TPS testing question?, Car is bucking under load |
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TPS testing question?, Car is bucking under load |
Jon H. |
May 25 2016, 10:26 AM
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#1
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Member Group: Members Posts: 237 Joined: 1-July 11 From: Ottawa, Canada Member No.: 13,264 Region Association: Canada |
Hello, I had my 73 2.0l out for its maiden voyage this year and the car was running great. On the way home I stopped at a light and when I took off the car was bucking horribly. I investigated and found the bolt under the plenum that grounds the wires for the TPS and, I think, the injectors had come out. I re-installed it checked the grounds, checked continuity between the ecu and the TPS and all is good. I checked the continuity of the TPS as the throttle is opened and closed and it appears that there are about three position that are open circuit. They are small gaps though, barely having to move the throttle to get continuity again. It this normal? Should there be 'flat' spots as I move the throttle or should there be 100% continuity all the time? I did remove the TPS and have a look and it looks fine. Could an arcing ground have caused the TPS to fail?
Thanks in advance! Jon h. |
BeatNavy |
May 25 2016, 10:54 AM
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#2
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Certified Professional Scapegoat Group: Members Posts: 2,924 Joined: 26-February 14 From: Easton, MD Member No.: 17,042 Region Association: MidAtlantic Region |
"Greater FI minds" than me will have more / better suggestions, but it's hard to know what exactly you mean when you say you checked continuity between TPS and ECU. How (which pin on the ECU to where on the TPS)? When you say you inspected the TPS, did you look at the circuit board and inspect the traces to see if they are worn or damaged?
Here's a reference: http://www.914world.com/bbs2/index.php?sho...=95583&st=0 I believe one way to check normal function is to put the ignition on (but engine off, obviously) and with a very quiet garage slowly move the throttle body from idle to WOT. You should hear about 20 tiny "clicks" in regular succession that are the injectors firing as it goes from trace to trace through the whole progression. If those don't happen in regular manner (or if you don't hear the right number), your TPS is not correctly sensing the movement of the throttle and you will get that trademark bucking. Could be worn traces or damaged contact arms. |
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