Intermittent "misfire" and flashing glow plug lamp

Intermittent \"misfire\" and flashing glow plug lamp

I have a '98 NB 5spd with about 122,000 miles. Starting a couple days ago just before I got to work(50 mile drive) the glow plug lamp flashed once with no abnormal engine response. That afternoon I was at highway cruise and the engine totally cut out for one revolution. Since then it has cutout several different times. I am not sure if the glow plug light flashes every time it cutouts but I have seen it happen a couple of different times. I have also had intermittent no starts since then; mostly after sitting in the hot afternoon sun. When this happens the check engine light and glow plug lights flash. I turn the key off and back on and everything is fine. I am thinking about relay 109? Am I on the right track? If so does anyone have a good description on where it is on my car?

Intermittent \"misfire\" and flashing glow plug lamp

I would say it is highly possible that it is something else. You need to meet up with someone that has VAG-COM (or equivalent - see link at top of page) and get the trouble code(s) read. Typically the glow plug light does not light up at all when you try to start if relay 109 is bad.

The description actually sounds like water in the fuel. Have you checked by draining some of the contents of the fuel filter? When was the last time it was changed?

When both lamps are flashing it is something the ECM considers serious trouble. The code reading will tell all.

Intermittent \"misfire\" and flashing glow plug lamp

I checked the codes the first day it happened. There were no codes. I will check again today at lunch and try draining the seperator. I have access to a scan tool that displays TDI specific sensors. What ones should I be concentrating on?

Intermittent \"misfire\" and flashing glow plug lamp

Relay 109's that are in the process of failing have been known to cause this.

To the ECU, if relay 109 drops out momentarily, it looks like the key was switched off and then on again. When it comes on again ... it activates the glow plug lamp and the MIL for half a second.

If I were you, I would buy a new 109, since a new relay is very cheap. Swap them. If the problem goes away, great. If it doesn't go away, having a spare good relay 109 is not necessarily such a bad thing for a $20 investment ...

Intermittent \"misfire\" and flashing glow plug lamp

I pulled the codes a couple of minutes ago and there are no current or historic codes. Can anyone tell me where relay 109 is located on a NB? I have no idea where it is or what is looks like.

Intermittent \"misfire\" and flashing glow plug lamp

There are a couple screws under the dash that holds the under panel on. Take the screws out and remove the panel. This is the panel under the steering wheel, where your knees would be while sitting. Look under there, and you will see a relay labeled "109". Pull out and replace.

Intermittent \"misfire\" and flashing glow plug lamp

Thanks to everyone for the help. It was relay 109. I took the relay apart and found the connection to the PC board was bad. After resoldering the terminal to the board everything is fine.