vincode8

iTrader: (8)

My brothers 91 Z28 with L98 is having serious performance problems. Spitting out a Code 42. He has replaced the Electronic Spark Module(?) and is still have a problems. The car runs fine around town at low RPM, but when he stands on it, maybe hits passing gear, or WOT the Engine seems to die and lose RPM with severe loss of power. Any help is greatly appreciated.

Gummie

Does it feel like a complete loss of power and does the engine actually rev down when you're getting on it (ie when it happens and you stay on the gas will it rev down for a little while then rev back up only to die again)? If so we're having the same problem but my computer isn't throwing any codes.

https://www.thirdgen.org/forums/tpi/...situation.html

RBob

iTrader: (1)

When code 42 is set the ECM commands to the distributor to control the timing. There is some built in advance but not much. This is part of the reason for the huge loss of power.

Now, as for code 42. This is set whenever the ECM stops seeing distributor reference pulses (DRP) for a short period of time. Or, the EST signal is locked out by the distributor (such as an open bypass line).

The DRP problem or EST problem can be caused by a bunch of things. First check that the bypass is firmly connected. Then check the general condition of the wiring for the distributor. Check that no pins are pushing out of a connector.

Can also be caused by a bad pickup coil, ignition coil, or the magnetic star trigger (below rotor). It may also be a bad ECM.

RBob.

mean57

wow this could be a huge coincidence but- i was at dragstrip with my car make a couple of passes all ok. 3rd pass engine light comes on vehicle falls on it's face . then lurches forward again. black smoke from exhaust. grab a quick piece of mechanics wire pull code 42. found friend in pits xpndbl from these boards. his friend calls autozone says est code. my brain hits only thing that could pull timing so bad (knock sensor) i crawl under car sure enough connector half broke and disconnected. check and see. could also be just a bad sensor (knock)

vincode8

iTrader: (8)

Yes the engine does Rev down gradually beginning around 3k. Changed out the Knock sensor(code43) and have now discovered several bad injectors. Not complete duds but below the minimum ohm rating. Only 3 were 17 ohms, the others were all between 5-12 ohms.....Ordered new set today, it can only help. We did unplug the worst of the 8 injectors and ran the car around the corner on 7 cylinders, aside from the lost cylinder the car now has plenty of power and is not having the same "Rev Down, and Flat at 3000 rpm problems"....I'm not convinced the problem is solved, but will know more by monday(or so) after the new injectors are installed.

vincode8

iTrader: (8)

Just an update for anybody who is interested. Installed the new injectors(8) and the car runs perfect now. Lays down rubber all through first and part of second gear without any problems. I would say the problem is solved. No more codes either. Thanks to all who showed an interest.