ERICCAMARO

OK heres the deal. I have a 92 RS with a 305 TPI. I have replaced ignition module, the coil, Plugs (autolite), Wires (MSD), Cap and rotor (hypertech), and at idle it feals like its missing really bad. Through the rpm range it feals good, maybe some power loss. Just sitting at idel its really rough and I cant get it to get down to 500 rpm. Im guessin I could fix that with a quik cleanin of the IAC. but After all that it shouldnt be missing at all. could it be the injectors? I mean if it was missin bad shouldnt I smell gas or wouldnt it back fire cause of the extra fuel that wasnt gettin ignited? Could this have something to do with the small exauhst leak on the passenger side collector?? I am stumped I just want it to run smooth Im gonna have to pass smog sometime and I dont think it will in the shape that it is. PLEASE HELP!!!!!!!!!!!!

12 Sec GTA

Have you tried setting the timing?

ERICCAMARO

yep its at the factory 6 degrees.

DannyT

Hey, location sacramentan here.

Did you do all of these things (plugs, wires, etc.)to try to fix this problem or did it start afterwards?

How bad is the exhaust leak?

ERICCAMARO

I changed all those things to try and stop the problem. I changed the wires like 4 times cause I was buyin cheap ones and thought they were all bad but turned out it wasnt so I bout super conductor msds and called it good. I moved onto the plugs that didnt help much. So I figured It was the dist cap and rotor so I changed those and it didnt have any effect. the exhaust leak is loud enough to hear but only at like 3/4 to WOT.

ERICCAMARO

does anyone know what it could be>??????

CraZ-28

You could have a faulty injector. You have the same problem my brother did on his 89 Iroc. After pulling my hair out I checked the injectors. 2 were reading really low and after replacing just 1, the car ran 100% better. I want to say we did an Ohm reading but I don't remember. All the injectors were reading 10(ohms?) and 1 was reading 2 the other was 7. Take a look there.

91bluemetalicRS

double check the position of the plug wires on your distributor. Sometimes I cross wires eventhough I have done it a thousand times.

ERICCAMARO

ohh no I would know If i missplaced plug wires. Thats a totally different fealing when 2 cyl. are missing than 1. Im really leaning twords injectors or a possible egr problem. I am goin to get fuel pressure gauge and do the lead down test to see if any are leaking, but B4 that I will throw a volt meter on there and check the ohm rating on them if that looks alright ill replace my EGR solenoid and if that does not help I will throw my new AFPR on there and change out the egr valve while I have the plenum off and if that does not do it Ill take my injectors off and try to find a local shop to clean em or ask cruisin performance if I can buy some of there special injector clean they use in the ultrasonic machine and see if I can go down to my moms work and use there ultra sonic machine to clean em. its a dental office. But this may take a bit to do seein how im talkin bout spendin around $200 to do all this and I dont have alot of extra cash. Im sure you all know how I feal there.

ERICCAMARO

anyone???

360Iroc

ditto i did the same thing and had to walk away for a day because i as so mad, when i figured out what the hell i did i felt so stupid...

i figured it out when i noticed that the two middle header pipes where still cold on the drivers side after it had been running

85MikeTPI

iTrader: (2)

What did/do the plugs look like? It's a long shot but I
had a bad miss that turned out to be oil getting
sucked into the intake thru the PCV valve.

The miss was worst when the engine vacuum was the
highest...

mike

mckenzie

possible vacuum leak? best of luck, tom

ERICCAMARO

ok Ive had some progress but the problem persists. I have fixed the exhaust leak. it was gettin worse so I replaced the gaskets and bolts and used some loktite on em this time. it still feals like its missing though. I fixed all the vacuum leaks as well. does anyone else have any Ideas? I checked the injectors too they are all firing. What else do I check? I also took off my egr solenoid and found that that was passing vaccum right through it. I think its broke but not throwing any codes. today I am going to pour a little water on each of the header pipes to make sure they are all hot and If ones not then at least I have narrowed it down. but what if they are all hot?? what next?

Cruzin Kaz

Just because your headers are hot, does not mean the injectors are firing properly.....They could have a pulse problem... works ... don't work...headers will still get hot...see what I mean. Being that the car is now over 10 years old...how many miles on the car. May just be time for new injectors.....take an ohm meter to the two contacts on each injector..it should read around 16.3 ohms or in that general area ...anything to low and you need new injectors most likely

mckenzie

how many miles are on the motor? may want to perform a compression test on the cyl. best of luck, tom

305sbc

iTrader: (3)

replace the plugs again.

ERICCAMARO

I went through to make sure that all of the header pipes were hot and I beleave they all were I am still a little suspicouse about the #8 pipe, but I will check it out later its really hard to get to with those edelbrock headers. But all the rest of them were plenty hot. I really dont understand why it is doing this but I think I might be onto something, I just need an expert to tell me if What im about to say makes any sense. I am suspicouse of the TPS and the CTS. Both of these sensors when out of adjustment or broken can cause a rich running condition which in turn would create a missing type of fealing in the engine. Since adjusting the TPS is basically free and the CTS is a mere 10-12 bucks Seems like it should be done either way. But heres the other thing, it has been two years since I have replaced my o2 sensor so I assume that thing is prolly fried aswell. but thats a little more pricey. So to the experts, what next??? really please, WHAT NEXT??????????

Viprklr

iTrader: (5)

According to the shop manual the resistance of your injectors should be 10 ohms at 140F. You only state that they're firing. That doesn't mean they're working properly. They could be firing at the wrong time. Check your resistance. It's easy and free.

CraZ-28

This is exactly what I said a month ago when I replied to this post.

vwdave

Start the car, pull 1 wire off at a time. If it sounds worse, that plugis firing. It there is no change, thats where your miss is. Seeing as you checked the obvious, check compression. If its low, adjust the valves on that cylinder and see if it raises it. If not, sorry.

ERICCAMARO

Im not to keen on the taken 1 plug off at a time while the car is running, Ive been shocked one to many times, no madder how many times it happens it still catches me off guard. Well I got a new problem today anyways now there seems to be a coolant leak but I never see any on the ground and there is none in my oil but it was almost bone dry this morning and I filled it up less than a month ago. But I will check resistance in my injectors but I dont have a multi-tester but I guess its about time to invest in one. ill let ya guys know.

Viprklr

iTrader: (5)

Taking one plug wire off at a time won't shock you.

vwdave

I've done it hundreds of times and have never been hit. My dad has done it thousands of times and he has never been hit. You probably had bad wires that didn't have great insulation.

ERICCAMARO

ill try it but if I get shocked im gonna be super pissed. LOL

mckenzie

i hope you use insulated pliers to remove the plug wires! best of luck, tom

ULTM8Z

I have a similar problem right now and I think it's related to the condenser (capacitor) in the distributor. Try replacing that, it's about $8 at AutoZone.

ERICCAMARO

You know about 20 minuets b4 you wrote this I was actually lookin up stuff about how to change the magnetic pickup in the distributor (this is what your talkin bout right?). cause I know thats about 8 dollars at autozone. I have already replaced every other aspect of the ignition. I have it narrowed down now pretty good though. Its either the magnetic pickup like u say, faulty injector, or a bad o2 sensor (i think this would send a code though so im pretty sure its ok),. just one question for ya.

have u replaced the pickup or as u refer to it (condensor) and fixed the problem or is it still in the speculation phase??

ULTM8Z

No, actually the condenser and magnetic pickup are two different things. The condenser is a little cylindrical capacitor that is on the 12+ ignition circuit. It filters out back-transmission through the electrical system caused by the coil firing. If it shorts out, then it sometimes causes electrical system noise (among other things)- which I suspect is what is happening to me.

The magnetic pick up coil is merely a sensor which indicates to the system which cylinder needs to fire. You can test that part for problems. The procedure is in the Haynes manual.

ERICCAMARO

Is it easy to replace?? do you have to dismantle the distributor? Cause when I had my amp hooked up in the back of my car I was gettin alot of interference that would go with the rpm's. it was like an audio tach LOL but it was so annoying I had to take the amp and subs out. but this might fix it. thank you

ULTM8Z

Not at all! In fact you can leave the distributor in the engine during the swap. Keep in mind that I'm running a Corvette large cap distributor, but I believe it's the same.

All you have to do is take off the cap and rotor to expose the condenser. It's a cylindrical part, silver in color and if it's like mine, it's permanently wired into a harness that runs from the distributor to the cap. Just unplug the harness from the HEI module and cap, then remove it. You'll have to by the harness along with the new condenser, but again it's only about $8 to $10.

Hope this works for you!

86iroctpi

Have you checked all of your vacuum lines closely? I had a similar problem with rough idle and it turned out to be collapsed vacuum line.

ERICCAMARO

Im havin a hard time finding anything on this condensor or capacitor. The only part that I have been able to find out about it the pickup coil. which is about $10. I have no idea if your distributor may be different or what but I cant even find that part for sale anywere. do you have a part number or the part name cause the only condensor is the A/C condensor or thats what they told me.

ERICCAMARO

Oh yea and the vaccum lines are all intact. no problem there.

ULTM8Z

I'm running a Corvette (large cap, integral coil) distributor, so it may be the case that the Camaro/Truck (small cap, divorced coil) type distributors do not have that.

I assume you have already looked in your distributor and did not find it?

ERICCAMARO

Yes I have looked at my distributor and it is not there and there is defintly no room for it in there if it ever was there. I know exactally what it looks like, I think that there is one in every points distributor ever made and for some reason theres one in yours. But there are only three parts to my dist, thats the Ignition module, the reluctor, and the magnetic pickup. so back to the drawing board.

91bluemetalicRS

Did you ever try this?

ERICCAMARO

yea you guys say it is easy and free but that is only if you already have a digital ohm meter but for all the different uses for it I defently should get one. Im so broke right now though im gonna see how much they are and if I can borrow one from a friend I think it would make my life much easyer and less stressful, hell or I could just drive it off a cliff, you know youve wanted to do it time to time. dont lie

91bluemetalicRS

Go to autozone they most likely will let you borrow theirs. (Still Free) You may get a nimrod that will want you to rent one, maybe, but you will still get your money back when you turn it back in.

If that doesn't work, go to Radio shack someone will let you use thiers.

Either way its worth checking out

D's89IROCZ

On my 89 5.oL I had a bad injector . It took me 10 days of diagnostic crap and troubleshooting . First off It seemed to be a progressive thing ....... a lopy idle, then a loss of power, then the friggin thing would hardly start , I couldn't even touvh the gas without it stalling .... it farted and spit and ran incredibly rich ( don't ask me why!!!!!! ) then I finally bought what is called a pulse tester ( I also wasted my money on a noid light .....but it's not important) This pulse tester hooked up to my injector ( one by one ) and it has buttons on it to " pulse" the injector manually. Single ..... at 40 P/sec ...and 100 p/sec WIDE OPEN . Only one injector was bad and it would trip the breaker on the Pulse tester everytime I hit it above the 40/sec test.


You gotta love that Batch fire system .....if one is screwed the whole bank will not fire right.
Sucks that something that would cripple the car ....won't even read a trouble code
BTW the resistance on my injectors where all within spec ...... but the Pulse tester weeded out the bad apple.

Good luck to ya

305sbc

iTrader: (3)

Which side was your bad injector on? driver or passenger?
Just trying to figure out how one caused the hole side to miss.
thanks.

ERICCAMARO

Alrighty the damn thing still seems like its missing. Heres what I have replaced so far
Ignition wires- msd 8.5s
Ignition module- stock replacement
Cap & Rotor- Hypertech
Spark plugs- NGK
Injectors all Ohmd out good and were flow checked and cleaned
I have done a compression check and all cyl. are around 160-170
No vaccum leaks I checked multiple times
No exhaust leaks replaced all gaskets (might be very small leak right befor the cat)

Ok heres whats happening, The car feals fine when I drive it, its not jumpy at all and it accelerates pretty smooth but when I have it just sitting idleing at a light or what not it getts very rough and lts like I can hear real faint backfires (very small) and it stumbles, I pulled plugs to make sure they are all firing and they all looked good. Its almost like it just randomly drops a cyl. every so often its never the same one or consistant at all and sometimes its a slight miss but sometimes its bad and the car shakes and it feals like its bout to stall but it hasnt actually stalled yet. Please help I really cant figure it out.

Viprklr

iTrader: (5)

My Beretta's the same way. I've replaced everything but the miss remains. I've decided that I need a leakdown test to see if I have a bad valve. Maybe you do.

ctandc

You looked at the pickup coil, or the distributor itself yet? That's where I would be looking.

Another thing, hook a timing light up, and while it's running just watch the timing to see if it's jumping around.

Have you tried advancing the timing any to see if it runs better?



HTH

ERICCAMARO

I have timed it and when the Est is disconnected and Im looking at the mark It hits the same place every time. I am gonna test my pickup coil and if it seems bad at all I will replace the pickup coil and the reluctor just for the piece of mind. and the bad valve idea, wouldnt that make the problem get worse as the rpm range goes up cause after bout 2200 rpm the problem is all but gone and the compression test went good shouldnt that mean all is well?

ctandc

No...

Leave the wire HOOKED up, and just have the light on it to see if the timing is JUMPING around with the ECM plugged up. It shouldn't be jumping around at idle....




HTH

ERICCAMARO

what should it be at?

ULTM8Z

Eric,

If and when you figure this out, PLEASE let me know what the solution is. I've been having the exact same problem as you describe and I've been fighting with it since last November! I've checked and/or replaced everything but to no avail.

It feels like one cylinder just simply isn't firing at idle speeds and then it smooths out at cruising speeds. It's the damndest thing! I've even had it in a professional shop and they couldn't figure it out.

Anyway, keep us posted (at least me, anyway).

Ed Maher

Do you get incredibly bad gas mileage, or fail emmisions because of this? If it's just a slight stumble or roll in the idle, even bad enough to vibrate the car at idle thats not really all that abnormal from a TPI car.

The way you describe it sounds exactly what like my car does. Seems like over time my idle quality has been steadily decreasing. Since i've taken it out of hibernation, it actually almost sounds like it has a small cam in it, my idle actually has a true lope to it. Not extreme, but it definitely rolls pretty nice. If i still had hollow cats it'd probably sound pretty mean. I've also noticed the same thing in other TPI cars. Some of it has to do with how the TPI ECM constantly varies the mixture and timing.

Other than that though, still gets the same gas mileage, and is as driveable as ever. Passed an E-check with flying colors in january. So to me, the car is in perfect health, a slight shake at idle is nothing for me to concern myself with. My only theory as to the cause of degradtaion over time is the timing chain is starting to stretch badly with all the abuse i've given this engine over the last 30k.

Since i can't see your car though, tough to say if what you're seeing is normal or not. If you expect the car to idle like glass, you're in the wrong car line. If it vibrates bad enough that your rear view mirror keeps falling off, then something more sinister is at work.

edit: have either of you tried a cylinder balance test. You need to get your hands on an accurate low range tach. Then at idle while it's doing it's miss thing, go around the cap and pull one plug wire at a time and watch to see how much the RPMs fall off. You should see a consistent drop. If one hole doesn't affect things as much, you've found the culprit. Don't try this with a stock tach though, you need a real tach for this.

ERICCAMARO

I get about the same gas milage, Im trying to fix this to pass emissions not that ive failed yet but I would like to get it to run as good as possible before I go in. It doesnt vibrate real bad It feals like it has a cam in it like you say but it doesnt. I am down to two things either the timing chain or its got to be the distributor. I am gonna try to knock the distributor out of the question and possibly throw a msd 6al on there I have layin around, but let me tell you this is really pissing me off. btw protour 71 have you had your car on a scope yet? or anyone with this problem had it scoped yet. I would but i dont have the extra 90 bucks. where would i get an accurate low range tach and how much should i expect to pay??

ohh yea and ed have you found anything that helps the problem at all? I just need to pass smog then im gold. either of you rebuild your distributor yet??