Engine/Transmission (1998.5 - 2002) High Idle

[petersonj]

When he first hooked up the scanner, he also told me that with the key on, and a fully warmed engine, that scanner showed the grid heater on, and the IAT was reading 146 degrees.

That would be a reasonable temperature.

He said the scanner showed the high idle was being commanded on by the ECM.

Did he by chance observe the APPS percent while the engine idled? That would be good to know.

He also said Boost pressure showed 15 lbs with the engine off? How is that possible.

Likely the scanner is reading absolute ambient pressure (atmospheric pressure - 14.7 psi).

Sounds more to me like the engine computer is toast.

At this point there is nothing to support that conclusion.

- John

 

[garylmoore]

That's exactly what I'm going to do tomorrow.
Can I disconnect the actuator for the wastegate and try to work that by hand?

 

[garylmoore]

Ok. I like what you have to say petersonj!
The guy rushed thru everything he had to say to me. I was lucky to get what info I wrote above.

 

[garylmoore]

I'll install the IAT sensor tomorrow and see if anything changes.

 

[petersonj]

Back to my previous post - I missed the part about the grid heater being on with a warm engine. That is not normal.

Also, if in fact the ECM is commanding the high idle, the APPS still should read 0 percent at idle.

- John

 

[garylmoore]

Back to my previous post - I missed the part about the grid heater being on with a warm engine. That is not normal.

Also, if in fact the ECM is commanding the high idle, the APPS still should read 0 percent at idle.
- John

I had just rolled off the Interstate minutes before and had really been hard on and off the pedal, just to see if it would change anything.
The truck runs great if you are not trying to go really slow.
I had originally wondered if the APPS was the issue. I pulled the cover Tuesday and all looked normal, The cable (linkage?, cam?) was resting against the set screw, and nothing was binding, but I did not look at the rheostat.
I also read up on setting the zero on a factory APPS. The write up I read was a complex one.
I had installed a Timbo on the last truck and it was simple in comparison.

 

[Ozymandias]

APPS would set a code when ever it is not at Zero at idle start-up.

But you can always reset the APPS by the following procedure. Switch ignition on, slowly depress accelerator pedal to the floor and then slowly release to zero, switch off ignition. That resets the safed values in the ECM.

I don't think that will solve the problem but it is an easy try at least.

 

[garylmoore]

APPS would set a code when ever it is not at Zero at idle start-up.

But you can always reset the APPS by the following procedure. Switch ignition on, slowly depress accelerator pedal to the floor and then slowly release to zero, switch off ignition. That resets the safed values in the ECM.

I don't think that will solve the problem but it is an easy try at least.

Crap. I forgot to try this today.
I did, change the IAT sensor and since it was easily accessible, I changed the MAP sensor. It changed nothing. Yes, I realize, being a parts changer, a part cannon mechanic, is not the way to do things, but this was my last Harrah.
I also used my friends $200 scanner and the only code that came up was a turbo overboost. This goes along with the last scan that said the wastegate was stuck closed.
So. The truck is going to Autoland on I-90/I-39 near the Wisconsin Line tomorrow. I know little about them, except for the fact that they are in the habit of searching out of state and bringing back Rust Free Gen 2 Diesel Rams to sell.
The toolbox went into the neighbors garage today (we towed the 3000 lb toolbox with a John Deere garden tractor) and another UHaul is in the cards for Monday.
Thanks to everyone for the hard work, I will report back when the truck is repaired.

 

[petersonj]

We will definitely want to hear what the fix is.

- John

 

[garylmoore]

APPS would set a code when ever it is not at Zero at idle start-up.

I don't think that will solve the problem but it is an easy try at least.

I failed to answer this comment. One of the problems from the very start is that there were no codes showing. My friend had one of the home user code readers that showed a lot more than most and we found out later there were code set that did not show up either on my friend's code reader or by the three key method.
The last time I read codes it gave me a turbo overboost and nothing else. I reset that code and it changed nothing.

 

[garylmoore]

Did you see the bulletin I posted?

Yes, that one met only one condition I had at the time. I had run across that on Mopar Man's site.

View attachment 139327 View attachment 139328

I need to thank you for these drawings. They were a huge help when locating the sensors.
I would lone to have the paper service manual on this truck.

 

[Ozymandias]

I failed to answer this comment. One of the problems from the very start is that there were no codes showing. My friend had one of the home user code readers that showed a lot more than most and we found out later there were code set that did not show up either on my friend's code reader or by the three key method.
The last time I read codes it gave me a turbo overboost and nothing else. I reset that code and it changed nothing.

That's the problem with these older trucks, the electronic diagnosis abilities are very limited compared to newer models.
And also it needs a sophisticated scanner to read them all, the point is all, many devices lack badly if it comes to the Diesels.
The only one I know for the old ones is AutoEnginuity that has full access, and the factory units like DRB III of course..

 

[garylmoore]

The truck is running.
The set screw on the throttle position sensor (linkage) was moving loose.
They set the apps at 0 degrees, loctited and staked the screw.
The Idle is about 800 rpm now.
Don't ask me how this happened. It must have been vibration, no one messed with that screw.

 

[Dl5treez]

Gremlins. They’re out and about now that fall/winter is upon us.

 

[BigPapa]

Glad you got it fixed. I thought you'd checked that already.

 

[petersonj]

Glad to hear it was a simple fix. The cause and effect match.

In an earlier post from you, "garylmoore said: He said the scanner showed the high idle was being commanded on by the ECM."

I had asked, "Did he by chance observe the APPS percent while the engine idled? That would be good to know." As hindsight, I would bet that the APPS was showing about a 5 - 10% throttle position. If it was, then of course the ECM would have commanded the higher idle.

Your experience has also shown that that codes are not necessarily set uniformly on all trucks and that all scanners are not equal.

- John

 

[garylmoore]

Glad you got it fixed. I thought you'd checked that already.

I pulled the cover and checked to see that the linkage was operating correctly.
The spring was fine and returned the stop to the set screw properly while operating.
I did not check the set screw to make sure it had not moved.

 

[garylmoore]

Glad to hear it was a simple fix. The cause and effect match.

In an earlier post from you, "garylmoore said: He said the scanner showed the high idle was being commanded on by the ECM."

I had asked, "Did he by chance observe the APPS percent while the engine idled? That would be good to know." As hindsight, I would bet that the APPS was showing about a 5 - 10% throttle position. If it was, then of course the ECM would have commanded the higher idle.

Your experience has also shown that that codes are not necessarily set uniformly on all trucks and that all scanners are not equal.

- John

This is the first time I know of where a fault did not set a code. I hope this does not become a trend.

 

[Brandilen]

I had the same issue last year and checked voltage on the APPS. It was too high. I replaced it and fixed the issue.