99 mk 4 1.8t missfiring on 4th cylender

[gladstone]

Hi can anyone help me with this, the problem is the car is missing on the 4th cylinder, this is an intermittant fault so isn't happening all the time, had the car to a local VW specialist, plugged it into the computer but no problem code was found, think this is due to my ECU not having missfire recognition. Tried swapping the coil packs over, new spark plugs but still no luck. I have noticed other people using this forum have had similar problems and was just wondering what the outcome was.

Thanks

[Crasher]

This is an AGU engine and as you say, the ECU has no misfire recognition abilities. If swapping the coil pack didn’t move the misfire then I would suggest changing the ignition amplifier which is the unit bolted to a heat sink on the back of the air cleaner. One complication though, a faulty amp normally damages the coil packs and vice-versa so replacing one part often means that part fails again in a short time period. I recommend replacing all four coil packs with genuine or top quality (such as Beru) units and the ignition amp with a genuine Bosch or Hitachi part.

[gladstone]

well crasher, looks like you were on the money with the ignition amplifier!!!, i removed the old one, ran a test on it and it turned out to be faulty. just fitted a new one today and its running sweet as a nut, nice one m8, cheers!

[slim1986]

well crasher, looks like you were on the money with the ignition amplifier!!!, i removed the old one, ran a test on it and it turned out to be faulty. just fitted a new one today and its running sweet as a nut, nice one m8, cheers!

Hey gladstone,how did you test on the ignition amp to check it was faulty??i got the same engine and same problem

[Crasher]

With a diode test light.

[slim1986]

With a diode test light.

cool,who would have one of these,i mean are they a mecanics tool or electricians??

[Crasher]

Both, they are easy to buy.

http://www.maplin.co.uk/Module.aspx?ModuleNo=5671

[slim1986]

Both, they are easy to buy.

http://www.maplin.co.uk/Module.aspx?ModuleNo=5671

Sweet!,my dads a leccy,he should have one,cheers

[gladstone]

i found a cracking step by step "how to test an ignition amplifier" on audi world forum, as this is the same unit. put in your search engine on your pc "how to test an ignition amplifier" and you should get the result. it has good pictures and descriptions to follow. you will require a multi meter a 1.5v battery and some wire. the unit itself is 140 quid from vw

[slim1986]

i found a cracking step by step "how to test an ignition amplifier" on audi world forum, as this is the same unit. put in your search engine on your pc "how to test an ignition amplifier" and you should get the result. it has good pictures and descriptions to follow. you will require a multi meter a 1.5v battery and some wire. the unit itself is 140 quid from vw

Nice thanks for that gladstone il be having a go at that