Engine Please help, rpm surge when shifting

AbhorrentSpecies

Active Member
Jun 14, 2020
204
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Las Vegas
Been a while since I've been on here. Anyway, I can't take it anymore. I've tried everything I know. I have a stock 89 GT. Only headers and x pipe. Not Everytime but almost, when I start the car it almost dies and recovers. It's done that ever since I bought the car. Over the last 6 months it started to develop a rough idle so did I base idle reset and now it surges like 400 rpms Everytime I shift. So now I have all three symptoms. Almost dies and recovers upon start up, idles rough and surges when shifting. I feel like I've checked everything but I'm obviously missing something. Any help is greatly appreciated.
 
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Yeah, no vacuum leaks, new ect, act, new IAC, new timing chain, new EGR, tps set to .96 and climbs normally to 4.6 volts, 10 degrees initial timing. I'd like to rule out anything else before the computer, since rebuilding ecu will have my car out of commission for weeks.
Check for vacuum leaks??
ECU need rebuilding?
I read somewhere that the tps can cause these problems though it seems to be functioning normally. One thing I did notice is if I try to read the tps at idle with the car running, the voltage is all over the place.
 
Yeah, no vacuum leaks, new ect, act, new IAC, new timing chain, new EGR, tps set to .96 and climbs normally to 4.6 volts, 10 degrees initial timing. I'd like to rule out anything else before the computer, since rebuilding ecu will have my car out of commission for weeks.
So I just noticed something. Someone said to check tps voltage at the black and green wire, not ground to green and it jumps all over the damn place. Even when I tap the orange and black it shows 5 volts for a second and then starts bouncing all over. Is that just a bad tps sensor or something more serious?
 
Check the 5 volt reference wire (orange/white) at the EGR with the TPS unplugged and see if it does the same thing. If it fluctuates then it could be the ECU. If not then my guess would be the TPS but I would think you would get a code for it. With that said have you pulled codes i.e. KOEO codes?
 
Check the 5 volt reference wire (orange/white) at the EGR with the TPS unplugged and see if it does the same thing. If it fluctuates then it could be the ECU. If not then my guess would be the TPS but I would think you would get a code for it. With that said have you pulled codes i.e. KOEO codes?
I actually just checked the reference wire with it unplugged and it stays completely steady at 5.04 volts. Only when I try black to green or black to orange at the actual sensor does it fluctuate all over. No codes at all other than for smog pump stuff, which i don't have.
 
Check the 5 volt reference wire (orange/white) at the EGR with the TPS unplugged and see if it does the same thing. If it fluctuates then it could be the ECU. If not then my guess would be the TPS but I would think you would get a code for it. With that said have you pulled codes i.e. KOEO codes?
Oh sorry, you said at the EGR, okay. Lemme do that. I just checked the constant inside the harness with the TPS unplugged.