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Posted by: Rant6 Dec 3 2013, 01:00 PM

Hi folks. I am chasing what I understand to be a common 914 problem, and that is bucking or stuttering. I had a previous post about this, and I worked through some of the suggestions with no luck. I understand that this problem could be in the distributer fuel injection points or the TPS, and I also understand that the distributer FI points are NLA, and so I have not investigated this area.

I very carefully replaced the circuit board in my TPS, and I used a magnifying glass to insure that the metal fingers were in constant contact with the foil runners, and they are. This did not fix the problem.

In the TPS there is an arm that carries the metal fingers. On this arm are two metal spring strips that contact two metal pins. Under acceleration one strip contacts one pin and current flows through this path, and under deceleration the other strip contacts the other pin and current flows through that path. (I wish I had taken a picture when I had the thing out of the car.) On my TPS, there is a center point where neither one of the metal strips is in contact with either pin. This point seems to be where I experience the bucking - that is, just very slightly off throttle, and so I'm wondering: is one or the other of these metal spring strips supposed to be in contact with its respective pin at all times? If yes, what can I do to remedy this problem?

Thanks,
Mike

Posted by: ConeDodger Dec 3 2013, 01:13 PM

Did you adjust it correctly after installing it? The bucking from TPS wear is usually at cruising RPM.

Posted by: boxsterfan Dec 3 2013, 02:41 PM

Checked your fuel pressure? How about your fuel injectors?

Posted by: Rant6 Dec 3 2013, 02:46 PM

Yes I did carefully adjust the TPS after reinstall. Injectors are fine. I can unplug them one at a time, and the engine gets noticeably worse.

I have not checked my fuel pressure because I don't have a gauge, but the car runs perfectly at cruising, full throttle, idle, etc. It only bucks when I lift VERY slightly off throttle. That's why I'm thinking that one or the other of those metal spring strips should always be in contact with one of the pins. Yes/No?

Posted by: Java2570 Dec 3 2013, 03:27 PM

Does it still buck the same way if you unplug the TPS?