au2 rough idle

Qwikcorty · 06-07-2012, 09:00 PM

i have a au2 wagon which at the moment is having problems with a idle and driving miss. i have changed plugs,leads and coil pack for new items. Timing gun on each lead shod dead patches still randomly in its strobe pattern on every cylinder. Does this point to a crank angle sensor?

Qwikcorty · 07-07-2012, 12:39 PM

new info, changed crank angle sensor no change. But it will start up smooth then develops a miss afterwards maybe 30 seconds or so.
Its definetely cutting spark to all cylinders randomly on idle or under load everywhere and gets worse as temperature rises.
I cant think now what to test next, is this ecu related?

rag top · 07-07-2012, 01:33 PM

Did you give the throttle body and ISC a very good clean?

Qwikcorty · 07-07-2012, 01:39 PM

i havent no, but that wouldnt cause a lack of ignition.
The back 3 cylinders are now showing to be lacking in spark compared to the front 3. I have tried now a 2nd set of new leads and swapped the front 3 plugs for the back 3 plugs, also went from 1mm to 0.7mm gap.
still missing/rough.

rag top · 07-07-2012, 02:43 PM

A blocked injector might cause a lack of spark, as no fuel getting through. But as you have found the spark issue, it would rule that out.

Have you checked the readings at the coil pack? Even though it is new, it could be a faulty item.

undertow · 08-07-2012, 01:47 PM

Weird...

The AU runs a wasted spark system and fires the plugs on both the compression and exhaust strokes. There are 3 seperate coils in the coil pack, and cylinders 1 and 6, 2 and 5, 3 and 4 are fired in pairs. A faulty coil pack or fault in the primary side wiring/ECU should cause a missfire on a pair of cylinders.

I know it's a pain to get to but try checking the primary side wiring. There are 4 pins in the coil pack connector, pin 4 is power, and pins 1 2 3 are switched to ground by the ECU to energize the coils. Connect a 12v LED test light between +12v (battery terminal will do) and pins 1 2 and 3 in turn and crank engine. Should flash once per engine revolution. If one or more channels is dead either ECU is faulty (blown switching transistor) or wiring between coil pack and ECU is dodgy.

Hope this helps.

Qwikcorty · 13-07-2012, 06:53 PM

im going to test the ecu outputs tommorrow, is there any chance it will be at fault? What about the coilpack, its new from ford spares, vdo brand, would iut be faulty?

falconnut · 14-07-2012, 12:05 AM

Not sure if you have the same problem but for me the rough idling/missing was a knackered inlet manifold gaskit around the 5th cylinder

Qwikcorty · 14-07-2012, 04:29 PM

tested today, got equal resistance between 1-6,2-5 and 3-4 leads about 18.5ohms. Coilpack is recieving pulses from the ecu for each coil eqaully.

front 3 cyls are consistantly firing at twice the rate in my timing light to the rear 3 cyls.

all cyls bar no cyl no1 make the idle speed drop when plug lead is removed. no1 plug was wet and black, suspect injector issue? tried swapping front 2 plugs and problem was still in no1 cyl. tried swapping front 2 leads and same result.

thinking ive got a faulty coilpack from ford (not happy), and no1 injector is leaking

Qwikcorty · 18-07-2012, 05:17 PM

tried today swapping coil packs with a good runnning au2, same thing is still happening. I can completely rule out plugs leads and coilpack now.
The other car strobes way way better in my timing gun than the problem car.
I also dont think its a vac leak as it will still run rough/miss at wide open throttle.
what else bar ecu would play games with the spark?

undertow · 21-07-2012, 02:10 PM

Only thing I can suggest is swapping cyl 1 injector for another, see if the problem follows the suspect injector. Also use test light to check for pulsing at cyl 1 injector wiring. Injectors are switched on the ground side by the ECU to fire, like coils. One wire in the injector plug is +12v, other is switched to ground by ECU to open injector (not sure which way around they are but should be easy to find out).

If idle speed drops when leads are removed from all the other cylinders then maybe ignition is ok after all and the timing light is just playing games with the wasted spark system? Sounds like the problem is in cyl 1.

falconnut · 21-07-2012, 04:42 PM

It sounds like it needs to have someone look at the ecu.

You could try this and see if you can pull some codes from it.

http://www.fordmods.com/documents.php?d=34

Maka · 21-07-2012, 06:06 PM

G'day Guys, it seems its possible a dirty injector could affect quality of spark ie; my au 1 had a little miss at idle, i tracked it to number 1 cylinder by laying a spare plug on the cylinder head with number 1 lead attached,starting car and it showed i had a inconsistent spark there compared to the other cylinders so i changed everything on the ignition side and the miss was still there.

After coming across this thread-http://www.fordmods.com/ford-4l-and-6-cylinder-f1/ef-and-au-after-market-coils-your-options-t62611-30.html and chatting to Greenmachine it seemed he went through what i went through and after changing number 1 injector the miss has smoothed out and after checking for quality of spark at number 1 the spark seemed a lot more consistent than what it was before.

Im not saying its the case with your car but it seems that a dirty injector can affect the quality of spark at that cylinder. Check your plugs for signs of lean running, that might give you a start. Lack of fuel =lean , lack of spark=rich, number 1 cylinder spark plug on my au was a bit whiter that the rest also.
Good luck with it and a shout out to Greenmachine for giving me a heads up.

cheers,Maka

Evgeni · 21-07-2012, 06:10 PM

Quote:

Originally Posted by undertow

Only thing I can suggest is swapping cyl 1 injector for another, see if the problem follows the suspect injector. Also use test light to check for pulsing at cyl 1 injector wiring. Injectors are switched on the ground side by the ECU to fire, like coils. One wire in the injector plug is +12v, other is switched to ground by ECU to open injector (not sure which way around they are but should be easy to find out).

If idle speed drops when leads are removed from all the other cylinders then maybe ignition is ok after all and the timing light is just playing games with the wasted spark system? Sounds like the problem is in cyl 1.

^^+1

If you have fresh ignition components, this will at least rule out the fuel side of things before going after that computer. The injectors will be on a common power feed, so it will be the same coloured wire accross all six.
Just to add, make sure you have consistent voltage across all of the injectors. A multimeter with a Min/Max function would also be able to tell you about the quality of the ground switching . Just want to rule out the wiring as well as a faulty injector. If something is not getting enough voltage or a full ground, the coils in the injectors will not be fully energised and may not provide enough fuel etc.

saint_nz · 26-09-2022, 03:09 PM

Quote:

Originally Posted by Qwikcorty

new info, changed crank angle sensor no change. But it will start up smooth then develops a miss afterwards maybe 30 seconds or so.
Its definetely cutting spark to all cylinders randomly on idle or under load everywhere and gets worse as temperature rises.
I cant think now what to test next, is this ecu related?

Hi there,

I have the exact same issue, did you solve this issue?

Cheers

saint_nz · 02-10-2022, 06:15 PM

A bad intake manifold gasket was the cause of my AU problem, and is fairly easy to replace.

**Uncle_Ken** · 05-10-2022, 10:17 PM

Well done