Jet Jockey/A4 Pilot

When all of a sudden, as I'm moving the car back into the garage for the night, the car starts bucking and running real rough, CEL starts flashing and the car dies on me (at least I made it into the garage).

VAG it and all there is as a fault is #1 cylinder multiple misfire. Oh ****, a coil pack, not tonight before the race tomorrow morning, tell me it isn't so. Decide to swap spark plugs, that did not work, decide to swap #1 and #2 coil packs, that did not work and now I can't get the car to run even in its new found rough mode. No more CEL, what the fvck? I guess it's not running long enough to record the fault. I call a friend that works on the 1.8T and knows his stuff about these cars. While I'm waiting for him I decide to try to start it again, but I notice that when the key is turned on, the usual relays seem to come on but the fuel pump does not always come on. My friend gets here we recheck the spark plugs, we check the coil packs and he says, they are not the problem, good I think?! Next step we check all the fuses, none turn up blown. Next we take part of the dash apart where the fuses are to get access to the relays. Check the fuel pump relay, #167 IIRC, we test it with an ohms meter and with it directly connected to the battery, no that's not the problem. Strange thing is, it won't turn on when the ignition is switched on. We hot wire the fuel pump by bypassing the fuel pump relay and bingo the pump goes on and fuel goes to the injectors. So now we have ignition by the coil packs and fuel to the injectors, it should start right? Well it doesn't. We then check the injectors just to make sure they are working, no problem there either. We then take the ECU out of its box to check all the relays and fuses in the ECU box, nothing unusual is found.

Well as it stands now the car is not starting, I guess I will have to call Audi on Tuesday. Unless it is a weird problem we can't figure out, some relay or a fuel pump problem, my friend thinks it could be the ECU itself that's not sending the signal to activate the relay to the fuel pump, darn that would be a major problem. Strange thing is, he says it would usually indicate a major fault like that if the ECU was screwed up. If anyone as any ideas, let me know.

I'll keep you all posted on this problem

s4wood

I had a car die on me several years ago..and the chip socket was faulty..re-soldered..and it was fine. Since you have an MTM chip..I don't think this is your case.

Good luck man.

mcpath

hope things work out.

QuattroRocket

Its rare that the ECU will intermittently coommunicate. In some circumstances the solder on chips will crack after usage with extreme hot and cold temps in the engine bay. This will result in stalling but it will show an intermittent ECU communication CEL specifically so I think you are looking at something other than the ECU.

Bronze

1) To check the fuel pump relay command, can you put a meter on the ECU side of the relay to see if it's being commanded on?

2) In my experience, there is the fuel pump relay output, which is a switch output, and then a PWM output to the fuel pump driver module.

3) Sinc ethe ECU can talk CAN to your VAG, it seems the micro is not out to lunch, so that means it's running code properly.

4) Not knowing the archietecture of the ECU, it's a bit of a guess if it's the ECU or not.

5) If the fuel pump weren't working, I'd suspect you'd get codes for all cylinders, not just one, so that kind of makes me wonder if something else is going on, and the fuel pump is only an effect.

No solutions, but I'll keep thinking.

bhvrdr

are. Coicidentally he filled the tank with year old high octane last night. Hopefully its just bad fuel. cheers! mike

Bronze

every spring just fine), but I hear more often stories and situations of old gas indeed being a factor, or a contributor. Hope that's the issue, since that's cheap to correct.

bhvrdr

It worked. Just talked to him. Car had to be completely drained from the rail and top of tank.

Bronze

for bad fuel he didn't get codes for all cylinders.

AggregatVier

...because it would give you something like what you're seeing but you'd have to bench it with a scope to really know.

Plus the failure was sudden - a sign of an electrical problem.

What was the final prognosis, doc?