Had a weird one today. Truck drove fine before, shut it off for a few minutes and when I restarted it, the throttle was real touchy.

When I would barely ease into it, I would get a blurp of power, would break the tires loose on the gravel. If I stayed in the throttle, it would fuel like never before. I was actually suprised how quick it felt and how much power.

If I stayed on the trottle, it would fuel for a little while, but it would defuel on it's own. I'd let off and then could get back on the throttle. Had some weird transmission shifting too.

Anyway, I did an APPS reset and cleaned the grounds. None of the grounds looked bad before. Only thing I saw was that I had used some baking soda to clean the tops of the batteries last week. It had dried around the negative post. Don't think it was enough to cause a voltage leak.

Seems OK now, but I also have an ECM issue (won't run the lift pump or grid heaters at Key ON).

What do you think, possible APPS replace? Another ECM symptom? Just a quirky deal unless it comes back?

No reader, so no codes checked. Maybe next week.

 

must be the return spring on the carburetor has come off.

just kidding, all i can say it must be APPS related?
the timbo apps is pretty cheap, might want to try that.

 

I'd try and reset the APPS before throwin parts at it.

Also, I'd try to get the codes checked out before trying to go much further if that doesn't do the trick.

 

Happened again yesterday. Sure made for an intersting ride through Topeka, KS!

Did another APPS reset and worked OK today.

Ordered a Timbo APPS yesterday. Hope it shipped today.

Thought about the codes this morning, going to check tomorrow.

 

Well darn, the Timbo APPS didn't fix it.

Put it on this morning and went for a test drive. Everything seemed OK, I thought it even ran a little better. Mainly that it stayed in 2nd gear longer and ran out better.

Drove it to town and everthing OK. Got back in to leave and the APPS was acting up again when I restarted it.

Didn't want to wait 30 minutes, so I tried an "accerated APPS reset". I took all the battery cables off. Turned the key ON, touched the negative and positive cables together, turned the key to START and then OFF. Hooked the cables back up and the did the APPS reset. Restarted the truck and everthing was fine.

I'm going to go measure the voltage range on the APPS and check for codes. Any other thoughts?

 

Darn thing did it again today.

Got an analog voltage meter to test the APPS. Full range on the APPS output is 0.66 to 3.87 volts. When running normally, looks like half throttle is about 1.5 volts. Tested the APPS output when truck is in error condition, it is 0.7-0.8 volts, definately getting more fuel than it is calling for.

Scanned the codes on Saturday when I replaced the APPS.
P1694 - No Bus communication
P1693 - Companion code
P0380 - Glow plug "A"

Cleared those and rescanned today when it was giving me isses.
P0606 PCM Processor Fault
P0380 Glow plug "A"
P1689 Mfg specific Powertrain fault

What else can I troubleshoot at home? Is there a way to rule out the ECM or PCM? Could it be the VP? My gut says it is the ECM or some communication with it.

Diesel shop says maybe a reflash from the dealer might be the best step to take next.

 

I wanted to get the truck the dealer last week, but no time to get it in.

The throttle acted up again last week. It did it when I did a restart with hot engine.

Now that I think of it, it is always done it with a hot restart. Could it be a sensor shorted out? Guess it could be the ECM PCM shorting out too.

Here's the new item, I shut the truck off and let it sit for a couple hours. When I went back, it restarted and everything was normal. That leads me to more of an intermitent electrical issue rather than a bad computer.

Anyone know exactly how the fueling works? MAP, IAT, Engine Temp, APPS are the sensors I am aware of. Anything else I should check? Thinking of backprobing the MAP and IAT when it happens. I would think it should set a code if it is acting up??

 

OK, scratch that. Just messed up when I started it for the first time today. Doubt it is a heat related short now. Still going to backprobe the sensors, need to research how to do it.

Anyone got a thread about how to read the MAP and IAT?

 

Dealer looked at the truck. Said the ECM was bad.

I decided to put a new one on myself. Bought a reman from Cummins. Put it on tonight, truck runs and drives, but it still doesn't act right on the electronics.

Main issue is that the ECM doesn't boot up right away. When I turn the key, all the gauges turn on except for the Wait to Start, lift pump does not startup right away. If I leave the key on for 5-10 seconds, everything will finally work OK. It was having this issue before.

 

Probably an ECM grounding issue or battery voltage is messed up.

 

you dont by chance have an after market security system? that might account for the delay . we have a 98.5 that does that but it is the after market system doing it . also my 01 had the same power surge issue until I had installed a catcher ECM in place of the stock one