I've been having a weird problem that's kind of intermittent. With no throttle, my engine doesn't settle down into a normal idle--it keeps reving, and the tach bounces between 600 ant 1000 rpm. It sounds like I'm blipping the throttle lightly, but I'm not. Very rarely it gets progressively worse until it eventually dies. When this happens it requires more cranking than normal to get it to fire.

I've already replaced my APPS with a Timbo1 part, so I'm kind of leaning towards the injection pump, which is still stock. There are no codes, even when I check with my Smarty.

Could this be caused by a bad sensor, like a crank or cam position sensor?

Thanks,
Mike

 

Well, I feel kinda silly. I just noticed that I never put any details in my sig. I don't see it now when I look at my post, so I'll include it all here. The truck is a 2000 with an Edge Comp (problem remains when it's disconnected), Smarty on fuel saver program, Mach 1s, and an older FASS 150 (completely reliable 15 psi fuel pressure all the time). Turbo is an older PDR HX35/40 hybrid.

The thing that I keep coming back to is a lack of codes being set which I'm thinking is probably significant. I've never heard of a failed sensor that didn't set a code, which leads me to the VP44. I have certainly seen enough posts here where a failed/failing VP44 didn't set any codes.

Somebody please tell me there's a cheaper part that will explain my problem.

 

I feel your pain, I have the same issue but my is not as "violent" as yours mine only bounces from idle to about 100 rpms max dont even think I have seen that even before tho either...I have no programmers all stock except for whats in my SIG I know this doesnt help much but just to give you an idea thats your not the only one.

 

No one else has any ideas?

Ben, have you noticed anything that may cause the behavior to settle down?

About the only thing I've come up with that makes my idle settle down is when I slow to a stop. For example, a hundred yards before a stoplight, I might through the transmission in neutral and coast up to the light. For that distance I see the tach needle bouncing. Then as I brake, the idle settles down just as I come to a stop. This doesn't happen all the time, but it's often enough that there's definitely some correlation.

 

mine usually does it when I seem to run it hard or sometimes it may just do it on its own but mostly when it gets ran hard, Its not nearly as bad as yours but it is very noticeable. I even tossed the snap on "super" scanner on it the other day just to see if i had any stored codes and got nothing. Some times if i give it some fuel while im stopped and then some times it wont straighten out at all but like we both have said before it only does it sometimes. I don't know weather its a fueling issue or injector or what it doesn't seem to hinder performance at all but it is rather unsettling tho, but i see you have injectors and stuff so I really cant pin point it im hoping we get some more ideas on here!

 

I would check for air in the fuel first, with lack of codes. A clear plastic line with a 6 inch upwards hump run for 5-10 min and if any air you will see it in the top of hose. Good luck