Engine will sometimes not rev

NoDOHC · 07-19-2010, 09:46 AM

It could be an intermittent vacuum leak for the rough idle, but if it is coupled with the inability to rev, it almost has to be limp mode.

This is puzzling.

I tried unplugging the TPS on my '91 and revving the engine and it revs just fine. I also tried without the MAP sensor - same results. It almost has to be an Oil Metering Pump feedback issue (I don't remember what all codes can set the limp home mode).

Did shutting the key off and turning it back on fix the issue this time too?

I wonder if the CEL is not setting because the fault is immediately clearing, but the limp mode is latched on.

07-19-2010, 09:46 AM	#21
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 18	It could be an intermittent vacuum leak for the rough idle, but if it is coupled with the inability to rev, it almost has to be limp mode. This is puzzling. I tried unplugging the TPS on my '91 and revving the engine and it revs just fine. I also tried without the MAP sensor - same results. It almost has to be an Oil Metering Pump feedback issue (I don't remember what all codes can set the limp home mode). Did shutting the key off and turning it back on fix the issue this time too? I wonder if the CEL is not setting because the fault is immediately clearing, but the limp mode is latched on. __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

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