Update to shuddering Transmission

[Mystery]

Drove from Augusta Ga to Maggie Valley NC last night. 2002 Newmar Dutchstar 3852 w 3126 e kitty. My prior problem was shuddering from the transmission ( at least that's what I thought) when I was climbing steep grades. The Allison service center serviced tranny changed all filters and fluid. According to tech fluid was very dirty. Took back to mountains the first time and still experienced the shuddering. Took back to service center and they tested and also felt shuddering but described it as skipping and not tranny slipping and then changed fuel filter which was extremely dirty. Evidently the fuel filter was the problem as the Mystery Machine ran great with no shuddering and climbed the biggest grades and never dipped below 40 mph to include a 1.5 miles up hill at 9% grade and got the best mileage. I normally would get 6.8 to 7 going up hill on this trip about 207 miles and I averaged 7.6 last night. So lesson learned, stay on top of the fuel filter!

[Mac99]

Did you get a bad batch of fuel, or had you not changed
your fuels filters as part of routine annual maintenance ?

[Mystery]

I can trace it back to a bad tank of fuel I bought outside of Ormond Beach FL at a smaller station. Should have stuck with bigger truck stops.

[Spinner]

I picked up a bad tank of fuel at Pilot in Paducah, KY last winter so it happens at big stops too.

[Skip426]

The trans controller, takes an input from the , TPS( Throttle Poss. Sensor) and expects a certain performance from the enigne at every TPS reading, anything that effects engine performance will echo through transmission ; even cruise control; operation.
So when chasing after any performance issue ,be it transmission or cruise control, first question should be , is the engine operating 100%.

[Mystery]

Just want to say thank you very much to all who chimed in on this thread! I appreciate all the input. This is a great forum for great hands on advice. The members of the forum are a great resource and truly care about the concerns and issues of the other members!

[Mystery]

Just one additional note. I did change fuel filter with my annual pm in March of 2013 and I am pretty sure my bad tank of fuel was in early October. However, I did not have tranny serviced at the pm bc the tech check fluid and said it was ok. It has about 75,000 miles on it now bought it with 58,000 in August 2012. We do drive in mountains on a monthly basis as we have a cabin in western NC just below the parkway outside of Maggie Valley NC.

[Scottspence]

Originally Posted by Skip426

The trans controller, takes an input from the , TPS( Throttle Poss. Sensor) and expects a certain performance from the enigne at every TPS reading, anything that effects engine performance will echo through transmission ; even cruise control; operation.
So when chasing after any performance issue ,be it transmission or cruise control, first question should be , is the engine operating 100%.

I am having similar shuttering while accelerating just before 1500RPM; the unit feels as though it is in too high of a gear. I have to push quite far in order for it to downshift and raise the RPM. The engine seems to be running great, we pulled large hills for 500miles. The alternator had a dead short which took out my belt. I assumed the low voltage was my issue. Once repaired and voltage back to 13.8V, I assumed the issue was resolved. It is better but still there. Any Advice?

[Skip426]

Originally Posted by Scottspence

I am having similar shuttering while accelerating just before 1500RPM; the unit feels as though it is in too high of a gear. I have to push quite far in order for it to downshift and raise the RPM. The engine seems to be running great, we pulled large hills for 500miles. The alternator had a dead short which took out my belt. I assumed the low voltage was my issue. Once repaired and voltage back to 13.8V, I assumed the issue was resolved. It is better but still there. Any Advice?

I'll assume the chassis batteries were disconnected during the alt. replacement. But just in case they were not it would be an idea to disconnect them for 2 to 5 mins. That will reset the controllers to base settings. The trans controller has " adaptive memory " it learns your regular driving patterns and performance demands and adjusts the shift pattern accordingly. The first 1/2 hour of driving after the re-set the shifting will feel rough as the controller re-learns.
Was the shift delay the same in " Econo & Performance mode ?
Has the trans been serviced recently ?
What your feeling, sounds like a delay in , torque convertor lock-up dis-engagement, a condition that would be effected by the mode selected, and fluid/filter conditions inside the trans.
EDIT: A second thought; there is also a part of the co-operative program between the engine and trans controller, that limits engine torque, momentarily while the trans completes it's shift from one gear to the next, to prevent trans damage. Not knowing your coach/ engine combination , I'm guessing on this. Might be better to do up your own post, in the Cummins forum to see if others with the 500HP engine feel the same delay.
RE-EDIT: I think slower than I type. Your description sounds like it could be two problems, 1 on acceleration, up through the gears, and 2 the delay of downshift.
Both could be a single cause ( shift program, dead spot in the TPS ) or could have there own source. But I'd get some feed back from other 500HP, Cummins owners , before chasing the condition too far.

[Scottspence]

Originally Posted by Skip426

I'll assume the chassis batteries were disconnected during the alt. replacement. But just in case they were not it would be an idea to disconnect them for 2 to 5 mins. That will reset the controllers to base settings. The trans controller has " adaptive memory " it learns your regular driving patterns and performance demands and adjusts the shift pattern accordingly. The first 1/2 hour of driving after the re-set the shifting will feel rough as the controller re-learns.
Was the shift delay the same in " Econo & Performance mode ?
Has the trans been serviced recently ?
What your feeling, sounds like a delay in , torque convertor lock-up dis-engagement, a condition that would be effected by the mode selected, and fluid/filter conditions inside the trans.
EDIT: A second thought; there is also a part of the co-operative program between the engine and trans controller, that limits engine torque, momentarily while the trans completes it's shift from one gear to the next, to prevent trans damage. Not knowing your coach/ engine combination , I'm guessing on this. Might be better to do up your own post, in the Cummins forum to see if others with the 500HP engine feel the same delay.
RE-EDIT: I think slower than I type. Your description sounds like it could be two problems, 1 on acceleration, up through the gears, and 2 the delay of downshift.
Both could be a single cause ( shift program, dead spot in the TPS ) or could have there own source. But I'd get some feed back from other 500HP, Cummins owners , before chasing the condition too far.

I have been reading up on the Allsion page and Cummins page and the most common response is that it is Engine fuel starvation from bad fuel filters. Hopefully....it would be an easy fix. I will keep you posted. Thanks

[Elictrix]

"...batteries were disconnected during the alt. replacement. But just in case they were not it would be an idea to disconnect them for 2 to 5 mins. That will reset the controllers to base settings..."

Skip426. This is not correct. The ECU will retain all settings when the battery is disconnected. Learned settings can only be reset with a diagnostic reader or laptop.

[94-Newmar]

Originally Posted by Scottspence

I have been reading up on the Allsion page and Cummins page and the most common response is that it is Engine fuel starvation from bad fuel filters. Hopefully....it would be an easy fix. I will keep you posted. Thanks

Scottspence, I suggest taking it to an Allison center and have them hook it up to the DOC program. As Skip426 suggests it could possibly be the throttle position sensor. I would lean more towards erroneous signals from the turbine sensor, which could cause the torque converter electronic lockup to either be retarded or erratic - that would give you the situation you describe in your post above. You have 4 sensors which control all shifting functions of the transmission, Powerplant input speed or RPM, turbine sensor which is the torque converter outer hub speed, the output shaft speed/driveshaft speed, and the throttle position sensor(TPS). Nonetheless, the DOC tool can invasively see/check for erroneous signals from the TPS and anything else that may be causing these driveability issues for you - realtime.

Using the shiftpad, have you checked for any stored error codes? There are many errors that can occur that do not inhibit driving you'd never see them unless you retrieve them. To see if any codes have been set turn key on, engine off, trans in neutral, push the up and down arrows simultaneously and hold for 3-5 secs. The shiftpad will enter into a code retrieval mode. It has the capability to hold 5 different codes. The shiftpad will blink 4 digit numbers if there are any codes. Cycle thru the 5 different stored codes by pressing MODE after reading each one.

Originally Posted by Elictrix

"...batteries were disconnected during the alt. replacement. But just in case they were not it would be an idea to disconnect them for 2 to 5 mins. That will reset the controllers to base settings..."

Skip426. This is not correct. The ECU will retain all settings when the battery is disconnected. Learned settings can only be reset with a diagnostic reader or laptop.

No. The WTEC II/III/IV controllers all reset any learned driving patterns when power is removed. The "base" logic is stored in non-volatile memory in the eeprom's on the boards. Base logic includes absolute min/max values for various things including min/max shift points, gear selection based upon TPS position, min/max rpm, idle speed before engaging 1st gear, etc etc all based upon the powerplant behind the transmission. These "base" values are not resettable nor able to be changed by the end user - they can only be programmed using the DOC tool, these base settings can also make for a harsh driving experience There are procedures Allison recommends to teach the ECU a driving scenario but in most cases, just simply driving the coach is the best way for it to learn your driving patterns again.

Adaptive mode merely caters to the end user by setting curves on shift points and smoothing the harshness of gear changes up and down. Once learned it doesn't simply stop learning as the transmission controller is always in adaptive mode unless a DNS (do not shift) condition or any other serious errors that produce an error code are encountered while in operation. IF you have a problem with the TPS, Turbine sensor or perhaps something else amiss that is not yet setting an error code, then your unit is attempting to learn on errneous input from another sensor, which of course, will never then learn to correct itself. I suggest taking it to an Allison center that can hook it up to the DOC and check for any problems before I went much further.

[Scottspence]

Originally Posted by 94-Newmar

Scottspence, I suggest taking it to an Allison center and have them hook it up to the DOC program. As Skip426 suggests it could possibly be the throttle position sensor. I would lean more towards erroneous signals from the turbine sensor, which could cause the torque converter electronic lockup to either be retarded or erratic - that would give you the situation you describe in your post above. You have 4 sensors which control all shifting functions of the transmission, Powerplant input speed or RPM, turbine sensor which is the torque converter outer hub speed, the output shaft speed/driveshaft speed, and the throttle position sensor(TPS). Nonetheless, the DOC tool can invasively see/check for erroneous signals from the TPS and anything else that may be causing these driveability issues for you - realtime.

Using the shiftpad, have you checked for any stored error codes? There are many errors that can occur that do not inhibit driving you'd never see them unless you retrieve them. To see if any codes have been set turn key on, engine off, trans in neutral, push the up and down arrows simultaneously and hold for 3-5 secs. The shiftpad will enter into a code retrieval mode. It has the capability to hold 5 different codes. The shiftpad will blink 4 digit numbers if there are any codes. Cycle thru the 5 different stored codes by pressing MODE after reading each one.
No. The WTEC II/III/IV controllers all reset any learned driving patterns when power is removed. The "base" logic is stored in non-volatile memory in the eeprom's on the boards. Base logic includes absolute min/max values for various things including min/max shift points, gear selection based upon TPS position, min/max rpm, idle speed before engaging 1st gear, etc etc all based upon the powerplant behind the transmission. These "base" values are not resettable nor able to be changed by the end user - they can only be programmed using the DOC tool, these base settings can also make for a harsh driving experience There are procedures Allison recommends to teach the ECU a driving scenario but in most cases, just simply driving the coach is the best way for it to learn your driving patterns again.

Adaptive mode merely caters to the end user by setting curves on shift points and smoothing the harshness of gear changes up and down. Once learned it doesn't simply stop learning as the transmission controller is always in adaptive mode unless a DNS (do not shift) condition or any other serious errors that produce an error code are encountered while in operation. IF you have a problem with the TPS, Turbine sensor or perhaps something else amiss that is not yet setting an error code, then your unit is attempting to learn on errneous input from another sensor, which of course, will never then learn to correct itself. I suggest taking it to an Allison center that can hook it up to the DOC and check for any problems before I went much further.

Wow Thanks, great wealth of knowledge!! Cheers, Scott

[Skip426]

Scott more info in case you don't already have it.