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DaveBr
10-04-2009, 13:03
When driving my 98 GMC sometimes when traveling at hiway speed. If I come to a full stop at an intersection and push the accelerator to resume speed the truck barely moves like it has no power at all. After a few second delay it will go as normal. This has only happened twice. (second time yesterday) It is a little un-nerving pulling out onto a hi-way with no power and traffic coming at you. Any thoughts?
BillCarry
10-06-2009, 13:03
Sounds the same as my 94 motor home when the accelerator pedal module went belly up.
JohnC
10-08-2009, 15:40
The APP unit should set codes if it is bad. If no codes, check the lift pump and change the fuel filter...
DaveBr
10-08-2009, 16:39
I have no warning lights on dash at this point. L.P. is working. I have a new filter and will install as soon as it quits SNOWING. I've done a lot of driving this week and the issue has not returned as of today. I will keep you all informed.

Thanks
JohnC
10-09-2009, 14:32
I have no warning lights on dash at this point.

There still could be codes stored.
DaveBr
10-13-2009, 17:44
Happened again and this time I put the hammer down which caused the check engine light to come on. Had one code PO456. Small leak evaporator system. Checked my gas cap - no cracks in the O ring so I will start looking for vacuum leaks. Would a malfunctioning EGR cause this?
DmaxMaverick
10-13-2009, 18:11
Your truck doesn't have an "evaporator". That's a gasser thing. I can't find that code specific to the Diesel. It is designated as gasser only. A "ghost", perhaps? If it's emissions related, it should be with other codes. Or, you misread it (it happens).

Also, fuel tank pressure isn't monitored by the PCM, like on gassers. A plugged filler cap vent can cause problems, but no codes because it has a poor seal.
DaveBr
10-18-2009, 12:12
I believe PO456 was a ghost as this was the code that was last seen on the reader from my wife's Jeep. This time the SES came on I checked codes with the engine running & warmed up.

PO236 - Turbo boost system
PO402 - Excessive EGR flow

I'm thinking the EGR solenoid stuck which caused ECM to go into limp mode. Just my diagnosis from what I've learned from TDP. Anybody with other thoughts please feel free.

Somewhere on the page I think I read solenoids can be cleaned. Is this right? If so could you enlighten me as to how?

Thanks for the help