QuestionQUESTION: A month ago the check engine light come on. Shortly after that the engine performance degraded. For example. the engine starts fine with no problems. However, you could tell there was a little hestitation in the engine while ideled before shifting to (D) Drive. While accerlation between 25 or 30 RPMs the vehicle whould shift into first gear real hard as if someone hit you from behind. Second gear would do the same thing but a little lighter. Third gear would shift the same as the second gear. Then when you come to an idle again the engine would shut off.
This eventaully got worst so I visited my family mechanic. He first thought it was the Speed Sensor. After replacing it, the vehicle continue with the same symtoms. Then he thought it was the knock sensor or possibility the valve body in the transmission and recommended that I should take it the the Nissan Dealership,which I did. They ran diagnostics and returned a fault code pointing to a bad TPS. Because they wanted to charge an arm and a leg to replace it, I then took my vehicle to another mechanic to replace the TPS with Nissan part and transmission fluid. That alone cost me $315.00. Anyways, after picking up the vehicle and driving home everything seemed back to normal. That afternoon while driving to get a bite to eat all the symtops reappeared. I called the mechanic back and informed him of this and he said that he could not help me. He said it had to be a computer problem. He explained that the computer was not sending a voltage to the TPS when the cars warms up but when the car cools down the voltage start to retransmit back to the TPS. After seeing four mechanic and out $315.00 I still haven't been able to get this fixed. Can you please tell me what I should do next. Since the Speed and TPS sensor has been replace what else could it be?. I hope it's not the computer.
ANSWER: Troy,
I would ask if the check engine light came back on? If so, go to Autozone or Checker and get the code read and email it back to me. If the harness or the connector are defective that can throw a throttle position code. Or, if the throttle position sensor was not clocked correctly it will not read where idle is and that will set a code and the engine will go into limp mode. Then, you will not have power and it will run as you state. Email me back and let me know.
---------- FOLLOW-UP ----------
QUESTION: Yes, the check engine light came back on. I did as you suggested and went to our local auto part store and had the code read. Here are the results.
DTO (Codes)
P0120
TPS/Pedal Position
Sensor A
Circuit Malfunction
P1705
Manfacurer Contrl. Transmission
DTC Pending (Codes)
P0325
Knock Sensor 1
Circuit Malfunction
Bank 1 or 1 Sensor
P0120
TPS/Pedal Position Sensor A
Circuit Malfunction
P1705
Manfacurer Contrl. Transmission
Since the TPS sensor has already been replaced. Should I take the car back to the mechanic who replaced it and have them put another one in just in case this one might be faulty out of the box? But I have a feeling he might say otherwise. There is something else I've noticed this week. When the ignition is started after the car has been sitting a while the OverDrive light flashes.
AnswerTroy,
Yes, I would ask the shop that did the TPS to check it since the code came back. The sensor could well be defective.
The knock sensor is showing that it is in need of replacement.
THe overdrive light flashing and the transmission code means that there is an issue with the transmission. Most probably the computer that controls it or one of the solenoids that activate the gears. I would go to Cottman transmission or the local dealer to get the manufacturer codes read to find out which it is.
