Hello,
This thing has me stumped, I guess I'll start off by saying it has an industrial injection hot rod pump, its been giving me drivability issues for months now. It started as a miss when idling once every couple min. Progressively got worse over a span of 2 months or so. Now it's a full out lope, it does it throughout the entire rpm range, making it a pain to drive. 5speed converted from auto. It has its days where it will high idle at 1400 when I push the clutch in or come to a stop. If I drag the motor down it will idle around 900, higher than it used to. And sometimes it will idle it self back up to 1400 before I take off again. It has terribly loud injector knock like the timing is way advanced at any rpm below 1600. Had a bad crank sensor, replaced it. No change, no cel. I rewired all the grounds, swapped out the apps. Nothing changed it. Today I hot wired the vp pump. Still loped, no high idle. Well it stayed around 900 at least. Put clear fuel line on, no air. Oh yeah also has new head gasket and 150hp injectors. Lope actually got worse after new injectors. Also the throttle is very touchy, like from the timing a smartly will give. Anyways I put an analog volt meter on the pump tap wire and you can see the lope through it. So it seems as if the fpcm is commanding this rough idle. Here's the strange thing, just out of the blue we decided to drain my fuel filter and fill it with trans fluid. Started it up and as we watched the red trans fluid through the clear line enter the vp44 the idle smoothed out and went to normal rpms. As soon as the fluid began to look more green the lope and higher than normal idle speed came back. This thing is a headache and I'm out of ideas of what it could be. Any help is appreciated

 

Ok so when you hot wired the pump, did you disconnect the main connector on the vp44 and just give it power and ground? If so, that tells me that either you have a fuel delivery/bad fuel issue or your injection pump is on it's way out the door. If everything smoothed out with just a power and ground, that would tell me that something is commanding to run in a negative way. This is not your case though. Couple dumb questions here. Change the fuel filters? What are you using for a lift pump?

 

It was just power and ground, no ecm connector filters are fresh and I'm running an air dog 165. I'm leaning towards ip. It runs perfect under load or full throttle, that's the strange part

 

You got enough air flow? Nothing plugged? I'm still hung up on the oiling your filters and getting it to run smooth.

 

Air filter is good, that's the part I don't get either. Like the best way to describe it is the timing is way too advanced, maybe running trans fluid it doesn't detonate as quickly and compensates for timing. Idk. Nothing about it makes sense, it doesn't fit a common symptom of failing injection pump

 

Well I started this thing today and it died twice with much cranking to start back up. Went down the road and got a dead pedal. I actually thought it finally died. Got a p0122, now it idles at 1200rpm all the time. Gonna swap out the apps with a buddies tomorrow. I've done it before and it didn't fix the lope. Maybe it's just a coincidence that the apps went out. Maybe not. Got a dead pedal 6 times in a ten mile drive