1999 24 valve high idle and bucking at highway speeds

[24vgarrett]

So I have a 1999 24 valve all stock no tuner.. and I can start the truck and it fired right up and it will idle around 800 or so rpm and when I hit the throttle it will idle at 1100 and at highway speeds the truck will buck and if I let off it’s fine until I get on the throttle again I just replaced tps/apps and set the correct voltage and done the pedal thing the map and iat sensor are showing they work on my scan tool but no codes I’ve only owned the truck for a couple weeks and the vp44 has a sticker on it and it looks brand new all my ground are good but idk what to do.....

[kzimmer]

Pull alternator fuse and see if the problem goes away. Possible AC noise from worn out alternator. 

[24vgarrett]

Ok I’ll try that thanks I’ll keep y’all updated 

 

That didn’t change anything

[Mopar1973Man]

Dump the APPS you and buy a Timbo's apps. There is no voltage to set. Currently your in throttling mode hence the high idle. I would just ditch that apps.

Edited January 28, 2020 by Mopar1973Man

[24vgarrett]

ok thanks man ill give it a try 

[kzimmer]

Was it doing this before you replaced the APPS?

[jag]

Really? No voltage to set?

Scan001.pdf Scan002 (2).pdf

[dripley]

7 hours ago, jag said:

Really? No voltage to set?

Scan001.pdf 514.56 kB · 6 downloads Scan002 (2).pdf 430.17 kB · 2 downloads

You are not setting any voltage on the Timbo, just taking a reading and watching for a rise in the voltage. Much different than the OE. 

Edited January 29, 2020 by dripley

[24vgarrett]

Yes it was doing it before so I bought another one from rock auto and it had no voltage to set it at so I found somewere the basic voltage and set it there and it did the same thing ig I learned my lesson buying cheap parts but my timbo should be here today 

[24vgarrett]

i installed the timbo apps and it still high idle i havent got it out on the highway yet... cant figure out what the issue is 

 

[jag]

Didn't say Jack about setting any voltage on Timbo.

The phrase "There is no voltage to check" could lead people astray.

If your not checking voltage, why do you need a voltmeter?

So do you set the apps according to instructions or just set it OE? 3 or 1

Mine is just about 10 years old, & if the instructions are followed to a T, you win, IF that was the problem.

 

 

 

[dripley]

I used a volt meter the first time I installed my Timbo. But once I saw what reading the voltage was for l have not used one since. Even the instructions say you can bolt it on and drive off. 

[Mopar1973Man]

Timbos APPS is all based on angle. That simple there is no electronics. As you can see there is just the contact strip. Voltage is only use to see if you cross the boundary from idle to throttling and then you unscrewing the stop pin till you come back to rest in the idle zone. 

 

[24vgarrett]

I’ll give it another try this is my first dodge cummins so sorry for all the confusion just trying to learn 

[24vgarrett]

I tried measuring the voltage according to the instructions sent with my timbo and it did the same so I said well I’ll try it with true ballcrank screw all the way out and I did that and reset the apps and it doesn’t buck and hiccup now but it still idles high

Edited January 31, 2020 by 24vgarrett

[Mopar1973Man]

How old are the injectors? If the injectors are over 100k miles for sure they are shot. As injectors wear the pop pressure falls. The engine load will reach 0 and the ECM will not be able to defuel enough to get the idle down to 800 RPM. If the injectors are questionable I would have them sent for testing. 

 

[Dieselfuture]

6 hours ago, Mopar1973Man said:

Voltage is only use to see if you cross the boundary from idle to throttling and then you unscrewing the stop pin till you come back to rest in the idle zone. 

I think that migt of been misleading to some that are doing this for a  first time. 

So if someone says no voltage measuring needed with timbo, but let's say when apps is installed and it's in voltage range where it's fueling, because idle screw was too far in, then it can be misleading saying no voltage adjustments needed.

Not even sure who said what or pointing fingers, this is what I got from reading some things in this post. 

A lot of us like to assume conclusions without facts and it leads us on wrong path.

Going back to my corner now 

[24vgarrett]

I’m not sure how old my injectors are I haven’t owned the truck long but if I put my truck in gear and let out on the clutch it will idle down to 800 until I hit the throttle again I can start the truck and it idle at 800 and then hit the throttle it go to 1100 and then I can put a load on the engine and it idles down

Edited January 31, 2020 by 24vgarrett

[Mopar1973Man]

Ummm. That's too high period. ECM possibly has fueling table issues.  I was think lower like 850 to 875. 1100 RPM is like the 6 cylinder high idle but typically brake pedal or touching throttle cancels.

 

It should not be 1100 rpm at any point after touching the throttle.

 

I've got an guy in Texas I've been working with he's got 3 trucks with the same issue. I'll post anything I learn on this too.

[24vgarrett]

ok thanks im gonna try and replace my intake air temp sensor and maybe my map sensor and see if that helps any...