Idle surging/stalling
 

Ok, I'm about to take my car into a shop and have them really tear into it. I have to power brake it at every stop, sometimes when just driving slow to make a turn. Rebuilt engine, at 150 miles now, a lot of replaced parts: Alternator, spark plugs, water pump, pcv and breather, MAF sensor, air filter, fuel filter, vacuum lines, TPS, and ECM. After all that here is what I am still getting: Car starts fine, but the idle surges (someone described to me that it sounds like it even pulsates), it will stall out when sitting at idle, spark plugs have been replaced twice now, the first set replaced got fouled out. Shop told me fuel pressure is at about 56, repair manual said its supposed to be 34-47, is there an issue with that? I'm almost certain the spark plugs got fouled out all over again, after the second set got put in, the car ran pretty good with only occassionally acting up as described. Car does not reach operating temperature. Not even close. About 115-130 degrees, no matter how it's being driven. The thermostat when being put in gave us issues with throwing antifreeze back at us, so the guy cut it open. I think its because we had a 180 thermostat when the stock is a 195, but not sure. Any ideas what could be causing the problem? Also, there is noise coming from the rockers, I'm told its normal that they need to be adjusted since theyre breaking in. Would the rockers being out of adjustment be the problem here?
As far as the driving, it shakes when driving, sometimes not much sometimes hard, and its hardly noticeable when accelerating. Feels as though it may be missing, probably due to plugs getting fouled out again.

Re: Idle surging/stalling
 

Thats too bad...

Sounds like your car is running so rich it can't even warm up, let alone try to idle.

Do you have the original injectors? They may be leaking.

Do you have the original fuel pressure regulator? The fuel pressure is definitely too high. This could be caused by a plugged fuel pressure regulator or a restricted fuel return line (pinched or clogged).

Try not to drive it, because if it is running SUPER-rich then you run the risk of burning out your catalytic converter.

Hope this helps.

Re: Idle surging/stalling
 

Yea, I don't plan on driving it anymore than just straight to the shop tomorrow morning. And yea, I have wanted those things checked. The very first shop I took it to said they adjusted the FPR to get higher fuel pressure, and claimed only to be getting only 20 psi and recommended a new fuel pump. Well, I took it somewhere else needless to say. So maybe the FPR just needs adjusted back down? If it only it were that easy I bet lol. Hopefully this can be resolved fast and a bit easy on the pockets... Thanks for the insight though, I will get those checked.

Re: Idle surging/stalling
 

Wow...I wonder if they didn't "adjust" the regulator cap with a hammer, by smacking the top of it to cave it in and raise the pressure. If you have a factory regulator they probably put a washer on the inside of it or hit it with a hammer. If you have an aftermarket adjustable regulator it is adjusted with two wrenches.

Good luck tomorrow.

Re: Idle surging/stalling
 

ok, so it has been worked on a bit since my last post... had some improvement, but also the opposite... We had the thermostat replaced, didn't affect anything. The shop noticed that almost all of the injectors were staying open, so we replaced all 8. Now they say the injectors are operating normal and fuel delivery is good. They had said the car was running good shortly after, but after a bit its taken a turn back to running bad. I went to go test drive it and see what I thought, and upon starting it cold, it stalled immediately. Did this several times until I decided to pump the gas once started, and then would just hold the gas a little bit to force it to idle. It would then idle on its own at about 900-1100 rpms, then slowly die out. I popped the hood, took a look around, unfortunately a clip came off of the throttle cable, and a hose from the radiator to thermostat was slightly loose and dripping a little antifreeze. Had them fix that. I backed off the idle screw to where it is no longer putting pressure on the throttle, and the car would start and idle rough at about 900 rpms. As soon as i put it in gear, stalled. I just left it and told them theres no way im taking off with it. So as it stands right now, I told them just to take a shot in the dark, replace the ignition coil and EGR valve. They think its just an electrical problem, say it might be the PCM being faulty. I dont see how that could be because the engine is the exact same as when I first bought it, including the PCM that was specifically burned for it. Any idea's what else could be a problem here, I can't think of anything else causing an issue.

Re: Idle surging/stalling
 

Did you try plugging the vaccume line that runs to the brake booster? Uplug it from the booster then plug the line try that.

Re: Idle surging/stalling
 

Too bad about all the problems. Keep in mind, sometimes a mechanic will end up at this website (or one like it) looking for the exact same answers you are. I think we can get excellent assistance here, without spending lots of money at the shop.

Please note, adjusting the idle isn't as easy as "backing off the screw."

Setting the idle:
short A and B on ALDL connector,
turn key on,
wait 30 seconds,
remove IAC connector,
start engine,
adjust idle to 450-550 (check your emissions sticker),
key off,
remove jumper wire,
adjust TPS to .54v at idle,
enjoy your great, new idle.

You may want to upgrade to a heated 3- or 4-wire oxygen sensor. The theory is that at extended idle the O2 never warms enough to operate properly.

Take the throttle body (TB) off and thoroughly clean it, including all the passages for the idle air control valve (IAC).

Hope this helps.

Re: Idle surging/stalling
 

Did you ever get this problem solved? I had the same issue on my 92 350 TPI and it turned out the be exhaust leaks causing the computer to false lean/rich. It would do just as you originally described. Got the leaks fixed and it works fine.

Re: Idle surging/stalling
 

No I have not been able to get the problem fixed. After the ignition coil, EGR, and O2 sensor being replaced, I noticed it ran a bit smoother, almost didnt feel like I had to power brake it, however it still ran slightly rough, and still stalled. I have taken it to a dealership where my automotive instructor at college works, and I asked them to have only him work on it. He's a master tech, so I am hoping if it's anyone to figure this out, it would be him. But I will probably bring up your idea with him tomorrow, cause I am not sure if anyone did test vacuum to see if there is a vacuum leak coming from exhaust rather than just the intake.

Re: Idle surging/stalling
 

ok, good luck with that. I know how frustrating it is.

Re: Idle surging/stalling
 

problem fixed finally! lol.. after taking it to my instructor, he found the timing mark wasnt lining up right, so he pulled the cylinder 1 spark plug and bumped it to TDC, made his own timing mark and re-timed it. Turned out 42 degrees off... no more stalling. Now to just work out the other small issues, but atleast its running right.

Re: Idle surging/stalling
 

great news!

Re: Idle surging/stalling
 

"Turned out 42 degrees off..."

Its a wonder your car was running. That is a lot of timing to be off.

Re: Idle surging/stalling
 

Yea it is, but quick question. Last time I heard the car, the engine had some valvetrain noise coming from under the left valve cover... since I wont be able to pick up the car or talk to my instructor about it until friday, was curious if that could possibly be caused by the timing itself and I should expect it to be gone when I go to pick it up. Or if even having too much oil in the engine would cause that, because he did say he noticed the engine oil was a little over filled, which confuses me cause the guy I had put together my engine, I handed him exactly 5 quarts... so no way he could of overfilled it unless he bought some more for some stupid reason.

Re: Idle surging/stalling
 

I wouldn't think that would cause the noise. Could be some lifters that aren't quite tightened enough. Chances are the balancer used was for a motor with a different timing position. ie; straight up vs low on the side. I had an 82 that we couldn't time for anything, come to find out, had the wrong balancer on it. I am guessing that's what accounted for yours being off.

Re: Idle surging/stalling
 

take valve covers off if any lifter moves around freely. tighten down. my question how was it off 42 degrees. dont they change by 2s? for example mine is at 6 degrees. and if i was to retarded even 2 degrees it would idle irradicly

Re: Idle surging/stalling
 

Alright, so I thought the problem was gone. I had taken the car back and have been driving it since the beginning of this week, but the car likes to idle at about 700-750 out of gear, and anywhere between 500-650 in gear. When it idles low like that, it sounds rough and like its going to stall. It never stalled all week til today, so it seems like its just getting worse. Do you think my idle speed needs to be reset? Also, the oil level is too high, its going in for an oil change tomorrow due to this, but its well past the full line, and I know it wasn't before. There is a possibility one of the shops did an oil change, because they had to replace the EGR and the fuel injectors, so they may have gone all the way down to the intake manifold... but just curious if too much oil would be causing my car to act like this?

Re: Idle surging/stalling
 

I believe your idle is correct for a TPI automatic car. The oil level shouldn't have any affect on the idle either, but you do want to change it and get the level correct. Sounds like there is a vacuum leak somewhere or maybe a sensor not working properly. Possibly an exhaust leak as well. I know you replaced it, but has your O2 sensor been checked to see if it is working properly?

Re: Idle surging/stalling
 

Well I will have to go back through the receipts the shop gave me to make sure they did replace the O2 sensor or not. Just never heard them talk about it so I can't say for sure until I look I guess. I remember when I told them to replace it, they said it looked good and fairly new or something like that, but I told them to replace it anyways. New parts doesn't mean anything cause they can still be bad, even before they are installed. I do want to find time to take the car to a exhaust shop and have them look for a leak, I do wonder if that is the case because I've noticed a couple times when I stop, there seems to be white steam or smoke that comes out from what looks like under the car, but only once in a great while. (It's down to freezing temperature here now so it looks like pretty much how the exhaust looks coming out of the tail when its cold) And the exhaust does sound funny to me, but I don't know if thats just the low idle since I've never had it idle this low before. I'm taking it to a shop just down the road tomorrow to have them do a valve adjustment, to be sure nothing too tight or too loose there. I hear some valvetrain noise, and the best way to describe it is almost as if a rocker is tapping on the valve cover.

Re: Idle surging/stalling
 

I know my issue has been an exhaust leak. Also, do you have headers? If so, you might have to install a heated O2 sensor as O2 sensors in headers are usually too far downstream to heat up properly.

Re: Idle surging/stalling
 

you know i once heard about a three wire heated O2 sensor or something like that... i am not sure if it is that kind or just a regular, but yes, it has hooker headers on it. i'll get that looked at when i take it in for its valve adjustment. thanks

Re: Idle surging/stalling
 

I found my 350 tpi 1991 z28 idling really rough and stalling (after I gave her an engine bath oops) ended up replacing the iac ( idle air control) and it fixed it right up even though it looked fine before. I assume the 88 has this also? If so id look there from my own experience. Good luck

Re: Idle surging/stalling
 

With headers you really need a heated O2 sensor. I use a Bosch 4-wire shouldn't cost any more than a 3-wre.
You need to replace the harmonic dampener, and reset the timing before doing any valve adjustments, especially if it's the correct one, but has spun out of alignment because now it's off balance, and more than likely it has moved again so your instructor's mark is now off as well. Replace it, its cost will be the least of your worries compared to the damage it will cause if the outer ring flies off.

Re: Idle surging/stalling
 

Cubby - good point. I forgot to even mention the IAC.

Re: Idle surging/stalling
 

the iac has already been checked/cleaned. it is operating correctly, so its not that. was very close to replacing it anyways, but my automotive instructor who spent some time on the car assures me it is working right. I talked to the guy who rebuilt the engine and is very sure that what the problem is, is a blown headgasket, leaking only compression from one cylinder to the other. so, i guess it's time for someone to really get that test done, if they can find the right adapter to get under the headers, as is the current problem.

Re: Idle surging/stalling
 

ok so i havent done the compression test yet, because the shop wants the car for more than a day to have enough time to let it cool down and actually looks things over on it. but i got to thinking about some other things. since im going to have to have all 8 plugs pulled for the compression test, i might as well replace the spark plugs yet again. and this time im trying to go back to the same kind that were in it when i first bought the car. They were a short autolite racing spark plug. just wondering if maybe thats what I have been missing this whole time, since the car has hooker headers on it and ive been reading a little about how sometimes you need a little more clearance when you have headers installed. just double checking if this may be a good idea before we go through with it. so thats what im down to, is thinking this is a problem with spark plugs (because i do notice sometimes there is a back fire when i let off the gas doing 70 down the highway), a blown headgasket like the guy thinks there is, or something stupid like a coolant temperature sensor or the throttle body/IAC weren't really cleaned out.

Re: Idle surging/stalling
 

hey guys, im back at it trying to figure out what is still giving my car problems. compression test was done, my instructor told me that the lowest compression was 110 and highest was 130 and says its fine. So there is no blown head gasket or anything like that. Spark plugs were changed to a short autolite racing spark plug, but nothing seems to really have changed about the car, except a couple idling issues that seem to happen more frequently now. so just to describe how the car is as of right now: on cold start, takes about 3 to 4 starts until it stays running, and once it does it will idle at about 900 fairly smooth. take off with it, seems to hesitate a little accelerating from idle. After a short drive it starts to idle down low at stops, anywhere from 500 to 600 rpms and sounds like it could stall, but never does. once it is slightly warmed up, the idle starts to surge up, causing my car to lose a little bit of speed. seems like after a decent drive, about 20 minutes, the surging goes away completely until the car is started again. if started warm, car idles real rough, low rpms, backfiring when I let of the gas at high speeds, and i noticed it has a real problem when i turn on the headlights shortly after it has been started, sometimes have to really fight with it to take off. so... any idea's? i've been trying to do some work myself, but its cold and snowing and I have no garage, and not enough money to take it to a shop right now..

Re: Idle surging/stalling
 

If you (or your instructor) messed with the minimum idle screw then you must follow the above instructions to set the idle properly.

What did your plugs look like when you pulled them, wet/dry or carbon-fouled?

What is the fuel pressure when this happens?

Is it running rich or lean or normal?

Hope this helps...

Re: Idle surging/stalling
 

well im having a heck of a time trying to find a 3 or 4 wire heated O2 sensor for this car. All I can find is a 1 wire, at best a 1-wire heated O2 sensor. anyone have a part number for one that might make the search a little easier? 1988 firebird formula 350 with hooker headers.
as for those last few questions, i honestly do not know what the spark plugs looked like. He didnt say anything about them, so I assume they were ok. I just simply wanted to reassure myself with spark plugs that were what have always been used with that engine prior to the rebuild. I have a fuel pressure gauge, so one of these days I will try to get out there and get that figured out. Also cannot tell if it is running rich or lean, how can I tell that without a scanner tool?

Re: Idle surging/stalling
 

This was recommended by another user on this site. It's a one wire, but it is supposed to work well. I have not ordered it yet, but will be in the near future.

Summitracing.com part number CEI-103025

Caspers Electronics 103025 - Caspers Electronics Heated Oxygen Sensor Retrofit Kits $88.95
Oxygen Sensor, Heated, 1-Wire, 0-1 V, Each
Part Number: CEI-103025

Re: Idle surging/stalling
 

Sometimes you can "smell" if its running rich or lean (burning eyes and rotten eggs or black smoke).

When I upgraded to a new style O2 sensor I just bought a factory 4-wire O2 sensor for an LT1 Camaro/Firebird (93-97), then wired up a relay to power it (most, if not all, O2 sensors have the same threads). It only took about an hour, I took the trigger for the relay from the fuel pump power (figuring that the O2 will warm when the fuel pump runs). I chopped off the 1-wire connector from the old O2 sensor and soldered it onto the new sensor. You also get the benefit of a dedicated ground wire for the O2.

Hope this helps.

Re: Idle surging/stalling
 

I actually had looked at that one. But since it said 1 wire I didnt want to do anything with it. What needs to be done with it since it comes as a kit?

Re: Idle surging/stalling
 

And also, I don't experience burning eyes, or smell anything like rotten eggs, and there is no black smoke. I haven't seen a trace of black smoke at all since the rebuild. I took it out for a drive today to return a movie, and it seemed to run better cold (after a fresh tank of gas and a little bottle of water/antifreeze remover dumped in with it) The idle still surged a couple times while driving once the car started to warm up a little. And the idle at stops was usually sitting at 500 rpms, and somewhat surging to 600. I decided to get on the gas from a red light, try to get it up a little over 3,000 rpms just to burn off some carbon possibly and see how it acts at WOT. Accelerated fast without any hesitation, but it seemed like it surged even at WOT.
Also thought of another thing, if the former owner of this car had a PROM chip burned specifically for how it is now, if one of the shops I had taken it to replaced my ECM, would that affect me any or should I still have that PROM chip in it and be ok? (They replaced it claiming it was giving them faulty readings)

Re: Idle surging/stalling
 

I just sent you a pm with the information the guy supplied to me.

Re: Idle surging/stalling
 

Did you fix it? When I purchased my bird over 2 years ago it had this problem. On top of the motor itself being blown. After thousands and thousands of dollars spent on a new block, heads, cam, ecm, Etc. Complete rebuild/restoration.. this problem still exist?!?!?! 80% of everything under that hood is brand new. It just got back from the best High Performance Shop here on my coast. The guys had it for 2 months... TRIED EVERYTHING you mentioned. Threw the towel in, he was so embarrassed he didn't even charge me. WTF could it be?!?! We tore the whole top end off, checked every damn sensor, distributor, injectors, EVERYTHING mentioned above has been tried. Everything. As soon as it warms up (2-3 mins) it starts surging.. runs great, but stalls out at every damn red light/stop sign.