Rough idle when warm

[Rich_NYS]

My car idles smooth when cold, but after warming a bit and I "kick it down" (I forgot what that's actually called,) it idles rough. I don't know if it would be considered hunting. I have four videos I made today: Cold start, first few minutes of idling, idling at 5min. after I kicked it down, and idling at 6min.

I'll post the videos one after the other in this thread. Here's the first one:


https://www.youtube.com/watch?v=fA4n5K_KJ4o

[Rich_NYS]

Idling at ~ 3-4 minutes....haven't "kicked it down" yet:


https://www.youtube.com/watch?v=UVb63m_rDkA

[Rich_NYS]

This is after I kicked it down. I'm holding the RPM's up at :18 and :37


https://www.youtube.com/watch?v=VjJP8DYO7qI

[Rich_NYS]

Recorded at the engine and I held the idle up at :20, then a bit higher & more steadily at :30

At the very end of this one you can hear what I get most often; kinda hunts, but not sure if it actually is considered hunting.


https://www.youtube.com/watch?v=8RMwTcxWHu8

[Bitsyncmaster]

Mine was swinging RPM a little more than yours but the simple test is to pull your hose off the vacuum advance and see if that corrects it. If so you need to find out why you get advance at idle.

After that test, you can try to adjust your curb idle screw about a 1/4 turn at a time to find a sweet spot the idle motor runs best at.

[NightFlyer]

1) Check for vacuum leaks.

2) Check for appropriate vacuum operation at the WUR/CPR and the ignition advance. When cold, there should be vacuum at the WUR/CPR, but when warm, there shouldn't be vacuum there. There should never be vacuum at the distributor for the ignition advance when the car is idling. When under throttle, there should only be vacuum at the distributor when the engine is warm.

3) Check the o2 sensor dwell or frequency valve duty cycle to see if they're in spec. If not, then you'll need to adjust.

4) Check the timing.

That's what I'd be doing, in that order.

Best luck :thumbup:

[Rich_NYS]

Mine was swinging RPM a little more than yours but the simple test is to pull your hose off the vacuum advance and see if that corrects it. If so you need to find out why you get advance at idle.

After that test, you can try to adjust your curb idle screw about a 1/4 turn at a time to find a sweet spot the idle motor runs best at.

I think that's the adjustment Jonathan showed me when he was here. I asked him for a refresher, but if you can help steer me toward it I could use the help.



1) Check for vacuum leaks.

A few weeks ago I checked for leaks by spraying choke cleaner all over the place, any other methods to try?




2) Check for appropriate vacuum operation at the WUR/CPR and the ignition advance. When cold, there should be vacuum at the WUR/CPR, but when warm, there shouldn't be vacuum there. There should never be vacuum at the distributor for the ignition advance when the car is idling. When under throttle, there should only be vacuum at the distributor when the engine is warm.

3) Check the o2 sensor dwell or frequency valve duty cycle to see if they're in spec. If not, then you'll need to adjust.

That's what I'd be doing, in that order.

Best luck :thumbup:

I'll try those next. Josh, ya think this machine is gonna make it to Dayton & back? :cool1:

[NightFlyer]

You definitely have some mis-detonation going on. Could be ignition related or fuel related. If ignition related, then it's a timing issue - caused by a vacuum line misbehaving or the timing being off. If it's fuel related, then it's either running lean (intake detonation), or running rich (exhaust detonation). If you're not noticing a smell of fuel in the exhaust, then you're probably running lean. A vacuum leak will cause it to run lean (until the lambda compensates).

Do you notice the mis-detonation at all if you throttle it when cold?

[Rich_NYS]

Do you notice the mis-detonation at all if you throttle it when cold?

I haven't tried throttling it when cold, I'll do that asap and make another video. Can you point me toward the WUR/CPR and the ignition advance? :blackeye:

[NightFlyer]

I think that's the adjustment Jonathan showed me when he was here. I asked him for a refresher, but if you can help steer me toward it I could use the help.

Not to disagree, but I honestly don't think it's a curb idle adjustment related issue, as she appears to idle nicely when cold, but it never hurts to get everything adjusted as well as possible.

http://specialtauto.com/delorean-parts/images/idle-speed-adj.jpg


A few weeks ago I checked for leaks by spraying choke cleaner all over the place, any other methods to try?

If you didn't find anything that way, then you probably don't have any non-line related leaks (at least none bad enough to cause any issues anyway).


I'll try those next. Josh, ya think this machine is gonna make it to Dayton & back? :cool1:

If you get the mis-detonation figured out and sorted, then I don't see why she shouldn't make the trip just fine :thumbup:

[Bitsyncmaster]

The reason I suggested curb idle adjustment is because I've found "dead" spots in the OEM idle motors. When you back out the curb idle screw your idle motor runs more open at all temps. Turn it in and it runs more closed at all temps.

The idle motor has the most torque at mid range and very little at full open or full closed. So most times it helps to back out the curb idle screw and run the idle motor more open.

[NightFlyer]

I haven't tried throttling it when cold, I'll do that asap and make another video. Can you point me toward the WUR/CPR and the ignition advance? :blackeye:

Following the vacuum routing diagram is the best way to understand this:

http://www.specialtauto.com/delorean-parts/images/ported-vac-diagram.jpg

To check the WUR/CPR:

When cold idling, you want to pull the vacuum line going into the front of the CPR and check for vacuum - you should be getting some (may not seem like much, but should be present). This should also effect the idling. When idling warm, you should not be getting any vacuum at this line.

To check the ignition advance:

When idling (whether warm or cold - check both), you want to pull the vacuum line off the vacuum connection spark advance and check for vacuum. There should NEVER be vacuum on this line when idling. There should only be vacuum on this line when 1) the engine temp is greater than 104F, AND 2) the engine is being throttled.

If you find that these vacuum connections are not operating as they should, report back your findings and we'll discuss further trouble shooting and the possible causes / potential fixes.

Best luck :thumbup:

[DMCMW Dave]

The reason I suggested curb idle adjustment is because I've found "dead" spots in the OEM idle motors. When you back out the curb idle screw your idle motor runs more open at all temps. Turn it in and it runs more closed at all temps.

The idle motor has the most torque at mid range and very little at full open or full closed. So most times it helps to back out the curb idle screw and run the idle motor more open.

The more "open" you run it the less range it has to cope with being cold or loaded (A/C or automatic in drive for example) and may be less able to react to a sudden close of the throttle from high speed. If torque is an issue I'd offer that the motor isn't working particularly well (i.e. sticky). Being a rotary valve, it does not have to work very hard to block or release air.

[Rich_NYS]

Following the vacuum routing diagram is the best way to understand this:


To check the WUR/CPR:

When cold idling, you want to pull the vacuum line going into the front of the CPR and check for vacuum - you should be getting some (may not seem like much, but should be present). This should also effect the idling. When idling warm, you should not be getting any vacuum at this line.

To check the ignition advance:

When idling (whether warm or cold - check both), you want to pull the vacuum line off the vacuum connection spark advance and check for vacuum. There should NEVER be vacuum on this line when idling. There should only be vacuum on this line when 1) the engine temp is greater than 104F, AND 2) the engine is being throttled.

If you find that these vacuum connections are not operating as they should, report back your findings and we'll discuss further trouble shooting and the possible causes / potential fixes.

Best luck :thumbup:


The diagram really helps....thanks!

I'll check for proper vacuum tomorrow.

[hmcelraft]

I would check the vacuum advance on the distributor for proper smooth function and also the vacuum advance switch. It is a guess based on the sound. What seems a bit strange is the cold smoothness. The Warm up regulator may have something to do with the issue. When the engine is cold it allows more fuel to enter the engine especially at initial demand as the pressure on the plunger barrel is at its lowest. When hot it leans out but also the oxygen sensor comes on line to regulate the fuel mixture at the set rate. When hot the plunger barrel may be sticking. You might want to put some marvel Mystery oil in the fuel. It is a really good cleaner in the K-jetronic system (because of the circulation of fuel) in addition to a top cylinder lube.

The other thing you might check is the induction pick-up in the distributor. Is it loose or damaged? A weak or faulty pick-up could show up with heat.

You could check the grounds at the ECU and Lambda control boxes also.

You might want to check the exhaust sensor function too. It could be faulty also and causing a bad reading for the frequency valve. And then there is the frequency valve. They rarely go bad but I have seen the connections get dirty and cause a malfunction or slow/uneven reaction times.

[Bitsyncmaster]

The more "open" you run it the less range it has to cope with being cold or loaded (A/C or automatic in drive for example) and may be less able to react to a sudden close of the throttle from high speed. If torque is an issue I'd offer that the motor isn't working particularly well (i.e. sticky). Being a rotary valve, it does not have to work very hard to block or release air.

That is true. But under normal conditions it never even approaches half open. Now if your trying to go up a hill without giving it some gas, I guess you could get it to run wide open. Higher torque is better when the idle motor starts getting old or dirty. I should setup a demo of the idle motor running with my ECU in test mode for you sometime. That test just runs through 256 steps of PWM from full closed to full open in a slow changing time.

[Rich_NYS]

Do you notice the mis-detonation at all if you throttle it when cold?

I made this video before work this morning. The first minute of idling sounds a bit rough, then improves. At the end of the video you can hear it start to get rough. After this video, I checked the idle screw adjustments while the car was still running; I remember now they're the ones that Jonathan pointed out to me, the screw is resting pretty heavily on the microswitch. Sometime this evening/tomorrow I'll check all the other things mentioned.


https://www.youtube.com/watch?v=7PzndOcvy-c&feature=youtu.be

[Rich_NYS]

Here's a short video made right after the previous one; I was attempting to show the position of the idle screw adjustment but the light wasn't good enough. At the same time, I noticed another microswitch by the throttle spool....is that flap in its normal position? I don't know what it is, but it looked out of place to me. In this video you can hear pretty clearly the rough idle when the engine is warm.


https://www.youtube.com/watch?v=q0GAFG7qyys

[DMCMW Dave]

That is true. But under normal conditions it never even approaches half open. Now if your trying to go up a hill without giving it some gas, I guess you could get it to run wide open. Higher torque is better when the idle motor starts getting old or dirty. I should setup a demo of the idle motor running with my ECU in test mode for you sometime. That test just runs through 256 steps of PWM from full closed to full open in a slow changing time.

I've never measured the actual opening in operation, but that sounds right. Good information. Wide open on the valve is 2000 RPM or so with no load and the throttles closed/engine hot. I typically try to set it so that the throttle blades are as wide open as possible at hot, no load idle still holding 775, and then a half to full turn more on adjustment stop screw. This gets the motor slightly open (as they tend to stick closed) but still a lot of range for operation when cold, with the A/C on and automatic in drive for example. That's about the worst-case idle situation.

My thinking is that you want the engine to be able to run under ideal circumstances with the valve nearly closed, so if it is sticky the engine won't stall when going from high to low load suddenly (for example acceleration to idle/clutch disengaged).

[Rich_NYS]

Do you guys see that microswitch flap I mentioned?

[DMCMW Dave]

Do you guys see that microswitch flap I mentioned?

That is for full throttle. It looks OK. Test it to make sure it isn't frozen, at least not frozen "closed".

[NightFlyer]

To test it (the full throttle micro-switch), manually actuate it with your hand - if you hear it clicking, then chances are it's OK. If you want to go full out in testing, you can put a meter on it - closed should be close to 0 with continuity present, and open should be close to infinity resistance.

To be honest with you, I'm not really all that concerned about the rough idle, nor should you be. To be honest, she idles well enough to not really be an issue. It's just a matter of fine tuning and confirming that the lambda system is healthy, which you can play around with trying to get perfect later.

What I'm concerned with, and what you should be concerned with, is the mis-detonation. To be honest, I couldn't hear it when you were cold throttling it (but that doesn't mean that it isn't there, as videos, while infinitely better than a mere written description, can only do so much), except maybe upon deceleration from throttle (which suggests sticky deceleration springs on the throttle butterfly/flaps/plates, but I'm not really concerned about that either, as many cars probably have such a condition and it's really not an issue worth dealing with IMHO).

What I'd be doing at this point, again, is confirming proper vacuum operation at the WUR/CPR and distributor. You don't need a vacuum gauge to do this, provided that you have good feeling in your fingers.

If vacuum is operating properly, then check the timing (although I'm leaning away from this being a timing issue), as this will at least give you a reassurance as to proper ignition operation.

If all that looks good, your next course of action is going to be performing a fuel injector volume and spray pattern test. I'm starting to think that the fuel distributor may be misbehaving on a few ports, or there's an injector or two that are sticky. While doing this, it would also be a good opportunity to baseline the CO setting. Lastly, you'd test / trouble shoot the lambda system and get the CO adjusted via dwell or duty cycle. But we'll go into the details of all this only if it becomes necessary after you do your vacuum and timing tests and report your findings on those.

After figuring out the mis-detonation, then you can play around with fine tuning your idle to your heart's content :smile:

Best luck :thumbup:

[Rich_NYS]

Thanks Josh, I'm going to test the vacuum tonite or tomorrow AM and I'll give a status update.

[Bitsyncmaster]

My thinking is that you want the engine to be able to run under ideal circumstances with the valve nearly closed, so if it is sticky the engine won't stall when going from high to low load suddenly (for example acceleration to idle/clutch disengaged).

After road testing today, I think your correct. Although I don't do the following, one person that uses my idle ECU does.

Leaving the car in gear going down hill and letting the engine RPM get very low (less than 1000 RPM). What this does to the idle motor is keep closing it since your RPM is above the set idle. So your idle motor ends up fully closed and when you step on the clutch, engine RPM drops to the fully closed idle motor and depends on the curb idle screw to keep if from stalling.

So to set your curb idle screw, with a fully warmed up engine no loads turn the curb idle screw clockwise until your not holding the closed loop idle then back it off a 1/4 turn.

[Rich_NYS]

To test it (the full throttle micro-switch), manually actuate it with your hand - if you hear it clicking, then chances are it's OK. I hear it clicking, but that adjustment screw seems to be pushing down on the microswitch pretty heavily at all times. I'm planning to adjust it today and see what happens.



What I'd be doing at this point, again, is confirming proper vacuum operation at the WUR/CPR and distributor. You don't need a vacuum gauge to do this, provided that you have good feeling in your fingers.


To check the WUR/CPR:

When cold idling, you want to pull the vacuum line going into the front of the CPR and check for vacuum - you should be getting some (may not seem like much, but should be present). This should also effect the idling. When idling warm, you should not be getting any vacuum at this line.

I had good vacuum during cold idle, then no vacuum when idling warm. Removing the vacuum hose had no effect on cold or warm idling.


To check the ignition advance:

When idling (whether warm or cold - check both), you want to pull the vacuum line off the vacuum connection spark advance and check for vacuum. There should NEVER be vacuum on this line when idling. There should only be vacuum on this line when 1) the engine temp is greater than 104F, AND 2) the engine is being throttled.

If you find that these vacuum connections are not operating as they should, report back your findings and we'll discuss further trouble shooting and the possible causes / potential fixes.

Best luck :thumbup:

I had no vacuum at the vacuum connection spark advance at any time; cold, warm, idling or revving.

[Rich_NYS]

I would check the vacuum advance on the distributor for proper smooth function and also the vacuum advance switch. It is a guess based on the sound.

I'll check that today (after I find it..lol!)



What seems a bit strange is the cold smoothness. The Warm up regulator may have something to do with the issue. When the engine is cold it allows more fuel to enter the engine especially at initial demand as the pressure on the plunger barrel is at its lowest. When hot it leans out but also the oxygen sensor comes on line to regulate the fuel mixture at the set rate. When hot the plunger barrel may be sticking. You might want to put some marvel Mystery oil in the fuel. It is a really good cleaner in the K-jetronic system (because of the circulation of fuel) in addition to a top cylinder lube.

How much MM oil is a safe amount to try?


The other thing you might check is the induction pick-up in the distributor. Is it loose or damaged? A weak or faulty pick-up could show up with heat. I'm not sure I know exactly what that is, but I'll figure it out and check it along with a run-through of the basics that I need to check for pre-trip anyway (plugs, wires....etc.)




You could check the grounds at the ECU and Lambda control boxes also.

You might want to check the exhaust sensor function too. It could be faulty also and causing a bad reading for the frequency valve. And then there is the frequency valve. They rarely go bad but I have seen the connections get dirty and cause a malfunction or slow/uneven reaction times.

I'll keep that on the radar. For now I'll verify proper vacuum at the places you & Josh mentioned, then go from there.

Thanks!

[NightFlyer]

I hear it clicking, but that adjustment screw seems to be pushing down on the microswitch pretty heavily at all times. I'm planning to adjust it today and see what happens.

You're talking about the idle micro-switch (the one that works in conjunction with the rocker screws), and not the full throttle micro-switch, right?

Did you confirm that the full throttle micro-switch (the one that is actuated by throttle spool position) was operating properly and wasn't stuck on (closed)?

As far as adjusting curb idle goes, you do want a little overlap of coming off the switch and throttling - but not much (it's very miniscule).

My advice here would be to adjust the rest point first (the bottom screw), and set it so that the throttle butterfly/plates/flaps are just resting off the internal stop in the body (in other words, you want to set it so that the butterfly/plates/flaps fully close and seat against the body, but don't slam into the body when coming off throttle, as instead their momentum is stopped via the adjustment screw and bracket). Then, adjust the micro-switch setting (top screw) so that there's about 4 degrees of throttle spool rotating before the the switch is deactivated. That should get you pretty close to where you want to be with the idle.


I had good vacuum during cold idle, then no vacuum when idling warm. Removing the vacuum hose had no effect on cold or warm idling.

So that vacuum connection is operating normally :thumbup:

This also tells us that it's highly probable that your multiport thermal switch (under the intake and not visible) is good :thumbup:

The reason you don't notice any real difference in engine running when removing the hose is because of the ambient temp. If you try this when ambient is cold (below 48), there will be a noticeable difference (although even then, it's not much, unless you have issues present somewhere else in the fuel system).


I had no vacuum at the vacuum connection spark advance at any time; cold, warm, idling or revving.

OK - that's not good, as you should have vacuum there 1) when the engine temp is above 104F, AND 2) you're applying throttle to the engine.

You mentioned earlier that it appears that the idle-microswitch is constantly engaged with the current settings. So long as the micro-switch is engaged (closed), it will prevent the solenoid from releasing the vacuum onward to the distributor so that it will advance during throttle. If your current setup is preventing the dis-engagement of the idle microswitch, then the adjustments on those screws are severely out of whack. Thus, perhaps it is time to play with the adjustment screws after all (see above for my advise of how to set them).

Hopefully, this is your problem (i'm thinking it is) :cool:. If not, then we'll continue to trouble shoot till we find and rectify the problem :thumbup:

Best luck and keep us apprised :biggrin:

[Rich_NYS]

I hear it clicking, but that adjustment screw seems to be pushing down on the microswitch pretty heavily at all times. I'm planning to adjust it today and see what happens.

I adjusted it using the diagram as well as instructions I found in one of Jeremiah's posts....I didn't notice it having any effect.





I had no vacuum at the vacuum connection spark advance at any time; cold, warm, idling or revving.

Correction: I DO have vacuum at the vacuum connection spark advance; when the car was really warm I barely had any vacuum, but when revving (and warm) I had vacuum.

[NightFlyer]

I adjusted it using the diagram as well as instructions I found in one of Jeremiah's posts....I didn't notice it having any effect.

Correction: I DO have vacuum at the vacuum connection spark advance; when the car was really warm I barely had any vacuum, but when revving (and warm) I had vacuum.

OK - so the micro-switch was previously and continues to be working properly, which is why adjusting it made no difference.

The only time you want vacuum at the distributor is when the engine is above 104F and when the car is under open throttle. At warm idle, there shouldn't be any vacuum there (it should be trapped in the solenoid waiting to be released when the throttle is opened). Sounds like you may have a slight leak in the solenoid, but the solenoid is otherwise working, thus it's not anything that I'd be concerned about.

So where does that leave you? You can check the timing if you want, but I'm thinking it's close enough.

I believe that your misdetonation is being caused by a bad injector(s) or a bad fuel distributor.

Thus, IMHO, it's time to do an injector flow rate and pattern test. So, that means that you need to remove all the injectors, place them in numbered jars or glasses (something that you can see through) where the number corresponds to the injector, jump the fuel pump on at the RPM relay, and manually work the air metering plate. You'll perform multiple of these tests, gradually increasing the amount your depressing and holding the air metering plate until you reach full throttle. So first test, you're holding it barely open, second test your holding it 1/4 depressed, third test your holding it 1/2 open, and last test, you're holding it fully open all the way down (full throttle). During each test, you hold the metering plate until you fill the jars enough to compare the levels. At the conclusion of each test, you take the jars with fuel in them, line them up on a known flat and level surface, and compare the level of fuel. They should all be equal (or pretty close). If there's any outliers, make a note of them (I like to take photos of the lineup of jars). If there are outliers, they should hopefully be consistent amongst the tests. While running the tests, you also want to observe the spray pattern of the injectors for consistency and a fan like spray (like holding your thumb over a garden hose). The first test may result in some dribbles, don't worry about that, so long as the injectors are opening together. If you have noted consistent outliers while performing the tests, you're next going to want to switch what port from the fuel distributor is feeding those injectors, with ports that are feeding a normal injector. Then run the test again in full throttle. If the outliers changed, then you know you need to rebuild or order a new fuel distributor. If the outliers remained consistent, then you know you need to order a new injector(s).

Before putting all the injectors back in their bungs, you're then going to baseline your CO setting. The CO setting screw is located in a hole in the mixture unit housing, just in front of the fuel distributor. It may be covered by the factory cover and anti-tamper plug (an aluminum slug). If so, you need to drill out the the cover (not very deep), so that you can thread a screw into the plug and pull it out with a pair of pliers. To adjust the screw, you'll need a 3mm allen wrench. You want to adjust it so that the injectors are just shy of cracking open with the air metering plate in its rest position. You do this by turning the screw to a point where the injectors crack open and start dribbling, and then slowly (incremental baby steps) backing it until the injectors stop dribbling. Once you're there, you can then re-assemble everything. Be sure to plug the adjustment screw hole with something, as it otherwsie represents a vacuum leak.

You can fine tune the adjustment with a dwell or duty cycle meter (we can even do it at DCS if you desire) provided that the lambda system is functional. Or you can set it while the car is at a warm idle, adjusting it to where you like the warm idle. Adjust in baby increments, removing the wrench and plugging the hole after each adjustment, until you get it set.

If the flow rate and pattern tests don't reveal a problem, then we're left with diagnosing the lambda system for your problem, which is probably going to be limited to either the ECU or the the 02 sensor. Best way to trouble shoot the system is to disconnect the 02 sensor and run the system open loop, but there's other tests we can try as well.

If you haven't changed the 02 sensor, they're cheap:

http://www.ebay.com/itm/NEW-BOSCH-OXYGEN-SENSOR-11032-FOR-BMW-VOLVO-ALFA-ROMEO-BENTLEY-1979-1987-/360897044374?pt=Motors_Car_Truck_Parts_Accessories&hash=item540723df96&vxp=mtr

Best luck :)

[Rich_NYS]

Yeow...it feels like the snowball is starting to roll downhill! Believe it or not, I've been "feeling" like a cylinder was starving just a tiny bit...that's why I asked about additives. Today I pulled all the plugs & took pics and saw one oddity but I think it's unrelated (some oil on the threads...electrode looked fine.)

Unless it'll leave me stranded on the way to DCS, I think I'll need to push this down the priority list until I get my "must-do" stuff completed. I'll save the procedure you posted and put it in my to-do file.

The O2 sensor was replaced when I had the exhaust manifold gaskets done.

Thanks!

[NightFlyer]

Yeow...it feels like the snowball is starting to roll downhill! Believe it or not, I've been "feeling" like a cylinder was starving just a tiny bit...that's why I asked about additives. Today I pulled all the plugs & took pics and saw one oddity but I think it's unrelated (some oil on the threads...electrode looked fine.)

Unless it'll leave me stranded on the way to DCS, I think I'll need to push this down the priority list until I get my "must-do" stuff completed. I'll save the procedure you posted and put it in my to-do file.

The O2 sensor was replaced when I had the exhaust manifold gaskets done.

Thanks!

It's actually not that bad - should take just a few hours.

Given that you're not fowling out any of the plugs, it's not something that will leave you stranded on the side of the road. As you aren't noticing any tell tale signs of running rich, I'm guess that you're running lean in one or two cylinders. While you can drive it like that just fine, the sooner you get the issue resolved, the better, as by running lean, you're pre-detonating fuel in the intake, which will cause carbon build up in it. If you haven't run a can of sea foam (or an equivalent product) with a half tank of fuel through the system yet, probably be a good idea to do so and won't hurt anything.

[Rich_NYS]

It's actually not that bad - should take just a few hours.

Given that you're not fowling out any of the plugs, it's not something that will leave you stranded on the side of the road. As you aren't noticing any tell tale signs of running rich, I'm guess that you're running lean in one or two cylinders. While you can drive it like that just fine, the sooner you get the issue resolved, the better, as by running lean, you're pre-detonating fuel in the intake, which will cause carbon build up in it. If you haven't run a can of sea foam (or an equivalent product) with a half tank of fuel through the system yet, probably be a good idea to do so and won't hurt anything.


I'm thinking back to when I mentioned in Dave's old gas thread that mine kinda sounded like it was dropping a cylinder a bit. If it's an injector misbehaving, that would make sense I think. I'll try the Sea Foam this week.

Here are pics of my plugs when I pulled them yesterday, they aren't 100% but I don't see anything alarming....what do you guys think?

27645 27646 27647 27648 27649

[NightFlyer]

I'm thinking back to when I mentioned in Dave's old gas thread that mine kinda sounded like it was dropping a cylinder a bit. If it's an injector misbehaving, that would make sense I think. I'll try the Sea Foam this week.

Here are pics of my plugs when I pulled them yesterday, they aren't 100% but I don't see anything alarming....what do you guys think?

Plugs look good/normal.

Pretty sure your mis-detonation is resultant of a lean condition caused by a bad injector(s) or a bad fuel distributor. Sea Foam would definitely be good to try - won't hurt anything (so long as you don't do it too often), but in the same respect, don't expect it to magically cure your troubles (but you could get lucky).

[Jonathan]

Hope it's ok to piggyback on this thread... it came up searching "high idle."

---> Can someone tell me if the electrical connector on the solenoid valve (as part of and shown on the vacuum routing label) needs to be on one way versus the other? Meaning, does polarity matter?

I was going over a few things in the engine bay looking to sort out an idling issue and after looking closer at the connector, noticed one of the two wires within the connector had backed itself out of the plastic (like it does at times with connectors in the fuse/relay area). It's fine now to go back together, but there's no obvious sign that it needs to go with a particular wire of the pair on a particular male connector end. You can install it just as easily one was as 180 degrees the other way. Thanks.

[Bitsyncmaster]

Hope it's ok to piggyback on this thread... it came up searching "high idle."

---> Can someone tell me if the electrical connector on the solenoid valve (as part of and shown on the vacuum routing label) needs to be on one way versus the other? Meaning, does polarity matter?

I was going over a few things in the engine bay looking to sort out an idling issue and after looking closer at the connector, noticed one of the two wires within the connector had backed itself out of the plastic (like it does at times with connectors in the fuse/relay area). It's fine now to go back together, but there's no obvious sign that it needs to go with a particular wire of the pair on a particular male connector end. You can install it just as easily one was as 180 degrees the other way. Thanks.

The ignition advance solenoid wires can be reversed with no ill effect.

[David T]

The ignition advance solenoid wires can be reversed with no ill effect.

While the above is true the same cannot be said for the vacuum hoses. They cannot be switched.

[Jonathan]

The ignition advance solenoid wires can be reversed with no ill effect.

That's great, Dave, thanks. I had assumed it was okay to reverse them, but getting reassurance while chasing an issue is nice. Cheers.

Nice picture of you and Christopher Lloyd from the show, btw. I saw you walk past a couple times in the hallway but didn't put two and two together as to who it was until it was too late to say hello. Glad you got home safe after your adventure too :)

[Bitsyncmaster]

That's great, Dave, thanks. I had assumed it was okay to reverse them, but getting reassurance while chasing an issue is nice. Cheers.

Nice picture of you and Christopher Lloyd from the show, btw. I saw you walk past a couple times in the hallway but didn't put two and two together as to who it was until it was too late to say hello. Glad you got home safe after your adventure too :)

Thanks. I just soldered two wires onto that solenoid and used black wires for both since there is no polarity. I then added a new "in line" connector that won't fall off like the OEM one does.