berkel

Hi all,

Car: 2000 A4 1.8T Quattro, GIAC, Milltek.

Here are symptoms, cool night (last Wed), got in car and idles fine. When trying to accelerate, I get misfire (I think). Actually got a cel, but just for a second. If I am at 1/2 throttle or more, when boost builds I would get the misfire. Basically, it seems like there was enough load to "blow out" the spark.

Took the car home, and drove to work the next two days with my wife.

On Sunday, I changed the plugs, they looked fine. Retorqued everything. Took the car for a drive, and it felt great. I thought the problem had been a loose plug and I was all set.

Yesterday, drove to work. It seems that now, I get mild misfire under load, but only when the car is cold. Once the car is warmed up, it goes away. Car idles fine. Did not scan the car yet.

Could this be a coil pack on the way out? Other ideas?

Any input is appreciated.

FB

Audi2ptzero

If the coil pack is bad it is BAD and wont fire the spark plug at all. Sounds more like the plugs might have too much gap and when the cylinder is still cold the spark blows out when you get boost.

Audiboy

It is the black long stem attached on the coil pack. Check for any cracks or carbon traces in this spark plug connector and the tip of the coil pack area. Check the resistance of the connector - should be around 2k ohms. These are the things that normally go bad - not the more expensive coil itself. When coils go out, they don't fire - as Audi2.0 mentioned. They will have a direct short to ground when measured with a ohmmeter. Normally, they are very low ohms anyway. However, if there is a crack in the housing or a particle trace in the coil pack tip, the electricity will take the shortest path. Cracks can usually be rememdied by a nonconductive epoxy - if one wants to save money. Carbon traces or dirt can be cleaned out.

The carbon resistor on the spark plug tip is the first to go - due to heat cycling and high energy.

move the coil packs, spark plug tips and spark plugs around too if you have a VAG so that you'll know which change followed which cylinder. Then go spend $16 on a spark plug tip.

Now the big question - VW has been using similar spark plug tips since their flat 4 engines with spark compression - new quieter radio feature around 1973-74. I wonder why till now, they haven't improved on them significantly. Our shop stocked these things and because they were only $2, we sold them with most tune ups after so many miles because they never lasted very long.

berkel

Thanks guys. =)

I figured if the coil was totally bad, I would get a bad idle (per other threads here). This is why I was surprised and also the fact that the problem is intermittent. I will try to get the car scanned and identify which cylinder(s) are misfiring and try to swap the connectors out.

FB

berkel

They are bosch 3 prong plugs (F7LTCR or something like that). Wasn't sure how to adjust the gap with the 3 prongs. I know you are supposed to leave the 4 prongs where they are...

I could try some "regular" plugs and gap them a little closer.

Anyone have a part no for a conventional plug that works, preferably copper?

Thanks,

FB

Audi2ptzero

This way if they foul I can replace them again with another set. After I get the car fully tuned I then put in the good set.