bigalpha
Moderator
- Location
- Tucson, AZ
Oh, I forgot about the RenX files. I need to go through that. Thanks for the reminder.
If I cover the IAC hole while the truck is idling then it should die, right? If not, that's indicative of a vacuum leak?
Assume vacuum leak causing high idle, good TPS and good IACV. If I disco the TPS, should the IACV kick in and fix the high idle?
So I was re-reading the RenX thread again.
Could a bad TPS/IACV cause a consistent high idle in P and N but not any drive gear (D, 3)? In a drive gear, it keeps a steady, high idle.
In D and N, it immediately jumps up real high and stays. What is the idle related to being in gear?
In gear the TC stops to slip around 1000 rpm and loads the engine down.
This must explain the delay. Turn on the truck, and it idles really high. Drop it into 'D', and about a second later, it kicks into gear, the truck lurches forward and the idle goes down (no surging or anything).
I'll have some free time this weekend to go more in depth and work on it. Hopefully it's something easy like loose manifold; somehow, I doubt it.
You are looking for an idle rpm of 725-775, in DRIVE, when fully warmed, about 15-20 minutes after starting.
Your idle will be higher in Park and Neutral, of course.
Your base idle is too low at 600 rpm. Your base idle should be 725-775, in D, engine and transmission fully warmed, NO accessories. A/C on idle should be higher to compensate for load. Cold idle will be higher, of course.
I think you should give the TB base idle screw an adjustment, as 600 no-load idle is way too low.
4.86 V supply from ECU to TPS is fine. More likely that one or more of your grounds is loose and dirty.I tested the constant 5V connection at the TPS and it shows 4.86V. Is this enough to screw things up?
Yes.Does this mean there's a massive vacuum/air leak somewhere?
Yes.
Unfortunately yes.I checked all of the upper manifold bolts on the intake manifold. Are there lower manifold bolts that I have to check by laying on the ground and come up from under it?
Unfortunately yes.
Bummer. Something tells me those are a real PITA. If one or more of those lower bolts were loose, would it be hissing?