OK, has ne1 had this type of problem. my z28 runs real strong when i have my foot on the gas but as soon as i come to a stop and i put her in neutral she drops down to 600 rpm"s and loads up on the fuel and putters , now one of 2 things happen i wait and let her kick up the idle or i rev it 2 times and it clears the fuel out of the system......what is her problem, she is not tripping any codes and i have checked everything something is being a royal pain in the a$$...........does ne1 have a possible answer.......thanks frank

 

clogged fuel filter maybe??

 

I have the same issue. Unplug the MAF, start your car, the SES light will come on (ignore it) drive it around, see if its better. If it is, then its your MAF. I tried this last night and found out it was, time for Z06 MAF Conversion

 

i actually swapped my maf with a buddy of mine"s.....and it still did it.....like i said i have tried pretty much everything and she is still acting up..............thanks for the input......ne1 else have a hidden secret that could help me

 

you might try the fuel filter, i had a "similiar" problem awile back and the new fuel filter fixed it.

 

could be a number of things. Bad Injector, fuel pressure incorrect. do you have an adjustable fuel regulator on your car?

 

IAC (idle air control valve)located on the bottom of throttle body.Try cleaning it.

 

IM waiting for my adjustable reg to come from summit, i havent tried the fuel filter yet" i will add that to my list" and the iac has been on my list justt havent got to it yet i just replaced my plug connectors for my o2 sims they were damaged put new o2 sims in her, checked my egr valve and cleaned her up she is working properly push it in and she stalls the car out,,,,,


1 fuel filter will be changed
2 i.a.c will be removed and cleaned

you guys are a great help cant get over all the replies im gettin,,,,,someone is gonna have the right one.....

 

1) After Wot she drops down to 600 rpms.....she kicks up on the idle by herself... sounds like either IAC slow reacting or Running too rich at wot and then it chockes when you let go of the gas. thats one guess.

The Sticky/slow IAC theory will explain the dropping RPMs down and slowly coming up on herself but wont explain the sputtering part.

Running too rich would explain some Bad RPMs at Idle but then did you see any black smoke come out? It will also explain why when you gun the engine it clears out but only if its only rich during wot.


2) I dont believe the Clogged Fuel Filter theory because logically thinking if its clogged how do "gunning the engine" makes it better?? It should make it worst. Also Logically thinking... If it was clogged she wouldnt be runnin strong would she??? Thats my guess too, so dont shoot me.


My guess is something is sticky.... Fuel Injector, IAC, Fuel pressure regulator, EGR?? maybe??


I would put some injector cleaner in the gas tank, clean the IAC to begin with...

and I am open for other ideas too..

Marvin

 

I had a similiar problem with my 97Z. It was the EGR valve. The codes it threw were random misfires that were never in the same cylinder. It would smell like fuel and idled low. It still performed well under hard acceleration.

It could be a few different things.... but this is one possibility. Good luck

Schantin
1997 Camaro Z28

 

what i mean by putter is not the normal idle, alot of black smoke exits the tail pipes while i sit there ,so much its staining my bumper cover.im definitly checking the iac cleaning it out is what will happen first and if needed new one thats a $115 my cost,lets pray lol and all of the other recomondations, the fuel filter i will do just because i havent changed it in awhile, plus its a good guess. is there a way to check the injectors to see if one is bad that seems like a needle in a haystack ...a very expensive one if you ask me lol, lets hope not....but fuel injector cleaner is only about 15 to 20 bucks so you know what i will even do that one also. the egr seemed to be working correctly cleaned it out with brake cleaner really good, thats a $355 dollar my cost part so lets hope not on that one also, why cant i burn my tires together and it go away.........the answer is out there somewhere,,,im sure with all of your help it will be fixed,,,,thanks guys and gals keep them comin

 

Ill be watching this thread close, I have a misfire as well and cant figure it out!!! keep the replys comming.

 

02 sensors..

 

Thats it. Its fuel related I would say, do not blame the opty until you read that Thecnical page that describes the workings of the Opty. I cant find it right now so I cant include the opty as a possible offender just yet.

If the IAC would get stuck you either rev up the engine or choke it off... You can create the exact same reaction by removing the PowerBrake assist hose with the engine runin... and keeping your finger on it.... let air in, the engine revs up close it back upn the engine almost dies until the IAC compensates. But no smoke there. so defenetely not the IAC. it wont smoke if it was.

Fuel pressure regulator?? I doubt it unless the diapragm is leaking but then It wouldn just go bad at WOT I think. It would throw your fuel delivery off wack at any and all RPMs and Gas pedal positions. Just yesterday I was messing with it...with the engine on I removed the vacum line on and off. I wanted to see if it was leaking. No problem there either and I didnt see smoke nor engine dropping RPMs when I did it so I dont think its your Fuel pressure regulator.

Fuel filter.... Nope. You are getting too much gas. the exact opposite happens when your filter is clogged. Next.


Oxygen Sensors... Sticky fuel injector... MAF... "Engine Coolant Temp Sensor... Lets pick the Coolant Temp Sensor... if it goes bad then it will make the PCM change either timing or fuel delivery or both... At all engine speeds and temps not just at wot. Next!

That leaves us with MAF O2's and Fuel Injectors. I already discarded the EGR posibility only cause the EGR will not add Fuel to your intake it would defeneteneyly make it misfire but I am yet to see one blowing all kids of smoke when you push the EGR open with your finger.... An EGR stuck closed is more likely to ruin emissions by running the Combustion Chambers too hot and increasin your Nitrogen emissions up.... but not smoke there. You got me?

The MAF will mess up your fuel delivery at All RPMS I think.... I am not sure if the PCM is reading the MAF at wot...Ask Shoebox about this.. (this is a posibility)

so whats left?? yeah the O2's. I I think either autozone or kragen have a program called F.A.S.T where you get your car tested for free... I read online you put down a credit card number and they let you borrow an AutoXray scanner.... I never used one but I would be interested in measuring the Injectors duty cycle vs the Oxygen sensor readings. This would take care of your O2s MAF and more or less your Injectors... I wont be looking for codes unles they jump at your face... I would be looking at weird readings. You know like duty cycles too high or too low... or PCM reporting wrong engine temps etc etc..

Do not buy parts unless you defenetely sure there is a problem with it.. I did a very long Post of a problem I discover with my IAT. I was malfunctioning only at certain Temps.. I described the problem and how I fixed it. a 13 dollar fix.... I didnt have to buy opty wires plugs and nothing else. just take your time and trouble shoot your parts one at a time... else you gunna spend mucho dinero.


Oh by the way DAM!!! $300 for an EGR? Bloody Murder. I have replaced many EGRs and never paid more than $50


Keeps us posted.


Marvin

 

I would try cleaning the IAC first as suggested (almost free to try). Take throttle body off and take the lower plate off the bottom (the IAC portion). Take IAC out and clean all the passages good.