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Question 2004 Pace Arrow 36B bad running 8.1 Vortec

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Newton36B

RVF Regular
Joined
Jun 12, 2021
Messages
35
Were travelling in Oregon and Washington, 2004 Fleetwood 36B Pace Arrow, runs well for first 100 miles or so, then starts missing pulling grades, can't get over 40 MPH, this goes on for 30 miles , then we stop at a rest area for a short time and when we leave it runs fine for another 50-100 miles and then starts missing again. I know about the engine heat issues with this engine/doghouse, and replaced the plug wires yesterday, my local shop replaced the O2 sensor about a month ago trying to fix the same issue. Any ideas ?

Thanks

John
 
If codes say lean O2 sensor readings on all banks and all sensors then look for a possible Mass air flow sensor.

If you have not checked the fuel pressure then look at that issue.

regulator
fuel filter
fuel pump

Fuel injector problems usually indicated by a miss fire code an the bad cylinder.

Note that I can not be asked questions anymore because I don't spend much time here.
Neal said to spend my time discussing what I feel is important on social media, I don't do that but my relay is taking up my time.
 
Last edited:
We need your expertise...don't waste it on social media (please)...that being said, I had this issue recently and finally concluded I received a tank of bad gasoline. Plus, I filled up with 89 octane instead of the usual 91. Once my head cleared and I ran it through the performance is back to "great". Not sure if that's your issue, but maybe some additives??? might help.
 
If codes say lean O2 sensor readings on all banks and all sensors then look for a possible Mass air flow sensor.

If you have not checked the fuel pressure then look at that issue.

regulator
fuel filter
fuel pump

Fuel injector problems usually indicated by a miss fire code an the bad cylinder.

Note that I can not be asked questions anymore because I don't spend much time here.
Neal said to spend my time discussing what I feel is important on social media, I don't do that but my relay is taking up my time.
Hopefully I'll get home tomorrow, I'll get the fp checked and the MAF, thanks for the help
 
Two things. It sounds like you have a ignition coil failing and or the plug wires are failing.
The coil will act like you described getting worse the more it is run. Cools down does ok for a while.
Plug wire will act same way. Plug wires tend to show up more under a load like pulling up a hill than just cruising on level ground.
I would replace both and probably the s/plugs Distributor cap, and rotor, while your there
 
Two things. It sounds like you have a ignition coil failing and or the plug wires are failing.
The coil will act like you described getting worse the more it is run. Cools down does ok for a while.
Plug wire will act same way. Plug wires tend to show up more under a load like pulling up a hill than just cruising on level ground.
I would replace both and probably the s/plugs Distributor cap, and rotor, while your there
You will likely get a miss fire code if this is the case. I don't exclude this as an issue just that codes should be generated if it is.
 
Two things. It sounds like you have a ignition coil failing and or the plug wires are failing.
The coil will act like you described getting worse the more it is run. Cools down does ok for a while.
Plug wire will act same way. Plug wires tend to show up more under a load like pulling up a hill than just cruising on level ground.
I would replace both and probably the s/plugs Distributor cap, and rotor, while your there
I replaced the plug wires and added the heat socks, ran good for about two hours and then started missing badly, stopped for fuel for about 20 minutes and it ran pretty good for the next 1-1/2 hours, then missing badly. We made it home stopping every 1-2 hours to let it cool down, I checked my records and we replaced the fuel filter 12/14/2020, I have an appointment with Oregon light truck in August to check it out, they think it may be a bad fuel pump ? The original fuel pump was replaced at about 1000 miles under warranty, the O2 sensor was replaced 12/14/2020 and again 4/2/2021
 
I replaced the plug wires and added the heat socks, ran good for about two hours and then started missing badly, stopped for fuel for about 20 minutes and it ran pretty good for the next 1-1/2 hours, then missing badly. We made it home stopping every 1-2 hours to let it cool down, I checked my records and we replaced the fuel filter 12/14/2020, I have an appointment with Oregon light truck in August to check it out, they think it may be a bad fuel pump ? The original fuel pump was replaced at about 1000 miles under warranty, the O2 sensor was replaced 12/14/2020 and again 4/2/2021
I would replace the coil. Look for gray arcing marks in the area circled. This is a sign that the coil is bad. The hotter a failing coil gets, the worse it runs. When it cools down, it will operate fairly normal. Until it gets to the point that it won't work at all.
Before you start spending money on sensors, know that a O2 sensor will not make it miss.
A bad Mass Air Flow sensor w will make the engine run like crap. You can usually tap on it (if you suspect a bad one) with a hammer handle or screw drive handle to check it. (TAP NOT HIT) If it starts running ragged when tapped on, it is bad. I don't think that is your problem though.
A bad fuel pump on a fuel injected engine will usually not let the engine run.

Hope you get it figured out. -- Danny
1624415974094.jpeg
 
I would replace the coil. Look for gray arcing marks in the area circled. This is a sign that the coil is bad. The hotter a failing coil gets, the worse it runs. When it cools down, it will operate fairly normal. Until it gets to the point that it won't work at all.
Before you start spending money on sensors, know that a O2 sensor will not make it miss.
A bad Mass Air Flow sensor w will make the engine run like crap. You can usually tap on it (if you suspect a bad one) with a hammer handle or screw drive handle to check it. (TAP NOT HIT) If it starts running ragged when tapped on, it is bad. I don't think that is your problem though.
A bad fuel pump on a fuel injected engine will usually not let the engine run.

Hope you get it figured out. -- Danny
View attachment 7511
I'll take a look today, it would be great to find the problem so I can fix it. Thanks for your input !
 

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