Hi guys!

I have a 1997 Z28 and it sputters and pops in the exhaust not in the intake.

It will do this from idle to about 1900 RPMs. It will also puff so black smoke when it does this. It smells rich when it does this.

I can feel it miss a little like when I am stopped at a red light but it don't stumble or hesitate to take gas when I go to pull out.

Now I had a leak in the water pump last year and I had the pump replaced.

I have put new plugs and wires, New AC DElco EGR Valve, Clean the Throttle body and did a throttle body by pass, on the car they are AC Delco. But it still does this.


What Do you Think? Opti, Fuel injectors, Fuel pressure regulator, coil, ICM, Fuel Pump?

It wont miss in the upper RPMs it runs supper?

 

TTT

 

TTT

 

Any codes or misfires detected with a scan?

Also please read http://web.camaross.com/forums/showt...&threadid=5485

 

except for the black smoke my sitution is very similar, i would have to ask u, does it also do this in nutrual?

and does it do this when its cold?

if so i think ive got the same problem as u.

i believe since u had a leaky water pump that ur opti is probably dead, just as mine probably is, but no one responds to my posts any more... so im without guidance

 

Please accept my appologies for TTT.



There are no codes or misfires detected by scan tool.

 

If your water pump crapped out, it could very well be your opti. My #1 proof that my opti was bad was sputtering at any RPM's under a load. IE, flooring it in 2nd going up a hill, it sputtered while under heavy load.. Also, my idle was pretty rough, even in open loop.

Toss out a few more symptoms to help us diagnose your problem. Does it do it when the car is cold, or only after it's warmed up? Does the engine sputter under heavy load, etc?

If you think you're being too specific, you're JUST being specific enough.

Regards!
Bryan

 

if it only does it when its warm what does this indicate?

 

It doesn't point the finger at any *one* thing.. But, it possibly rules a few things out. My main concern was, when the engine has warmed up, the PCM goes into closed loop, and begins taking readings from your O2's and using them to calculate fuel mixture... Most times, sputtering problems in closed loop turn out to be bad O2's..

 

so O2's would also explain my bad gas mileage

but what would explain a rough idle? could that be my exhaust leak?

 

No, rough idle in open loop could be one of a few things, but in relation to this topic, O2's generally won't cause a rough idle while the computer is still in open loop, because the computer isn't even using the O2's at this point.. A dirty or broken EGR valve could be a reason for sputtering during open loop, as well as your opti, coil, MAF, MAP, ICM, IAT, IAC, CTS, and a million other things. Detailing as many symptoms as possible helps to narrow it down, but nothing beats taking it to a shop and having them take voltage readings and/or scan your computer for codes...

 

Thanks Guys For your help!

Any one else want to take a crack at it?

Thanks Lee!