[urq] Violent Misfire
spotatashleys at hotmail.com
Tue Jun 15 02:36:43 EDT 2004
Thanks for this Steve - and all those who replied. We have now identified
the problem. It was the Hall Sender in the distributor. We checked the
voltages at the ECU end they were way out. We connected up an old
Distributor off a coupe quattro (non turbo KV engine) and the voltages were
fine. So we dismantled both distributors and swapped the Hall senders over.
Problem solved. It is now better than ever. Carl has now ordered a brand new
Hall Sender to fit.
Thanks again for the help.
----- Original Message -----
From: "Buchholz, Steven" <Steven.Buchholz at kla-tencor.com>
To: <urq at audifans.com>
Sent: Tuesday, June 15, 2004 2:43 AM
Subject: RE: [urq] Violent Misfire
> ... I had intended to reply to the post that made it through earlier ...
> found a bunch of messages backed up for moderator approval ... finally
> to raise my head a little bit for air ...
> Let me preface my comments with a note that I'm not at all familiar with
> troubleshooting the WR ... but I have been around its WX cousin for many
> years ...
> Are you absolutely sure about the loss of spark comment? I suspect it is
> "red herring" ... but more below ...
> Is the car idling well at all? I suspect that you've got a big air leak
> the intake tract between the airflow sensor plate and the engine. Once
> engine sneezes into the intake it makes any issue all the more acute. On
> the WX there's a whole bunch of hoses that sit in the area between the
> airbox and engine which are part of the metered intake section ... a leak
> anywhere will screw up the mixture by allowing unmetered air in. From my
> experience, the hose that goes from the "igloo" on top of the airflow
> and goes down to the elbow at the turbo inlet is the most oft found
> If the intake tract looks good, I'd then triple check the timing between
> crank and cam, and the distributor.
> I checked out the firing order against the crank timing, and according to
> calculations cylinders 1 and 5 are adjacent to each other ... cyl 1
> nominally being at -0- and cylinder 5 firing at 72deg ATDC ... so perhaps
> there is something to be said about the flywheel sensors ... I remain
> skeptical, but you may want to look over the flywheel teeth to look for
> or contamination, and try another sensor that senses the flywheel teeth.
> You might also want to find someone with a MAC-01 who is willing to let
> try it in the car ...
> Now ... if you had a WX, I'd tell you to check out the WGFV ... but you
> don't have one of these. It does raise the issue of system and control
> pressure though ... be sure to get a fuel pressure gauge and confirm that
> system and control pressure are in the proper range ... especially when
> engine is off idle ...
> Good luck!
> Steve B
> San Jose, CA (USA)
> > A friend of mine without I-net access owns a very tidy 84 WR.
> > The car had been off the road for 13 years when he bought it
> > a year ago and he was told that the original owner (who had
> > since died) parked it up because it had developed a terrible
> > misfire shortly after having a new exhaust manifold fitted by
> > a VAG dealer.
> > When he got it running it seemed very smooth, yet under load
> > there was a bad misfire. After checking all the usual
> > suspects the HT leads, cap and rotor were changed and all was
> > well. This was about 150 miles ago. Then on a recent trip the
> > car had been running fine and smooth for a couple of hours
> > then stuttered violently and now has a serious misfire that
> > will not clear.
> > The curios thing with this misfire is that at idle No.1
> > cylinder has no spark. As the throttle is opened No1 starts
> > sparking but No5 immediately loses it's spark. This happens
> > even at the smallest throttle openings.
> > What on earth can be causing this? I suspect a timing sensor
> > but which one and why? I only suspect this because most other
> > things have been checked.
> > Has anyone else suffered this?
> > If not any ideas how to cure it?
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