Engine/Transmission (1998.5 - 2002) Head scratcher, need help (missing + high idle)

[mgoncalves]

Here's the deal. I originally set two codes 0216 + 0122. I got the 0122 to go away without replacing the APPS, but could never get rid of the 0216. So, I got a hot rod VP 44, after installing I had a high idle when warm (1000-1100 rpm) and a miss or stumble at the same time along with code 0216. I figured it was time to replace the APPS, I did that and nothing changed. I talked to Brady, and he suggested the cam sensor, I popped one in and still no change. So, I sent the pump back in and put my original back on. I drove about 1000 miles last week on my old pump and didn't have any problems and was code free for about 800 miles then 0216 came back.



Now, after we got home I put the Hot rod pump back in that Brady had sent back to me. I installed it again and still have the same problem. I called Brady, he said they checked the pump when they got it, and it checked out fine. He put in a new rotor (just to be safe), reflashed the computer, recalibrated and extensively went through the pump, and is confident the pump is good. He said there must be something else going on with my truck that the new pump brings to light. I was trying to get in to ATS today to see if they could pin anything down with the DRB-III, as per Brady's reccomendation. I did not make it in today though.



I'm trying to get a hold of a Cummins Insight program and VP44 tester from a buddy, but I can't track him down. Any suggestions, what I should be looking for, or things I could try. I am getting frustrated with this ordeal, and am ready to get back to BOMBING.



Oh yeah, one other thing, comp, injectors, and hi idle have been removed to avoid complicating diagnostics.



Thanks for any help,

Matt

 

[mgoncalves]

Update:



I tried a couple of things today and found out a little bit more info. We could not find the insite program in the computer today, and the snap-on tester did not want to cooperate. VP44 tester confirms that the pump is fine, runs very smooth at idle, and snaps to 1450 rpm instantaneously where it also runs smooth as can be. Alex Peper program didn't show us what the problem is. No longer setting any codes



The only new symptoms we can pinpoint are baffling us at this time. When the truck is coasting in neutral above 9 mph, it idles at roughly 1000 rpm. As soon as the truck slows below 9 mph, it drops idle to roughly 900 rpm, where it sputters and just doesn't sound right. We unhooked the speed sensors and then the truck would idle at the 900 rpm rough running condition, no matter the speed.



The Alex Peper program was sometimes showing an input from the APPS during the higher idle. The APPS is new, and checks out fine. Somehow, the ecm is wanting to change engine speed based on vehicle speed (9mph magical point) but we still don't understand what or why it would do that.

I'm leaning towards the ecm being bad, but I'm very suspicious of some off the wall sensor being slightly out of whack, and confusing the ecm.



Have you guys heard of anything like this before??

Any ideas as to why the engine idle speed changes at 9 mph??



I'm at a loss here and need to get this thing fixed before I go crazy.



Thanks,

Matt

 

[GKinney]

idle speed

I can't tell you why it does the two step idle thing..... but mine does the same thing, except mine is a little lower rpms(925 down to 850). I have no codes or any other problems that I know of... . runs smooth at all rpms. Hope this helps... . guess I better stay tuned to see what you find out.