88TPIZ

I can not figure out what is wrong with my '91 z28. It is an l98 with 129,000 miles. It has a new fuel pump and filter, o2 sensor, plug wire rotor cap. ecm, tps, icm, coil, i tested the converters, thermostat, radiator, fans are working, cant find any vacum leaks, good fuel pressure .

here is what it is doing.

It will start and idle fine but once it warms up and i start to drive it will starts to knock and when i put the pedle to the floor it will stay at 2000 rpms and knock like crazy, however when it is in neutral or park i can rev it as high as i want. When the engine is cold it drives fine, it only acts up when is warms up.

It finally gave me a code 32 so I replaced the egr valve, still no change.


Please help me, the rest of the car is too nice to not be able to drive.

NY3RDGEN

Sounds like the cat, i see u tested them. But i would double check that. IMO anyways.

Glenno

Did you convert from a MAF to a MAP system? If so the knock sensors are different. Keep us posted. Good luck

88TPIZ

I am positive the cats are good. I have not changed the map system.

marrober9

I have a Vette doing the same exact thing did you ever get this resolved? Thanks

Jeffs82TA

iTrader: (1)

disconnect the ecm's control over timing, if that stops it from doing that then it is either the internal ecm est module or knock sensor.

TPI-Formula350-

How's your oil pressure?

88TPIZ

Ok I got it fixed and its running great. The problem was the intake manifold gaskets were rotten and leaking air, it was backfiring through the throttle body and that was the 'knocking' I was hearing. While I had the intake apart I replaced the injectors too.