Losing power on the hills. Please Help!

[LETMGROW]

Originally Posted by CJ7365

Not sure if there is an actual GM part #, but the one on my W22 is a Delphi



https://www.amazon.com/Delphi-AF1004...low+Sensor+Asm

It could very well be a Delphi. They are an OEM supplier for GM parts as well.
The AF 10043 Delphi will fit a whole host of GM vehicles including GMC and Chevrolet trucks and some car models.
I only have a limited source here at home for parts interchange information. It does not cover Workhorse in the interchange I have access to.
Lynn

[vettenuts]

This is what UltraRV Products has for a 2003 W22: https://www.ultrarvproducts.com/Work...Asm?filter=297

Likely has a GM/Delphi cross reference.

[RV Poppy]

The MAF is indeed a Delphi. I removed it and cleaned it and now attempting to get the CE light reset and go for a spin. I do not think this will be the issue but worth a try since had it off and cleaner is only 10.00.
The CAT has been mentioned more than once and even though the shop told me they checked for any blockage I just have this strange feeling it may be just that.
Calling a different garage tomorrow and will keep all posted as we go along. We all might learn something. LOL
Thanks again to all for your support and enjoy the holiday!!!

[jerboy]

Originally Posted by RV Poppy

The MAF is indeed a Delphi. I removed it and cleaned it and now attempting to get the CE light reset and go for a spin. I do not think this will be the issue but worth a try since had it off and cleaner is only 10.00.
The CAT has been mentioned more than once and even though the shop told me they checked for any blockage I just have this strange feeling it may be just that.
Calling a different garage tomorrow and will keep all posted as we go along. We all might learn something. LOL
Thanks again to all for your support and enjoy the holiday!!!

I may have missed it being mentioned but a clogged CAT usually puts out a very strong Sulphur smell.

[LETMGROW]

Originally Posted by jerboy

I may have missed it being mentioned but a clogged CAT usually puts out a very strong Sulphur smell.

Sometimes, sometimes not.
The best way to check for an exhaust restriction is to install a vacuum gauge to the intake manifold and take the vehicle for a ride. If the vacuum drops to zero or close to it you can suspect an exhaust restriction which could be a plugged converter. A quick throttle opening can and most likely will drop the gauge reading. This is normal. It will steadily rise again. You have to apply steady pressure and as the RPM increases the vacuum will drop off if the restriction is present. It will stay low as the RPM increases and stay there until you release the throttle.
Lynn

[RV Poppy]

Hello jerboy. I do not know if I would consider it a sulfur smell put there were a couple times it smelled. The first time it happened I thought the shop put the wrong belt on or something because it smelled more like rubber burning. To the faithful that have followed this post, cleaning the MAF did not solve my problem. She ran a little better today but still showed the same signs. Two questions to all. I have researched a lot because I am not a mechanic and am having a very hard time trusting anyone these days. The research I have uncovered seems to lead to a bad fuel pump. Every time I had issues today I stopped to check the flow from the exhaust and it seemed the same as when I started. Of course it happens on mountains the worst and could not pull over on the slope it almost cut off.

[Full-Timers]

The way the fuel system works is, the fuel is pumped from the tank by the in-tank fuel pump through the filter to a fuel pressure regulator under the hood, on top of the engine. The unused fuel it returned back to the tank and dumped right on top of the fuel pump. If the tank is under ½ full this heated fuel will heat up a weak pump motor and it will start to fail.
One way to test this is to fill your fuel tank and take it for that drive. In a full tank the pump will be completely submerged and will not be affected by the heated return fuel and will not fail.

[vettenuts]

Originally Posted by Full-Timers

The way the fuel system works is, the fuel is pumped from the tank by the in-tank fuel pump through the filter to a fuel pressure regulator under the hood, on top of the engine. The unused fuel it returned back to the tank and dumped right on top of the fuel pump. If the tank is under ½ full this heated fuel will heat up a weak pump motor and it will start to fail.
One way to test this is to fill your fuel tank and take it for that drive. In a full tank the pump will be completely submerged and will not be affected by the heated return fuel and will not fail.

Forgot about this issue. Wasn't this an issue with the fuel system prior to the change where Workhorse moved the fuel return to the filter? Not sure what year that happened.

[jettyjock]

Had the same thing and mine was the low fuel pressure.

[TexasTom]

After reading all this I can quickly come to the conclusion that I am not an expert in this area.

But.....I will offer that when I had this similar problem with this same engine in a different vehicle I spent a fair amount of money working to track down the issue. And while we were convinced it was the cat it actually ended up being a faulty fuel pump.

[noice74]

Originally Posted by Full-Timers

The way the fuel system works is, the fuel is pumped from the tank by the in-tank fuel pump through the filter to a fuel pressure regulator under the hood, on top of the engine. The unused fuel it returned back to the tank and dumped right on top of the fuel pump. If the tank is under ½ full this heated fuel will heat up a weak pump motor and it will start to fail.

One way to test this is to fill your fuel tank and take it for that drive. In a full tank the pump will be completely submerged and will not be affected by the heated return fuel and will not fail.

[emoji1304]

[Wbonsell]

You need spark, fuel and air. More fuel and air when needing it heading up grades as the rpms increase. A spark issue would more than likely cause a miss. If the air filter is fresh and installed properly, then my guess would be fuel. Either a bad gas cap throwing the CEL or a fuel pump issue as the fuel filter has been changed.

Also any chance you have driven through rain and the filter, while new, got wet? Happened to me and the power loss about 3K was noticeable.

[CJ7365]

Originally Posted by RV Poppy

Hello jerboy. I do not know if I would consider it a sulfur smell put there were a couple times it smelled. The first time it happened I thought the shop put the wrong belt on or something because it smelled more like rubber burning. To the faithful that have followed this post, cleaning the MAF did not solve my problem. She ran a little better today but still showed the same signs. Two questions to all. I have researched a lot because I am not a mechanic and am having a very hard time trusting anyone these days. The research I have uncovered seems to lead to a bad fuel pump. Every time I had issues today I stopped to check the flow from the exhaust and it seemed the same as when I started. Of course it happens on mountains the worst and could not pull over on the slope it almost cut off.

You can go to Auto Zone or Oriellys and get a fuel pressure gauge that attaches to the Schrader valve on the fuel rail, easy to do.

Attach the gauge and go for a spin, you should have between 56-62 PSI


How many miles on the 8.1?

[Full-Timers]

Originally Posted by vettenuts

Forgot about this issue. Wasn't this an issue with the fuel system prior to the change where Workhorse moved the fuel return to the filter? Not sure what year that happened.

You are correct. I don't remember the year either.