Injector Help

[AAH!]

Still trying to get to the bottom of my problem of only four cylinders firing. Number two is the non-firing cylinder

Having changed all the coil packs yesterday, still no joy, same cylinder still not firing. So hopefully it is not my wiring. A lot of the wiring from the old packs was very brittle and I suppose they would have given up the ghost sooner rather than later, especially after 130k miles. Well thats what I'm telling myself to justify the expense.

Before replacing the coil packs I did an output test and all the injectors seemed to click happily. I also swapped round the spark plugs (new 7 months ago) and checked the MAF with a DMM as per S2 Central.

Having moved on to the thought that it might be a blocked injector, I have removed the injectors and am currently in the process of soaking them in IPA. I have noticed that on two of the injectors (not from the one from the non firing cylinder) the brown plastic cap/nozzle that surrounds the spray holes have some evidence of cracking. Should these be replaced or can the injectors be serviced and these bits replaced or doesn't it matter?

I have read about ultrasonicly cleaning the injectors, does anyone know a place in London that does this as well as perhaps servicing them?

Thanks ....Angus

[AnLe]

does the non working sylinder fire? I dont know how to attach advance strobe to coil on plug installation.. sparkPlug changed ofcourse? And if you have the injectors taken out, dont forget to change those little O-rings.

[BRY]

Have you tried swapping the injectors around from one cylinder to another?

[AAH!]

I've just refitted the injectors and swapped them around and still no joy. Cylinder number two still not firing. Repeated the output test and all injectors are clicking.

So maybe it is a coilpack wiring problem the other side of the connector or a bad connection in the "thing" the brown and black coilpack conector plugs into?

Any ideas? I've run out and can see a trip to a "specialist" coming on ..........

Angus

[Doug_RS2]

Sounds like it could be a power amplifier.

There is a redundant stage, you can rewire that to get the duff one to work.

[AAH!]

is the power amplifier the "thing" on the bulkhead that the coilpacks plug into?

Is this it? "Ignition Coil Power Output Stages (POS)". Similar to the pic (this from a '92-'96 S4 AAN), courtesy of www.sjmautotechnik.com

Thanks for the help ... Angus

[Doug_RS2]

That is them.

You can swap them over to see if the non firing cylinder changes.

[AAH!]

As suggested I swapped the connectors to the power amplifiers around (POS) and the non firing cylinder moved from number 2 to number 5. So that suggested it is a a dodgy channel on one of the power amplifiers (left).

I located number 5 coilpack wire/terminal and relocated it in the spare channel on the coilpack to power amplifier conector. I had to guess which of the 2 wires/terminals going into the ecu to power amplifier conector fed coilpack number 5, there is also a third wire which is an earth. I made a guess and relocated the red & black wire. I replugged evrything leaving the power amplifiers switched around an it WORKED! All five cylinders firing. (Out of intrest i tried relocating the other wire (green) and cylinder 4 & 5 didn't fire).

I wish I'd checked the power amplifiers first as it is such an easy check and it would have saved me the price of 5 new coilpacks and a lot of time. I don't know how I missed the info on this one, I'm now seeing it everywhere . Oh well you live and your learn.

I will order two new power amplifiers as I suppose if one channel has failed the others could be on their way out too.

Thanks everyone for the help

Angus

p.s. should i change the injecotrs with the damaged nozzles as mentioned above?

[flossymeister]

Glad its fixed, Angus. 4 cylinders is just not as good

Tim

[~Delta]

Sounds like it could be a power amplifier.

There is a redundant stage, you can rewire that to get the duff one to work.

I doubt it could be a power amp problem. From memory, the 2 amplifiers control 2 and 3 cylinders. A duff amp would therefore affect 2 cylinders minimum.

[~Delta]

I stand corrected