1997 Chev Lumina - Running Rough - FIXED

[DARRAH]

Is there a way to determine if the timing chain on this application has jumped time without taking the front cover off?


DARRAH

[Jeff @ Able Auto]

I would bring #1 up to TDC and do a cylinder leak test. Could pull a valve cover and check valves against piston TDC. Eithe should give ya some indication of a "skipped" chain.

[steven kiser]

low compression is a tell. if it still runs and sounds like a cement mixer chain is gone. for the most part i only see belts jump. if a chain is jump it usually goers all the way.

[DARRAH]

Cylinder pressure tests fine, car still runs very rough...enough to stall.

We've checked secondary resistance on the coil packs (roughly 5.72 Kohm), but is there a way to test them to eliminate them as a possibility (or condemn)?

Also - what about a MAP Sensor or Ignition module...are these parts that anyone thinks can be tested? I'm having trouble finding the diag. process for my technician.

DARRAH

[steven kiser]

what are to 02's reading? you may have a vac leak. check pcv, if i remember correctly they are inside the plenum.

[DARRAH]

Although the work isn't completed yet, our technician discovered what he called a "hard spot" on the crank, where the engine won't turn over, and it can't be moved with a breaker bar. The car runs (rough) and starts fine otherwise...

All of his diagnosis led him to a need to see under the timing cover, so I will keep you updated as to the condition/diagnosis, and confirmed fix.

DARRAH

[DARRAH]

The manufacturer told us that this is not an interference motor, and base on our diagnosis, there is an internal issue, probably spun bearing or damaged crank. We're replacing the motor for the customer instead of going on the clock and taking this one apart.


DARRAH