Loss of power when driving

[init6]

I have a 2005 pace arrow with a workhorse chassis that seems to have lost a lot of power. The the point that it can barely make it up a hill or get up to 65 mph on the interstate. This comes after pulling it out of long term storage. I haven’t driven it in a while but have had someone starting it for me once a month and adding new fuel and stabil when needed while I was serving overseas.

Any thoughts on what to look for? It sounds like it is running fine for the most part aside for a sputter every now and then when I put the gas pedal down all the way. At some point today while going up a hill, the check engine light came on.

Thanks in advance

[init6]

wnjj wrote:

afidel wrote:
So the response of the ECU to a bad knock sensor is to max out the fuel trim. What that means is it runs the engine as lean as possible which would definitely account for the lost power. Looks like knock sensors run about $100 each, harnesses are around $45 and labor will probably be a few hundred.

Btw there's a known issue with rusting of the knock sensors so when they're replaced make sure they follow the TSB and put in the silicone dam to stop future water intrusion which should keep you from needing to do the repair again in the future.

I agree that it’s really strange to have both failing at the same time. I wonder if some other condition causes the engine to think the sensors are bad.

If you do replace them, they’re only $36.79 each for the ACDelco sensors on rockauto.com.

When I looked into this a bit, it seems the 8.1L has the knock sensors on the outside of the engine below the exhaust manifolds so the water intrusion isn’t an issue there.

https://www.youtube.com/watch?v=z1V5Gb0VRFM

Also on Amazon:

Sensor

Connector

Wow, great info. Thank you.

[afidel]

Ah,same rust prone sensors but at least they are not in a valley under the manifold like on the smaller engines.

[wnjj]

afidel wrote:
So the response of the ECU to a bad knock sensor is to max out the fuel trim. What that means is it runs the engine as lean as possible which would definitely account for the lost power. Looks like knock sensors run about $100 each, harnesses are around $45 and labor will probably be a few hundred.

Btw there's a known issue with rusting of the knock sensors so when they're replaced make sure they follow the TSB and put in the silicone dam to stop future water intrusion which should keep you from needing to do the repair again in the future.

I agree that it’s really strange to have both failing at the same time. I wonder if some other condition causes the engine to think the sensors are bad.

If you do replace them, they’re only $36.79 each for the ACDelco sensors on rockauto.com.

When I looked into this a bit, it seems the 8.1L has the knock sensors on the outside of the engine below the exhaust manifolds so the water intrusion isn’t an issue there.

https://www.youtube.com/watch?v=z1V5Gb0VRFM

Also on Amazon:

Sensor

Connector

[afidel]

So the response of the ECU to a bad knock sensor is to max out the fuel trim. What that means is it runs the engine as lean as possible which would definitely account for the lost power. Looks like knock sensors run about $100 each, harnesses are around $45 and labor will probably be a few hundred.

Btw there's a known issue with rusting of the knock sensors so when they're replaced make sure they follow the TSB and put in the silicone dam to stop future water intrusion which should keep you from needing to do the repair again in the future.

[init6]

parker.rowe wrote:

init6 wrote:
Well, I was able to get someone with a Code reader to go over and check it for me. It was creating 2 codes - The first was P0327 and the second was P0332. According to what I have looked up on them, one is Knock Sensor 2, circuit low bank 2

The other code was - Knock sensor 1, circuit low bank 1

I'm still suspecting a fuel filter which is nearly impossible to find with an adapter kit to take it from 3 ports down to just 2. I have tried to order from numerous places and they all seemed to be back ordered. I won't be back at the RV until around Oct at the earliest. If not then, December will be my next attempt.

I would check the wiring for the knock sensors. It may be pulling timing way back if the knock sensors are not reading correctly, as a failsafe. that would make it loose a bunch of power and it could backfire when you get on it, as you reported. But it is odd for them both to fail at once so I would inspect the wiring harness to the sensors.

I'm not sure why you are suspecting the fuel filter when the computer is reporting a problem reading both knock sensors.

Not that it hurts to replace the fuel filter.

I don't know much about engines. Thought maybe the lack of fuel due to a fuel clog caused it to backfire and that is why 2 knock sensor errors came up. But if that isn't likely, that's good to know as well. Trying to get a good game plan together before I arrive back at the RV.

Thanks

[parker_rowe]

init6 wrote:
Well, I was able to get someone with a Code reader to go over and check it for me. It was creating 2 codes - The first was P0327 and the second was P0332. According to what I have looked up on them, one is Knock Sensor 2, circuit low bank 2

The other code was - Knock sensor 1, circuit low bank 1

I'm still suspecting a fuel filter which is nearly impossible to find with an adapter kit to take it from 3 ports down to just 2. I have tried to order from numerous places and they all seemed to be back ordered. I won't be back at the RV until around Oct at the earliest. If not then, December will be my next attempt.

I would check the wiring for the knock sensors. It may be pulling timing way back if the knock sensors are not reading correctly, as a failsafe. that would make it loose a bunch of power and it could backfire when you get on it, as you reported. But it is odd for them both to fail at once so I would inspect the wiring harness to the sensors.

I'm not sure why you are suspecting the fuel filter when the computer is reporting a problem reading both knock sensors.

Not that it hurts to replace the fuel filter.

[init6]

wnjj wrote:
Did you ever get this sorted out?

Edit: Never mind, I just saw your other post about your RV being miles away.

Well, I was able to get someone with a Code reader to go over and check it for me. It was creating 2 codes - The first was P0327 and the second was P0332. According to what I have looked up on them, one is Knock Sensor 2, circuit low bank 2

The other code was - Knock sensor 1, circuit low bank 1

I'm not sure if these are the result of a back fire when I put the gas pedal to the floor trying to go up a hill because it already had no power and no check engine light or if this was the problem already before the check engine light eventually did come on.

I'm still suspecting a fuel filter which is nearly impossible to find with an adapter kit to take it from 3 ports down to just 2. I have tried to order from numerous places and they all seemed to be back ordered. I won't be back at the RV until around Oct at the earliest. If not then, December will be my next attempt.

[wnjj]

Did you ever get this sorted out?

Edit: Never mind, I just saw your other post about your RV being miles away.

[init6]

wnjj wrote:

init6 wrote:

wnjj wrote:

init6 wrote:
Just an update…. Have tried a new tank of gas. Ran all the old out first. Replaced the air filter and vacuumed out some deteriorated foam in there with a shop van. Replaced the mass airflow sensor with a new one and still the same issue.

I’m wondering if it isn’t fuel pump or fuel filter related.

Did you also replace the MAP sensor? Also, you said the check engine light came on. What was the code? Mine was setting p0101 when pulling grades.

I don’t have a code reader but plan on getting one to see what code it is throwing. Not sure where the map sensor is.

You can stop by most auto parts or oil change places and they’ll check for free.

The map sensor sits on top of the engine under the big plastic cover. It is held in by one bolt with a washer that hangs over the sensor. Its really easy to change. I did both at the time because the MAF test uses the MAP to cross check.

Look here for a picture of it.

Ah cool. Thanks for the info. Ordering a cheap code reader off Amazon since I probably need one anyway.

Cheers

[wnjj]

init6 wrote:

wnjj wrote:

init6 wrote:
Just an update…. Have tried a new tank of gas. Ran all the old out first. Replaced the air filter and vacuumed out some deteriorated foam in there with a shop van. Replaced the mass airflow sensor with a new one and still the same issue.

I’m wondering if it isn’t fuel pump or fuel filter related.

Did you also replace the MAP sensor? Also, you said the check engine light came on. What was the code? Mine was setting p0101 when pulling grades.

I don’t have a code reader but plan on getting one to see what code it is throwing. Not sure where the map sensor is.

You can stop by most auto parts or oil change places and they’ll check for free.

The map sensor sits on top of the engine under the big plastic cover. It is held in by one bolt with a washer that hangs over the sensor. Its really easy to change. I did both at the time because the MAF test uses the MAP to cross check.

Look here for a picture of it.

[init6]

wnjj wrote:

init6 wrote:
Just an update…. Have tried a new tank of gas. Ran all the old out first. Replaced the air filter and vacuumed out some deteriorated foam in there with a shop van. Replaced the mass airflow sensor with a new one and still the same issue.

I’m wondering if it isn’t fuel pump or fuel filter related.

Did you also replace the MAP sensor? Also, you said the check engine light came on. What was the code? Mine was setting p0101 when pulling grades.

I don’t have a code reader but plan on getting one to see what code it is throwing. Not sure where the map sensor is.

[wnjj]

init6 wrote:
Just an update…. Have tried a new tank of gas. Ran all the old out first. Replaced the air filter and vacuumed out some deteriorated foam in there with a shop van. Replaced the mass airflow sensor with a new one and still the same issue.

I’m wondering if it isn’t fuel pump or fuel filter related.

Did you also replace the MAP sensor? Also, you said the check engine light came on. What was the code? Mine was setting p0101 when pulling grades.

[Janss]

I have the Workhorse 8.1L, but not W24. Few years ago I was driving on the freeway and suddenly heard a loud sort of backfire noise and dropped to about half power. Limped off the freeway at the upcoming exit and went to a repair shop. The O2 sensor in the exhaust pipe had popped out. It was actually hanging down from its wire, creating a hole in the exhaust pipe up in the front half of the chassis. You might want to get under the rig and inspect the whole length of the exhaust pipe.
Another time I was driving on a different freeway and suddenly lost all power. That was a fuel pump failure. No warning. It worked, then it didn't...as Grit dog stated.

[lryrob9301]

Replace your fuel filter !!!