Ok, here's the problem. On a cold start my vacuum start off at 18 but then it will quickly rise to about 11... Once it hits 11 the Vortech starts feeding it more gas which causes the car to start stalling, which in turn raises the vacuum closer to atmosphere...

As soon as I start my car I have to start moving. Now everytime I approach a light as long as I am in a sloooow roll my vacuum is fine at 18 - 20. As soon as I come to a dead spot it starts climbing again.

Once the car is fully warmed up the problem seems to go away. I have replaced every vacuum line on my car o.O There is no leak. I'm wondering if this could possibly be caused by the IAC?

Another problem is I hear a fluttering noise at idle. It doesn't sound smooth. I can hear it in the exhaust manifold and resonates all the way out the muffler...

I'm running 30# injectors, with 20-22psi of fuel at idle. Cold start idle is at 1100, after it warms up it drops to 900. Before I drive a couple miles though I have to constantly mess with the gas in order to keep it from stalling. I'll be doing a compression check this evening once I get my gauge back and I'll post the results. I just did a head rebuild though before adding the turbo and everything was excellent. Anyone have any ideas?

Originally posted by UpToSpeed
Ok, here's the problem. On a cold start my vacuum start off at 18 but then it will quickly rise to about 11... Once it hits 11 the Vortech starts feeding it more gas which causes the car to start stalling, which in turn raises the vacuum closer to atmosphere... As soon as I start my car I have to start moving. Now everytime I approach a light as long as I am in a sloooow roll my vacuum is fine at 18 - 20. As soon as I come to a dead spot it starts climbing again. Once the car is fully warmed up the problem seems to go away. I have replaced every vacuum line on my car o.O There is no leak. I'm wondering if this could possibly be caused by the IAC? Another problem is I hear a fluttering noise at idle. It doesn't sound smooth. I can hear it in the exhaust manifold and resonates all the way out the muffler... I'm running 30# injectors, with 20-22psi of fuel at idle. Cold start idle is at 1100, after it warms up it drops to 900. Before I drive a couple miles though I have to constantly mess with the gas in order to keep it from stalling. I'll be doing a compression check this evening once I get my gauge back and I'll post the results. I just did a head rebuild though before adding the turbo and everything was excellent. Anyone have any ideas?

how do you know the vortech is giving you more fuel at 11 vac? this in itself is not right, it shouldnt raise the pressure at all until you hit boost.

Maybe it's not the Vortech then... If I watch the fuel pressure, once it starts choking and the vacuum starts decreasing I see about 30 - 32 psi of fuel in the line. It starts stuttering really bad as well.

Unforunately, my A/F Ratio box broke during shipping so I ordered a new one over night, I won't be able to monitor the mixture until tomorrow :(

With the problem going away after warming up, and the weird vacuum; and being the armchair mechanic i am; possibly fouled or malfunctioning PCV; that or maybe sticking EGR?

I have my EGR blocked off and I replaced the PCV valve :P

All though now that I think about it, I blocked off the EGR with the ol'coke can gasket trick. Maybe it's possible that under boost the coke can created a vacuum leak now? I'll have to go check that out...

The gasket seems good but while I was driving to go install my missing link the problem got even worse...

In addition to the above problem, I tried running at WOT, I made 2 pounds of boost and the needle stuck, the car felt like it was bogged down, then the needle shot to 7psi and I redlined instantly, after slowing down I now am only making 2psi...

My car is feeling like it's bogged down and doesn't want to respond...

AAAARRRRGGGHHH

nm.

Sounds like you have serious leak somewhere. I was thinking valve issue but you had the head rebuilt so not likely. Cracked intake manifold comes to mind since the issue goes away once it heats up, but thats a premature assumption so we wont go there yet. Could be bad injector o-rings, one of the 3 gaskets bad, IAC is possible if its gummed up and sticking partially open. The minute the vacuum is raised the SFMU will raise pressure. Its called idle pressure and static pressure, each is directly proportional of the other depending on how you set the SFMU.

To check the SFMU, get the car idling, pull and plug the vac line going to the SFMU, check fuel pressure. Should be higher than your idle pressure. for now drop the static to your idle pressure while testign so you have a good idle. Restore it back afterwards. If you stay out of boost you can leave it this way for drivability until the problem is resolved.

Do this to narrow down the possabilities:
1. clean IAC...should do this once every 2 years as good maint

2. Get a can of carb cleaner spray.
Spray lightly around the injectors, intake gaskets, TB gaskets. listen for idle changes. if the idle changes, you have a leak.

3. Do a compression test to verify no leaking valves, the noise you say you hear in the exhaust mani worries me. even though you just rebuilt the head, you may have a valve problem so lets eliminate it.

4. Do a leakdown test on each cylinder. If you dont have a gaue then just hook your air compressor up the each cylinder and listen for leaks out the exhaust and intake. Note: you will need to have each cylinder on its compression stroke.


Let me know what you find

Terry

Wow, great post thank you. I am currently waiting for my car to cool down as I have to change out my water pump :( Don't buy PartsDinosaur water pumps apparently. I went and got a new one from NAPA so hopefully that will fix the leak.


I did do a compression check and got 210 across the board. Before I added the tubo there was no fluttering noise and it was running better than the day I bought the car...

When I had the head off the car I also inspected the intake manifold and there were no hairline cracks or anything, I also added all new gaskets and there is no leaking that I can tell. I used a spray bottle of water around all the parts and I was not able to tell any leaks.

After driving my car around though, I discovered the problem still persists even after the car is warmed up... that was a misconception based off of when I first drove it. It seems like it takes longer to start stalling however whenever I drive the car hard or on the highway for a while...

I also got my A/F Gauge hooked up and I am definitely running very rich. If I watch the A/G (as jumpy as it is at idle) I can still see it hit 1.04 at idle just when it starts stalling. I'm going to lean it out after I get my water pump installed and see if that seems to help. Could this problem come from running really rich at idle? My gauge read 20 - 22 psi of fuel at idle which should be correct on 30# injectors but I am running really rich. Maybe the engine just starts to flood after it idles for a while which caused the idle to drop?

Also I noticed that my PCV valve (which is brand new) is fluttering around at idle... could this be a leaking valve that is building up pressure in the valve train and bleeding it over into the intake manifold through the PCV valve hose?

Ok, I've checked every vacuum line, every everything and now I'm beginning to think the problem lies somewhere else...

I noticed today that it started stalling while I had my stereo up, the AC on and I was at idle... I also have a UDP on and the MSD direct replacement coil pack, and an inline pump... I turned off the AC and stereo and it seemed to regulate itself out.

Perhaps my alternator is going or it can't produce enough juice at idle? Maybe that's why after long highway drives the battery has some extra power stored up and it won't stall at the next 6 or 7 lights in a row...

Could this be the problem?