My car has no bottom end, It is a 93 z28 A4 with 118,000 miles, new plugs and wires, no cat, air, or egr. The rest is stock. I can mash the gas at a stop and it just slowly takes off, it used to spin the tires. I have also been getting really bad gas milage, around 9 in town and 13 on the highway. The car runs great from about 2 grand and on, it doesn't miss all the way to 5800. I did the seafoam and some injector cleaner, and that helped a lot but it didnt fix it the problem. It seems to run the same hot or cold. I tried a new coil and ICM with no results. When I get on it going down the highway and let off it will back fire and shoot a flame out the tail pipe. And sometimes it wont want to start, mostly when it is cold. Not throwing any codes. Anyone know what is wrong, but for I start spending money??

Thanks

Taylor

 

i'll say O2's

 

It's probably your opti. O2's could also be bad, but they are not your main problem.

 

ill take a shot in the dark and say its knock sensor related. if for the sensor was signaling the PCM to pull lots of timing for some reason then youd feel a loss in power and drop in gas mileage.

 

definately change the o2s

 

agree with the o2 sensor idea, you have a service engine light?

 

How exactly will o2s cause a backfire and stumbling at WOT? Explain that to me please.

O2s are ignored at WOT. It's obviously an ignition problem.

 

I think he was saying that the backfire was after taking his foot off the gas. I do agree that it sounds like the Opti (root of all evil). That is the way mine started to go. It got progressively worse until I think I could out run the car at take off on foot! The O2's would add to the problem. Also if it has been running pig rich and you're smelling raw gas would hurt to change (at least Check) plugs and wires also if you do have to change the opti.