BLOWN HEAD GASKET

[RonD]

Could be, but wouldn't cause the stalling, 140 psi is low but not that low

 

[Broosedamoose]

I think it's stalling because the idle is so rough. When I go from drive to reverse it idles down so low that it dies. He did a smoke test and everything is sealed up. He double checked the plug gapping and they were all right on the money. I don't know what else it could be other than the timing being off.

 

[RonD]

The computer should increase RPMs when you shift into R or D using the IAC Valve same as when you turn AC on

I would expect cold start RPM to be 1,100-1,200 if outside temp is under 45deg
After 5 to 8min of warm up 750-800rpm
In gear 800-850rpm

This is done by computer using IAC Valve and ECT(engine coolant temp) sensor

The DTR(digital transmission range) sensor tells computer when to kick up the idle when "in gear" using IAC Valve


Have you test vacuum?
18-21" is expected, lower could be valve timing issue

Does engine smooth out when RPMs are higher and under load(driving)?

 

[Broosedamoose]

I think he said he got 12 on the vacuum test. The engine does smooth out while driving. If I'm cruising on the highway it runs smooth. It's only rough when idling.

 

[RonD]

I would re-test vacuum, thats way too low even if you were in Denver, 5,000ft elevation, lol

Test with engine running smooth so raise RPMs if idle is rough, and hold RPMs steady at say 1,000

Test gauge on another engine just to see if its accurate

 

[Broosedamoose]

I did a vacuum test with my gauge (which I know is acurate) and the engine at 1,000 RPM's and I got 16.5-17.0! I retested with the engine at idle and got 12.0-12.5. It's got to be the timing!

 

[RonD]

Yes, that's pretty low vacuum, even in Denver, lol
So BIG LEAK or valve timing is off

 

[Broosedamoose]

Turns out the timing was off. He said it was only off by a fraction of a degree but it was enough to cause the intake valve to hang open a little too long. She runs perfect now!

 

[RonD]

Good work