Newbie here so please be gentle. I have a 99 24v, 4x4 auto 134k miles that started idling at 1000 rpm's and has a miss to it. Happened out of the blue while wife was driving. Idle stays at 1k and misses unless put in gear. when put in gear, it idles @ 900 rpm and smoothes out under load of trans while in gear. Truck runs out great as long as its accelerating but when you let off throttle you can hear it miss. Fuel psi is 19 at idle with a air dog 100 lift pump. Truck is stock besides lift pump. Only code its giving is p0234 and I found waste gate stuck. All exh temps from exh man are within 40 deg f of each other. Iat, ect , and map look good on scanner. Batteries are 6 months old and test good. I have checked and cleaned grounds. I have a timbo apps about 1 year old. Truck doesn't smoke any out exh pipe. I checked for ac voltage and got a high of .030vac. Any ideas? What will make a cummins idle high? ecm? I have auto enginuity on my laptop to scan with. Please help!

Edited April 6, 20169 yr by Itaintez
forgot to add some info

AFAIK all idle inputs are sent via the ECM so if it's fluctuating, it leads me to believe it's something mechanical.

 

-Dirty fuel filter

-Injector issue

-Outside air temp.

Idle is controlled by coolant temperature so if you thermostat is cold and not making full 190*F of temperature then the idle will be high.

 

High idle will go up to 1,200 RPM but impossible to have while driving. If coolant is over 140*F it will never re-arm again.

My coolant temp is reaching 190 deg. Ect sensor is reading properly on scanner an I even swapped ect to see if it changed the condition and it didn't . I run fleetguard fuel filters. Filter has 1k since changed. I took filter off to check for water and contaminants and it looked good. Iat sensor is also showing good temps and I even swapped to see if I got a change and did not.?? Any thoughts, suggestions, tests? I'm willing to test whatever to fix my cummins!

Remember live data and dash data are always going to match. You need to use a IR temp gun on the sensor or install anothe temp gauge to see differences. Like Dripley has a dash gauge that reads low (160-180*F) but his aftermarket gauge show 190-195*F. Which create weird issues because the ECM uses that data.  But of course if he hooked up a live data tool it would show the same low temp reading as the dash.

 

Does the ECT and IAT match on cold morning start up? ECT controls idle so if the ECT is colder than normal the idle will be higher.

 

Double check your Timbo's calibration make sure you not in the throttling position. If so the ECM will most likely idle in that 1000 RPM bracket too.

I have a temp gun and will check temps for differing temps. I believe Iat and ect were the same on cold startup but will check again. According to scanner apps is picked up after pressing slightly on accelerator pedal ,but i will check voltage at the harness to verify calibration. Thanks for advice and I will post results as soon as I get them. 

Newbie question, how do I fill out my profile to show my truck specs?

Edited April 6, 20169 yr by Itaintez
Spelling and sentence structure

On Timbo's APPS you want to adjust the stop pin (idle) in till it rises then back out till it stop falling in voltage then add another 1/2 turn to the screw for slack.

3 hours ago, Itaintez said:

I have a temp gun and will check temps for differing temps. I believe Iat and ect were the same on cold startup but will check again. According to scanner apps is picked up after pressing slightly on accelerator pedal ,but i will check voltage at the harness to verify calibration. Thanks for advice and I will post results as soon as I get them. 

Newbie question, how do I fill out my profile to show my truck specs?

 

Click on your profile name in the top right of the screen, go to Account Setting, then signature will be middle left.

Thanks notlimah. Got it now.

Had a few hrs today to work on my truck. The ect was 60 deg and the Iat was reading 58.7 deg  on cold startup. I recalibrated  my timbo apps and started my truck. Same results, went to 1k rpm, idle ran smooth for about 20 sec then started missing and cutting out. I was watching rpm on scanner and it was fluctuating  from around 920 to 990. I accelerated to about 1800 rpm and let off and it was still fluctuating. I printed off the troubleshoot guide from bluechip diesel and proceeded. I started with the vp44 connector. When I unplugged it I noticed 2 wires from the comp board on top were smashed in between the vp44 connector and the pump housing so I moved them up out of the way. I proceeded to check the pins in the pump connector, voltages were good except pin 5 had a very slight .107v while engine was running but when shutdown it went to 13v for a few seconds then voltage went away as it should. What I did notice is that the truck idled at 950 rpm and it was smooth!!! No missing!? I let I run for about a min and shut it off. I checked the two wires on the pump I had moved and noticed the outer covering on the wires deteriorated and cracked all over. When I touched the wires, the insulation fell off!!. Now I'm trying to figure out how to cover the wires. I"m thinking cut the wires, put on some heat shrink tubing and solder the wires back together? I believe these 2 wires are for timing fuel on the pump. They run towards the eng block not the 2 that go between the fuel lines. Anyone ever solder these before?? Sorry so long.

On 4/6/2016 at 7:37 AM, Mopar1973Man said:

On Timbo's APPS you want to adjust the stop pin (idle) in till it rises then back out till it stop falling in voltage then add another 1/2 turn to the screw for slack.

I have the same issue with my 2000 / 24v. I installed new thermostat (made in Germany 190*) and check all temp by my digital temp gun and all are correct but regardless of weather cold or warm start idling @ 950 rpm then fall down to 750 rpm & reduce the battery voltage too (I notice it on night when interior light was ON,also panel light they became light & bright.)  then goes up to 950 & keep do in it till warmed up and stays @ 950. as soon as I pot trany on R or D, it fall to 700 @ all time until change the trany to P or N again RPM goes up to 950. could I adjust mine with this method? where should I start & how do I do it? any advise /  suggestion appreciate.

Thanks for your time and effort.       

I don't think you can adjust a factory apps like this method. If you have the timbo aftermarket apps, then yes you can use that method.

Appreciate for respond. I don't know what the timbo apps is? I checked at leas 20 trucks with same engine none of em had high idle like mine. they're around 700 to 750 but mine 950!!!!! it's really bugging me. I personally don't like high idling, and apologizes to whom they like it. I think after engine warmed up and got to safe operation temperature, there is no need of high idling, it's just wasting fuel and engine life but if LORD VP44 like it, I've no CHOICE and must bow to him and say noting further.

Best Regard

Same 53

Here's a link for TIMBO

 

And look through Mikes article on how to calibrate your stock APPS, maybe something got out of whack there.

 

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/electrical/stock-apps-sensor-voltage-adjustment-r34/

 

Could also be a TV cable issue but I'd start with your stock voltage and see if it's good.

Edited April 9, 20169 yr by notlimah

Thank You

I'm still waiting to receive the link you sent me, my PC still circling.

where do I need to check the voltage?  

Edited April 9, 20169 yr by Sam53
grammar

I edited my previous post, hope it works now.

 

You should read through the article, it's fairly in depth.

Thank You so much.I got it now.

Actual programmed idle speed should be 800-850 RPM.

 

700-750 RPM is too low and not normal.

 

The only thing I can thing off your IVS switch is still on throttling position which would cause it to ignore idle software causing a higher idle RPM.

What's the IVS switch mike?

Idle Validation Switch or IVS. Pins 6, 2, and 1. Typically on a stock APPS the voltage with toggle these two switches. On a Timbo APPS the sensor angle is what toggle these two switches. Basically Pin 6 is grounded to Pin 1 if in IDLE position or Pin 2 is grounded to pin 1 if THROTTLING. Never are both open at the same time nor are they both ground at the same time.

 

So if for some reason the IVS is tripped to THROTTLING it will follow the voltage as a idle which is wrong and typically causes the engine idle faster than normal. So once the IVS is flipped to IDLE position now the APPS sensor voltage is ignored and the ECM software takes over for idle speed and should land right at about 800-850 RPM typically.

 

So what would cause a lower idle then 800-850?