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PO301 through PO306 codes. Triggering CEL + VTM-4 lights. Car has 175k miles.

Work performed after reading through this great forum:

-Valve adjustment performed by local mechanic in Portland, OR
-Coils replaced with ones from a 50k mile motor by local mechanic
-New plugs
-EGR port cleaned
-New EGR valve
-New air filter
-Fresh oil change
-Lucas injector cleaner added to full tank of gas
-Premium gas always used

Problem:

-CEL + VTM-4 lights still coming back on after clearing codes

Questions:

-Should I take to Acura dealer have them perform valve adjustment again? What else am I missing here or should I try? This seems to be a common problem…
-Is there a way to ‘disconnect’ the connection between the CEL and VTM-4? In other words, it’s a big bummer to needlessly lose AWD in winter months when the car seemingly runs fine and the CEL goes on. Thoughts?

Thanks!
 

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Low fuel pressure might cause missing w/o setting codes. There should be some change in the Long Term Fuel Trim's (Increased positive LTFT) indicating low fuel delivery. Measure fuel pressure at idle and under load to check.

good luck
 

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my 2005 had a similar problem when I bought it... It had a intermit check engine light for p0300 random misfire. I did the valve adjustment, new plugs and new pcv, and valve cover gasket along with new intake gaskets I also cleaned the intake manifold, egr, and throttle body. I cleared the light and test drove the car. still had a pending for misfire. engine purred like a kitten! So I got out my snapon scanner and cleared the crank shaft relearn. I preformed the relearn and BAM no more pending misfires!!! sometime Honda's can learn a BAD pattern and then when you FIX the problem it will compare a BAD crank shaft sensor patter to a good one and mark the good one as BAD! I have fixed many GM's and FORD's and HONDA's that have crank shaft relearning software in the pcm. see if your mechanic has that ablity. sometimes doing a PCM reset along with a crank shaft relearn will fix the problem.
 

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Thanks for posting an update. So often, someone will solve a difficult problem and "keep it to themselves".

In this case, you were dealing with the difficult situation of something that "was done" really wasn't... that's hard to find because you've mentally checked that one off the list of possibilities and moved on looking for other problems. At least you didn't have to re-do the valves! ;-)

FWIW, I would tend to not replace 175000 mile coils - chances of them failing is a lot lower than the random used or new ones you'd put in their place. That's not to say you did the wrong thing while looking for a misfire, but I'd suggest it mainly when you have a single cylinder throwing a code, rather than all of 'em (the odds of all six going funky are about the same as being hit by a meteor). ;-)
 

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Unusual for EGR fix to resolve a problem w/o P0401, P0403, P0404, P0406 code. Did you ever have an EGR code?

good luck
 
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