Auto repair experience


3S-FE engine won't rev past 3000

The owner of this Toyota with a good old 3S-FE engine came for diagnostics and told us that the engine stalls after 3000 rpm.

Okay. There are no errors, the check engine light is off. But the car is stalling.

For diagnostics, we will use an oscilloscope. And the first thing we will check will be the crankshaft position sensor.

wrong marker crankshaft

Here is his waveform. We see that there is an incorrect sensor signal on the oscillogram. This means problems with the marker. You need to remove and inspect the crankshaft gear.

broken crankshaft gear 3s-fe

We remove the gear

broken сrankshaft gear

The marker was broken and then welded on. This was the reason for the poor performance of the engine.