Community Forums

77Travco · 02-26-2021, 03:36 PM

Quote:

Originally Posted by twinboat

Its not any kind of test holding the throttle for a few seconds.

For it to prove anything, you need to hold it to the floor for longer then you would feel comfortable doing. At least 15 seconds for boost to build.

This is a non turbo engine.

twinboat · 02-26-2021, 04:48 PM

Quote:

Originally Posted by 77Travco

This is a non turbo engine.

OK, but your still not going to starve it for fuel in a few second full throttle bump.

iamdogstar · 03-01-2021, 04:42 AM

I've found a mechanic (who deals in commercial vehicles and buses) to take a look over it later on today - so i'm going to give him a quick spin in it and leave it with him - i'm hoping he may find out exactly what the devil is wrong ....

i'll keep you all posted
and thanks again everyone for your invaluable assistance

i'm even thinking of going on a commercial mechanics course !! i know i'll be having a forever motorhome so i better get myself educated properly into the maintenance

the changing of the transmission filter and oil went well ! i done it !! it just didn't resolve the problem (but the oil definitely needed changing - it was pretty darn dark) ... now it has Dexron III in it .....

Quote:

Originally Posted by 77Travco

I don’t remember where you are with the maintenance. Have you changed the fuel and water filters for the fuel system? That’s the first thing to do. If it’s firing on all cylinders then your injectors are probably good. Do you have a lift pump? If you do then you need to make sure it’s working as well. That could be the whole issue.

Unplanned Tourist · 03-01-2021, 06:22 AM

Quote:

Originally Posted by iamdogstar

I've found a mechanic (who deals in commercial vehicles and buses) to take a look over it later on today - so i'm going to give him a quick spin in it and leave it with him - i'm hoping he may find out exactly what the devil is wrong ....

i'll keep you all posted
and thanks again everyone for your invaluable assistance

i'm even thinking of going on a commercial mechanics course !! i know i'll be having a forever motorhome so i better get myself educated properly into the maintenance

the changing of the transmission filter and oil went well ! i done it !! it just didn't resolve the problem (but the oil definitely needed changing - it was pretty darn dark) ... now it has Dexron III in it .....

You should get Guy Martin to check it out. That would be stellar!

I hope it's not too serious.

iamdogstar · 03-02-2021, 10:22 AM

I'd never heard of Guy Martin before but you've peaked my interest and i'm buying his book 'if you dead, you dead' ..... !! cheers

Quote:

Originally Posted by Unplanned Tourist

You should get Guy Martin to check it out. That would be stellar!

I hope it's not too serious.

Unplanned Tourist · 03-02-2021, 10:52 AM

Quote:

Originally Posted by iamdogstar

I'd never heard of Guy Martin before but you've peaked my interest and i'm buying his book 'if you dead, you dead' ..... !! cheers

He's a super cool guy, that Guy! Anyone that's a truck mechanic AND races in the TT is a hero to me!

He has loads of Youtube videos out also.

Enjoy the book.

phil8656 · 03-02-2021, 12:11 PM

Auto tranny's have thing thing called a "modulator". Sometimes they are on the outside. And sometimes they have a vacuum hose going to them. Make sure your vacuum hose is good, very good, because a bad vacuum hose can look fine but have tiny cracks that you can't hear because they are sucking in. The modulator is part of the shifting mechanism.

I am planning on just replacing all of mine soon since they are not expensive. You can buy it by the foot and it usually comes in three different sizes for various things around the engine and heater control system. This should be considered routine maintenance on all engines after a certain amount of time or mileage since rubber deteriorates anyway. Power brakes run off of the vacuum too.

CAUTION; Be sure and only take ONE off at a time. If they get mixed up it is hell trying to find the right place to put them.

Unplanned Tourist · 03-02-2021, 02:24 PM

Quote:

Originally Posted by phil8656

Auto tranny's have thing thing called a "modulator". Sometimes they are on the outside. And sometimes they have a vacuum hose going to them. Make sure your vacuum hose is good, very good, because a bad vacuum hose can look fine but have tiny cracks that you can't hear because they are sucking in. The modulator is part of the shifting mechanism.

.

She has a deisel engine. No vacuum modulator.

RickNC · 03-02-2021, 06:52 PM

Assuming you got the the 6.5l diesel that came on Usa versions. You likely have the 4L80e transmission. It is controlled primarily by the ECM.

The shifting issue you describe is the same issue I had on my gasoline version with the same transmission. I traced that to the Throttle Position Sensor (TPS). The TPS controls the shift points.
I Replaced it and no issues in the past 18k miles. The engine temperature sensor to the ECM also plays a role in choosing the shift points but to a much lesser extent than the TPS
The sensor on the 6.5 I believe is located on the throttle pedal assembly.

Link to a supplier http://www.ssdieselsupply.com/p179_t...sor_92_93.html

Unplanned Tourist · 03-02-2021, 07:17 PM

I suspect she has the 6.2 non turbo engine. All mechanical, with no electronics.

Likely it has a throttle position sensor for the transmission controls.

Ray,IN · 03-02-2021, 09:32 PM

Quote:

Originally Posted by clifford j

Dogstar, do this simple test,,, Start the engine, let it warm up. Once it's at operating temperature, put your foot hard on the brake, (use Emergency brake too), now drop it into forward gear and while holding the brake step on the gas and quickly bring up the rpm's and load the engine hard for a few seconds, notice what the engine dose under heavy load, dose it bog down or dose it stumble and want to die. Don't keep doing it, just a couple times will give you some good information.

CLIFFORD
BTW, what city are you in. Are you out the M4

In post #6 she said Liverpool.

RickNC · 03-02-2021, 09:39 PM

Quote:

Originally Posted by Unplanned Tourist

I suspect she has the 6.2 non turbo engine. All mechanical, with no electronics.

Likely it has a throttle position sensor for the transmission controls.

Yes, In the 6.5 it is correctly called a Transmission Control Module. Interesting that it is the same case and wiring harness connectors as the gas engine’s ECM.

iamdogstar · 03-03-2021, 04:31 AM

excellent advices - i thank you very much for taking the time to let me know all this .... I have a proper mechanic looking over it now and he showed me a photo with exactly this deterioration and he is going to sort it ... he says it is possibly fuel injectors and the sensor on the speedometer not working correctly .... !! i'm waiting to hear further from him but i'm more hopeful now ....Cheers again

Quote:

Originally Posted by phil8656

Auto tranny's have thing thing called a "modulator". Sometimes they are on the outside. And sometimes they have a vacuum hose going to them. Make sure your vacuum hose is good, very good, because a bad vacuum hose can look fine but have tiny cracks that you can't hear because they are sucking in. The modulator is part of the shifting mechanism.

I am planning on just replacing all of mine soon since they are not expensive. You can buy it by the foot and it usually comes in three different sizes for various things around the engine and heater control system. This should be considered routine maintenance on all engines after a certain amount of time or mileage since rubber deteriorates anyway. Power brakes run off of the vacuum too.

CAUTION; Be sure and only take ONE off at a time. If they get mixed up it is hell trying to find the right place to put them.

iamdogstar · 03-03-2021, 04:34 AM

Yep .. brilliant ... i took her on a little road run with a mechanic beside me and he said it could be the sensor !! he found a lot of oil in and around it and said this is possibly the problem !! he's looking her over now and hopefully it will be sorted by a Man who Can ....

I really want to take up a commercial mechanics course now
I need to know these things as I'm always going to have a Winnebago in my life

Thank you everyone for your help and assistance
Has helped get me through in a calmer light

Quote:

Originally Posted by RickNC

Assuming you got the the 6.5l diesel that came on Usa versions. You likely have the 4L80e transmission. It is controlled primarily by the ECM.

The shifting issue you describe is the same issue I had on my gasoline version with the same transmission. I traced that to the Throttle Position Sensor (TPS). The TPS controls the shift points.
I Replaced it and no issues in the past 18k miles. The engine temperature sensor to the ECM also plays a role in choosing the shift points but to a much lesser extent than the TPS
The sensor on the 6.5 I believe is located on the throttle pedal assembly.

Link to a supplier TPS Throttle Position Sensor 92-93 :: SSDiesel Supply :: GM 6.5 TD Specialists