i have a 88 camaro with a 2.8 v6. Recently when the car gets warm enough to idle at normal idle (750rpm) when i take off from a stop it misfires multiple times and is very choppy, when i get to whatever speed i want to stay at it stops and runs fine and does this at every stop. sometimes at stoplights the rpms fall to 500 then jump up to 1000 then back to 750 and repeats untill i take off. it runs perfect for a few minutes when its first started cold. theres no vaccume leaks and i just did a tune up 3 months ago. any ideas are welcome THANKS!!!!!

 

Sounds like ignition coil, ignition module, dizzy, IAC, or o2 sensor..any ecm codes?

 

I agree with 3rd gen RS; I would remove/clean the IAC (Idle Air Control) motor's tip:

1. Turn the engine off and take the keys out of the ignition- make sure the car's completely off while you do this.

2. Unplug the square 4-pin IAC connector, and remove the IAC motor from the throttle body using a big adjustable wrench.

3. Hold the IAC motor so the tip (will probably be black with carbon) is pointed down, spray the tip (JUST the tip) with carb/choke cleaner. Don't get any spray inside the motor or it'll be an $80 mistake. Let the motor air-dry for a minute then put it aside.

4. Remove your air intake hose. Spray the cleaner into where the IAC motor was, there's a passageway that goes to the front of the throttlebody. You'll see the gunk come out of the front.

5. Reassemble everything when it's all dried. Don't overtighten the IAC motor when you put it back in (don't want to ruin the threads in the throttle body).

I'd say it could be the ignition timing too but you said you just did a tuneup...

 

What exactly is it that makes carb/choke cleaner bad for FI engines? I hear it all the time, but I have never actually heard the reasoning behind it and what it actually damages..

 

Isn't it because there's a chemical that removes some kind of coating that protects whatever you're spraying?

 

Yes, but not all injected engines have the coating. Pretty sure ours don't. 88's don't have a screw-in IAC, theirs bolt-on, BTW.

Sounds like what I went through the month before my ignition module got fried for good. It was already bad, but sparking off the coil without a direct path through to ground fried it for good (they were checking the injector spray pattern and sparked off the coil good... I wanted to hurt that guy... ). If you have a tachometer in the dash, watch it as the engine misfires. If it jumps, the module is toast or is going to be shortly.

 

Wierd, where would the coating normally be, the intake manifolds? Just seems odd, and ours probably wouldn't have it...early year FI.

 

I replaced the IAC because it just looked awful it does run better but did not fix my misfiring prob i will try o2 tomorrow. it shouldn't be my ignition module i replaced that 2 years ago when i got my car if that's the prob ima be pissed lol. thanks for all the ideas everyone! i think were getting closer

 

Coating is normally either in the intake plenum or on the back of the throttle plate or both. A lot of newer Fords specifically have a label saying "DO NOT CLEAN THROTTLE PLATE. PLATE HAS A SPECIAL COATING" and something like that.

 

my camaro does the same thing. it idles really low. like in the 200-300 rpm range. it will stall when stopped at lights if i dont give it gas. and sometimes when i go to accellerate its boggy and jerky, and i have no power. i thought it was my fuel filter/O2 sensor put both in new and nothing changed. please help!

 

That sounds like a vacuum leak... Either that or the IAC on the throttle body is dirty and needs to be cleaned really bad.

 

thats the thing i did a vaccum test and it was normal. and today i pulled my IAC and cleaned it. my Intake manifold looked really dirty, not sure how to cleAn it properly. and now my car has a missfire....which explains the rough running... just have to locate the source of the missfire. i checked all my plugs. and regapped them. i was thinking moisture in my distributor, or a faulty plug lead. how do i test my leads?

 

i just did this today. i sprayed the "tip" meaning the carbon coverd end, and the little spring? cause i sprayed that to....could i have F***ed my IAC?

 

Plug wires should have no more than 20K ohms resistance from end to end...

Only worry about the IAC when you figure out if the engine runs properly or not with new plug wires and what not. Also, remove a plug and hook the wire back to it. Remove the front fuel injector harness connector (to keep the engine from firing) and crank the engine, noting the color of the spark. If the spark isn't bright white, you probably need a new ignition coil.

To check if the IAC is working, put it back in and put the wire into the ALDL as though you are looking for codes. Turn the key on (but don't start the engine) and go place a couple of fingers on the IAC. If it's working, you can feel the IAC vibrate as it's working.

:edit: Also, what reading did you get for the vacuum test?

 

ok im gonna replace my wires, and the vaccum test was 16 psi when idle. .. and what do you mean by "Also, remove a plug and hook the wire back to it."

 

Well, you have to take the plug wire off of the spark plug to remove it, right? Put it back on and crank the engine, with the plug resting on a plenum bolt or somewhere it will ground the body of the plug.

 

ahhhh. ok i will try that when i get a chance. thanks ill let u know my results

 

My son's 91 Rs did had a similar problem. I found it at night. my clue was a ticking noise on the passenger side of the engine. The V6 igintion coil mounts on a bracket which bolts onto the cylinder head above the exhaust manifold. The round part of the coil body comes very close the the right valve cover, close enough to make contact. The normal vibration of the engine can cause a hole to wear in the coil body alloing spark to jump to the valve cover. This was worse when the engine was warmed up and under load as when accelerating. A new coil solved the problem. hope this helps you.

 

Half a can of Carb and Choke cleaner (on my spring, under air filter, all over exposed TB parts) is helping mine. Someone mentioned "coil" and i also want to change the fuel filter. Still cant find it.

the "running rough" usually meant my vacuum "patch" wore off, lol.

Here is that nice duct-tape job now. i was respectful enough to get my camera back, so if i ever have a question i can photograph what im asking about. in this case, a large vacuum eak made the car act as if it had no gas, OR a dead battery.. and it finally started up but sputtered and didnt really ever do that again until what you see taped (EGR, on the right) came loose. it hasnt come loose again and now im wondering "what to do next" - spark plugs and fuel filter and wires i WANT to do. it also starts off WITHOUT mew having to -floor- the gas since spraying 1/2 can carb/choke cleaner on exposed TB and down fuel throat while car is running, HTH.

 

Could use a couple more pics of that setup... That doesn't look like an EGR valve to me only due to the fact that the one line off of the taped part feeds into a plastic assembly. If it were an EGR valve, every part in the system would be metal because the exhaust would easily melt the plastic. Is you car a stick shift? If it is, you could be looking at something completely different.

 

The part you have tape on is for the air to be pumped into the exhaust manifold from the air pump . Your fuel filter is in the carb on the drivers side at the bottom of the carb next to the choke . If you look you can see a metal line going into a big nut looking thing . That houses your fuel filter . To remove the filter hold the filter houseing with a 1'' wrench and use a 1/2 '' wrench to turn the nut on the line . If at all posible use a 1/2'' line wrench so you don't round off the nut .

 

I have more. It goes up into a valve i thought was an EGR the tape "Holds well" i thought it had to do with vacuum, this part. Was debating "Seafoaming" the car through the PCV valve, which works well (I pulled it, carb/choke cleaned it, put finger against it, it works good.)

This is not a threadjack,i notice my car uses a LOT of fuel (?) and id really like to know why. Someone says the "Float" int he carb is probably stuck, also a "needle" that lets gas drip ti the IMG? That would make sense, as i sometimes smell gas from under the hood.

It gets gas mileage like a Silverado 2500.

Unrelated, i also noticed that upon first starting the car, the voltage seems to fluxuate (intermittently levels f brightness for a few seconds on dash lights accompanied by rough running, before it stabilizes out, smoke from tailpipe for 5 minutes or so before it goes away completely, longer on cold days, and i also have NO FRONT turn signals ONLY and i have to manually FLICK it every time i do that, back works fine, flicking manually.)

Hopefully adjusting a carb float and needle isnt a big deal? I loosened up the "Choke" plate w Carb and Choke cleaner, still is fuelish and has some gas issue. I dont think my ING is blown, but they said "The needle could let gas run down into the IMG" wow

Im 28 i have an 84 Camaro looks like this and i thank you all for the insight and help. And my 2.8 DOES run rough so i feel im in the right place.

Thank you

Valve: (If that IS Air Pump it should hold right, it comes Out of Exhaust headers three tubes one for each cyl join into one, they meet at a pipe. My pipe BROKE hence the tape, goes up into a Metal VALVE above the tape, then goes into a hose, into another valve and then it has hoses that go to Throttle Body.)

My car: 1984 Camaro 2.8 Auto V6, sludged, 163,850 miles, im the second owner, cleaning her up, licking some issues! Runs WELL when warmed up, need help w a few things.

 

First thing I would check is plug wires- they can get burned through real easily. Second is check the resistance on ALL your fuel injectors. If even one is off, that can screw the computer up.
Mine was running like crap then not starting at all. Two wires were TOAST- I mean the boot was burnt so bad it was all white chalk. Turned out the EGR gasket was blown and the gases were cooking my wires. I had two injectors that were bad as well. Replaced them all with Bosch IIIs and new 8 MM Taylor wires and so far, so... don't wanna say it, might jinx things!

 

mick, he doesn't have fuel injection... His 84 is carbureted, and his plug wires are obviously brand new.

OP, I don't think you want to tackle the carb adjustment yourself. In my tech manual, it's like a 25-step process that involves complete breakdown of the carb and 2 special tools (float and needle are inside the carb). Although, like I've said before, I think most of your problems have to do with the AIR management part that's broken and a choke problem. The reason the voltage is fluctuating at startup is because the choke isn't acting right and the engine isn't running right, not the other way around. The reason you're using so much gas is because there is a problem with the choke not opening fully. It's possible that the accelerator needle is either bent or contaminated and not closing fully, but since this mainly happens on startup, I'd check the choke and linkages first, which is when those mainly come into play.

:edit: Oh, and duct tape will NEVER hold on that AIR check valve. Duct tape is good to about 400*... Exhaust parts get up to a good deal more than that (02S won't work below 600*).

 

Maverick H1L I really appreciate the information! Im going to try to find someone familiar with the carb (ounds like it can cost a bit, if those two things are harder to get to) and not really use the car until i can, except for shorter trips. Thanks!

Also, it sounds like my Intake Manifold Gasket is NOT blown, just eeding those two things adjusted? I really do appreciate it and i thank you.

If i had larger problems, id be having worse symptoms than "Smoke for 5 minutes on start up" i wonder if adjusting these things will solve that too! Thanks Maverick.

Ill report back when i can get it apart, and yes im going to contact someone and ask them about these two things. (Ill just watch so i can take notes.)

One last question: What "parts" do i go to the parts store and say "I need this and this and this" to get the tape off that AIR valve? i agree it will disintegrate in time, PO (previous owner) tape did and thats when all this started. it ran PERFECT before that. so maybe ill get the AIIR thing adjusted, THEN carb.. then i should be good to go, maybe even new Fuel Filter and spark plugs for good measure

All this misadjustment did this, btw

 

The tools aren't hard to find or get to, and they're probably dirt cheap. One is called a shepherd's crook and the other is a ruler of sorts (have to look up the name of it). Definitely find an old-timer that knows a thing or 2 about carbs, as he will know for sure if it's either the float, accelerator pump, inlet needle, or choke that's causing your problems (most of us newbies pretty much only know fuel injection and enough to know what a carb is, but not how to fix one). I'm sure that, most likely, a carb overhaul/rebuild will probably work wonders for that old engine.

 

I was just looking on Ebay and found a air check valve new and the line for the manifold that the valve attaches to . The pipe is a Standard Motor Products AT113 and the check valve is a GM 22040897 or 12562568 or 214-998 . You could check for these parts at a part store using these numbers or look on Ebay but the ones on Ebay would run you almost $80 for both . If you only need the check valve it is almost $22 on Ebay includeing shipping . You may find it cheaper at the dealer or part store .