Community Forums

M&Aeller · 01-30-2020, 12:23 PM

I have a 2007 Winnebago Adventurer Model 35L with a Workhorse Chassis with a 8.1L Chevy engine and a 1000 model six speed Allison Transmission. While running on level terrain at about 60 to 65 mph the tachometer starts surging from 2,000 rpm up to 2,500 rpm as if the transmission is trying to shift but never does. I may have driven anywhere from 25 to 30 miles before it starts surging. The surging can go on for 2 miles or as many as 100 miles then stops and goes back to normal operation. I have had the Transmission rebuilt, replaced the ECM module and replaced the spark plugs and wires. Additionally, I have taken my coach to Allison’s main district area shop in Houston, Texas, and other locations. I was told that without the Check Engine Light or a Code indicating that there is a problem, that this issue cannot be diagnosed and therefore the problem is unable to be repaired. I would welcome and greatly appreciate any ideas or solutions that may provide a “fix” for this problem.

TonyMac · 01-30-2020, 12:35 PM

Sometimes surging is a vacuum leak issue. Sometimes spraying the vacuum hoses and diaphragms with starting fluid while the engine is running will show you where the leak is. It's mostly alcohol, so it all evaps away rather quickly.

jeanluc001 · 01-30-2020, 12:53 PM

I for one wouldn't be comfortable spraying a flammable substance on a hot engine. but that's just me.

TonyMac · 01-30-2020, 01:18 PM

Quote:

Originally Posted by jeanluc001

I for one wouldn't be comfortable spraying a flammable substance on a hot engine. but that's just me.

Yeah, I understand. It doesn't have to be a hot engine, and it won't flame up even if it is. It will cause a slight increase in rpm while the spray is directed at the vacuum leak of running engine. This is an old school tool I learned from a Marine Corps hobby shop when I was a Marine brat at Lejuene. Marines tend to accept some losses.

clifford j · 01-30-2020, 01:20 PM

I think more information about the surging issue is needed. What is meant by surging , the vehicle starts going faster, or just the tach starts to jump up 500 rpm's ? What does the speedometer do. Is the tack steady or jumpy, does it clear off by itself . Must the vehicle be up to operating temp. or will it do it
when cold.

CLIFFORD

Unplanned Tourist · 01-30-2020, 02:38 PM

Are you sure the engine rpm's are changing?

It could be a problem with the dash cluster. They have been problematic in the past.

at 60-65 mph the rpm's will drop much less than 500 rpm going from 6th to 5th.

Maybe if it's dropping from 6th to 4th, but you should be able to hear that easily.

I have a W24 and the same drivetrain.1800 rpm in 6th gear is 64 mph.

Happy Glamping.

Arch Hoagland · 01-30-2020, 03:30 PM

I was told the RPMs will vary if the torque converter has not locked in.

How many miles are on it?

I'm surprised to hear you had the transmission rebuilt. What was wrong with it?

M&Aeller · 01-31-2020, 08:57 PM

Thanks to all of you who have sent suggestions and ideas of things that might help with finding a solution to my problem. Some of you have had additional questions which I will try to address. I have 80,000 miles on my RV. I have been working on this problem since September, 2019. I find that after the engine is up to normal running temperature and drive 20-25 miles, the surging starts. However, there have been instances where I have gone 40 to 200 miles and some distances in between before I have experienced the surging which I will define more in depth later on. The miles driven before the surging occurs have not been at a specific number of miles. The RV has a 8.1L Workhorse/Chevrolet engine that operates on a Throttle body Assembly with a wire not a cable. To date I have changed the fuel filters, plugs and wires, the transmission has been totally rebuilt with new torque converter, pump, bands and sensors. Additionally, I have changed the TCM Module and had it flashed. What I mean by surging is the tachometer will start surging from 2,000 up to 2,500 rpms and then back to 2,000 rpms. The engine appears to go up in speed as if it is trying to change gears but this does not happen. When the engine appears to be trying to go up in speed the speedometer is not reflecting ANY change in mph. The indication of any change in the engine speed is an audible sound only with no indication of a speed increase on the speedometer. I have made a video of the tachometer and speedometer while running that clearly shows the tachometer surging to 2,500 rpms with the speedometer staying right on the same speed whether 60 or 65 mph. The video picks up the sounds of the engine trying to shift. The amount of time that the surging takes place varies. When it does stop everything goes back to normal operation. It appears that if the transmission is in 6th gear it stays there and does not shift to 5th gear even though it sounds like it is trying to do so. The same thing happens if the transmission is in 5th gear. It stays there. I am in the process of changing out the HO2 sensors and the Manifold Absolute Pressure (MAP) sensor. I hope this clarifies some of your questions.

M&Aeller · 01-31-2020, 08:57 PM

Thanks to all of you who have sent suggestions and ideas of things that might help with finding a solution to my problem. Some of you have had additional questions which I will try to address. I have 80,000 miles on my RV. I have been working on this problem since September, 2019. I find that after the engine is up to normal running temperature and drive 20-25 miles, the surging starts. However, there have been instances where I have gone 40 to 200 miles and some distances in between before I have experienced the surging which I will define more in depth later on. The miles driven before the surging occurs have not been at a specific number of miles. The RV has a 8.1L Workhorse/Chevrolet engine that operates on a Throttle body Assembly with a wire not a cable. To date I have changed the fuel filters, plugs and wires, the transmission has been totally rebuilt with new torque converter, pump, bands and sensors. Additionally, I have changed the TCM Module and had it flashed. What I mean by surging is the tachometer will start surging from 2,000 up to 2,500 rpms and then back to 2,000 rpms. The engine appears to go up in speed as if it is trying to change gears but this does not happen. When the engine appears to be trying to go up in speed the speedometer is not reflecting ANY change in mph. The indication of any change in the engine speed is an audible sound only with no indication of a speed increase on the speedometer. I have made a video of the tachometer and speedometer while running that clearly shows the tachometer surging to 2,500 rpms with the speedometer staying right on the same speed whether 60 or 65 mph. The video picks up the sounds of the engine trying to shift. The amount of time that the surging takes place varies. When it does stop everything goes back to normal operation. It appears that if the transmission is in 6th gear it stays there and does not shift to 5th gear even though it sounds like it is trying to do so. The same thing happens if the transmission is in 5th gear. It stays there. I am in the process of changing out the HO2 sensors and the Manifold Absolute Pressure (MAP) sensor. I hope this clarifies some of your questions.

clifford j · 02-01-2020, 05:56 AM

Throttle body with no cable,,, it's called fly by wire. I would not keep throwing parts at it ,,, MAP sensor won't cause that symptom . Since the rpm jumps to a specific point I'd suspect the torque converter is going in and out of lock up.
When the rpm change occurs are you going up a grade, on level highway .

CLIFFORD

mdka99 · 02-01-2020, 05:59 PM

I thought that Winnebago quit using the workhorse chassis around 2010. All the 2014 Journey rv's I saw online had a diesel engine. What am I missing?

brokenrule · 02-04-2020, 10:17 AM

I second the suspect the torque converter is going in and out of lock up since it does it in 5th gear also.

Rebuilt trans does not always mean a new converter...

Unplanned Tourist · 02-04-2020, 10:48 AM

Quote:

Originally Posted by mdka99

I thought that Winnebago quit using the workhorse chassis around 2010. All the 2014 Journey rv's I saw online had a diesel engine. What am I missing?

You are missing the first sentence in the first post.

Please read through the posts, you will gain a lot more knowledge that way.

I know it's easy to skim over, but sometimes it's best to take your time.

Happy Glamping.

yeloduster · 02-04-2020, 01:16 PM

I also think the torque converter is going in and out of lockup. It could be the converter or it could be any number of engine/transmission signals that causes the transmission controller to issue the unlock/lock command.

Perhaps someone can help with a test for torque convert lock/unlock condition.