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Old February 20th, 2013, 14:14   #60
FlyTDI Guy
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Join Date: Nov 2001
Location: PNW
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I see where your concern is now. I'm primarily experienced w/my ALH and have had my EGR 'neutered' for some time now. The operation of the ALH EGR is mostly digital in that it's either on or off and not much inbetween. Low duty cycle indicates off and high indicates on. Normally at idle, it will start off on and cycle to off after a minute or two. It goes off when accelerating but can come back on when cruising at a steady state. When on, it's recycling exhaust back into your intake tract. On your engine series, the logic may be more analog in that there are various states and degrees it may be on. Why your duty cycle is above the "normal" range may indicate a sticky mechanixm or clogged intake. I would interpret the overly-high duty cycle to mean your ECU is issuing the command to open but flow is not reacting as anticipated and measured by the MAF. The ECU therefore increases duty cycle to attempt to get the feedback it's expecting.

If you don't have "EGR Insufficient Flow" or other EGR related errors, I wouldn't be overly concerned. You may want to check your intake for clogging and verify your EGR is working properly with a Mity-Vac (assuming it's 100% vacuum operated). Also verify you have adequate vacuum (+/-30in/hg on and ALH) with no hose or connection leaks. Another test might be a leakdown test on the EGR actuator, again w/a Mity-Vac.

I've probably already said too much as I'm not an expert with your engine series. You may want to re-post this question in the Passat section and see if you have better luck.
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