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Juan Crespo
Juan Crespo, Tech Trainer
Category: Lincoln
Satisfied Customers: 1492
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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2003 Lincoln navigator check engine light flashes rough idle

Customer Question

2003 Lincoln navigator check engine light flashes rough idle and at 40-50 jerk and shakes. Changed coil, spark plugs, timing chains, pvc valve, and Catalic converters. Still come up with codes p1000, p0171, p0174, p0300, p0304, p0307, and p0316. What could it be
Submitted: 7 months ago.
Category: Lincoln
Expert:  Juan Crespo replied 7 months ago.

A flashing MIL indicates imminent catalytic damage, so I would advise not driving the vehicle until whatever the issue is that is prompting the PCM to flash the MIL has been repaired.

I see on your post that several components have been replaced, however, that information alone doesn't give me the information I need to formulate a diagnosis. Has the PCM been scanned for codes? If so, what are those numbers?, Any freeze-frame data captured along with the codes? Any history on how this came to happen?

Expert:  Juan Crespo replied 7 months ago.

Sorry, I did not see the latter part of your post that included the codes. So that information I got. How about freeze-frame data and history on how this come to be?

Customer: replied 7 months ago.
We changed the catalytic converter three days ago.
Customer: replied 7 months ago.
The timing chain renter broke and had a guy come over and change it along with the water and oil pump and change out the coils and spark plugs.
Customer: replied 7 months ago.
Keep getting codes so took it to a muffler shop and hand the converter changed he said two out of four were bad. But still getting codes.
Expert:  Juan Crespo replied 7 months ago.

Thank you for that information.

On these engines, most of the times when the timing chain jumps out of place the result is internal damage to valves and pistons. Did the guy start the engine right after he changed the timing component? Was it running rough? Did he perform a compression test?

Customer: replied 7 months ago.
He started it after making sure it had compression and after making sure you that was in time
Customer: replied 7 months ago.
The first test was saying misfire on 4&7 and catalytic converter converter
Expert:  Juan Crespo replied 7 months ago.

Misfires are usually the result of an air/fuel mixture that's too lean - confirmed here with lean codes P0171 and P0174. Another factor to consider is the random misfire indicated by P0300.

In conclusion, if compression and ignition are good, then fuel must be the cause. Have your guy test fuel pressure; if not 35-45 psi, have him replace the fuel pump and retest.

Please let me know what you find.

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