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Audi 80 1.9 TDi 1994 - Misfire fault - Fixed #

Posted by Jim Watson on August 17, 2010, 2:42 pm

Year of Manufacture *: 1994
Engine Size and Code *: 1.9 tdi engine code 1Z
( Optional ) Scanner Used: launch X431
( Optional) Fault Codes: none

Hi all, this 1994 Audi 1.9 tdi Avant, has a strange misfire only under load/medium throttle and mostly noticeable in 5th gear at about 1500 rpm. It can be felt in the lowe gears but much less noticeable, it feels like a cylinder cutting out(lot of vibration, gear lever jumping about) but without loss of power and returns to normal if you release the throttle and above about 2000 totally disappears, however very occasionally there is a stutter at higher revs, but has done this for a long time now, fuel filter is not that old, and there are no fault codes stored, I can't get it to misfire off load either. Had a look online and in the archives but can't see anything similar to this, wonder if anyone has any ideas please?

Re: Audi 80 tdi

Posted by Mark Carter <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT1428' width='330' height='300' border=0 style='border:none;'> on August 17, 2010, 8:18 pm, in reply to "Audi 80 tdi"
Mark Carter

Possible cavity pressure problem? or Injector problems? HTH

Regards mark

Modern cars, Its all wizardry and witchcraft

Re: Audi 80 tdi

Posted by John Ritchie <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT2638' width='330' height='300' border=0 style='border:none;'> on August 17, 2010, 8:30 pm, in reply to "Re: Audi 80 tdi"

Hi Jim ,

Had something similar years ago which i can only describe like a ht misfire .I ran some pro-tec fuel treatment through it and no more problems so possible sticking injector?

Regrads
John

Re: Audi 80 tdi

Posted by Jim watson <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5178' width='330' height='300' border=0 style='border:none;'> on August 17, 2010, 10:21 pm, in reply to "Re: Audi 80 tdi"

Thanks both, had put a bottle of Forte diesel fuel treatment in the tank about 4 weeks ago but it feels like an injector, I am assuming that when you back off the throttle and reduce demand that is why it more or less returns to normal, thanks, Jim.

Re: Audi 80 tdi

Posted by Keith Geach on August 20, 2010, 8:07 am, in reply to "Re: Audi 80 tdi"
Message modified by board administrator August 20, 2010, 11:00 am

Do they what to spend money sorting this or will they ignore it if it costs more then £400-500?
Could be the normal problem diesel shops see.

Re: Audi 80 tdi

Hi Keith, not sure what you mean, I will take the injectors and get them tested next week, Jim.

Re: Audi 80 tdi

Posted by Keith Geach on August 20, 2010, 6:35 pm, in reply to "Re: Audi 80 tdi"
Message modified by board administrator August 23, 2010, 7:28 pm

Hi
Unlikely the injectors but they will probably be worn, has all the basics been checked? I suspect it is "bucking" is the idle even? Can you drive through it and also back off the throttle and come out of it? Is it usually under slight load rather then heavy load?

Re: Audi 80 tdi

Posted by Jim Watson <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5178' width='330' height='300' border=0 style='border:none;'> on August 21, 2010, 12:12 pm, in reply to "Re: Audi 80 tdi"

Hi, thanks for looking, yes the idle is perfect never deviates from exactly 800, it seems the worst time is about 15oo rpm in 5th gear with medium acceleration applied, slightly noticeable in 4th gear and as soon as you back off it goes back to normal, at higher speeds is fine, all hoses/vacuum hoses are fine, thanks, Jim.

Fixed #

Posted by Jim Watson on September 30, 2010, 7:56 pm, in reply to "Re: Audi 80 tdi"
Message modified by board administrator October 1, 2010, 3:36 pm

A replacement high pressure fuel pump sorted this, fitted a secondhand one as a new one is at least £500, many thanks to Keith Geach for guidance on this, Jim.

Re: Fixed #

Posted by Keith Geach on October 3, 2010, 5:42 pm, in reply to "Fixed #"
Message modified by board administrator October 4, 2010, 3:48 pm

Jim
No problem, glad you sorted it.

Re: Fixed #

Posted by Andy Amor <iframe src='https://members.boardhost.com/ukautotalk8/info/user=UKAT5184' width='330' height='300' border=0 style='border:none;'> on July 20, 2011, 7:52 pm, in reply to "Re: Fixed #"

Hi Keith.

I have one with the same problem, same year and same engine code (1Z)

No fault codes stored, fuel filter replaced, high pressure pump replaced with a re-manufactured one and injectors were reconditioned.(or so i'm told?)and basic setting performed etc....

Idle hunts from turn of the key and it 'hiccups' at low revs but no loss of power and drives through it without problem. On the odd occasion the idle is perfect but soon goes back to a light surging (if that makes sense?)

Can you offer me your expert advice?

The car owner clearly loves this car as they have already exceeded the value of the car, but they want it fixed (I didn't do the pump and injectors by the way)

Thanks in advance Keith

Andy

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