Converting 767 to EFI with stock manifold

[jangell]

I'm finally moving forward with an EFI conversion on 767. To start, I'm only going to do fuel, but I want to do spark in the future. I'm cataloging this with as much detail as I can on my website (in no small part so I can keep track of what I'm doing). This is probably going to be a slow process, as I only get a few hours each weekend to work on my car. I don't expect to finish before Christmas, but maybe things will go more quickly than I expect.

My plan is to use MegaSquirt with the stock intake manifold based on other conversions that Owen (spittybug) has helped with. I've already procured the rails, brackets and idle air motor and box from Owen (thanks!). I also have all of the fittings from JEGS (again thanks to a list from Owen).

Now I'm up to the point where I have to order the rest of the parts so that I can start installing everything. Which leads me to a few questions:

- I'm planning on getting the MS-II 3.0 board (pre-built). I noticed discussions about problems with the 3.57 board with the DeLorean, which I think was related to spark control over 3000 RPM. Since I do want to eventually do spark, I'm leaning towards the 3.0 board. While I remember reading that there was a fix for the 3.57 board, it's not clear to me if this fix is in current production hardware, so I figured I'd play it safe with the 3.0.

- I haven't quite decided where to mount the MS unit yet. I was thinking near the stock ignition controller behind the passenger seat, assuming it will fit there. I'm guessing the 8' wiring harness is enough, but I'm considering the 12' one just in case (since it's easy to shorten wires but not so easy to lengthen them).

- I found posts suggesting that I remove the thermotime switch and re-tap the adaptor that goes into the water pump to 3/8" NTP so that I can use a GM temperature sensor for CLT. That seems straight-forward enough.

- Another identical GM temperature sensor would be used for the IAT. I get the impression that others have installed this by drilling a hole in the air cleaner box and screwing it into there; is that correct? I'll be using the stock mixture unit with the fuel distributor removed, and thus will use the stock air cleaner box as well.

- I have DPI's SPEC I exhaust; this supports two O2 sensors, but for the time being I'm going to get just one wideband LC-1 to try to keep the costs down a bit.

- Any suggestions for a fuel pressure regulator? I noticed that DIYAutotune sells a few, and I imagine any of those will work fine.

- Any good sources for fuel injectors? It seems that 19 lbs/hr 48mm tall ones are what I should be looking for. I believe Owen said I should get the tallest ones I can find. I'll also need to get the associated electrical connectors, I imagine.

- I'm considering a TPS, possibly mounted by the gas pedal as (I think) bitsyncmaster had suggested in the past rather than figuring out how to mount it on the throttle spool. Still, it seems that people have been having good luck with just MAP, so maybe I'll just skip it.

- I'm planning on getting tach from the coil negative, but I've seen posts about using the VR output of the dizzy in the same way that the stock ignition computer does. Since I'm not doing spark yet, should I just stick with getting tach from the coil?

- I'm going to leave fuel pump control in the hands of the RPM relay, since I've upgrade to bitsyncmaster's unit already, and from what I've read there's little need to switch to MS control if I have that.

Thanks!

-- Joe

[Bitsyncmaster]

My 2005 Malibu has a throttle position sensor mounted at the gas pedal. It seems that is the only thing the gas pedal does so there is no cable to move a butterfly valve. Maybe a junkyard would have a TPS you could use.

[Spittybug]

Quite a post.. let me try and answer inline.

I'm finally moving forward with an EFI conversion on 767. To start, I'm only going to do fuel, but I want to do spark in the future. I'm cataloging this with as much detail as I can on my website (in no small part so I can keep track of what I'm doing). This is probably going to be a slow process, as I only get a few hours each weekend to work on my car. I don't expect to finish before Christmas, but maybe things will go more quickly than I expect.

My plan is to use MegaSquirt with the stock intake manifold based on other conversions that Owen (spittybug) has helped with. I've already procured the rails, brackets and idle air motor and box from Owen (thanks!). I also have all of the fittings from JEGS (again thanks to a list from Owen).

Now I'm up to the point where I have to order the rest of the parts so that I can start installing everything. Which leads me to a few questions:

- I'm planning on getting the MS-II 3.0 board (pre-built). I noticed discussions about problems with the 3.57 board with the DeLorean, which I think was related to spark control over 3000 RPM. Since I do want to eventually do spark, I'm leaning towards the 3.0 board. While I remember reading that there was a fix for the 3.57 board, it's not clear to me if this fix is in current production hardware, so I figured I'd play it safe with the 3.0. It is my understanding that the fix was as simple as adding a resister in-line. If so, I'd go for the 3.57 because it is surface mount technology rather than individual components. Ask Matt at DIYauto.

- I haven't quite decided where to mount the MS unit yet. I was thinking near the stock ignition controller behind the passenger seat, assuming it will fit there. I'm guessing the 8' wiring harness is enough, but I'm considering the 12' one just in case (since it's easy to shorten wires but not so easy to lengthen them). Mine is mounted behind the driver's seat. I will dig up pictures. Others have put it in this same place and it works well.

- I found posts suggesting that I remove the thermotime switch and re-tap the adaptor that goes into the water pump to 3/8" NTP so that I can use a GM temperature sensor for CLT. That seems straight-forward enough I don't remember the names of everything down in the valley, but IIRC my coolant sensor screwed right into the passenger side arm of the Y pipe under there. I did nothing to my water pump.

- Another identical GM temperature sensor would be used for the IAT. I get the impression that others have installed this by drilling a hole in the air cleaner box and screwing it into there; is that correct? I'll be using the stock mixture unit with the fuel distributor removed, and thus will use the stock air cleaner box as well. Yes, you will want this going into plastic not metal so that you don't get heatsoak and false readings.

- I have DPI's SPEC I exhaust; this supports two O2 sensors, but for the time being I'm going to get just one wideband LC-1 to try to keep the costs down a bit. Shouldn't be a problem. If one side is reading materially different than the other, you've got bigger problems since all fueling is done from only one table!

- Any suggestions for a fuel pressure regulator? I noticed that DIYAutotune sells a few, and I imagine any of those will work fine. The DIY one is fine if I recall. ~$150

- Any good sources for fuel injectors? It seems that 19 lbs/hr 48mm tall ones are what I should be looking for. I believe Owen said I should get the tallest ones I can find. I'll also need to get the associated electrical connectors, I imagine. I think I used these guys: http://www.southbayfuelinjectors.com/‎

- I'm considering a TPS, possibly mounted by the gas pedal as (I think) bitsyncmaster had suggested in the past rather than figuring out how to mount it on the throttle spool. Still, it seems that people have been having good luck with just MAP, so maybe I'll just skip it. It is only used for acceleration enhancement and I think the other guys have found that the MAP works just as well.

- I'm planning on getting tach from the coil negative, but I've seen posts about using the VR output of the dizzy in the same way that the stock ignition computer does. Since I'm not doing spark yet, should I just stick with getting tach from the coil. While you are fuel only you have no choice since your ECU will want the VR wire. You can tap it by the coil or by the ECU, it doesn't matter. As a rule however, don't use wire taps and other "cheapo" means of installing MS. Solder on connectors and shrink tubing over them. You'll appreciate having everything plug connected rather than hard wired.

- I'm going to leave fuel pump control in the hands of the RPM relay, since I've upgrade to bitsyncmaster's unit already, and from what I've read there's little need to switch to MS control if I have that. Nothing at all against Dave's relay, but in my opinion life is easier if you make the whole MS setup "self contained" and free from legacy systems of the car. I find it much easier to diagnose and fix if necessary. For MS, I tap two types of power from the passenger side, 12v on key and 12v continuous(x2). My new fuel pump relay is energized by the "on key" and allows the continuous 12v to then flow to fuel pump and the coil of another relay (for clean, no voltage spike 12v directly from a battery connection) for MS, O2 & injectors. Fused of course. Fuel pumps can be "noisy" and by pulling my 12v from the battery I minimize the noise on the circuit going to electronics. The wiring is easy.

Thanks!

-- Joe

[AdmiralSenn]

It sounds like you've pretty much got a good handle on things.

One of the main issues you will likely combat is electrical noise. I ended up switching to the VR configuration because I had TERRIBLE coil noise problems. Some people have had great success off the coil negative, others have had terrible results. It seems to be a 'depends on your car' thing.

The posts about tapping the thermotime switch adapter were probably from me. That's one way to do it, but as Owen has pointed out it's not necessary.

TPS will most likely give you headaches and it is definitely not required. I burned through four units before I gave up trying to figure out why they kept dying.

The GM intake air temp sensor has the same threads but I don't think it's the exact same sensor. Mine has a 'birdcage' around a sensor element vs. the coolant temperature being solid metal on the outside.

I can also confirm you will want taller injectors. I went for higher flow since I have long-term plans that will warrant it, but the injectors I ended up with are short and stubby - on my car I have to remove the rails to get to the spark plugs. Taller is better.

[jangell]

3.0 vs. 3.57:

It is my understanding that the fix was as simple as adding a resister in-line. If so, I'd go for the 3.57 because it is surface mount technology rather than individual components. Ask Matt at DIYauto.

Great -- I'll shoot him an email.

MS Mounting Location:

Mine is mounted behind the driver's seat. I will dig up pictures. Others have put it in this same place and it works well.

Right -- I meant behind the driver's seat where the ignition controller is, not the passenger seat. Got myself turned around there. Thanks.

CLT:

I don't remember the names of everything down in the valley, but IIRC my coolant sensor screwed right into the passenger side arm of the Y pipe under there. I did nothing to my water pump.

I was wondering about that. I thought I remembered people using the Y pipe, but when i searched I found references to replacing the thermo-time switch.

The parts manual (1-3-0) shows two switches (25 and 26) on the Y pipe: LAMBDA sensor and "Therm Vac" (which I think is for adjusting vacuum to the distributor based on engine temp... I'll have to check the routing diagrams again). I gather I won't be needing the LAMBDA sensor once I go EFI for fuel, right? I'm guessing this is the one you replaced. If it screwed right in, I'm assuming it's already a 3/8" NTP thread. I have to take off my intake manifold to fix some broken bolts anyway, so it should be simple enough to replace the sensor while I'm in there.

IAT:

you will want this going into plastic not metal so that you don't get heatsoak and false readings.

Good point -- thanks.

1 vs 2 Wideband O2:

Shouldn't be a problem. If one side is reading materially different than the other, you've got bigger problems since all fueling is done from only one table!

I think I remember seeing that having two sensors was helpful if you were doing really high performance stuff, or something like that. I think I'll be fine with one.

Pressure Regulator:

The DIY one is fine if I recall. ~$150

Great, that was easy.

Injectors:

I think I used these guys: http://www.southbayfuelinjectors.com‎

I took a look at their web site, and they seem to sort the injectors by brand, which I guess makes sense for most of their buyers.

The hard part seems to be searching for injectors with the right specs -- 19 lbs/hour, 48mm or however tall I can find, and whatever the diameter of the injector bungs are. A quick look at a few injectors on their site don't show any of that information. This lack of information seems to be a pretty common on sites that sell injectors, which makes it rather hard to find what I'm looking for.

TPS:

It is only used for acceleration enhancement and I think the other guys have found that the MAP works just as well.

Ok. If I change my mind later I'll try bitsyncmaster's junkyard Malibu sensor.

Tach:

While you are fuel only you have no choice since your ECU will want the VR wire. You can tap it by the coil or by the ECU, it doesn't matter. As a rule however, don't use wire taps and other "cheapo" means of installing MS. Solder on connectors and shrink tubing over them. You'll appreciate having everything plug connected rather than hard wired.

Ah, ok; I had a feeling that using the VR wire while the ECU was still using it could cause problems. Coil it is!

Years ago I did use the clip-on wire taps to add accessories to the car, before I knew all that much about how things were wired. I replaced my fuse box a few weeks ago, and this weekend I'm going to clean up some of those old taps and replace them with proper connectors and solder. I'll definitely be using connectors on the MS harness as well instead of hardwiring.

Fuel Pump Control:

Nothing at all against Dave's relay, but in my opinion life is easier if you make the whole MS setup "self contained" and free from legacy systems of the car. I find it much easier to diagnose and fix if necessary.

OK; my logic was that keeping the RPM relay would make it simper to do the installation, but I admit it means having two systems operating instead of one.

I honestly can't remember what else the RPM relay does; is it just to run the fuel pump? Do you need it once you've switched pump control to MS?

For MS, I tap two types of power from the passenger side, 12v on key and 12v continuous(x2). My new fuel pump relay is energized by the "on key" and allows the continuous 12v to then flow to fuel pump and the coil of another relay (for clean, no voltage spike 12v directly from a battery connection) for MS, O2 & injectors. Fused of course. Fuel pumps can be "noisy" and by pulling my 12v from the battery I minimize the noise on the circuit going to electronics. The wiring is easy.

Cool. Ok, I'll look into setting up something similar as well. I actually already have a dedicated accessory-switched direct-from-the-battery line for some fused accessories I added (heated seats and a power inverted, mostly), so adding a second dedicated wire run that is always live when the key is in start/run shouldn't be a problem.

Thanks!

-- Joe

[jangell]

One of the main issues you will likely combat is electrical noise. I ended up switching to the VR configuration because I had TERRIBLE coil noise problems. Some people have had great success off the coil negative, others have had terrible results. It seems to be a 'depends on your car' thing.

I gather you're doing MS-controlled spark if you're using the VR, right? How obvious was it that the problem you were having was noise? Did you need to do a lot of trial and error, or were you seeing an obviously bad signal in MS?

I noticed the MS docs suggest using an isolator from Radio Shack if noise problems become enough of an issue. I'm not totally sure what an "isolator" is defined as (just a big capacitor?) or where exactly you'd put it (if it's a big capacitor, then presumably not on the tach line, since I assume it would smooth out or mask the tach pulses themselves).

TPS will most likely give you headaches and it is definitely not required. I burned through four units before I gave up trying to figure out why they kept dying.

Ok; I'll stick with MAP for now and keep it simple.

The GM intake air temp sensor has the same threads but I don't think it's the exact same sensor. Mine has a 'birdcage' around a sensor element vs. the coolant temperature being solid metal on the outside

I was looking at this specific one for both because the DIYAutotune description suggested it would work for both CLT and IAT. I have no idea how the closed vs birdcage sensor designs might behave differently, or if they're functionally identical for these purposes.

I can also confirm you will want taller injectors. I went for higher flow since I have long-term plans that will warrant it, but the injectors I ended up with are short and stubby - on my car I have to remove the rails to get to the spark plugs. Taller is better.

Now I just have to find some.

Thanks!

-- Joe

[jangell]

I emailed DIYAutotune about 3.57 in our cars, and Matt Cramer got back to me with this:

I simply wired a 10K resistor inline with the distributor pick-up. Happens on certain VR sensors, but DeLoreans are the only one I've seen have that with a distributor; it's usually been high tooth count crank wheels.

That sounds pretty simple. Looks like I'm going to go with 3.57 after all.

-- Joe

[jangell]

And since I can go with 3.57, I'm thinking of getting MS III instead of II. It's more expensive, but it seems like the convenience of the built-in USB/serial adaptor and the SD card for data logging would be nice, as well as the ability to use the extra inputs and outputs for custom stuff later on. It's just a question if the extra $200 is worth it...

-- Joe

[Spittybug]

Go for it. You can become the ms3 expert of the forum.

[jangell]

I did a lot of searching around for fuel injectors today, and came up with nothing. Well, I could find 19 lb/hr (or 200cc/min; same difference) injectors, but I couldn't find anything about how tall they are. I did find one place that sold 76mm tall injectors, but they were 32.5 lb/hr, which isn't going to work here. I'm considering just going to the nearby NAPA and asking for their tallest 19 lb/hour injectors and seeing where that gets me.

Also: any preference between high or low impedance injectors?

Thanks again

-- Joe