bbexperience

Hello all. Long time lurker, first time poster.

First off, I want to state up front that, compared to most of you, I'm probably something of a car idiot. So when reading this and replying, keep that in mind.

The car in question is a 91 Camaro RS (V8/305). I just got it out of storage this year. It had been sitting in a barn for about two years prior to this without anyone touching it. I know that wasn't good, but it is what it is now. Anyway, I charged up the battery about 3 weeks ago and, to my surprise, it came to life. I took it on a very short test drive and all seemed well, engine-wise.

So, Tuesday, I have the brilliant idea of driving it to work and then over to a friends house after. I figured I should probably get an oil change so I took it over to a quick change place Tuesday evening. They did a standard oil change and replaced the PCV valve.

Wednesday I go out and the car starts as normal, a little bit of a delayed start but it starts. I back out of the garage and realize that I need to run back in the house for something. Our driveway has a mild slope to it, so at this point the car's idling in park with the rear pointing slightly downhill. I mention that because I don't know if it has anything to do with the issue at hand. Anyway, I come back to the car from the house, throw it in reverse, start to back up and it stalls. It started back up right away, and I started to reverse again, and it stalled. At this point, just from the little bit of gas and momentum, I'm at the bottom of the driveway. I managed to get it back up to the garage a couple feet at a time by starting it, throwing it in drive, giving it some gas, wash rinse repeat.

I looked at it that night and in park it would idle up to about 1300 and then drop down and stall. It may have cycled up to 1300 and down to around 300 a couple times before stalling but it would never stay running. Even applying gas would have no effect. After much reading across the internet I decided to try an ECG valve. That seemed to help some but the surging idle continued. It would then surge up and down in park but not stall out. I could also give it some gas in park without stalling. No dice in gear though....instant stall. Today I replaced the IAC valve. It now surges up and down but then steadies out anywhere from 1300 to 1000 RPM. Idling in gear it goes from around 1000 and down to around 500, eventually steadies out but then stalls soon after any gas is applied. So putting it in gear and then applying the accelerator gently, but constanly results in slight movement, followed by a stop as the RPM drops and then a sudden lurch as the RPM jumps back up and it gets gas, followed by a drop in RPM and a stall. During the surging in either park or gear the battery "charge" gauge drops from around 13 to around 8 and then back up. The oil pressure gauge also drops up and down. I don't know if either has anything to do with it.

And now here's the part where I finally get to the questions:

1. Since it was stored for so long with somewhere between 1/2 and 3/4 of a tank it's possible there's water in there. Is it possible that having it idling on a reverse incline for a few minutes would stir something around to cause the current issues?
2. The PCV valve that the oil change place put in seems to be fine. I removed it and the valve doesn't appear stuck. However, it did come out pretty easily. It seems like there should be a gasket or something there that seals it better. Could a loose PCV cause this or is there something else they might have done that screwed something up?
3. I have the carb cleaner to do a vacuum leak test but haven't actually done it yet. I've looked at the vacuum hoses and all seem fine. It doesn't seem logical to me that this is a vacuum problem though since it was running fine. It seems as though, unless a hose breaks or becomes disconnected, a vacuum problem would be more gradual as the gasket or hose erodes. Thoughts?
4. My next thought was the TPS but from reading around it seems like that effects acceleration rather than idle. Any comments there?

So that's my (long) story. Any help you guys can give me would be greatly appreciated as in its current condition I can't even get the thing out of my driveway, much less to a shop to have it looked at.

As I said I'm not that knowledgeable in this arena but I can learn (and have been!).

Vader

You might want to test fuel pressure. Even if the pressure is acceptable, changing the fuel filter would be a good idea.

bbexperience

I actually attempted replacing the fuel filter last night. No dice. That thing is rusted solid on there. I'll have to try again from a different angle.

Would the fuel filter cause this though? It seems like if the filter was clogged it would force the pump to work harder to force the gas through, but it would still come through in a steady stream. It seems like it might idle rough, but it would idle consistently. No?

I noticed one more possible symptom last night. After it idles up and then back down there's a buzzing sound coming from the engine compartment. It sounds like it's coming from under the air cleaner from the IAC valve or TPS area. I've never noticed a sound like that when it was running properly. Anybody ever heard something like that from that area? Any clues as to what it might be? As I stated above the IAC valve was just replaced.

Thanks again.

transam85dudeman

that buzzing is your AIR diverter solenoid energizing. it takes air from the smog pump and diverts it to either the headers or the cat. with the to on position can you hear the pump priming in the tank? do you got and engine trouble codes?sounds to me like maybe either a fuel or igntion problem

bbexperience

I can hear the fuel pump priming.

When I used the high-tech paper clip test last night I only got code 12. No others. I'm leaning towards one of the sensors being bad. Maybe the MAP?

transam85dudeman

no dude, map shouldnt be bad dude.. try pressing your injector's fuel rail's schrader valve, looks like a bike tire valve. if fuell squirts out and hit the under hood then your fuel pump is ****. it could be an ignition problem. but if you want to replace the fuel filter which is recomended after 4 oil changes, you could try using PB cataylist, its a step up from wb40., the fuel pump had an intake filter on itself in the tank, yes GAS goes bad after 60days. its like water. but just oil. say if you want to try testing the resistance of the ignition coil, pickup coil, get the ignition control module tested at autozone and be sure to use thermo-grease on the bottom of module when reinstalling or the module would heat up and burn out. and why not pickup a haynes manual at autozone. way better than chiltons, and it includes torque values, ignition resistance, ohms, voltages and etc.

bbexperience

I feel like a total retard but I CANNOT find the schrader valve anywhere. A little help here.

Also, I'm still not convinced it's a fuel pressure problem. I just don't know why it would idle surge like that with bad pressure. Seems to me it would either not start or idle rough for lack of gas...

bbexperience

Okay, new "symptoms". Hopefully I can get some responses from them.

I was starting and restarting it today, just racking my brain. I did that about 3 or 4 times when I noticed that it smelled really strongly of gas. I had been revving it a little to keep it from stalling out but this was REALLY strong. Much stronger than it should be I'm sure.

So now I'm even less inclined to think the primary problem here is a fuel pump or fuel filter. How about the fuel pressure regulator? If it's faulty could it cause things like this?

SpitotRs305

91 RS wont have a shrader valve... TBI engine
gonna require a T fitting with a pressure gauge to check actual preasure.... if it has been sitting that long with fuel in it i would change it out IE siphon as much as you can out of the tank disconnect the fuel line from the TBI and get your self a piece of hose to drain into a bucket then cycle the key on/off 3sec on 5+ sec off until the tank is completely empty

then you can really work at getting those fittings off the fuel filter... with out worrying you will crack one and pour gas everywhere

bbexperience

Ok, probably another stupid question, but can I remove the air cleaner assembly, plug the vacuum hose hole in the throttle body and run the car without hurting anything? The point would be to try to see what the injectors are doing.

92drptp

Have had mine in storage for several years as well and now am having a similar if not the same problem. Its a 92 rs with TBI and i already replaced the fuel pump and fuel filter and it did not fix the problem. My vacuum lines look good as well (be shocking for same line to leak on both our cars) i have not started testing sensors yet. I'll tell you if i have any luck.

bbexperience

Thanks! I'm glad to know there's somebody else out there sharing my pain. Any clue on my previous question about running the car without the air cleaner? Have you ever done that? It doesn't seem like it should cause a problem if it's not for a prolonged time but I don't want to break anything else either.

SpitotRs305

the car will run just fine without the aircleaner on just make sure there isnt anything around to get sucked in

bbexperience

Oh joy, I found something new.

I ran it without the air cleaner tonight to check out the injector pattern. They looked normal to me, both firing in conical shape on startup. Someone can tell me if that's not right.

Anyway, I turned off the car and looked over the throttle body. I noticed a little white smoke coming from around the butterflies so I manually opened the throttle, and sure enough there was quite a bit of white smoke in there. Something tells me that's not normal. Any thoughts on what could cause that??

SpitotRs305

yes the spray pattern should be conical and even with no disturbances/voids in the shape

as for the smoke... probably not smoke but fuel vapor or a small back fire... not anything real worrisome there unless we are talking vast amounts...

bbexperience

Thanks Spitot.

I don't know if I'd say it had no disturbances. Hmm.

Above I mentioned that I'd replaced the IAC. What is the "official" idle relearn process? The service manual says to start the car and let it idle for a few minutes, then put it in drive and let it idle. What if the car won't even idle in the first place, then what? I'm wondering if the new IAC isn't getting reset.

I'm really banging my head on the wall here.

bbexperience

I thought at this point a summary might be helpful to both those sharing this problem (or a similar one) and those trying to help.

'91 RS 5.0L, stored for 2 years untouched.

Symptoms:

• At first it ran ok, then mysteriously started stalling out at idle. In the beginning the idle would roam back and forth from ~500 up to ~1500. Now it starts, runs for a couple of seconds and then stalls. The issue started the day after an oil change (could be unrelated).
• Keeping the throttle open at a constant level causes it to rev up and then stall. You can see/hear the injectors giving more gas as the throttle is opened.
• Sometimes (but not always) when the throttle is opened and then it starts to stall you can hear the injectors make a weird hissing/sputter sound. Once in a while when it stalls they'll make a sound like opening a well shaken pop bottle and shoot gas UP to the hood. Is that a misfire? I've not seen one with the injectors exposed.
• When the throttle is opened there are puffs of white smoke that come from the exhaust
• After throttling and after the car is off white smoke can be observed around the butterflies. Manually opening the throttle reveals more white smoke in the throttle body. Per SpitotRS this could just be fuel vapor or a small misfire.
• After throttling the car even a small amount the exhaust fumes/smell is much stronger than it should be. And yes, I have the rear of the car at the garage door, which is open. The other, two bay, garage door is also open.

Parts replaced:

• EGR Valve
• Idle Air Control Valve

What I DON'T think it is and why:

• Coolant Temp Sensor - I disconnected the sensor, started the car, and had the same issues.
• Fuel Pump/Fuel Filter - Though I'm sure the fuel filter needs to be replaced, it doesn't make sense to me that more gas can easily be given when the throttle is opened, but it can't stay running. If it was the filter you'd think it may struggle to give it more gas but it would be able to sustain a stream at a constant throttle level.
• Vacuum lines - I've inspected all of them that I could find and found no cracks, hisses, or leaks. Also, it seems that, unless a line suddenly broke, a vacuum leak would cause a gradual issue instead of a suddenly-one-day-it-won't-stay-running scenario.

Things I suspect:

• Throttle Position Sensor - It seems to me that if it's bad the ECM might think the throttle is open when it isn't or more open than it is, resulting in a bad fuel/air mixture.
• Spark plugs - The plugs on this thing look like a PITA to get to so I haven't pulled them yet. However, if one or more are bad could they cause something like this?
• The distributor or some part of it

So, there you have it. Again, the more suggestions and advise the better because this thing is really killing me!

92drptp

I have just started with mine so i have done alot less then you. But i also have the white smoke been told not to worry its ok. My exhaust has a similar smell. I dont believe its a fuel delivery problem because i have replaced both the fuel pump and filter and the problem is still there. before i start changing sensors out i am gonna have my alternator checked to make sure its giving enough juice (unlikely the problem but free to have checked and easy to remove) i also plan on swapping out my coil because there is a small chance (i believe) that it is the coil burning out. i have an accel 300+ ignition for the car but dont want to install it untill the car runs right. Does any one know if i can use the coil from this without installing the ignition controller. or do i have to put a stock replacement in and then if that fixes the problem then in stall the accel unit.
Like i said not sure either of these things are the prblem but i figure start were it will cost me the least money and go from there.

Shinobi'sZ

You changed the cats too right.

I have the white/grey smoke to if the cars sits over night or for awhile..the very first start up and it has a big cloud of smoke...I only have 50K original miles on this car and it sat for 12 years in the garage..still has the original tires from 1991.

I think the white/grey smoke (that doesn't smell like fuel because I run back and sniffed the cloud lol) is oil leaking past old valve seals...this could be the case...and if oil is going out he exhaust there is a good chance it can clog the cats.

However I jumped in the car, switched the ignition on, listened to the fuel pump prime, and the car fired up immediately this morning and didn't miss a beat...in fact some little Dodge Neon was trying to go faster up a grade then me this morning and would let me pass him easy so I got on it and hit 100mph with no problems. I can't wait to put an LSx in this car...it didn't take him by that much...my Z06 wold have dusted his azz.

Anyway I don't know when I will get to this swap though..so I would like to fix this low mileage TPI car.....looking at what everybody has done I'm thinking it could be a TPS based on the parts replaced...but you should replace the fuel filter too along with ohm'ing out the fuel injectors.

afremont

If you unplugged the coolant temp sensor and it didn't make a difference, then I'd suspect it has problems. Unplugged, the computer will think the coolant is -40F and enrichen the mixture way too much. It should have also thrown an error code when it was unplugged. Unplug it and measure the resistance of it when the engine is cold and when it's warm, that will tell you if it's working right or not.

92drptp

went and logged some time with mine tonight found that alternator and coil were still ok as i thought (but never hurts to check) I replaced the map sensor because a few freinds (mechanic and body men) thought it was a possibility. None of this helped but did discover that one of my plug wires had come loose (appeared connected but wasnt) so essentially was running on 7 cylinders. getting that hooked upm helped a ton still running rough though. I am assuming all the time toying with out fowled out the cylinders pretty bad (especially the on not firing) stilll have to change all the plugs and hope it fixes it but thought this might be helpful. Sometimes looking for the big problem we overlook the little stuff. You live you learn, die and forget it all. i hope that fixes mine and you have similar luck ill check to see if you have any luck and see if i cant help out. Have you tried replacing the ESCM that was what some speculated with mine.

bbexperience

No, I didn't try that. I replaced the TPS tonight, but no love. I thought I went through and checked the plug wires but didn't find anything unusual. I never did actually pull the plugs though. Oh, and I tried the disconnecting the coolant temp sensor trick again. This time it threw an SES light at me with a code 15 - coolant temp too low. However, it didn't seem to change the way it ran. I think I remember reading somewhere that if you disconnect that sensor the computer uses some default values.

It's being carried off to see the professional tomorrow. I really have neither the time nor inclination to continue struggling to figure out what's wrong. I'll be sure to update here when he let's me know what he finds out.

Shinobi'sZ

So you did read the fuel pressure and measure the ohms on the injectors?

bbexperience

No I did not.

Nobody around here rents out fuel pressure guages/equipment, which means I'd have to buy one. Then I'd have to go through the process of installing the thing which is a pain from what I understand, due to the lack of a Schrader valve. I also don't have a digital multimeter at the moment which means I'd have to buy one of those too, and then figure out how to use it. I know they're <$20.

At the end of the day, I decided that I'd rather just send it off to somebody that has the time to look at and give me a laundry list of what's wrong. That's not to say that I'll have him fix most of it but at least I'll know what's wrong with it so that I can fix it. Maybe if I didn't have so much other crap going on right now it would be a different story but right now I just don't have the time to spend all of my non-working waking hours with the car.

I'll update here when I know anything, to (hopefully) benefit others that have similar problems.

92drptp

just thinking i know you sent yours off but did you check the O2 senser

hurm2006

im working on my brothers 91 camaro 5.0 tbi with similar problems, the car had been starting hard for awhile. would have to crank it for 15-20 seconds to get it to fire and then it would sputter and die, would start back up right away but sputter then after it warmed up a bit it would idle fine. but when you drove it the throttle was very hesitant. i was driving it the other day and it started runing rough all the time, i limped it home and messed with itthe only way i can make it stay runing is by sprayen throttle body cleaner down it...it will run great if you keep sprayen tb cleaner at it. my thoughts are the fuel pump, or filter although they were both changed not very long ago, had plugs, wires, cap, and rotor recently also going to check fuel pressure and check for codes tomorrow. also thinking maybe sumthing with the pulgs because id imagine tb cleaner will burn easier than gas...i will let you know if i find anything

bbexperience

Okay, I got mine back Friday but I didn't have time to post. Turns out the issue was indeed the fuel pump, so good call to whoever it was that named that as the issue. The fuel filter may have also been a contributing factor as he changed that also.

After the fixes it idles fine and has much better acceleration than it did before it started stalling out. The next issue will probably be fixing the exhaust system as I have a crushed Y-pipe, a small hole in the muffler, and small holes in both tail pipes.

Thanks to all who contributed to figuring this out even though I eventually outsourced the diagnosis, and I hope it helps somebody else out there.

entrig00

iTrader: (1)

bbexperience - So it was the fuel pump. How did you figure that one out before even purchasing one? I was having the same problems as you can tell. My camaro turns on then turns off like everyone else here. I think my fuel pump it out of going out? How can I find that out without using a fuel presure gauge? I turn the key and press down on the fuel release valve thats on our fuel rail and a lot of fuel squirts out....people said if that happens then your fuel pump is fine. Did you do that before you changed it out?
Just making sure before I go and get a fuel pump...

Oh yeah what kind of fuel pump did you get?
Thanks in advance....

bbexperience

I actually didn't do the work myself but I asked the guy how he determined that it was the fuel pump. Apparently he has some sort of rig that basically runs a fuel pump outside of the car. I'm not sure exactly how it works but it bypasses the existing pump and must tie in to the fuel lines somehow. The idea is that if the fuel pump outside of the car fixes the issue then the problem lies with the existing pump. That's probably not really helpful to you unless you happen to have one of those things. But if you had one of those you'd think you'd have a fuel pressure gauge. Honestly, I don't know if there is a surefire way to tell if it's the pump without a fuel pressure gauge unless you want to have it towed somewhere to have the testing done.

I'm not sure what brand of pump he put in as it doesn't give that detail on the bill.

entrig00

iTrader: (1)

wow wish I had that Lol....but hey glad you got yours running


Thanks again...

jjz109

bbexperience, i'm having the same exact problem. I have a '90 Auto 5.0 TPI with the stall/surge problem but I have a new fuel pump. The car sat in a barn for 2-3 years too. It will start fine but after 5-10 minutes driving, it will surge and then idle will go really low and stall. Seems to do it mostly at stop signs, lights and on hills. Weirdly, when the A/C is on the stalling goes away. Of course as soon as I turn the A/C off, the stalling comes back.

My mechanic did a tune-up, replaced the IAC, the fuel pump (he had to replace the sender) and replaced the fuel injectors with these: http://www.fiveomotorsport.com/Injec...sTPI.asp#caddy
And after all that, it's still stalling.

He then said the pickup on the Distributor was bad so he replaced the distributor with a rebuilt Cardone from Auto Zone. The distributor made sense to me since he said the A/C generates a charge which raises the idle. But after replacing the distributor, it's still stalling. My mechanic is about out of ideas and he said there are no vacuum leaks but he now thinks it could be service bulletin #91-239-6E Low Speed Drivability (PROM) New Knock Sensor Available (Feb. 28, 1991) and that I need to replace the PROM with #16163139.

Does anyone know of this PROM chip is still available and/or do you think this is the problem? The car is bone stock except for the Flowmaster and the exhaust smells kinda bad.

91 F Body

Hey Guys.

I have a 91/305 TBI which is my wifes car and I just finished rebuilding the engine since the rad fan died again and was overheated one too many times. With 265,000 it didn't make sence to just try to fix the Head Gasket.

Problem.

Engine runs good until it warms up and then it surges at an Idle and while driving. I had to replace the O2 sensor and Air Pump and now have changed every sensor including Knock, Idle Air on the TBI, Water temp sender and the one on the intake by the thermostat. The Water temp gage also will indicate 260 and higher but the engine is not overheating. I verified all the grounds and they are good. Now I just replaced the ECM and ESC as a last resort but it remains the same.

Any Ideas?

I did change the Ignition switch a couple of months ago could it be an issue?

Chriznoznae1

I'm having the same problem and replaced all my sensors but it still has the stalling issue. I back probed and voltage drop tested all my grounds and verified all voltages to the sensors and they all checked good. I also have no kind of vaccuum leaks and have been racking my brain over this stalling and surging. The only thing I did find wrong with my car is that the air diverter/selector valve for the smog pump has a bad solenoid because it measures no resistance and according to my manual if either of those solenoids are bad along with the cts or the idle air control it will burn out the drivers in the computer. So I'm wondering if anyone can chime in and yay or nay this for the truth and tell me that my problem will be fixed if I replace this diverter/selector valve and replace the computer.

honestabe77

I have a 91 camaro with 305 v8, when I first bought, it started fine and it hesitates when it give gas around one to two rpms. So I replaced all wires,plugs, rotor and cap. Now when I start it will somestimes stay on and when it stays on, I can give a good run around the block and it will stay on. But once it turn it off and then turn it back on, it wont stay on. I have to give it gas for it to stay on and if i ease off the accelerator, i might be lucky that it will stay on. Any suggestion?

91 F Body

Well I Figured this one out!

The day following my post I took the car down to my cousins shop and put it on the Scanner. OBD I doesnt offer much more than what you can pull from the Check Engine Light Code readings so I pretty much wasted the day which several others trying to figure it out with no determination.

The next morning I had the thing up on the ramps and I was laying under it trying to come up with some alternative ideas that haven't been already tried while double checking all the engine grounds etc. Some of the plastic wire loom was coming appart so I pulled it off to replace it and there it was! The Temp sender wire and the O2 Sensor wire had about a 6-inch section inside the loom that there was no insolation left on the wire and they were shorting out. The O2 sensor was putting voltage to the Temp Gage (False overheat indication when driving) and the Temp Sender was causing a ground fault to the O2 wire going back to the ECM causing it to go into Limp mode.

$0.10 worth of wire and things are good as new. Wish I could have found it before the other $500.00 worth of parts, senders and a computer.

I looks like mice had been chowing down on the loom and wire insolation and as the vehicle was driven the loom slid back down over the exposed wire hiding the issue all along.

Thanks everyone for the help in the past and I hope this post helps someone in the future.

transam85dudeman

thanks buddy

Nathansinke

Try the idle air control valve on the throttle body. See if that does anything or rhe mass airflow sensor

88TPI406GTA

Why necro a 7 year old thread...that had a solution?

Shellcat1969

my '89 iroc sat under a carport for 6 years...and is doing the SAME thing with the idiling! If I turn the a/c on...perfect...turn it of and surging! Do you mind sharing what you've done to fix yours? Thanks! (I've replaced mass flow sensor, new computer, fuel pump, plugs, wires (tune up) just to name a few) thanks in advance!

Chriznoznae1

Well I did the same song and dance as far as doing an entire tune up and more. I changed the computer and the chip to no avail. What fixed the problem for me was changing my throttle body back to the original 48mm instead of the bbk I had on there.....hopefully that helps.

Nitro212519

I know it's an old threat but I had to post my solution for my high idle issue (1300 RPM) I did the same thing 91 F body did I pulled off the wire loom to replace and inspect it and there it was! the O2 Sensor wire was damaged so I fixed the damaged area




1992 Camaro RS 305 5.0L V8 TBI

ActualSceptile

It's you fuel pump and fuel filter change both that will get you running right.