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bravewarrior · 11-06-2018, 01:38 PM

I own a 2004 winnabago brave 30w. Since I last got the unit smogged, I have been experiencing an issue where my engine loses acceleration. The engine does not shut down, but will not rev higher than 2000 rpm. I shut the engine off for a few seconds, turn it back on and the engine runs fine until the next time that it repeats the same issue. There seems to be no timeline or specific driving pattern that causes this issue. I have had the unit in the shop twice for this problem. I should mention that the check engine light comes in and stays on. First they changed o2 sensors and the next time they changed the accelerator modulation sensor ( not sure if this is the correct name) but it was not the throttle positioning sensor, which they said was ok. Taking the unit back in soon, looking for insight into this problem before I do.This unit is a Chevy workhorse 8.1 w/ allison tranny. Thanks for any and all help on this matter.

Sue46 · 11-07-2018, 04:02 AM

"Since I last got the unit smogged"

Never heard of this before. What is it?

twinboat · 11-07-2018, 04:38 AM

Quote:

Originally Posted by Sue46

"Since I last got the unit smogged"

Never heard of this before. What is it?

California's engine emission testing.

Sue46 · 11-07-2018, 05:10 AM

This is just for my education. Why would sniffing a tailpipe cause engine problems?

Dav L · 11-07-2018, 05:30 AM

Do you know what Diagnostic Trouble Codes exist? Do you have a OBDII scan tool?

CountryB · 11-07-2018, 06:18 AM

Could be the Throttle Position Sensor (TPS). If shop just looked for an "engine trouble code" related to TPS (and assumed TPS was good because no code was found) they could have missed a problem with it.

I have seen many fail in my days as mechanic (back in the 90's) where the TPS would get a flat spot (it's a rheostat) at the position where throttle pedal spends most of its time sitting (like at 20% open throttle) that would cause rough engine or stutter but not set a code since it was still in the operating range of the TPS limits. Testing with an Ohmmeter or scan tool would find this. You would rotate the TPS through its travel range while watching TPS signal looking for spike or drop at some point in the travel (where a smooth change in readings indicates a good sensor).