01vetter

I removed my intake manifold last spring to replace the passenger air check valve. Ever sense then my idle is somewhat lumpy. I have tried may things to track down a possible vacuum leak to no avail (used smoke, throttle body cleaner and propane, checked vacuum lines, inspected PCV valve and lines, capped some vacuum lines, etc.)

I have a SPA digital vacuum gauge that reads to 1/10 PSI. It reads the same as before I removed the intake manifold and holds a steady 10 psi vacuum. Since I have checked for vacuum leaks using other techniques is this a good indication that I may not have a vacuum leak?

stevieturbo

If all of the above do not indicate a leak, why are you so insistent there is a leak ?

Poor running could be a multitude of things.

Josh@AandASuperchargers

This is the best way I find vac leaks from T/B back. Must remove and cap off the evap and/or PCV nipples on the intake first for testing. Pressurize the intake with shop air and listen for air escaping. If it leaks out it can leak in, lol.
If you have a boost gauge you can even see how much pressure you build up while testing.



ps- I cut 2 deep grooves into that PVC cap so that it would squeeze the silicone into the grooves and act like a reverse bead and keep the cap from blowing off when hitting over 15psi.

01vetter

The car runs fine other than having a somewhat lumpy idle and I have no codes. The symptoms are typical of a vacuum leak. I have also checked the ignition (coils, plugs, wires) and cleaned the MAF and throttle body. I need my engine analyzed for other causes.

01vetter

Josh,

Thanks for the picture and suggestion. I was thinking of performing a boost leak test but read that you need to close all of the exhaust valves to stop air leaking out through the exhaust. Do you do this by releasing the rockers?

Also, I don't have a large compressor. What size do you think I will need?

robert miller

More than not it is in your tune. I am sure the tuner is going to tell you all kinds of crap that it is the car & not his tune.

If it still keeps on doing it get a new tuner man.

leo12

who does your tune in mass vetter?

01vetter

Slowhawk Performance. Is there another local tuner?

Idle

The op clearly stated it was after he performed work. Car was tuned probably a year before that with no issues.

So, not the tuners fault or issue.

The op could of fixed an issue that the tuner tuned the car around though.

01vetter

You are correct. This happened after I removed my intake manifold so my tuner isn't at fault.

You are also correct about my tuner possibly tuning around an issue with my car. When I removed my intake manifold I found some leaf debris on my MAF screen. My air filter had fallen off my air bridge several times and it appears that my SC sucked up some leaves. I cleaned my MAF and vacuumed my intercoolers to clear them. I had my car retuned after I installed headers so it is possible that it was tuned with a partially blocked MAF screen !