26 March 2012

Jerking at low rpm.

Today my car started jerking at low rpm, about 5% throttle.

While I depress the acceleration pedal up to 5%, the engine will rev, but once I go beyond 5% throttle, the car will suddenly surge forward. (Reading from my VAFC).

And when I try to hold the rpm at about 2500rpm when car is stationary, the rpm will rev up and down.

This symptom maybe due to:

Faulty Throttle position sensor (TPS)
Bad connectivity at the sensor (oxidized sensor plug)
TPS not calibrated
Or poor tuning.

(In my case, I had my TPS changed, plug cleaned, TPS calibrated and tuning was untouched.)

Since the VAFC was reflecting that the throttle sensor was working fine (I can see the % change gradually as depress the pedal), I suspected the signal into the ECU or the ECU or setting might be faulty.

After simple trail and error, I found out my ECU plugs was not seated properly (The catch on the plugs was worn off).

Long term fix will be to change the plugs from my spare harness.
My short term fix now is using cable tie (Very long ones) to hold the plug in place.

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