severe misfire at idle

Post by **stealthyspeeder** » Tue Jul 03, 2012 11:07 pm

My RS6 is up to its old tricks of causing me amazing highs followed by intense bouts of frustration!

I serviced her on Sat (air filters, oil + filter, and sparks) she had a missfire that was nearly completely resolved after sat. But not 100% so I bought coilpacks and relpaced them this evening.

I did everything as was done on Sat, replaced the coil packs, and then the car started missfiring like a b*stard when I turned her on, really horrible idle. So I replaced all the coilpacks back to the originals as I thought the new ones I had got were dodgy. Anyway got the originals put back in and started her up, same fecking problem, horrendous idle and engine management light on.

The battery on my laptop is so fubared so I cant use my Vagcom until I get a new one this weekend.

So its obviously something I have done between the inital dissasemble and reassemble, any ideas what it could be?

Im too shattered to do any more work and accepted the fact that I shall have to get up early tomo morning to be a busw*nker

so yea, any ideas much appreciated!

Post by **Stoo.** » Tue Jul 03, 2012 11:31 pm

Disturbed any earths perhaps?

Post by **chunky79** » Wed Jul 04, 2012 6:33 am

How about a hi?
What plug's have you put in?

FON

Post by **stealthyspeeder** » Wed Jul 04, 2012 6:59 am

Stoo. wrote:Disturbed any earths perhaps?

I hadnt thought of that, in fact i hadnt noticed any earthing points at all. Is there any pics or diagrams floating about whicg show where these are located?

Post by **stealthyspeeder** » Wed Jul 04, 2012 7:08 am

chunky79 wrote:How about a hi?
What plug's have you put in?

FON

Oh yea sorry, im not quite as new as my post count, was never a regular poster except in time s of distress!

Stealthyspeeder was my old id but i lost my password and old email with its details

http://forum.rs246.com/memberlist.php?m ... le&u=31622

The plugs are not fancy ones, i just had the guy at the parts shop ordee them up. They were working 100% until last night.

I threw out the boxes for them, but i'll have a hunt 4 the reciept and see if i can find the make/model.

Post by **Shoppinit** » Wed Jul 04, 2012 8:53 am

They need to be NGK PFR7Q.

I am guessing you have not put the airbox back on properly and you have got a huge air leak.

Post by **adsgreen** » Wed Jul 04, 2012 9:24 am

Shoppinit wrote:I am guessing you have not put the airbox back on properly and you have got a huge air leak.

WHS

Post by **PhilT** » Wed Jul 04, 2012 9:34 am

stealthyspeeder wrote:
chunky79 wrote:How about a hi?
What plug's have you put in?

FON
Oh yea sorry, im not quite as new as my post count, was never a regular poster except in time s of distress!

Stealthyspeeder was my old id but i lost my password and old email with its details

http://forum.rs246.com/memberlist.php?m ... le&u=31622

Fixed, you are now one and the same

Post by **bam_bam** » Wed Jul 04, 2012 9:54 am

PhilT wrote:Fixed, you are now one and the same

PhilT'll fix it.

Post by **chunky79** » Wed Jul 04, 2012 10:50 am

Did you have the problem before you serviced it? Your first post kind if reads like you serviced it cause of the problem.

Post by **stealthyspeeder** » Wed Jul 04, 2012 11:23 am

Shoppinit wrote:They need to be NGK PFR7Q.

I am guessing you have not put the airbox back on properly and you have got a huge air leak.

Hmmmm, thats what I thought when it first happened, I remember reading on here that it could cause issues, so I reseated it 2x each (once with the new coilpacks, once with the old). Is there a secret tecniqueto seating this box? I never took the airbox apart yesterday (as I did on Sat to change the filters), I just disconnected it from the 1st intake pipes, undid the allen bolt in the midde on top of the engine, lifted gently, disconnected the MAFS and set aside. Putting on again, I did the reverse, I even put nearly my full weight near the back when I repeated to ensure it seated right! Is there some other place for a leak or is there a better way to seat the airbox?

PhilT wrote:Fixed, you are now one and the same

A gentleman of the highest order, thanks!

chunky79 wrote:Did you have the problem before you serviced it? Your first post kind if reads like you serviced it cause of the problem.

I had a little missfire issue, like at idle it would jump every couple of seconds by 100- 200 rpm or so. So your right I kind of did service it because of that!

When the saprks were changed, it nearly completey resolved it, like 90% cure! and from the pic of the spark, you can see they needed changing!

But the idle im getting now, it terrible, I wouldnt risk driving the car!

Post by **Shoppinit** » Wed Jul 04, 2012 11:31 am

If you've got a Vagcom or generic obd2 reader that can do live readings, then you can check the air intake values at idle to see what's going on.

Where did you get the plugs from? If you haven't put the right plugs in, you are taking a big risk. Did you get them from ebay? If they are fakes you could kill your engine.

What a bizarre deposit on the plugs. Have you been running with some kind of fuel additive? What fuel have you been using?

Post by **stealthyspeeder** » Wed Jul 04, 2012 11:57 am

Shoppinit wrote:If you've got a vagcom or generic obd2 reader that can do live readings, then you can check the air intake values at idle to see what's going on.

Where did you get the plugs from? If you haven't put the right plugs in, you are taking a big risk. Did you get them from ebay? If they are fakes you could kill your engine.

What a bizarre deposit on the plugs. Have you been running with some kind of fuel additive? What fuel have you been using?

Yea I have VCDS, although my laptop battery can manage about 20 seconds without the lead attached before the laptop sh*ts itself, going to get an extension lead now at lunch so I can get her plugged in this evening.

The plugs were got by a motors factor who does everything off the chassis number, so I'll post up later what they are when I find the reciept. As the car was running 99% fine before I attempted to change the coilpacks (still a very slight missfire but waaaaay better than before the service), im not too concerned about them.

I have been using Maxol E5 as I am in Dublin, and in the ROI its the only petrol that has an octane rating of above 95 RON (99RON actually), and the occasional fill up un BP super unleaded when Im home in Belfast every few months. But yea it does look a bit odd, I just though thats what they looked like when they were totally knackered!

So in advance of tonights investigation, what values are around normal for air intake? just in case its a broken lead or something and the diagnostic shows certain cylinders misbehaving, what is the layout of the cylinder numbers?

Is it as per the below (standing looking at the engine bay from the front of the car?)

1 ------ 5
2 ------ 6
3 ------ 7
4 ------ 8

Post by **stealthyspeeder** » Wed Jul 04, 2012 8:19 pm

So the following errors related to this rough idle showed up on the scan

Which on ross-tech wiki brings up

17763/P1355 - Cylinder 1 Ignition Circuit: Open Circuit

Possible Symptoms
Malfunction Indicator Light (MIL) ON
Misfire
No Spark

Possible Causes
Faulty Ignition coil(s) with output stage
Fuse(s) faulty
Wiring and/or Connector(s) from coil(s) to ECM faulty

Possible Solutions
Check/Replace Coil(s)
Check Fuse(s)
Check Wiring and/or Connector(s)

So any ideas what could cause this on all 8 cylinders from a coilpack change?

Here is the log, does it shed any light on my problem?

Post by **Shoppinit** » Wed Jul 04, 2012 8:47 pm

Air flow looks OK.

What a bizarre problem. There must be a wiring problem somewhere. Broken earth wire maybe.

Check the earth connection.

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