Momentary Power Loss and Flashing Glow Plug Light

I get a flashing glow plug light from time to time, not constant. I also have a "miss" or temporary power loss at high throttle setting, and the cruise control drops out everytime this happens. I don't get the glow plug light and the power loss at the same time, but they seem to be connected still. Started happening at almost exactly the same time. Wish I still had my VAGCOM, but lost the damn cable somewhere.

Did some research here, and first thought was 109 relay. Cheap and quick, so I replaced it. The one that came out was grey, so I know it was the "newer" version, not the older black version. Can also tell because the newer ones end up with "109" upside down when installed. Anyway, drove it again today and have same symptoms. Now thinking either MAF (and I always thought the B4 MAF was rock solid...not so with my A4) or possibly N75 valve.

I just replaced all the vacuum lines, so I went in and checked to make sure they were all still on tight and no kinks. All checked and looked good.

Any ideas out there? Thanks in advance.

What's the state of tune of this particular vehicle? Chip, tuning-box, Evry resistor-mod?

Factory as far as I know, and I've owned it since about 67K miles. At 194K miles now. T-belt due at 200K miles. Rebuilt fuel pump about 50K miles ago.

Don't know if this problem occurs in the A3/B4s, but this almost sounds like the same problems as the A4 brake switch. It really is hard to diagnose without reading any codes the computer might throw. This also sounds like a bit of a common issue with tuning boxes on these cars, but since you don't have one, that probably isn't the case.

Vento, if it HAD a tuning box, where would that be? When I first got this car several years ago, it was head and shoulders faster off the line than my white 96 Passat TDI. Once I had the fuel pump rebuilt, it was about even w/ the white car. Now the white car leaves it in the dust. I'm wondering if maybe the previous owner had a tuning box in it and I just never noticed. I've never been much interested in getting away from stock.

Tuning box is easy to locate. Take the engine cover off. Now, look at the fuel pump. You will see an electrical plug on the drivers side of the pump near the front. If there is some kind of device attached there, that is the tuning box. If the wiring looks tampered with, with a lot of electrical tape present or something, I might suggest digging through it to see if the previous owner put a resister in there (this is called the EVRY mod).

Finally popped the hood this weekend, and as I recalled from changing the fuel pump, no box of any sort on the electrical connector to the fuel pump. Also checked the brake/turn/running lights and all are working. Maybe get a chance to run a VAGCOM on it this weekend and see what codes are being stored. Other than that, I'm fresh out of ideas, and suspect maybe water in the fuel, N75, or MAF. Sure does seem electrical to me, though. Not a gradual power loss, but a sharp off/on type of power loss. Maybe take the 109 relay out of my white Passat this weekend (known good) and try it in the green Passat.

Re: Momentary Power Loss and Flashing Glow Plug Li

AH HA! Now I think there are two gremlins running around, but I may have cornered one just awhile ago. When I took the good 109 relay out of the other Passat and put it in the green Passat, it ran without the high power hesitation. I still get a flashing glow plug light ALWAYS accompanied by the dropping of the cruise control (which remains inoperable as long as the light is flashing), but the car has NO hesitation with the good 109. Back to the dealer to return the faulty 109 and get another one.

If I can connect w/ my nearest VAGCOM guy, maybe I'll corner the other gremlin.