Just swapped a motor from a 98 gt into mine. Just bolted it up and started the car. car starts fine, idles fine for a few seconds, then will rev up close to 2k rpm. It was a full motor swap, npi shortblock, pi heads, comp 270 cams, edelbrock victor jr intake, edelbrock fuel rails. Tried a new computer, didnt work. tps seems to be fine. O2 sensors are showing pegged out in volts? did i pinch the harness or something putting the motor in?
Motor swap, mustang revs up on its own help?
- Thread starter lowrybl
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txstang84
15 Year Member
There have been two separate [known good] TPSs installed on that TB so far, swapped computers [also good], and still no fix. Volts are stable when KOEO, but KOER TPS spikes from actual voltage/throttle pos + fluxing voltage; e.g. fluxing from 1.4V ~ 1.8V slightly above idle...2.4V ~ 2.8V mid throttle, and so on. Also, O2s as mentioned are pegged....
ttt
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usaf_branham
15 Year Member
i would initially suspect iac, tps, or vacuum leak. im not saying it couldnt be something else, but that is where i would start.
wmburns
SN Certified Technician
the solution to your problem is in your post (the "fluxing" of the TPS).
With regards to the function of the TPS, the most important thing is a stable closed throttle value. It doesn't matter what the value is as long as it is the same value each time the throttle is closed.
For confirmation, monitor the TP-MODE PID. Is it switching from "C/T" to "P/T"?
Start first by checking the throttle return spring. Is it tight? Next look for loose or wore out throttle linkage.
Check out the following for addtional information:
Is your mustang stumbling, dieing at idle or idling rough? - Page 14 - Ford Mustang Forums
txstang84
15 Year Member
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