Vaccuum Smoke test, is these results normal??

[niccoIndy]

I have a 1998 2.5L. I have been having rough idle problems when the engine is cool or cold. In addition if I rev the engine when its cold and let it quickly return to idle it stalls.

The long term fuel trims say the engine is running lean at low throttle openings. + 18% Not enough to set a code, but enough to be abnormal.

So I addressed, the MAF, IAC, TPS, Plugs, Wires, to no avail.

Now I just did a smoke test to try to find a vaccuum leak and noticed a couple things that I am not so sure are normal.

When running the smoke test, I had smoke coming out of the bottom of the saucer/diaphragm portion of the egr, a decent amount of smoke actually. Also it looks like there is smoke coming out of the iac, it looks like there is a little vent built into it which is blowing out smoke.

I just want to make sure that this is normal or not, if not I can see the EGR being the culprit. I am less suspect about the IAC as it appears to have the vent built in for a reason.

Any thoughts??

 

[srteach]

That is not normal. Needs new gasket. The EGR should be tight. It shouldn't cause a problem, because it shouldn't open until it is at higher throttle.
A blown EGR diaphragm could cause a vac leak, though. Clamp the EGR vac line to check if the EGR diaphragm is bad.
I had a 96 2.3L that acted like that. Replaced the O2 sensor after checking the readings and that cleared it up.
The IAC smoke is not normal. I believe that valve is an overpressure valve, which would mean back pressure in the intake. Possible valve problem. Compression check would rule that out. If compression is good, and there is back pressure, where is it from is the next question.

 

[niccoIndy]

Thanks, I didn't think it was normal. I followed up with spraying the base of the EGR with starter fluid yesterday. You can certainly notice a change in idle. I don't think it is the diaphragm itself. I blocked off the vaccum line and no change. Its almost like its losing vaccum where the shaft goes through the valve to meet the diaphragm. At this point, what do I have to lose in changing it, It looks like almost the only part that is OE. 181k on any part and I am not too upset about changing it.

Unfortunately I think it is going to be a bugger to take off. That connection to the tube that runs to the exhaust manifold is not going to be fun.

Ahh what you just said about the IAC makes perfect sense. The back pressure probably just due to the fact that I was doing a smoke test. I tried spraying that with starter fluid when running with no change in idle. Since the engine isn't running when pushing smoke in there it makes sense that the manifold was slightly pressurized.

I suspected the worst initially about compression, so I hooked up the guage I am getting right around 172psi on each cylinder. I was actually surprised.

Oh yeah and I changed the 02 sensor very recently as well.
Also checked exhaust back pressure via vaccuum guage and with a test port.
I've checked fuel pressure and volume --- This one was strange, engine off key on the pressure would not raise much. But when running the pressure was steady and at the appropriate pressure.

 

[niccoIndy]

No dice

It wasnt the EGR valve, I blocked it off to see if it resolved the problems. No luck. I also looked up some more info in EGR valves. I believe it is a positive back pressure EGR which would explain the venting to atmosphere when there is no exhaust backpressure.

Sooo, a bad replacement IAC is still a possibility? coils? Any other ideas? anyone?