RPM drop after acceleration

[R31]

Hi I have a auto 99 4 cyl that can't maintain a constant rpm. e.g. coasting then accelerate to desired rpm and it will suddenly drop by 200-400 rpm with a low to moderate load, labouring the motor slightly. It drives great for 230k kms (cambelt done at 206) and after doing the usual service oil,fuel/air filter,plugs and leads,ATF/diff oil recently I'm all out of ideas.

[trentmeyer23]

Was the issue there before the service?

[Hiro]

Does it do it in all gears at all speeds or just particular ones?

Could be the torque converter locking and unlocking

[R31]

I do a lot of country driving and it only happens in top gear (70-90km/h) and gets worse depending on the incline. Its like I have to give it more throttle then it needs so it wont drop a few hundred revs. I'm sure it's been there as long as I've owned it but is annoying me a lot lately.

I occasionally get a CEL camshaft posistion sensor code, it might stay off for a week or two, flick on and off for another week but the car hasn't missed a beat at all so I havent worried about it except clearing the code.

[Steven]

sounds like the torque converter is locking at the wrong time

[R31]

Thanks for the answers everyone I have found a few threads describing my problem after searching torque converter