Ok so my 1990 Camaro RS 3.1L always idles really high(~1250RPM), and when it tries to idle low(<1000RPM) the car shakes and then the lights dim and it wants to stall out, but the IACV opens up and raises the idle speed, then it tries it again and does the same thing. This makes it really hard to get going from a stop because the car hesitates and bucks and just doesnt want to get going, or stay running. But once the car gets running it works perfectly.

I've had all new ignition, checked my battery numerous times, had the alternator replaced, so the elctrical system is in good shape.

I've gotten 2 new injectors(2 failed in the summer) and I SeaFoamed it, and i dump fuel system/fuel injector cleaner in it all the time.

New Parts:

New IACV
New PCV Valve
New Grommet to go along with it
New TPS
New Idle AIr temperature sensor(The one on the air cleaner box)
New intake manifold gaskets
New gaskets around the entire intake and throttle body
New EGR valve

All my parts are cleaned and readjusted all the time, because I am still trying to get it running right, and I try to make the proper adjustments. I have also reset my computer, and have hooked it up to my code scanner tool, if any code at all it gives me a code 25, which is a bad VSS, but I know that mines dead on all the time and works fine.

Another question though is.....what is the proper/normal idle speed supposed to be set to? I read that the maximum when to operating temperature should be 900RPM, and it should generally idle 600-700RPM, thats the speed that mine seems to want to idle at, but then it surges back up.

Also, Ive checked all my vacuum lines, sprayed throttle body cleaner on them and havent been able to find any leaks, cleaned my throttle body out, and checked the spark plugs and everything.

Is there something that I'm missing?!

I'm out of ideas, so any help anyone could give me would be greatly appreciated, thanks!

 

You forgot the MAP sensor... Check the voltage signal coming out of it, check the vacuum line for damage and remove it from the sensor to see if ANYTHING comes out of the sensor, be it water, "goo" (yes, that's a technical term ), or anything else. Also check the little elbow thing that attaches to the MAP for cracks that are sealed in the normal position.

:edit: Code 24 is a bad VSS... Code 25 is a bad IAT sensor in the air filter can or wherever you have it.

 

Lol no I just forgot to say I replaced it, its about 5 months old now, but its been replaced!

 

Still should check the signal... It IS possible you got a bad one.

:edit: Also check the connection between the intake bellows and the PCV pipe. Breaks occur easily there, especially with as many times as you've had it off.

 

Alright, I guess its time to get out the OHM meter, If i can find it haha, there shouldnt be anything in it, when I had it replaced, it was when the car was broken down b/c of the bad injectors, they zip tied the connector together because it was causing problems, maybe I jsut got a bad one....

 

So far I havent been able to find any bad vacuum lines on the engine, ive sprayed them all down, with no changes to the engine speed, is there something in that category that I could be missing?

 

Also check ALL of your fuel injectors when you do the MAP. Each injector should read 12.4 ohms plus or minus .8 ohm. Any more or less and you need new ones.

:edit: Also check the canister purge solenoid... Is it possible you're throwing a code 45?

 

Half the time the engine doesnt throw any codes at all, but sometimes it will give me a code 25 and thats it, and thats short circuit on VSS, doesnt make sense, if it was off it should just make the car think that its still moving right? But then the way to check that would be to look at your speed, and when I do its on with radar( Ive got like 2 speeding tickets and they were dead on so far lol) and it says I'm stopped when I'm stopped.

The canister purge solenoid vacuum line was in question a while ago, but I fixed it, and the connections are good.

How hard is it to check the injectors? And what should the MAP sensor read on the OHM meter?

 

my friends 2.8 fiero was doing the same thing turned out to be a bad computer

 

I told you before that code 25 is for the IAT sensor, NOT the VSS (code 24). You don't ohm out the MAP... It puts out a voltage signal similar to the CTS and IAT. You do, however ohm out the injectors, one at a time.

I'm also not talking about the canister solenoid's vacuum line, I'm talking about the solenoid itself (could be leaking or not working and stuck open).

 

Thirdgen says code 24 is VSS, and 25 is IAT and vacuum issues

https://www.thirdgen.org/service-eng...ht-error-codes

But nonetheless it is giving me a code 25 now, and thats exactly what I was looking for, and now I know for sure that I have vaccuum issues, or vacuum related parts issues. Its getting dropped off at my Chevy Dealer tomorrow morning for an oil change and to get his problem fixed.

 

Well, that's not what BOTH of my FACTORY service manuals say. And you do realize that the dealer is going to flat-out rape you, right?

:edit: Checked your link, they have it wrong... The low/high codes are generally right next to each other (23 is IAT low, 24 is IAT high, 33 is MAF/MAP low, 34 is MAF/MAP high, 44 is O2S low (lean), 45 is O2S high (rich)...).

 

Its my hometown dealer, I almost had a job there and all the guys know me and like me, its one of the dealers that might be getting cut by the GM dealer reduction, and they might be going out of business, so I'm glad to help them as best I can. I lost the book that came with my code scanner......its just an Actron Code Scanner tool.

I dont trust the garages around here anyway...one didnt fill me up with the right amount or type of oil one time the other tore apart my engine when it was broke down, and then almost couldnt put it back together, they completely disregarded the fuel injectors.....and that pretty much sums up the rest of the garages around here....so I feel better going to a dealer

 

Now that you put it that way, I see why. Yikes!

 

Yeah...its absolutely ridiculous, I'll just tell them that I want them to find out what the problem is before they fix it, that way maybe I can do it

 

I hope they don't take too long and cut you some slack. Just for diagnosis, around here at a dealer I interned at, the rate was something like $70 an hour.

 

Thats what it is at Blaise Alexander Chevrolet, but I'm taking it to Hulsizers Chevrolet, they charge $55/ hour vs Blaise's $75/ hour. One time they diagnosed my car for FREE! Another time they hooked my car up to the code scanner tool and performed an idle learn for FREE! And when I order parts there the guy used to be my neighbor and he really likes me, and he give me employee pricing on the parts I need. That and the fact that the guys in the body shop are big 3rd gen fans, makes it the perfect place for me to go, and its right in town!

 

When they figure it out, could you let me know? I've been having the same problem for a while now and still can't figure it out (the only thing I can possibly think of that I have left that could cause the problem is my MAF and this will be the third one in 4 years). Except that I'm running a code 45 and can't figure that one out either... Between 2 coils, 2 sets of plugs (which don't show that I'm running rich), 2 sets of plug wires, and 3 sets of fuel injectors, TPS, IAT, CTS replacement along with checking the signals to the ECM from the ignition module, 3 ECM's and 2 FI systems (302 and 730), I'm stumped. And now the car is stalling if I spin the tires for any more than about a second (crappy NY weather!).

 

Holy cow! Yeah ill be sure to let you know what they came up with, you've given me enough help and Ill help you as much as I can. It just pisses me off that it will run just find but idl like ****. Ive replaced most of my sensors and i have all new igntion, and my cars also had like 4 other ecms in it....I'm just stumped as to what to look at next, I'm pretty sure that I have a vacuum leak somewhere tho, at least I'm really hoping

 

My computers been interchanged with a new one, and been tested numerous times, it always checks out in perfect condition

 

The funny thing is that I know I don't have a vac leak (smoke tested the system so I know it's good). It does misfire, pretty much making sure I can only make short-range trips (good thing I don't have to go 20 miles to work a day). I wonder what would happen if I made a small one? Hmm. Either way, I have to find my compression gauge and test cyl #5, which seems to be the worst offender.

 

Ok so you have good vacuum, and your not sure about compression, have you checked timing? What about fuel? You should be getting spark since you replaced wires and plugs and such. Hmmm......Is your torque converter good? If its not it can make a tranny lock up and stall a car at any time, that could be your wheel spin issue right there

 

I've been thinking that maybe one or both of the #5 valves may have loosened up or that the head gasket cracked again between cyls 3 and 5 (replaced both back in 05 because of 110-130 PSI compression in both cylinders), but I haven't been able to find my compression gauge since I last used it a few months ago. It's probably buried in my pile of 3100 parts... But, anyways, when I last tested the 3.1, all cylinders, with the exception of #6 because the valve guide needs to be replaced and is leaking oil into the cylinder and causing compression 20 PSI higher than the rest, the remaining 5 cylinders were around 160-170 PSI.

Timing was last reset 2 months ago and I don't think has changed since I actually tightened the dizzy bolt this time (usually leave it loose enough that it does take some force to turn the dizzy but it don't turn on its own).

The engine does the same thing between 3 sets of injectors...

Don't have a 700R4 in the car as I swapped to a T5 back in the early part of 06 (actually, the 700 is in my garage under my work bench). With the roads and lots being so crappy around here, I generally start in 2nd so I can actually GO somewhere. Thing is, the engine speed drops pretty low and then comes back, but the SES light comes on and the idle speed goes up to 2K a couple times and she dies (with my foot disengaging the clutch).

I might have worked something out today... A controlled vacuum leak in my EGR line, which is ported. I have a T in the line between the EVRV and the throttle body, which is supplied with very little vacuum at idle (roughly about 3" Hg when last tested) to let a little more air into the cycle, and opens up as the throttle is opened, of course. I'm thinking that my MAF is reading high for some reason (maybe it needs to be cleaned because of my K&N style filter, IDK) and the ECM is adding extra fuel to compensate. I'd check the MAF signal, but that requires either a scantool or my laptop being hooked up to the ALDL with a cable (neither of which I have). I'm going to see what happens in the morning in terms of misifiring as I head to work. But, for right now, she at least seems to be better with no misfiring at idle when hot and a nice, steady idle at 800 RPM.

 

Thats weird because when I start my car in the morning it wants to idle at 3000+ RPM. It pisses me off because I know it should not be doing that at all. When I put it in gear tho it drops right to 1250 rpm, which is still fast but thats the normal place that it idles for me. Ive been trying to check my egr valve to see that its not dirty and stuck open, but everytime I try to get it taken off, the bolts are rusty and impossible for me to remove, so idk how they got it off at the shop when they replaced it last year....

When mine gets nice and warm and im sitting at a red light, it wants to idle at 700-800 rpm but it just cant, there has to be a vacuum leak somewhere in the system because it is just constantly hunting and hunting an hunting for a good idle speed, and the computer so far hasnt been able to compensate and get a good speed, it will surge for a while and then return to 1000 rpm and then try to drop down to 700-800 and then it goes to like 500 and surges and repeats the cycle, so idk anymore, i still havent taken it to the dealer because we got snow on friday when i planned on taking it, and i didnt drive. But its gotten a bit warmer out here so I'm going to change my oil myself now!

 

Check the signal out of your new TPS. It may be out of spec (no more than .96V, IIRC). If you have to, enlarge the mounting holes so you can bring the TPS voltage down to around .6VDC. When I recently replaced my TPS (as per the code 45 repair tips), my TPS was WAY out of spec (.55VDC on my system, running at .76V) and my idle did that. The TPS tells the ECM where the throttle plate is, and if it's out of adjustment, the ECM adds fuel relative to where it thinks the throttle plate is located along its travel. The signal is checked between the blue (or green) wire and ground.

 

I adjusted my TPS today and now it will idle nice and steady around 900-1000 still fast but much better, now the test will be to see how it idles when i first start it in the morning tmrw

 

It's supposed to idle in the ballpark of 1200 RPM until closed loop, where it should drop down to about 7-800 or thereabouts, depending on where it's set. Adjust your minimum air rate and see if that helps. Should be about 600-700 RPM with the car in Drive and parking brake set, with the IAC closed and disconnected.

 

I need to teach it its proper idle then....how? lol

 

There is another way besides using the scantool as recommended by my FSM. It may be in the FAQ, but other than that, you'll need to do a search. I believe you have to put the car in Drive and stand on the brakes until the coolant fan comes on, shut the engine off, and do the same again.

 

Did a search on what I think Maverich was talking about.
Try this out hopefully this helps....

Idle Learn Procedure for 3.1L V6 (auto only?):

Disconnect battery, wait one minute, and reconnect.

Turn off A/C.
Turn off Backlight Heater (rear window defroster).

Do Not Touch The Throttle at Any Point.
Do Not Touch The Steering Wheel at Any Point.

Set parking brake and chuck tires.

Start engine, let settle a bit and put trans in drive.

Let engine run until fan cycles on then off.

Turn off engine.

Wait five minutes.

Start engine and place in gear.

Let idle for five minutes.

Shut off engine.

End of procedure.


If the throttle is touched at anytime during this you have
to start from the 'disconnect battery' again.

If the steering wheel has pressure applied you have
to start from the 'disconnect battery' again.

If the engine stalls at any point just restart and place
back into gear.


Been reading some of this from you guys and good stuff I'm picking up. Im having problems with fuel pump or now doing research and reading your guys stuff I dont think it is. Either way I wish I had your guys knowledge...good stuff you guys put on the table...

 

Only problem is that:

1) I dont have a rear defroster lol
2) I know for a fact that the car will not reach the point to where the fan comes on, at least not when its this cold outside.


I left it run for almost 20 minutes the other night after i drove it home, and i was in the car the whole time, and it never reached a temp anything higher than 210 on the gauge.

 

If you have a garage, run the engine in there with the tail pipe coming out of the garage. Keep in mind that our gauges and gauge senders are old and may be inaccurate (my fan comes on before the 210 mark on the gauge, usually). It may also be that the CTS is screwy as well. I know that if I let my engine run long enough, even during the winter (turn the heater off, by the way... it's another radiator), I can expect the fan to come on at some point if I let it run long enough.

 

No, my sensors are new, and my dash has been worked on to make sure that it works, its the original dash, but the guy who had it before me had it serviced. I have a new temp sensor, and new fan switch, and brand new anti-freeze. And i dont turn the heater on. well i do but not when i try to get it hot. plus i made sure that the coolnig system was correct, and everything worked the way it was supposed to in the summer, because i did NOT want the car to overheat, and well it never did lol its a cool running car

 

the CTS is new, and so is the thermostat, well now before i replaced these and the anti-freeze the car would get hot and the fan turning on was something normal, but not now

 

Damn ?

Well at least you can turn your camaro on lol....

 

entrig00 you still dont have yours up and running?! omg i remember you telling me about it back in july

but yeah ive replaced a lot on the car, it runs pretty damn good now too i must admit myself, im so proud of that car!

i just cleaned the inside of it today and when i got it i didnt notice this black stuff on the floor on behind the drivers side, never could figure out what it was either but i just got it to come out with guess what....WATER, and a little bit of scrubbing lol i never tried to get it up caz the mat covered most of it, but now its gone!

whats wrong with yours entrig00? whats it doing now?

 

Hey man hope all is well. As for the camaro the damn thing is really pissing me off lol. But to be honest with you I think its the fuel pump. But ya back in july it was the sensor after sensor now Im very positive its the fuel pump but that should be fixed some time next week I'm hoping. This sucks!!!!

 

Goodluck getting it back up and operational.

So i guess it was running sometime in between now with the fuel pump and back in july with the sensors?

 

Ya you can say that. Funny thing is that when I had bought the camaro the guy said that he had replaced the fuel pump which I know he did because he had made that cut out the to get easy access, the know rather then dropping the tank.

All this time I think the problem was the fuel pump now that I know what symtoms relate to it. I know I had a bad TPS and that was a bitch to mess with.

I'm going to have to PM you and see if you can help me with testing or changing out the ignition coil or the pick up coil or ignition module....I have no knowledge in this and alot of people are telling me to check that out.....

Your help would be great LOL

 

Ehh....as far back as I go in ignition systems is the distributor.....I don't know anything about the coils or anything. I just know that its the battery, ignition coils, distributor, rotor, cap, wires, wire boots, spark plugs, igntion.

Check your boot wires if anything, if one of them is bad it will make it miss like a MOTHER, had that happen to me once.

And I don't know what you've done so far, but check your cap and rotor and the top of your distributor for rust or carbon lines. Anything like that can mess it up. Now rust on the distributor isn't as bad, but it can get bad like all problems with rust.

You can't check the distributor with out really taking it out for this, but if its bent it will also cause poor ignition and ignition problems.

Carbon lines on the inside of your cap are bad, as the spark will run along it and completely mess up the ignition cycle of the engine, sending a spark to a cylinder that isn'y supposed to fire until the next second or so, you know what I mean.

I know that cracked, rusted, bent, or dirty corroded coils will also give poor/unreliable spark. But thats about it.

And if you haven't already, just give it a tune up with new spark plugs and wires, plus cap/rotor.

New spark plugs can make a world of difference.

If they are wet, or smell like they got a bath in gas then you know somethings not good with the sparkplugs, and they could possible be fouled out.

Also, last but not least, if your battery's voltage is running too low or high, it will throw the whole system off. Get it tested. Last time i got mine tested it was running at 12.55 volts, which is right around 12 and close enough that it passed the test.

But other than that, I dont really know much more about ignition unless you want to get into the ignition parts in the steering column and that. I had a steering column part go bad on me that wouldn't let me turn the key to give the spark fom the column to the rest of the system to signal the engine to start cranking, but it doesn't sound like your having those types of issues.