stumble bad at idle.

[kraus]

Vac should be more than 4-6

I bet you have a really bad vac leak...is it idling really high?

No it idles like complete crap. It idles at like 850 900 and it is rougher then driving over rumble strips on a road course.

 

[Lil Truck]

Check the MAF screen, vacuum lines around the boost controller and the PCV valve and hose.

 

[kraus]

It does not have boost solenoid or any egr stuff. The screen at maf is clean. Pcv is hooked up hose is new to it. When it is running pcv seems to be jerking like it is opening and closing when idling.

 

[Lil Truck]

The PCV problem would be due to low vacuum. It seems to be a problem that could occur when lifting off the throttle or a back fire. Check all the hoses for cracks, blown one way valve etc. check the vacuum block gasket.

 

[captrob]

EGR block off plate is a good leak point as well

 

[gsgnnut]

Time to pressure test the system. You have a large vac leak somewhere.

 

[kraus]

Time to pressure test the system. You have a large vac leak somewhere.

What is easiest way to do this? Stock intercooler etc.

 

[bigballsbilly]

If he had a large vacuum leak wouldn't the blms be much higher?

 

[gsgnnut]

Yes you are right the bl # normally would be higher with a vac leak.

 

[Bescurred]

If he had a large vacuum leak wouldn't the blms be much higher?

Depends on when he took the readings...

Like right after a computer reset

 

[gsgnnut]

Check the intake manifold bolts. mine had loosened to almost finger lose at the egr area and that caused all kinds of idle problems. I retorqued and its been fine ever since.

 

[kraus]

Check the intake manifold bolts. mine had loosened to almost finger lose at the egr area and that caused all kinds of idle problems. I retorqued and its been fine ever since.

I will check that tomorrow when I swap out regulator.

 

[kraus]

All intake bolts and egr plate are hood no leaks. Replaced regulator still runs like poo, fuel pressure still stuck at 40 once running. Pulled pcv off upper plenum hook up, it is chugging at the port. Is it possible intake gasket is internally leaking?

 

[Lil Truck]

What does the vacuum gauge needle do at idle? Is bouncing around or holding fairly steady? How long has the motor been together? Did it have any problems before the wires were replaced? What else was replaced or worked on? Any back fires or popping on accelerateion ?

 

[kraus]

Car ran perfect motor has been in and together for about a month and half. It was driving daily till this issue. Got caught in rain and one wire popped off since then has issue.

Vaccum bounces all over at idle. When try to accelerate it at idle it hesitates and stumbles etc.

I have replaced plugs , wires, module, coilpack and regulator. Unplugged maf, cam sensor, still runs same. Sprayed around intake with carb cleaner for leaks. Also sprayed around with soapy water. Never idles up or down. Checked all the grounds, disconnected battery, pulled computer, checked fuses, checked maf screen.

 

[Lil Truck]

If you have a vacuum pump you can check the regulator, BUT I don't think it has anything to do with the problem! It is aresult of the low vacuum problem. The only time I have experienced this rough idle was a bad MAF or a bad ignition module (non GM replacement) I have not had any problems with theIAC so I don't know if it could cause this? A loose or broken wire to anyone of these could also cause problems!

 

[Lil Truck]

Have you checked the ECM connectors for moisture or corrosion? T top cars are prone to moisture at the ECM.

 

[Lil Truck]

Sounds like you have checked a lot!
One thing I did not see listed was the crank sensor clearance and wire connection?

 

[LSTTYPE]

My car got its ECM connection wet and corroded from rain. Caused all kinds of problems. Also didn't people used to have issues from a loose fuse panel? Does the car still have a cateletic converter? I would also try a different maf for sure. Could the fuel pump itself have issues? Just throwing out some different ideas

 

[ATEURV8]

It does not have boost solenoid or any egr stuff. The screen at maf is clean. Pcv is hooked up hose is new to it. When it is running pcv seems to be jerking like it is opening and closing when idling.

Have you pulled the valve covers and looked for a broken rocker or pushrod or valve spring?