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View Full Version : Codes 42 and 91 in memorandum



DChristie
10-20-2003, 17:39
Dearly beloved we are gathered today in loving memory of my poor truck, :eek: I was its undoing I'm afraid.
I was accelerating WOT 16 psi on boost gage I heard a couple of pops I let out of it. It loses power idles down to death and won't recover. Towed it home with a friends gasser :rolleyes:
I checked codes and came up with 42 and 91 as well as a 78, wastegate solenoid, I know that one and with a bypassed wg I'm not surprised.
So now what is an ignition timing stepper motor fault? or a cylinder unbalance?
Is it possible for a timing gear to jump a cog or two?
Is the stepper motor the cylindrical piece with two leads(red and black) under the intake manifold and attached to the IP sticking out from the center of the eight fuel lines? Can it be replaced or is this a new IP type fix?
All help is greatly appreciated by a guy with no job and now no truck. On the bright side I'll have plenty of time to fix it.

ChevyDooley
10-20-2003, 18:51
16 psi with no intercooler?

DChristie
10-21-2003, 05:41
The 16 psi boost is not normal for this truck, typically it's 12ish at WOT, 5-7 above 70 mph and 0-3 below 'til I accelerate.
There is an IC in the truck but it isn't plumbed in yet.
I was so excited to see 16 that I stopped and idled it for several minutes and then did it again. that's when it died.
I wasn't concerned about the lack of an IC because I don't pull anything regularly, and the boost never has the residence time to do damage.
I'm not sure what would have changed to increase the boost like that. I haven't modefied anything recently enough to be able to point the finger at it definitively.
I heard three distinct and unique pops similar to an uncorking champagne bottle and She drank her last.