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Rpm's stick at 2000/80 kph

04-silver

By 04-silver
in Ask A GM Technician

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04-silver Enthusiast

04-silver

Posted
Posted

I originally posted this under"gas engines" I did get some help/advice from one member but the more info the better........lol

 

This is what happens: (the RPM and K numbers are relatively close but not 100%)

 

Truck shifts fine, 22-2500@30k's, 22-2500@60k's. When I continue to increase to 80kph the RPMs hit 2500 and drop to 18-2000RPM, same as before except now when I accelerate from 80 kph the RPMs will not budge from 18-2000 and I do get a slight grinding feeling from the gas pedal, I will get the truck up to about 105/110 kph before the RPM's eventually jump to 25-2800. Its almost like the it sits in a lock postion.

 

The only other way I can get the RPM's to increase is to either punch on it and the RPM's scoot to 3500-4000 or I can take my foot off the pedal for a split second and re-apply.

 

This will happen in D, 3, w/wo auto, w/wo tow haul doesn't matter will always stick at 1800 and 80 kph when gradually accelerating.

 

This does not happen if I accelerate fast as in from an on-ramp.

 

:flag:

John

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted

I'm not sure what you're saying here. Is it that the engine rpm's go up, but the tach doesn't move, the rpm's don't go up, or the TCC doesn't come out of lockup?

04-silver Enthusiast

04-silver

Posted
  • Author
Posted

All I'm going by here is what I see on the tach and the speedometer.

When the tach diplays 2000 rpm and the truck is travel at a steady speed of 80 kph this is where the rpms on the tach seem to stick. From this point I will gradually increase the speed from 80 klm to about 110 klms, during this acceleration period the tach has/will not move from 2000, untill the truck is doing approximetly 111kph then the tach jumps to 2500/2800.

 

edit-unless

The only other way I can get the RPM's to increase is to either punch on it and the RPM's scoot to 3500-4000 or I can take my foot off the pedal for a split second and re-apply

 

 

I just going by the gauges the tach and speedo, there does seem to be a slight grinding feel during this period.

 

:flag:

john

mrchw New Member

mrchw

Posted
Posted

All I'm going by here is what I see on the tach and the speedometer.

When the tach diplays 2000 rpm and the truck is travel at a steady speed of 80 kph this is where the rpms on the tach seem to stick. From this point I will gradually increase the speed from 80 klm to about 110 klms, during this acceleration period the tach has/will not move from 2000, untill the truck is doing approximetly 111kph then the tach jumps to 2500/2800.

 

edit-unless

The only other way I can get the RPM's to increase is to either punch on it and the RPM's scoot to 3500-4000 or I can take my foot off the pedal for a split second and re-apply

 

 

I just going by the gauges the tach and speedo, there does seem to be a slight grinding feel during this period.

 

:flag:

john

 

 

 

 

 

For what it's worth, I've got the exact same condition in my 99 Blazer. I was a little worried when I first noticed in in December 2003, but since then I've come to ignore it. I have the a cabled throttle, so it's not that like someone else had mentioned. I cleaned out the throttle as well, that didn't make a difference.

 

If you find a solution, let us know, as I'm quite curious! I'm planning on selling my blazer in the next month, but I'd still like to know for curiosity's sake!

 

Cameron

04-silver Enthusiast

04-silver

Posted
  • Author
Posted

Well thanks for the info.

 

I just had the truck in for its yearly about 2 months ago and they/mechanic told me the truck has all the updates. Guess I'll just wait untill the truck's 18th month check up and see what happens by then. Still have 2 years left on the warranty and this clitch is noted on the mechanic's work order. When I find fix or whatever I will let you know.

 

From my other post one member told me possibly the program maybe corrupt in the PCM and or the VSS (vehicle speed senor)

 

Previous post

 

 

:D

John

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
From my other post one member told me possibly the program maybe corrupt in the PCM and or the VSS (vehicle speed senor)

 

GM doesn't use Windows and I have never heard of the program being corrupt. :D And the VSS has nothing to do with the tach. VSS is vehicle speed, not engine speed.

04-silver Enthusiast

04-silver

Posted
  • Author
Posted

:cool:

 

Initially it sounded good to me, I guess I let it slip that mechanic is not my profession :cool:

 

Thanks GM-Tech

 

:D

John

 

Edit-in all fairness this is his whole quote

It's the torque converter clutch locking when you see the rpm's drop to 2000. Why it doesn't go up from there is a good question. Sounds like a VSS (vehicle speed sensor) problem to me, or some corruption in the PCM program. The dealer only sees that the program is there and functioning. It cannot see if the program is corrupted if no codes are being set

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