Engine/Transmission (1998.5 - 2002) Uncontrolled Engine Acceleration

[BLACKRAM]

On two separate incidences I have had a runaway engine.



The first time in Montana with outside temperatures over 95*, and today in Seattle traffic at about 85*. In both incidences the engine went to maximum throttle and nothing would stop it except shutting off the engine. Considering the BOMB'ed torque of my engine (DDII's and TTPM) this was not a fun situation. The brakes could not hold the truck back, and the smoke (diesel and tire) was off the chart. No accident, but definitely a sphincter tightening experience! After a few minutes, the vehicle started and performed as normal.



If anybody has an idea on how to remedy this problem, I welcome an answer.

 

[SOOT]

Sounds like ECM or TPS has an intermittent problem

 

[Whitmore]

Yep

I would suspect the tps throttle position senser first

MMclain ---Sounds like ECM or TPS has an intermittent problem

 

[JTroiano]

I have never seen a TPS fail and give all the reference voltage back to the ECM. In twenty years as a tech every failed TPS I've seen has shown and open or intermittent open, which would meen a stumble or a complete open would meen only idle. I Don't know what it could be, but I would remove any fuel electronic fuel enhancers. If you think it is temp related you could block of your drill on a hotter day and see if you can redublicate, just be carefull and watch your temp. Hope you figure it out.

Jon T

 

[emjay]

Hmmm... sucking oil through a flaky turbo seal, maybe?

 

[SOOT]

Originally posted by JTroiano

I have never seen a TPS fail and give all the reference voltage back to the ECM. In twenty years as a tech every failed TPS I've seen has shown and open or intermittent open, which would meen a stumble or a complete open would meen only idle.

Jon T

Doesen't mean that it is not possible.

 

[JTroiano]

MMclain, I'm just saying it is very unlikely. I would think that there is a better chance of it sucking oil or the ECM being bad than the TPS causing it. I could be wrong. I guess if one of the little fingers in the TPS broke off and some how was making the connection it could be possible but I've never seen it and nobody I know has ever seen it happen.

Jon T

 

[duaneparks]

Are you sure your truck didn't eat an Audi 5000? LOL!



That must have been scary indeed in traffic. I have no input, but wanted to make a little light of the situation.



Hope you get it fixed before any damage is done to you or someone else.



Duane

 

[SOOT]

If I affended you I am sorry, I was just making a statement.



In that case then it could very well be the ECM If it was sucking oil then it would not have quit when shutting off the key. So to me it sounds electrical.

 

[clong]

I had a case like this once. Was going down the hiway with the cruise on and all of a sudden the engine went to full speed and would not slow down until I turned it off. (ever tried to drive one of our trucks at almost 100 mph with the engine turned off?) Turned out to be a short in the cruise control.

 

[kaffine krazed]

If it was cruise control wouldn't hitting the brake stop it? I know the truck I fixed that had a cruise control that would arm itself then accelerate when you hit the brakes the cruise would disengauge.



Are there any codes in the computer? How about a throttle cable sticking?

 

[clong]

Was a short between two wires in the vacuum unit. Could not turn it off with the switches or by hitting the brakes.

 

[BLACKRAM]

I spoke with DD, and Bill Kondolay regarding this problem. Bill said Stefan had the same thing happen at the race track (I hope the light was green) and the problem is the TPS or a vacuum leak. If a vacuum leak, the problem will get worse until the engine will NOT shut off at all----a true runaway engine.



Either way, the vehicle will be at a Cummins shop tomorrow before somebody gets hurt.