racerxrick

I know, I know...since I bought this car and first trolled the forums I've read about vacuum leaks. I've tried hard to remedy what I can (silicone hoses, Laust manifold, removed and simplified some of the "extra" stuff). I also had Phlip do a venturi delete while R&R the head and upgrading the turbo.

Recently I was struggling with a intermittent and then consistant idle problem. As the problem got worse I was also experiencing diminished throttle response at the lower RPM's. On boost everything seemed fine.

Tried a TPS (more of a bitch to swap then I thought...damn these cars are tight!). That wasn't it. Thanks for letting me "borrow" one Phlip!

Then "I" decided it had a bad and/or leaking ISV (or is it ICV?). Took the car to Phlip who hooked up his smoke machine to check for vacuum leaks. Yes, there was a substantial leak at the ICV. And two of the four injector seals were a solid smoke stack. Plus a small leak at the throttle shaft. And then finally a leak (my fault) where I tapped into the banjo bolt/line for the MBC.

HOWEVER that was not the idle problem...he unplugged the o2 sensor and the idle straightened right out, DOH! When I had my Turbo Buick I used to change out o2's as a prevention (used a lot of leaded fuel when drag racing). The thought never occurred to me.

I'm down to a slight leak around the shaft on the throttle body (fairly normal?) and one more small leak at the electrical connection on the ISV. The car is now pulling a solid 18" of vacuum at idle and throttle response is GREAT

The test:

I had a 04' CTS-V at my disposal so I had a buddy drive it and we lined up the cars...2nd gear the V jumped a length on the 951 which I took back about the time I hit third and then pulled him.

2nd run we went from a first gear roll. I expected the V to get a better jump on me but it only grabbed a fender and I solidly went by in 2nd gear.

It would of only been worse at higher speeds

Scott H

JB weld around the electrical connector on your ISV will fix that leak, I've done it to several. To fix the throttle body buy a rebuild kit from arnnworx and pay attention to the directions and you'll be set.

I remember you posting a dyno and the power coming on way late, butt dyno feel any improvement in that area?

racerxrick

butt dyno say's hell yeah

oh...and thanks for the suggestions!

zerMATT951

Wow, I bet it feels good to finally chase down a tough-to-find problem like that! I'm going to save this post as a reminder to check my ISV soon now...

I've got a Arnnworx TB rebuild kit on my workbench right now and plan to dig in this weekend between in-law visits for Easter. May tear into the PS pump if the TB goes well :-)

Scott H

PS pump is a cakewalk compared to the TB. PS takes 10, 15 minutes tops. TB can take hours if you aren't careful.

zerMATT951

Ok, you just convinced me to start with the PS pump.

racerxrick

haha

Scott H

Dunno if you've seen this, but: http://www.youtube.com/watch?v=PsZOhqSfy-Y Be careful with the impeller assembly, the rest is straight forward.

The TB isn't difficult, but can be kind of fiddly.

Tedro951

This should motivate me to fix my new idle problem! I've got the hunting from 1500RPM to dying every 2-3 seconds until it warms up. I can hear the ISV take a big gulp of air to try to keep it from dying, but I've heard everything from bad ISV to vac leak to DME temp sensor.

I'll get on it right after new rack install....

zerMATT951

Thanks!!

choinga

Hmm....wish I could find someone to do the smoke trick on mine....I'm pretty good off but know I probably have a few small leaks (deleting the CV and all the connections under the intake fixes quite a few places where leaks pop up) that need to be fixed. I have all new rubber/clamps, new ISV, silicon lines with zip ties everywhere, rebuilt my TB, etc... I warm idle at about 15-16hg, which seems pretty tight.

Where did he 'inject' the smoke?

carlege

+1 where can you go for a smoke machine or can you take some dry ice in a tupperware cup and see if you can route that into the car?

racerxrick

I'll have to ask him...Phlip works on a lot Mercedes/European cars, it's how he makes his living. I am embarrassed to say i didn't look to see where he injected the smoke??