Workhorse 8.1L Vortec engine trouble

[garypann]

I have a 2004 Dolphin MH with the Workhorse 8.1L Vortec engine and have had an on going problem with the engine losing power.  It has happened on 3 different trips.  At first I thought it was a fuel pump problem and had that replaced. (in the gas tank).  It happened a 2nd time and the mechanic again worked on the fuel pump and it seemed OK.  It just happened the 3rd time.  The "service engine" light came on.  (Codes: P0131 and P0151 - "low voltage Bank 1 and Bank 2)  I was driving on the interstate at 65MPH with no sign of problems and the engine would just slow down to 5-10MPH.  I would pull over then all of a sudden,  back to full power.  It appeared that when the engine cooled down a little the engine would start normal and run great but when it got warm, it would start dying out again.  I did get home but this happened approximately 8 - 10 times on a 200 mile trip.  The symptoms appear to be a lack of fuel problem but maybe more of a computer problem.
Has anyone out there had a similar experience?  My instrument cluster also has stopped working but I'm estimating the mileage to be about 48,000 miles.  Any help or suggestions would be greatly appreciated.

 

[PJ Stough]

Does your exhaust go up and over the rear axle, then exit out the side?  A friend who has that exhaust configuration, and the same problem, insulated the gas line in the area where the exhaust goes over the axle as a temporary fix, but later rerouted the exhaust to exit in front of the rear axle.

 

[Arch Hoagland]

Had the exact same problem and fought it for a year when I had about 50,000 miles on my coach.

Changed the fuel filter, no help. Replaced the O2 sensors, no help.

Did a rain dance and barked at the moon, no help.

Then on a trip from California to Utah going across I80 I couldn't climb any mountain without a problem and couldn't find a shop anywhere on I80 that would work on it.

In Salt Lake City a shop knew right away what was wrong and they cleaned the MAF sensor along with replacing the air filter.  Problem was cleared instantly and I had a ton of power again.  Been fine ever since...about 15,000 miles since then.


So I believe your problem is the MAF sensor is dirty. It is located by the passenger side front tire. If you pull the air filter out you can spray MAF cleaner in there as the sensor is right after the air cleaner. It the round thing with the wires coming out of it.

 

[Roy]

You may have O2 sensor problems.check out this post
http://www.irv2.com/forums/f22/8-1l-vortec-loss-of-power-check-engine-light-118272.html.

 

[Arch Hoagland]

You may have O2 sensor problems.check out this post
http://www.irv2.com/forums/f22/8-1l-vortec-loss-of-power-check-engine-light-118272.html.

That's what everybody on here said when I was troubleshooting mine. That was why I changed the O2 sensor which didn't cure the problem.

The fact that he is getting a P0131 AND a P0151 means both O2 sensors are seeing a problem.  If it was ALWAYS just one or the other then the sensor would be a suspect.

Both means there is an air to fuel mixture problem which is what the O2 sensors are designed to detect.

 

[lokikutsch]

I have had two vehicles where the Mass Air(flow) sensor went bad, with exactly the same kind of symptoms you described.  that screws with the Fuel air ratio, so it sometimes shoes up as O2 sensor issues.

 

[garypann]

Thank you all for your response.  I will pass on all of the suggestions to my mechanic and will post our findings when that buggy is finally up and running properly. 

 

[dan2]

I have since found out I have a P32 chassis....mine has a sensor ( on the lower drivers side ) that I think screws into the radiator
that controls the dual fans.  Worth a look 

Good luck
Dan

 

[dan2]

Sorry wrong thread; should b posted for new member with a 94 Bounder....

Dan

 

[Roy]

I had the same problem on My Jeep replaced bank 1 and bank 2 os sensor reset OBD 2 and it came back.
The problem was not the sensor but a broken wire sending the voltage  to them I had a dip in voltage.

You posted "low voltage Bank 1 and Bank 2)  .

 

[Marvhein]

I realize this is an old thread, but I want to thank Arch Hoagland for his posts and to reemphasize them for anyone else with similar issues.

My symptoms (2009 W24 chassis) were identical to his.
Cleaning the MAF and replacing the air filter were exactly the right solution.
Here's one example that helped me:

No more O2 sensor check engine lights, more power and less downshifting.
Cruise control while towing is now very smooth. Couldn't even use it before.
Mileage up from 7-8 to 10-11 mpg while towing.

It's like having a brand new engine.

 

[Arch Hoagland]

Thanks for the update. Glad to hear all is well!