awilli6

Afternoon all. I just completed an intake refresh on my 89 S4 and now it has an extremely high idle 2000+. When I put it in gear, it drops to ~800. Am I looking at a vacuum leak or mis-routed vacuum lines? Where should I begin the hunt?

Thanks in advance

Ash

Zirconocene

You should start reading @Michael Benno 's recent thread on getting his idle under control. He was able to track everything down, and got a ton of solid advice about where to look and how to test.

Link: https://rennlist.com/forums/928-foru...e-stumped.html

Good luck

Michael Benno

That is a very high idle indeed. If that were a vacuum leak, it would be quite large, possibly the MAF has popped out of the throttle boot. Alternatively, check the throttle cable that goes from the accelerator pedal to the throttle linkage to make sure that it is not Come unseated from the firewall, and that it is moving freely and unrestricted back to its rest position

Remove the air cleaner and check to make sure your MAF is properly seated as well as all other breather hoses that you can see.

Report back what you find

PorKen

SwayBar

If you can't find the vacuum leak in a day, put a smoke machine on it. In 5-minutes I found that a vacuum-plug popped-off the bottom of the throttle body.

This was after 3-weeks of looking/trying this and that. My next step was to remove the intake - I was SO happy to see the smoke billowing out from under the intake!

awilli6

Thanks guys. I’ll check for leaks tomorrow and report back

FredR

Ash,

Given this happened immediately after an inlet manifold job I would tend to think there is a fair chance you may have forgotten to connect one of those breather pipes under the inlet manfiold.

A good approach when boxing up is to prepare a simple check list of all the actions needed and of course strike them out as and when each item is completed. Needless to say ne of these days I will follow my own advice!!

awilli6

Hey guys. The MAF was seated correctly. I had to run to DC for a week or so. I’ll get a smoke machine when I return and report back. I’ve all ready had the intake off 3 times. I hope not to do it again.

awilli6

Hey guys,

I’ve been away from the car for a while but finally got to redo the intake. Now she’s running smoother and idling correctly. I think the issue was a combination of things. The injectors were not seated thoroughly and I think the throttle cable was in a bind.

Now on the issue is back to my original problem. I get a bad studded (like a coil is bad) when taking off through about 50 mph. When idling it feels as if someone is bumping the car. I changed the coils for new (used) one from 928 Intl. wires have less than 5k miles on them. I’m going to put my old wires on tomorrow and change the spark plugs. I’m also going to add shims to the battery posts. I can’t seem to get my battery ground cable tight. Maybe that is causing the studded.

Thanks for all of the advice. If you have any additional recommendations on the studded, let me know.

Ashley