Car Doctor Q&A: That Smoking Good Deal is Smoking for a Reason

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Sometimes a good deal is a pretty bad deal in the long run, like this ’07 Navigator that’s throwing a lot of scary sounding codes.

Q. I recently purchased a 2007 Lincoln Navigator in what I thought was in really good shape at a smoking good deal. The after having it for a bit, engine runs rough, smoke a little, but and I just assumed it needed a tune-up.

The check engine light is on and it feels sluggish for a 5.4 liter V-8. The truck has pretty low mileage for the year only 128,000. When I hooked it up to a scanner, there were a whole slew of codes P0022, P0340, P0300, P0303, P0304, P0352, P0356, P0012.

The more I look things up the worse it gets. Where do I go from here?

A. These engine certainly had their share of problems starting with the variable camshaft timing (VCT) solenoids, timing chains that stretched and low oil pressure due to bearing wear. At this point I would start by looking at the oil pressure.

If it is low and the oil pump and screens are okay, the engine just may have too much wear to fix. If you hear a rattle coming from the front of the engine the timing chains may be stretched or loose due to a broken tensioner. If the oil pressure is okay then look at the VCT solenoids. If you find the solenoid screens are plugged, replacing the solenoids may fix the problem poor running issue.

Bottom line this vehicle may have been correctly diagnosed and the only fix is a replacement engine. If the rest of the truck is in pristine condition a replacement engine at $3000-$4000 plus installation may be money well spent.

John Paul is public affairs manager for AAA Southern New England. A certified mechanic, Paul tests dozens of new cars each year and also hosts a radio show on AM 950 and 550.