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Problem after engine changeout, 99 Neon

I completed the change a couple days ago. Vehicle starts, runs fine. After

15-20 minutes on the road the speedometer becomes erratic, fluctuating rapidly up and down, eventually after about a minute, settles to zero, where it remains until the vehicle is stopped and allowed to sit for a while. The auto shifting becomes irregular after the speedometer with higher than normal revs being required when it does finally change. A 30 minute cooldown period allows the vehicle to perform correctly for about another 15-20 minutes at which time the erratic behavior happens again. I have seen posts indicating the eeprom might need a reflash. Does anyone have any ideas about this problem? TIA CenturyTek
Reply to
CenturyTek
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There is definately something with your computer/sensors. I know that until the engine reaches running temp, there are verious sensors that are set to open circuit. I do not know the whole list of them other then the O2 sensor, which would not cause that issue. The engine you put into the car, was it the same as that that came out? If the transmission and engine type are not the same as what the ECU was programmed for, this would be your issue.

Reply to
Mike

Sounds like a speed sensor problem, or the connections to it. Did the transmission get changed with the engine or is it the original? When I had my transmission rebuilt almost two years ago, something happened to the sensor as a result of the transmission removal/installation. The speedometer was erratic, or inoperative. I probably should have gone back to the original shop to have them make it good, but I did it myself in the interest of time.

-Kirk Matheson

Reply to
Kirk Matheson

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