The W8 forum Homepage
Forum Home Forum Home > Problems, Tips and Tricks About the W8 > Mechanics
  New Posts New Posts RSS Feed: Intermittent misfires
  FAQ FAQ  Forum Search   Register Register  Login Login

 Shoutbox  Your message
You must log in to shout!

Intermittent misfires

 Post Reply Post Reply
Author
Message
long_w8 View Drop Down
Senior Member
Senior Member


Joined: 14-May-2011
Location: Detroit, MI USA
Online Status: Offline
Posts: 338
  Quote long_w8 Quote  Post ReplyReply Direct Link To This Post Topic: Intermittent misfires
    Posted: 30-Jan-2019 at 20:42
Hey all, long time no post. Hope everyone's doing well and driving the crap out of their W8s this winter.

I've been struggling for months with a problem that I haven't been able to find the root cause of. It's getting pretty frustrating, so I thought I'd ask here and see if any of you have ideas.

This all began last summer, when I was driving along happily in the car and it suddenly started to run very roughly. I got a couple of codes on the ECU, P0203 and P0303--cylinder 3 injector circuit malfunction, and cylinder 3 misfire detected. The problem was (and remains) intermittent, but gets worse under heavy load such as hill climbing, acceleration, or at RPMs over ~4000 or so.

Based on the fault code, the logical thing to do was to replace injector #3, which didn't help. The next suspect was the ECU, which I tried to have fixed a couple of times, and eventually just replaced. This helped some, but not completely. The next thing was to re-wire the harness from the ECU to the injectors, which at least made the P0203 go away, but I still get the misfires from time to time. I've replaced all the spark plugs and the coils, with no improvement.

It's pretty frustrating at this point...the car mostly runs great, but when it acts up, it's really a bummer. You can easily imagine how much fun it is to try to nurse a "W7" home when it's missing on cylinder 3.

What else am I overlooking? Any ideas? Has anyone else had a similar problem?

Thanks for any advice or ideas!
'03 Variant MT6 Sport Package
'91 Mazda MX-5 "Miata", supercharged
Back to Top
Uberhare View Drop Down
Groupie
Groupie


Joined: 16-Nov-2017
Online Status: Offline
Posts: 42
  Quote Uberhare Quote  Post ReplyReply Direct Link To This Post Posted: 03-Feb-2019 at 23:13
Any chance you checked compression?

Suck, Squeeze, bang, blow. Need all 4.
04 Passat W8 Wagon,04 Phaeton W12, 10 A3 TDI, 05 Passat TDI Wagon (6spd M/T), 93 Corrado VR6
89 VW LT31 Florida, 89 Vanagon Whitestar, 67 Beetle Limo, 64 PA28-140
Back to Top
long_w8 View Drop Down
Senior Member
Senior Member


Joined: 14-May-2011
Location: Detroit, MI USA
Online Status: Offline
Posts: 338
  Quote long_w8 Quote  Post ReplyReply Direct Link To This Post Posted: 04-Feb-2019 at 20:54
Hmmm....hadn't thought of that. It's worth checking. The problem is intermittent, so it might be hard to catch.

Thanks for the idea.
'03 Variant MT6 Sport Package
'91 Mazda MX-5 "Miata", supercharged
Back to Top
orangeokie View Drop Down
Senior Member
Senior Member
Avatar

Joined: 13-Jul-2010
Location: Oklahoma City
Online Status: Offline
Posts: 109
  Quote orangeokie Quote  Post ReplyReply Direct Link To This Post Posted: 11-Feb-2019 at 05:04
Notwithstanding your error codes, the rough running sounds like the cam adjuster problem. Have you taken it to the dealer?
Back to Top
long_w8 View Drop Down
Senior Member
Senior Member


Joined: 14-May-2011
Location: Detroit, MI USA
Online Status: Offline
Posts: 338
  Quote long_w8 Quote  Post ReplyReply Direct Link To This Post Posted: 12-Feb-2019 at 19:31
No, but it's been to a very skilled independent shop a couple of times now. They were the ones who re-wired the injector harness.

I wondered about the cam adjuster issue myself. Whether it's relevant to the symptoms or not, it's definitely worth giving the car a preventive shock treatment.
'03 Variant MT6 Sport Package
'91 Mazda MX-5 "Miata", supercharged
Back to Top
orangeokie View Drop Down
Senior Member
Senior Member
Avatar

Joined: 13-Jul-2010
Location: Oklahoma City
Online Status: Offline
Posts: 109
  Quote orangeokie Quote  Post ReplyReply Direct Link To This Post Posted: 15-Feb-2019 at 00:55
Shock treatment did not work for me. Replacement of the newly designed cam adjusters (both sides) resulted in perfect, sustained mechanical operation. Expensive, but worth it, IMO, if one is going to keep the car.

Edited by orangeokie - 15-Feb-2019 at 00:55
Back to Top
 Post Reply Post Reply

Forum Jump Forum Permissions View Drop Down

Bulletin Board Software by Web Wiz Forums® version 9.56a
Copyright ©2001-2009 Web Wiz

This page was generated in 0,041 seconds.