 TPS question, Chasing the bucking bronco |
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| Rant6 |
 Dec 3 2013, 01:00 PM
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#1
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Newbie  Group: Members Posts: 8 Joined: 18-June 12 From: Daytona Beach, Florida Member No.: 14,574 Region Association: South East States  |
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 |
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Replies(1 - 4)
| ConeDodger |
Dec 3 2013, 01:13 PM
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#2
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Apex killer! Group: Members Posts: 23,611 Joined: 31-December 04 From: Tahoe Area Member No.: 3,380 Region Association: Northern California 
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Did you adjust it correctly after installing it? The bucking from TPS wear is usually at cruising RPM.
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| boxsterfan |
Dec 3 2013, 02:41 PM
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#3
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914's are kewl Group: Members Posts: 1,776 Joined: 6-June 03 From: San Ramon, CA Member No.: 791 Region Association: Northern California |
Checked your fuel pressure? How about your fuel injectors?
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| Rant6 |
Dec 3 2013, 02:46 PM
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#4
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Newbie Group: Members Posts: 8 Joined: 18-June 12 From: Daytona Beach, Florida Member No.: 14,574 Region Association: South East States |
QUOTE(boxsterfan @ Dec 3 2013, 03:41 PM)  Checked your fuel pressure? How about your fuel injectors? 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? |
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| Java2570 |
Dec 3 2013, 03:27 PM
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#5
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Senior Member Group: Members Posts: 649 Joined: 7-May 11 From: Fishers, IN Member No.: 13,035 Region Association: Upper MidWest |
Does it still buck the same way if you unplug the TPS?
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