CEL light flashing upon start up and engine shaking. From other posts, thought that this could be the coils. Towed it to the shop. The shop says they have run tests that rule out everything (coils, no kinked wires, etc.). The issue is in Bank 1 - the only other detail I have is there is positive pressure in the intake. They are telling me that it could be a timing issue in the head and are quoting between $6K and $7K to have the head tested and repaired at the machine shop. The car ran perfect to this point, no overheating, no smoke, NO indication that there was a problem at all. 91K miles. Can anyone offer advice/opinions? I need some serious help!

 

It sure sounds like the coils. What codes are coming up!

 

Here are the codes and the txt description from the shop:

Pulled fault codes:
16684 RANDOM/MULTIPLE MISFIRE DETECTED
PO300 001 MIL ON
16685 CYLINDER 1
PO301-001 MISFIRE DETECTED MIL ON
16687 CYLINDER 3
PO303-001 MISFIRE DETECTED MIL ON
16686 CYLINDER 2
PO302-001 MISFIRE DETECTED MIL ON
16688 CYLINDER 4
PO304-001 MISFIRE DETECTED

Text written on invoice:

"CHECKED IGNITION COILS, OK AT TIME INSPECTED. CHECKED SPARK PLUGS, WORN BUT NOT THE CAUSE OF THE MISFIRES. CHECKED LOW SIDE FUEL PRESSURE, OK. CHECKED RUNNING COMPRESSION, 150 PSI. CHECKED FUEL INJECTOR PULSE, OK . REMOVED INJECTORS AND VERIFIED GOOD SPRAY PATTERN. PERFORMED LEAK DOWN TEST ON CYLIDER 1, CYLINDER HAS VERY LITTLE LEAK DOWN. CHECKED BACK PRESSURE ON BANK 1, OK. CHECKED SPECIFIED VS ACTUAL CAMSHAFT TIMING, OK.
NEXT STEP WOULD BE TO PERFORM TEAR DOWN/INSPECTION OF CYLINDER HEAD AND TIMING CHAINS. INTAKE VALVES ARE NOT CLOSING ALL THE WAY CAUSING POSITIVE PRESSURE INSIDE THE INTAKE MANIFOLD.

Thank you so much for looking at this problem and offering your advice.

 

Based on the codes, the dealership is saying its not the coils. Please see the earlier post to see everything that the shop has tried.