Car shakes in gear at 2,000 rpm

When our car is moving in gear and reaches 2000 rpm it starts to shake violently. Just before this happened it hesitated slightly while driving at about 40 mph. If you rev the engine in neutral you can rev much higher than 2000 rpm with no shaking. When battery was disconnected and reconnected it stopped for about 3 days of driving. Then it started again. 1995 Maxima 5 speed manual transmission.

I’m baffled, does it start shaking at 2000rpm regardless of the gear you’re in, or just in higher gears? Does it seem to accelerate normally (not sluggish)?

It shakes in all 5 gears. Acceleration is normal until you get to 2000 rpm. Mechanic says there is no rpm limiter on this manual trasmission. Can’t figure it out.

Has basic maintenance been done? Fuel filter, spark plugs, etc.?

yes, maintenance has always been done and a mechanic checked fuel filter and ignition systems and they are ok.

How many miles on the car? No check engine light?

I might suspect a worn out distributor, if this car has one.
Or a fuel/air ratio problem. Maybe a dirty MAF sensor, or a problem with the TPS.

Or, it’s the transmission, not the engine…

The car has 220,000 miles. The check engine light is on. A mechanic said it showed a temperature sensor and engine knock sensor. Neither of which I believe. No overheating as the temp gauge is right where it’s supposed to be and certainly no knocking. It has no distributor, 1995 maxima. A transmission specialist said no problem with the transmission. The problem has not recurred in about a week of driving.

The temp sensor with problem might not be the same one that drives the gauge.

Find out the error codes and post them here. They look like P0123.

The sensor codes are: P0115 coolant temperature sensor problem, P0325 Knock sensor problem (bank#1), P0125 coolant temperature sensor problem. These codes were read about 20 minutes after the car shook at about 2000 rpm. The shaking only occured for a minute at this time, and it has not done it again for 2 days now. I don’t hear any knocking in the engine at all. It runs very smooth and acceleration is smooth unless I have an occurance of the shaking at 2000 rpm.

You said this was a '95 Maxima - but it has an OBD-2 system (those are OBD-2 codes). Are you sure all of that is correct? Is it maybe a '96 Maxima? (Or maybe some cars had OBD-2 before '96?)

Anyway - presuming the codes are correct, you need to correct both of these issues. The coolant temp sensor & wiring need to be checked & tested along with the knock sensor.

The root issue may lie in the temp sensor since if the car’s computer thinks that the car isn’t up to temp then it will continue to run rich and this will create issues (as well as increased fuel consumption). I’d be tempted to chase that down first.

Disconnecting the battery will often reboot the ECM (engine control module or computer). Your car is old enough to have a defective computer. If you do have a bad one, the problem will happen again and the remedy will be the same. The problem usually gets worse with time.

A defective computer can put up bogus codes. The previous poster is making sense when he says that those codes should be addressed and may help you solve the problem. They could help.