W22/Allison Engine or Transmission Surging

[Kreskin]

I have a W22 chassis (2002 Bounder 36S) with 8.1L that has started to have a 200-300 rpm surge while cruising down the road. It is intermittent in nature and doesn't happen on every trip, when it does happen some of the time I can get it to stop by significantly altering my speed either up or down. It almost feels like the trans would if it was dropping out of OD but it only changes rpm 200-300 and doesn't shift that I can tell. This issue can and does happen whether it's just the coach or while towing.

I first thought it was OD related so when it happened I would shut off the OD but it would still surge but now at even higher rpms because we were out of OD. Next I thought it may be cruise control related so I would kick off the cruise and try to hold the pedal steady, the surging would continue even off cruise.

I checked the trans fluid and the level is good and the fluid appears good (not burnt) and no burnt smell while hot.

I've searched but only came up with one other similar thread and the OP of that thread said the issued stopped before figuring out the cause. Any thoughts?

[edgray]

Welcome to iRV2.com. Glad you joined and posted.
Have you considered replacing your fuel filter?
ED

[mikewy]

Just got my 2004 Newmar Mountain aire back from the shop today. (only 9700 miles), This is my 2nd set of plug wires. Motor had been surging when going up a hill or when car in tow, really during any extra load. They added new plug wires, new plugs, new Fuel filter, and new air filter. They also added the Cooloing vent kit, My Service center contacted Workhorse, they covered this under emissions warranty. That was good news, Hoping this does it.
Also was asking about the Bosch brake recall: Still no parts available, maybe this summer. Service center said they will have a back log of 2 years to retrofit over 200 coaches in my area.

[Kreskin]

At this point I have not considered changing the fuel filter or anything else as I was still in "scratch my head" diagnosis mode

Not sure why but I actually never considered this as a possible fuel delivery issue, guess I was so fixated and concerned it was a possible trans issue that was going to cost me big dollars to fix I overlooked some of the simple stuff.

Perhaps it's time for an all around tune up plugs, wires filters etc.

[Dagwood]

Kreskin I had exactly the same symtoms last Jan but I was bringing it home after 3 weeks in the shop. Mine was a quart low(transmission) but it did it after filling and then quit. Only local trips since then so I really dont know if it will return.I might go for changing to transynd if it does. I changed the filter last summer so it was possibly just a valve body problem because it had been down to 16 degrees that week. Hurry up and find out so I will know what to do with mine. lol

[Mutha]

Kreskin, if your fuel filter and tune up DO NOT solve your problem, then you might want a GM shop with a TECH-II to check your "Crank Shaft Sensor". Many of the 01 and 02 8.1's had a problem with the early version of the sensor and they had to be replaced with a re-engineered and updated sensor. The 03 and up all came with the new updated sensor.

Good Luck !

[BDJ]

Had the same problem. It turned out to be the ABS computer telling the TCM to unlock the torque converter. After having 2 WH shops look at it I finally brought it to an Allison shop who hooked their laptop up to it and we took it on a test drive. Within 2 blocks the tech saw the TCM receive the signal from the ABS computer to unlock the torque converter. Now it was back to the WH shop who downloaded the codes from the ABS computer. It turned out there were multiple codes for a right rear sensor failure. Changed the sensor and still had a problem. They finally found the wire going to the sensor had an intermittent short. BTW we never had any indication of an ABS problem.

The service manager at the Allison shop explained that this is a safety feature so if there is an ABS failure it tells the TCM to unlock the converter so you don't stall the engine if you lock up the brakes. He also stated that in most of the cases they've seen there was no indication of an ABS failure on the instrument panel and there are no codes in the TCM because it's just doing what its suppose to.

Good luck, That wire ended up costing me over $1,000.00 and trips to 3 different shops.

[edgray]

BDJ:

THANK YOU for sharing your experience. I bet most of us would have NEVER thought about the ABS connection with the TCM. Hopefully, your expensive learning curve will save another member from the expense you've incurred. GREAT POST!!

[John350]

How do I determine if I have the revised crankshaft sensor??? My chassis build date is 11/02. Chassis Vin: 5B4MP67G233364660. Also, what is the revised part number? Ths is an interesting post. Thanks John

Tiffin Allego Bay
2002 W22

[Dagwood]

BDJ I think you might have found my problem also. I was having brake issues and replaced everything on the front brakes but not the rear and I am getting an intermittent abs light. I know my rr gets a lot hotter than the left so I will check there next.

[Kreskin]

BDJ, thanks for the lead on a possible issue/solution. I've (touch wood) had no brake issues to date so if that turns out to be my problem it would likely have been a very difficult diagnosis like yours.

[Mutha]

Quote:

Originally Posted by John350 How do I determine if I have the revised crankshaft sensor??? My chassis build date is 11/02. Chassis Vin: 5B4MP67G233364660. Also, what is the revised part number? Ths is an interesting post. Thanks John Tiffin Allego Bay 2002 W22

John there is currently only one Crank Shaft Sensor for ALL 8.1 engines. It is GM#12575172 or AC Delco #213-1556. If you are not having any engine problems you probably do not have to worry which sensor you have. If you are having engine problems and it is your Crank Shaft Sensor it will show up on a TECH-II diagnostic scan.

Good Luck.

[John350]

Many thanks for the info

John

[bdaball]

Kreskin,
See I told you someone would come up with something.

Don't forget the Workhorse chat tonight at 9:00PM EST where all of the worlds problems gets solved.....!