HOW TO DIAGNOSE ENGINE PROBLEM?

2006 Lexus SC 430

Tiny

dwafford

October, 18, 2011 AT 1:02 PM

My SC430 was running perfectly, then began to misfire. A scan showed a misfire on cyl 5. Checked plug, wire, coil, could find no problem. Couple days later running rougher, scan showed misfire cyls 1, 3, 5, 7. Couple days later, refused to start. Acts like it would if engine immobilizer had been activated: runs about 1 sec, then shuts off. Scan showed problems with both cam position sensor and crankshaft position sensor circuits. Replaced cam position sensor: no change. Reluctant to believe crankshaft position sensor is bad due to progressive nature of faults. Any suggestions would be greatly appreciated.

FOUND 148 RELATED QUESTIONS

3 Answers

Tiny

KHLow2008

October, 18, 2011 AT 1:34 PM

Have the timing belt checked. Though mileage might be low, there is a possiblity of one of the cam skipping a tooth.

The other possible cause would be a sticking VVT solenoid.

Tiny

dwafford

October, 19, 2011 AT 11:16 AM

Can you tell me how to determine if the timing belt has skipped a tooth? I'm a reasonably competent mechanic and I have a service manual. Or is this something that only a dealer can do? Thanks again!

Tiny

KHLow2008

October, 26, 2011 AT 7:16 AM

Remove the both upper timing belt cover and turn the crankshaft until the timing marks lines up for the pulley and the camshaft pullies and check if any is out of position.

Testing the engine compression might show some differences between the two banks.

Please login or register to post a reply.

Crankshaft Position Sensor Replace Chevrolet
Crank Angle Sensor Replacement Mercedes Benz
Crankshaft Main Seal Replace - Front