler days to the point after any drive I had the hunt.

I tried a new idle ECU = same
I tried a stock ISM = same
I tried a spare ignition ECU = same
Mixture change = same (I have wideband controlled mixture)

Thinking about the problem showing up when hot, that is when the ISM is running close to closed. So I backed out my curb idle and that cured (so far) the idle hunt. For you info, the ISM (both stock and Volvo) have less force moving the idle control valve near full closed and full open. It's just the way a PWM linear valve works.

I wonder if I am developing a vacuum leak somewhere that caused this problem to show up.

So if your idle hunting is occurring with a hot engine (stock or my ECU), try backing out that curb idle screw.

[Bitsyncmaster]

The idle ECU has two 6 pin connectors and one has 5 pins and the other 4 pins. They put plastic plugs (keys) into the blank locations so they can't be mixed up and plugged into the wrong side. I have 11 pin ECUs so you need to remove the two keys in the connector that has two of them installed. You don't need those two anyway because the other connector with one key will prevent mixing up the locations with either the 11 pin or stock 9 pin ECUs.

The keys have a little tab molded onto it so it locks into the connector housing just like the pins lock into the housing. However the plastic key does not bend so only way I found to remove them is to cut that little tab off with an X-acto knife. That can be done from the wire side of the connector. Just be careful you don't cut your finger or damage the connector shell. I use one of those locations to wire my AC bump circuit with my 11 pin idle ECUs.

Like I said, you can remove those two keys even before you order my 11 pin ECU. So many people insist on keeping the 9 pin ECU which I don't have units built up in inventory since most people keep or sell their 9 pin cores.

[bytes311]

Hi Dave,

Does the ECU lose all its learned values after the battery is cut off?

[Bitsyncmaster]

Hi Dave,

Does the ECU lose all its learned values after the battery is cut off?

No. It keeps any learned values with no power.

[bytes311]

No. It keeps any learned values with no power.

Cool, thanks!

[bytes311]

Does the mixture change a little if the idle is set higher than 750 RPM? I hooked up my dwell meter and noticed the needle swinging more towards the rich side of the spectrum but still within range for the FV to buzz.

I have the idle ECU set at 850 RPM. I removed the diode, backed out the idle screw, and adjusted the curb idle as instructed (using the LED on the board as reference), but nothing else has changed as far as I know.

[Bitsyncmaster]

Does the mixture change a little if the idle is set higher than 750 RPM? I hooked up my dwell meter and noticed the needle swinging more towards the rich side of the spectrum but still within range for the FV to buzz.

I have the idle ECU set at 850 RPM. I removed the diode, backed out the idle screw, and adjusted the curb idle as instructed (using the LED on the board as reference), but nothing else has changed as far as I know.

I've not seen it change mixture much with changing idle RPM setting. I guess it would depend on how good your FD is working. I have seen better more stable readings at higher idle RPM which I think is due to the non-heated O2 sensor running a little hotter. Maybe that is why the book says to adjust mixture at 900 or 950 idle RPM. You really want the mixture centered at cruising RPM anyway.