im at an end with this car. its an 86 camaro iroc-z, 150xxx miles. 305 tpi. the problem im having is that when i turn on the car will idle fine for alittle bit. and then it seems to get a surging idle, slowly creep up then down then up, but when i drive the car it feels perfectly fine until i get to a stop sign, then the car turns off on me. at first i thought it was a vacuum leak but i dont hear any noises and i just disconnected the throttle body cleaned it all out and attached it all back together and even cleaned the iacv which was pretty dirty. also i had the module checked, changed the ignition coil, checked the pickup coil, all new distributor cap and wires. new fuel pump and fuel filter. new battery and alternator.

i have not yet reset the iacv, but when i tried to raise the idle or lower it, it would still manage to surge and stall. the car does throw a code for tps, oxygen sensor or short circuit, i forget the code number but its 13 i believe. and the car does seem to be running rich, since theres a strong smelling exhaust coming out and grey smoke. that would leave me to believe its the oxygen sensor, but unfortunately im extremely low on cash right now, and im just trying to get the car to daily running condition.

my next task will be to ohm check the injectors, reset the iacv, disconnect the injectors one at a time to check how it is.

now my question is, is this more likely to be a fuel related issue or an air related issue? when i cleaned out the throttle body i was amazed by how much black gunk it had inside it.

any tips will be appreciated. thanks

 

Something you might want to check is the EGR valve. Its a very common cause of a surging idle.

 

wouldnt that throw a check engine light with a different code?

 

Well maby and maby not. I like you would expect it to throw a different code but then again its strange how these things react sometimes. All i can say is that ive seen a fair amount of cars whos idel surges as result of a bad EGR valve. However your could always measure the voltage at the oxygen sensor and connections as well as check the TPS sensor for sticking.

 

ill check the tps tommorow when it stops raining, and will also check the cts since i heard it could be that aswell. my only question is if it were the coolant temp sensor, wouldnt my fan not turn on?

 

I think the tpi engines have 2 coolant sensors.1 for the gauge and a seperate one for the fans.They are also setup so that if the fan switch goes bad it'llrun the fans all the time.

 

thanks thats some good insight. tommorow im taking it to class and hopefully we can track down whats wrong

 

Im interested to see what you come up with. Im going through the same exact thing. So far Ive replaced the TPS, IAC, fuel filter and checked the vacuum lines. I actually replaced all of them just to be sure. I just cleaned the EGR today. Im waiting for my wife to get home with the new EGR gasket so I can see if that does the trick. Unlike you though.....mine wasnt throwing out any codes. Hopefully one of us will get it solved and itll fix both our problems.

 

yeah, i havent replaced parts yet since im kinda tight on money, today i checked the tps sensor and i think its toast. i couldnt get any sort of reading any way i setup the multimeter. tommorow im taking it to class and hopefully we can figure something, the only problem im having now is that somehow it got progessively worse and doesnt like to idle even when cold. so im gonna have some time driving it to class.

 

Man that sucks you have to drive it that way. I feel for ya. Mine has progressively gotten better. At first it would not even start and when it did I had to pump the gas in rhythm with the car. It got better after I changed the TPS and fuel pump relay (which I dont think had anything to do with the problem). Then a few days later.....I changed the IAC. It seemed to be slightly even better. Today I cleaned the EGR and checked the fuel pressure. Cleaning the EGR didnt seem to do anything. The fuel pressure was at about 7 psi though. My operating range is 9-13 psi. So......it looks like I'll be replacing the fuel pump. Which pisses me off because a performance pump cost about 200 bucks. I been trying to ugrade parts as I replace them but it looks like thatll have to wait. Gonna go get the 50 dollar cheapo when I can scrape up $50. Maybe youll find out something cheaper. I damn sure hope so. Hope you made it to class

 

i made it class, but the problem was leaving. what happened was i developed a coolant leak at my lower radiator hose connection to the block so i brought it in to class we pull off the hose, and drain coolant, then put the hose back on. after that we didnt have enough time to get to the problem. so im leaving and the car doesnt wanna stay on, teacher says leave it an we'll get to it tommorow. but on the way to school i had loads of problems, this morning was exceptionally cold, and the car could tell, because it was ridiculously hard to get it to start, as if it were carb or something, and when it did run, it ran pig rich. i had to use to feet to keep the car on. i finally get a block away from school and i see steam coming out of the car, turns out its coming for a loose hose clamp, great. we fix it, but we run out of time to diagnose it. i start to leave and the car is running super rich. idling all over the place, stalling, just horrible. so i had to take the bus home, but were gonna check the egr and the tps to see if it helps at all.

 

Well that blows........Atleast you have a bus system there. Today while I was looking at the car hoping something would jump out at me and tell me whats wrong but that didnt happen. My wife gave me a fuel mixture gauge a few days ago.......so I decided to hook it up. Got it on no problem but when I was running the car....I noticed that when the idle was at its lowest (300 rpm) the mix gauge said I was running lean. Whe it was at its peak (1600) it was extremely rich. Im begining to wonder if it wasnt the O2 sensor all along. Let me know when you find anything out and I'll do the same. My only other option right now besides the O2 sensor is to change the fuel pump and that job in itself is a ****.

 

Hey read this post.....its on page 3 of tech/general the topic is 91formula runs poorly...i think thats it. its by krok91gta. Sounds like this guy had the same issue. new injectors fixed his problem. Now Im at a loss.....dont know whether to get a fuel pump or injectors. The thing is........its a pain in the *** to drop the tank to replace the fuel pump and cost about $65......Its an easy job to replace the injectors on mine because its a TBI but it cost over $100 and hard to find the injectors I need at a cheaper price. Im ready to go out back with my M-16 and shoot the sh$t out of that thing.

 

yeah hopefully tommorow ill find out something. dropping the tank isnt that hard, but if you wanna do it the easy way you can just cut a hole in the rear hatch area, theres a thread floating around about doing it without turning it into a hackjob

 

Im sitting here wide eyed and saws all in hand!!!!!! lol Gonna look for that thread. Good luck today!

 

vacuum test revealed a bad egr valve, im replacing it tommorow

 

Damn.........I wasnt expecting to hear that. I cleaned mine really good. Im going to check it out tomorrow and see if its working or not. My wife seems to think its the O2 sensor......every post on here points to the fuel injectors.......and a low fuel pressure points to the fuel pump!!!!! This has me all F&CKED UP. I dont have the spare money to replace one of these things let alone however many parts it takes to get lucky. Have you done a fuel pressure test? Now Im wondering if the EGR can make the fuel pressure low in some way.

 

Oh and I forgot........I talked to my sister inlaw who I bought the car off of. I was telling her about the fuel pump and she asked me if I pulled the carpet up yet. I told her no and she says "well.......I had to do the same thing about 3 years ago so its already done". I looked at it and she did a damn good job. The girls in my wifes family are all awesome wrench heads. If I do have to do it.......its going to be easyyyyyyyy!!!

 

Crasher0083, what seems to be your problem if you dont mind me askin? It sounds like you at a bit of a loss im not TBI expert but i do have a few factory manuals that cover it so i might be able to help.

 

Crashers 92 Camaro RS TBI is roller coaters idling between 300 rpm and 1800. At 300 rpm his fuel/air mixture ratio gauge is showing its running very lean and running very rich when it spikes at 1800. He's replaced the TPS, IAC, and all vacuum lines. The vacuum lines are all secure and installed correctly. He also installed a new fuel filter and cleaned the EGR really good. Its showing a fuel pressure of 7 psi while running. My sister who was the previous owner installed a new fuel pump less then 3 years ago so Im doubting its the fuel pump but ya never know. I was thinking maybe the O2 sensor but with 7 psi it makes ya wonder if its not the fuel pump. It should be running 9-13 psi.

 

Well If your fuel pressures low then ide be tempted to say that it needs alittle attention. It dosnt seem like 2 pounds of pressure would make that much difference but keep in mind that is about 20% of its fuel pressure. However lets start with the cheap stuff first and make sure befor swapping parts. Like i always say you can work hard or work smart lol. Now like you were wondering there are lots of things becides a bad pump that can cause low fuel pressure. So lets run through some troubleshooting procedures. First off youve already established that you have low pressure with the car running and im assumeing youve already checked the car over for leaking fuel lines correct? First change the fuel filter its unlikely but possable thats causing your low pressure. Next you mentioned that fuel injectors fixed another members problem. This is also a cause of low fuel pressure. Sometimes they just leak. So look over the fuel injectors and the fuel meter cover for leaks. Next if you see no leaks dissconnect the fuel injectors connectors, pinch off the flexable fuel return line and apply 12V to the ALDL pump test terminal. If the fuel pressure reading is still not greater than 13 PSI then you can be assured its time to replace the pump. If it is above 13 PSI then weve got a whole other set of things to check out and its not the pump.

 

Good news. My wife was running some part tests on the car and had the fuel pressure gauge on the whole time. All of the sudden she yelled "got it!!!" and ran to the back of the car and started heading to the fuel pump. The pressure had dropped to 2 psi. So she figured she knew it was the pump. After taking the pump out....she found a nice size slice in the little rubber pump to sending unit hose. Popped on a new piece of hose and bam......car runs great again. Fuel pressure is at 8.86 psi but it runs excellant. Thanks for your time thunder and gurk. Im so happy I have my toy back. Now I have to make progress on it so I can smoke my wifes GTA lol. I hope gurks problems fixed. I'll be checking back to see. Yall take it easy and thanks again.

 

Yea that would do it lol. Its ok just because the guage reads 8.86 dosnt mean its actually 8.86 psi as there not perfectly accurate anyways. Although congrats on the car anyways a nice cheap fix as well.

 

after managing to take off my egr i accidentally pulled this wire off this little sensor looking thing on the egr. so i have to wait till saturday till the new part arrives.

 

Dammit man!!!!! You sound like you have the same luck as me. Oh well....guess well have to wait another day to see if thats the problem. I sure hope it is.