This is a 2000 ATQ A6 2.8, it presents this chronic problem of on off no sparks to cylinder 1 and 6. i have change all spark plugs, wires and ignition coil and module without any resolution of the problem. i tested and found no power in the wire connector to coil number one which supplies cylinder 1 and 6. while the other wires continue to have power. Symptomatically, the car drives and idles rough for the most part but inadvertently picks up for a smooth short run of about 2 mins and does this over and over again. i open the electronic box and found nothing. i am thinking of replacing the electronic control module. any ideas guys?

 

Hi Kimi,

Your issue is hard to diagnosis without actually being able to see or inspect the car. Do you have a CEL(Check Engine Light) on? If so you may want to check for any diagnostic trouble codes to help with the diagnosis.
Another thing you want to do is ensure that you don't have any wires leading to or from your coil packs or injector harnesses that lead to cylinder 1 or 6 which have exposed or chaffing wires that may be grounding and causing a loss or spark.
Lastly, depending on the mileage on your car you should consider removing the spark plugs for those two cylinders and inspecting them for wear or fouling. Good Luck with it!

 

thanks TwinTurbo, the CEL code is P0300 random misfire, but it is clear that it reflects cylinder 1 and 6. Does this car have any ignition timing relays or ignition module other than the module on which the three pack coils sit on?

 

Are you sure you don't have a vacuum leak?

 

I have the exact same thing!! First it was 2&4, and now its 1&6. Just got it back from the dealer and they have no idea...

 

thanks guys, did change all vacuum lines, cleaned all injectors but still no good results. the remarkable thing is, i found out when the car transitions into a smooth run, the wire connecting and supplying power to coil one which in turn supplies cylinder 1 and 6, has power, but in the rough face there is no power to this wire. i must confess guys, i have no clue what is going and i am out of ideas, i am going to change the ECM and i am also looking for may be an ignition relay hiding some where in the closet

 

up dates on this issue. I took out the connector wire to the air intake temperature sensor, measured the resistance and found it to be at 5 oms, i am not sure what this means, but it would seem to me as if the resistance is quite high, as most of the other sensors were ranging between 1 and 3 oms. so i have gone ahead and ordered a new sensor hoping it might just be the magic bullet. my ECU ordered arrives tomorrow, so i will keep you guys updated about my trials, but at the same time i am requesting for your input, cant do this alone guys

 

I was told to check the engine ground strap. Where is it???

 

If you are having intermittent power loss in the wires to the misfiring coils (and assuming you have replaced the coils with known good ones as part of the testing), you need to investigate the harness with these wires all the way back to the ECU. It is the obvious problem, unless the ECU itself is bad. I suggest also using electronics spray on the connectors to the ECU that house the coil outputs. Buy a can of good electronics spray and go at every connector in the line back to the ECU. Also use a meter to check continuity of the wires while wiggling them to imitate engine vibration. Be sure the ECU connector is taken loose before putting the tester on the line since the tester uses a voltage for the testing..