Engine miss on grades

[chirodad]

This is my first time ever doing a "chat-line" forum thing so please bear with me. I have a 2005 Pace Arrow on a W24 (8.1) with a little over 27,000 miles. The trip before last I was near empty when I filled the gas tank. I had another 100 miles to go before reaching home. There were 4 to 5 major hills and it appeared to run normally. The MH sat for about one month before my next trip. This time I filled up when the tank was half empty. After about 25 miles I drove through a pretty steady heavy rain for about 50 miles. I don't know if it was coincidence or not but this is when I noticed it starting to miss on any significant grade. There was some loss of power, but not much. Everything seems to work normally starting out from a stop and cruising. I was at my destination for three days (no rain - warm & dry). My trip home (225 miles of dry road) resulted in the same situation...missing on significant grades. My first step was to replace the fuel filter. After which I took a short (8 mile) test drive. The problem was still apparent, although I would say not quite as bad. I then added an appropriate dose of fuel additive for my 75 gallon tank, but I have yet to drive it. My question is do I have to take a trip to run this tank of gas out to find out if it was simply case of getting a batch of bad gas from Fying J? I assume the alternative is more serious problems such as the fuel pump or ignition problems? Any thoughts or suggestions. Thanks.

[Wanabee FTer]

Hello chirrodad and welcome to irv2!

I am not a GM expert, but I expect others will be able to give you some good advice regarding your concern.
Some things that may help diagnose your concern is did the check engine light come on?
If so, a scan should be done to help diagnose the problem.
If no check engine light is on, you may be on the right track about getting a bad tank of fuel. You mentioned it was raining at one point and I'm wondering if water may have gotten into Flying J's holding tanks. If that's the case, you may be able to contact the store manager to see if there is any recourse to have your fuel tank removed and cleaned out. If there is a small amount of water in the tank you may be able to disperse it by adding some woodgrain alcohol or other known water dispersants.

[stearn]

I would check your plug wires. The back two on both sides. I experianced a simuliar situation found burnt wires. If that is what is causing your miss, you will find several posts about the problem.

[edgray]

Chirodad: Welcome to iRV2.com! The workhorse CHASSIS forum is the best place to get answers to all your chassis related questions. I'm requesting the admins to move this thread there. Again, Welcome! Ed

[Mr JP]

Sounds like you might change the air filter. Some coaches seam to have a problem with the air intake design. run a search in this forum and you will find many different solutions. Along with cleaning the mass air flow sensor and a good set of Taylor wires. Good Luck and let us know what the fix ends up being. Oh Yea "Welcome"

[pkmesser]

1. Agreed, he needs to get on Workhouse forum.
2 MAF sensor problem would normally throw a code., (if it is that, try cleaning it first, cheap fix, and it usually works.)
2. Don't start buying parts and throwing them at it until you know the problem There are several things this could be, and it could get expensive, just buying replacement parts. There is enough resources in the Workhorse forum to probably find the real issue. Then buy what is needed, and it will probably work.

[chirodad]

The air cleaner is good and no "check engine" light has come on. It's hard to tell with the road noise, and the best way to describe it is I get what sounds like a "clack" when I take my foot off the gas pedal and sometimes when I put it to the floor.
Thanks, Chirodad

[CoastieSCPO]

You have received some very positive responses so far. Here is my experience regarding an engine miss. Some years ago, the number 7 spark plug burned due to poor air flow thru the engine. Pulling a steep grade, it displayed a code, the engine went into limp mode and I ended up getting a tow to a WH service center. New plugs, Taylor wires and a DIY air kit solved that problem. Two years ago during our Alaska trip, the engine was missing slightly both on level roadways and hills driving thru some heavy rain. I changed the soaked stock air filter twice. Finally, 80 miles from Tok, Ak the yellow light displayed, I drove it 80 miles to a mechanic and we changed out the MAF sensor. That solved it until we ran into more heavy rain on Hyw 16 in British Columbia where I felt a very small miss. The rains stopped, everything dried out and we drove home to Tennessee with no further problem.

After returning home, I ordered an Ultra Power cold air kit from Brazels, installed it and we've never had an engine miss again...knock on wood! I am no mechanic, far from it, but IMHO, I believe that a wet stock air filter causes lots of problems.

Bob

[CoastieSCPO]

I just read your last post. Hearing a "clack" when accelerating or slowing is a different situation. Don't know if I can comment on that.

[dieselclacker]

If you are running OK on the flats, and only missing on hard uphill pulls, I would suspect ignition wire problems. Check the #5 and the #7 plug wires for being burned.

Dieselclacker

[DriVer]

Quote:

Originally Posted by chirodad The air cleaner is good and no "check engine" light has come on. It's hard to tell with the road noise, and the best way to describe it is I get what sounds like a "clack" when I take my foot off the gas pedal and sometimes when I put it to the floor.

Chirodad, I'm expecting that the problem could be with the MAF (mass airflow sensor) located behind the air filter. The MAF is identified as a device that has wires coming from it that is located about 6 to 8 inches directly to the rear (toward engine) in the air intake pipe.

That's what it sounds like to me.

[JCM]

One other possibility is that letting it sit for a month with the tank only 1/2 full could have caused some condensation = water mixed with your gas.
Refill ASAP and try that a few times (refill often and keep it topped up) to see if it helps (no cost). You could also put in some Alcohol - proper gasoline type - not from your bladder. If that dosn't work look at the air filter. Possibly got wet or lastly a burned plug wire.
KISS

[max49]

Let us know what the problem is/ was.
I'd raise the front wheels and start pulling plug wires starting with # 5 and see if one is brittle and breaks. Another test is to set the parking brake, and try to drive and see if your engine shudders, mine always did with one dead cylinder,

[RottenRalph]

I had a steady even miss when climbing hills. No check engine light came on. Called Readers Chevy in Knoxville about 2 hrs away. They took me right in, plugged in their Tech II scanner and found #8? (passenger side rear) spark plug and wire were bad. 1 hr later I was on the road again.