audi a3 misfire and its not the coilpack or icm

[trem3412]

Hi all i have a audi a3 1998 1.8t engine code agu

Right the car just started to missfire so i pulled the plugs on the coilpacks and no3 did not do anything so i went and brought a new coilpack fitted that, only to find the misfire is still there.so i went and purchased a new ignition control module from allparts fitted this to find the misfire is still there but now is on cylinder4 i have checked power coming out of the module on all 4 with the car running and they are all at 14volts and the same upto the coilpacks,also checked the earth which all seems fine,If i put the test light on the positive terminal on the battery and put on the wire from the module to coilpack on 1,2,3 the car goes to die but on number 4 does nothing could it be a faulty ignition module or possibly a ecu fault anyhelp would be really helpful as i have tried everything i can think of even start to check all the wires in the loom and still nothing

 

[markyR]

check compression on the effected cylinder. i had this problem on my old agu and it was the old ignition amplifier but i just used to pull the plug and clean it out from time to time. Also check the pins on the amplifier plug, maybe squirt some cleaner in there.

 

[Vwdan80]

It does sound like a faulty part, try putting the original part back on and see if the misfire moves back to cylinder 3.

 

[trem3412]

hi thanks for the reply the compression was 174 180 180 182 forgot to say i had checked that i am just lost as the icm is new

 

[Vwdan80]

If its not a genuine part then it could be playing up, try the original again as it would confirm if the wiring is ok on cylinder 4

 

[trem3412]

i took the old icm apart to find that two of the soldered bits were broke and if i put it on the car struggles to even start

 

[Vwdan80]

If the part isn't genuine then it could still be faulty, I would put the original back on to at least confirm the wiring is ok on cylinder 4

 

[Vwdan80]

Forget last post, stupid internet playing up
I would take the part back to the shop saying its faulty and get another to try

 

[trem3412]

Right put another new ignition control module on and still exactly the same but after some more testing it is pointing to the ecu as the 4 wires from ecu to the ignition module 3 of them have .22v going through and the other only had .06 and it was this measurement coming out the ecu so to me points to the ecu anyone have any ideas thanks

 

[vfr800]

Have you looked at the coilpack wiring harness/loom? They do a good job of falling apart around the hot parts of the engine.

Whip the connector off the ECU, trace the wires and check their resistances?

 

[trem3412]

Yes it all seems fine all getting the same from the icm to the coilpacks opened up the ecu but can't see any bits burnt out !!!

 

[trem3412]

Just thought I would update everyone that when I rechecked the wiring 1 wire from the ecu to the icm had less voltage it turned out to be an ecu fault so since my obd port is not working I brought a unlocked mapped ecu for 200quid and now runs sweet and also a lot more enjoyable to drive !!!!!