Truck dies on cold starts,,,

[Silverado]

I own a 97 Chevy Silverado with stock fuel injection, yet with 383 stroker; and on cold starts the engine either dies after a couple seconds (just as oil pressure rises), or will try to turn over but idle is VERY rough for about 15 seconds....we're talkin ka-chug ka-chug. IAC valve takes over after awhile and then things go back to "normal." I'm not sure if its a vacuum leak, fuel pressure regulator, spark problem, MAP sensor, or injector issue. Here's what I do know:

Sprayed starting fluid all around base of intake manifold to see if idle would rise...it did not.

Checked other hoses etc. for possible vacuum leaks. Found none.

Checked plugs, and found out that one banks (passenger side) plugs were in bad shape. Lean condition or vacuum leak symptoms. Yet other banks plugs were perfect.(bad 02 sensor?)

Checked MAP on scanner and I'm getting 14.8 at idle (LT4 Hotcam)

No trouble codes

This only occurs on cold starts. On warm starts (up to 1.5 hours between starts) Engine will start fine.

 

[T-Keith]

Do you have any tuning done to this? The computer can do a little to adjust, but major changes like a stroker kit or cam require work on the fuel curve and usually a bump in idle speed. You could be running dangerously lean, or too rich.

-T

 

[Alan]

Is the IAC clean?

My Dads explorer had a similar problem except it came to a point where it wouldn't start.Cleaning the IAC with Aerokroil fixed it.

 

[Silverado]

Any other suggestions? Its only on cold starts.

 

[TheLoneRanger]

quote:

---

Checked plugs, and found out that one banks (passenger side) plugs were in bad shape. Lean condition or vacuum leak symptoms. Yet other banks plugs were perfect.(bad 02 sensor?)

---

Silverado, yep, I'd say a "lazy" O2 sensor at the upstream bank 1 position. This is the only thing, other than a vacuum leak, that will give a lean condition on only one bank.....

 

[Rick]

Ok here, he sayed cold starts. No sensor works when cold. The computer is in open loop. The O2 doesn't even work when it's cold. I would think that because you have modifed your engine and you have not changed anything about your fuel curve. Then like this was sayed above, you might want to have this taken care of. That will very well create issues when the engine in cold. If not tuned correctly. No sensor will fix that, you will need to get the ecu programmed to accomidate your engine mods.

 

[Silverado]

Computer is tuned to engine specs. This is a new problem that has evolved. I've driven this engine for 8 months with no problems at all.