Auto revs and stalls when out into gear

[Alec Rich]

Hey so I am having a major problem and can't seem to find the answers to any of them. My truck cranks up just fine but then idles super weird. It randomly revs itself up then goes back down and repeats this. Then if I put the truck in gear (drive or reverse) it will continually idle weird but then suddenly just die or stall. I am also getting a yellow spark coming from my coil, but I have tried another brand new coil and I am still getting a yellow spark. Any help would be nice thank you

 

[Greg Ducato]

More info on the truck would be helpful, year model, engine size, carb type or EFI, ignition type, these would be a good start to helping someone trying to give you some answers.

 

[Fastereddie]

Iac valve?

 

[Alec Rich]

More info on the truck would be helpful, year model, engine size, carb type or EFI, ignition type, these would be a good start to helping someone trying to give you some answers.

It's a 1989 Chevy k5 blazer 350 tbi

 

[Alec Rich]

Iac valve?

I replaced the IAC valve and still have the same problem

 

[Alec Rich]

Also when I put it in drive it will idle for a second but if I flip my A/C on high the engine dies immediately

 

[Fastereddie]

I see you tried a coil already. I hear about the disty module doing wierd stuff.

 

[Greg Ducato]

If you can remove and clean the EGR valve you might want to try that. If the EGR needs to be replaced I would suggest springing for the AC Delco version, the aftermarket parts are usually universal and seldom work well.

 

[thearborbarber]

Sure sounds like a vacuum leak.

 

[Alec Rich]

If you can remove and clean the EGR valve you might want to try that. If the EGR needs to be replaced I would suggest springing for the AC Delco version, the aftermarket parts are usually universal and seldom work well.

I will probably try that next but could it possibly be the ignition pickup coil?

 

[bp71k5]

Sure sounds like a vacuum leak.

X2, make sure there's no vacuum leaks before worrying about anything else. My rubber hose caps always dry out and crack at the back of the throttle body.

 

[major teragon]

im kinda having the same problem with my 87 k5 it doesn't seem to be making any vacuum from the throttle body to the egr or the vacuum over flow any ideas?

 

[thearborbarber]

I'd start checking for vacuum leaks. You can either spray brake cleaner around the throttle body and other vacuum components and listen for the engine to rev up a little when you found a leak or use an unlit propane torch the same way.

 

[Alec Rich]

I'd start checking for vacuum leaks. You can either spray brake cleaner around the throttle body and other vacuum components and listen for the engine to rev up a little when you found a leak or use an unlit propane torch the same way.

Haven't found any vacuum leaks yet but I guess I will continue to look

 

[Alec Rich]

I ended up putting a whole new distributor in and that fixed my stalling/dying problem but now my truck is revving itself up and down and is throwing codes 22,32, and 42