Status Update, Fast Idle - put to bed finally Options

[lsintampa]

75 2.0L D-jet

Hey guys, it's been a while but I thought I'd just sort of give a status update on my car.

I had a number of posts about fast idle, surging, hunting, and other sorts of D-jet issues, but now that I've had my MPS rebuilt, replace the TPS board, etc. etc. and also went to school (thanks to those that offered their expert advice), I'm happy to report that I finally am happy with where I'm at.

A while ago I asked why some throttle body plates have holes in them and others do not. Well I still don't know, but I have a pretty good theory which is this:

My car had dealer installed A/C - which some PO removed a long time ago so it's long gone. I think that when the dealers installed A/C, they needed to adjust idle settings for the compressor being an added burden on the motor. Especially when the clutch engaged. So what I'm thinking is they replaced the throttle body plate, with one that had a small hole in it. This would cause the car to idle faster without mucking with the air bypass control.

In any event, I have no way of knowing if that's a valid theory or not, but I can tell you that I took the plate off and soldered up that hole, and my idle is now manageable!!!

Curious if anyone knows if this makes any sense. I talked it all over with a fairly good Porsche guru and he thinks it does. Again, no way of knowing but the results of closing up that hole has made a big difference.

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Thanks to all that got me parts and schooled me - you all know who you are!!

Len

[914Mels]

Way back when, I had a single center carb system on our 914, the combo of carb and cam wouldn't allow me to get a high enough idle speed without really cranking the idle adjuster screw. This created a problem with the transition port in the carb as the throttle plate was open more than designed just for no load idle. to fix it I drilled a 3/16" hole in the throttle plate to create more of an air bypass allowing the throttle plate to stay in it's normal idle range. Obviously the carb was not matched well to the application but it is what I had to run with at the time.