- Ok, I could go on for days about this, because that's how long it has taken me
to get to this point... I've had the motor running, but have been trying to solve
multiple idle problems for over a month! Well, I'm just about there, I think!
The first problem was a bad vacuum leak. Turns out that the Holley Throttle Body requires a special plate to seal the IAC (idle air circuit) on the bottom between the manifold and the TB base. Well, of course, I didn't have the plate! However, thanx to the wonders of the internet, a Holley engineer came to my rescue and sent me one!
The pictures below show the problem. The first picture shows the base of the throttle body:
The next picture shows the 2" spacer lying on the base of the TB. You can see about a 1/4" gap from the edge of the spacer to the open area of the IAC:
And finally, the standard gasket doesn't even completely cover the open space, as you can see:
The next picture shows the plate and special gasket which are used to seal this space on the throttle body.
And here we have the plate lying on the base, showing how things SHOULD look! :)
- Now, generally once you solve a major vacuum leak problem like this, all goes well
from that point forward... But of course, not for me! I could at least get the engine
to idle better at this point (around 1000-1100 rpm), but I couldn't pull it down as
far as it should have gone. I knew it should idle around 850rpm or so, but I couldn't
make the computer or TB do it...
So, many emails, message board posts, and moments of cursing later, Doug from Holley saves my sanity again and tells me that the Holley TB uses a Chrysler IAC circuit rather than a GM one, as most all the other TB's use. And of course, the wiring is different between the two. Doug gave me the wiring conversion, and I put it into place....
And guess what... It STILL DIDN'T WORK! At this point, the block of aluminum was about to take a trip down the driveway by itself... What the heck?! Well, turns out that it appears my FAST wiring harness was hacked up by someone to convert it from the square GM IAC connector to the FLAT Chrysler/GM style. However, whomever did this didn't connect the wires correctly, so when I swapped them as Doug described, they weren't correct. It took a phone call to FAST to figure this one out.
But before I did this, I borrowed a new TB from a different manufacturer with a GM IAC motor on it from a friend of mine. Put it on the motor, reconnect the wires to the GM pattern, and fire it up... Guess what? It worked! Ahhh..... I can pull the motor all the way down to 800rpm idle, but it doesn't like being there! :) I need to start my tuning now, but at least I can. This has been a REAL pain in the ass!
I've decided to get one of the new TB's that worked, rather than swapping the IAC wires again. I like some of the features of this TB, so I'm going to go with it. Hopefully it's all going to work out ok.
- At this point, the motor runs/idles mostly ok, but I still have some cold start issues to work out. Once it warms up, it will hold a nice 850rpm idle for me! But there is much tuning to be done...
