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#11
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Could this be a lambda issue?
On Wed, 15 Jul 2009 08:21:34 +0100, Chris Bartram
> wrote: > Blah wrote: >> Redwood wrote: >>> 1993 Audi 80 2.0 single point (ABT engine). >>> >>> It's my dad's car, had it from new & been well serviced over the >>> years. I'm trying to diagnose poor top end performance and thinking it >>> may be the lambda sensor, or any other suggestions welcome. >>> >>> Starts & drives well but gutless at top end. Up to about half >>> throttle it has plenty of pull but put your foot down for overtake or >>> approaching inclines and there isn't much there and takes a long time >>> to build up speed - usually have to knock it down the gears. Feels as >>> though it wants to go but a lack of fuelling at top end is holding it >>> back. In fact if your cruising along say at half throttle and plant >>> your foot down it feels like it actually slows down before very slowly >>> starts to build up speed. TPS & various other sensors appear ok >>> (within Autodata spec) & checked for any vacuum, air leaks. The >>> injector unit to manifold rubber flange looked a bit worn & cracked >>> but I've replaced that. >>> >>> Only thing I can think of is the lambda sensor as the cars done about >>> 120k miles on the original so was wondering if that could be on its >>> way out and slow at sending the correct signal to increase fuelling at >>> top end? >>> >> Has it got an air flow meter? Is it stuck? > That was my thought- maybe a MAP sensor of a MAF or whatever it uses to > measure airflow in. I'm not familiar with the setup on this engine > though. It's got one. The normal plug it into Vag-Com applies butodds are it's an air or fuel flow restriction. |
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#12
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Could this be a lambda issue?
"Redwood" > wrote in message ... > 1993 Audi 80 2.0 single point (ABT engine). > > It's my dad's car, had it from new & been well serviced over the years. > I'm trying to diagnose poor top end performance and thinking it may be the > lambda sensor, or any other suggestions welcome. > > Starts & drives well but gutless at top end. Up to about half throttle it > has plenty of pull but put your foot down for overtake or approaching > inclines and there isn't much there and takes a long time to build up > speed - usually have to knock it down the gears. Feels as though it wants > to go but a lack of fuelling at top end is holding it back. In fact if > your cruising along say at half throttle and plant your foot down it feels > like it actually slows down before very slowly starts to build up speed. > TPS & various other sensors appear ok (within Autodata spec) & checked for > any vacuum, air leaks. The injector unit to manifold rubber flange looked > a bit worn & cracked but I've replaced that. > > Only thing I can think of is the lambda sensor as the cars done about 120k > miles on the original so was wondering if that could be on its way out and > slow at sending the correct signal to increase fuelling at top end? Blocked cat / exhaust is mine. NOT Lambda sensor. Or cam timing incorrect. Tim. > |
#13
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Could this be a lambda issue?
"Duncan Wood" > wrote in message
newsp.uw3p5xwrhaghkf@lucy... > On Wed, 15 Jul 2009 08:21:34 +0100, Chris Bartram > > wrote: > >> Blah wrote: >>> Redwood wrote: >>>> 1993 Audi 80 2.0 single point (ABT engine). >>>> >>>> It's my dad's car, had it from new & been well serviced over the >>>> years. I'm trying to diagnose poor top end performance and thinking it >>>> may be the lambda sensor, or any other suggestions welcome. >>>> >>>> Starts & drives well but gutless at top end. Up to about half >>>> throttle it has plenty of pull but put your foot down for overtake or >>>> approaching inclines and there isn't much there and takes a long time >>>> to build up speed - usually have to knock it down the gears. Feels as >>>> though it wants to go but a lack of fuelling at top end is holding it >>>> back. In fact if your cruising along say at half throttle and plant >>>> your foot down it feels like it actually slows down before very slowly >>>> starts to build up speed. TPS & various other sensors appear ok >>>> (within Autodata spec) & checked for any vacuum, air leaks. The >>>> injector unit to manifold rubber flange looked a bit worn & cracked >>>> but I've replaced that. >>>> >>>> Only thing I can think of is the lambda sensor as the cars done about >>>> 120k miles on the original so was wondering if that could be on its >>>> way out and slow at sending the correct signal to increase fuelling at >>>> top end? >>>> >>> Has it got an air flow meter? Is it stuck? >> That was my thought- maybe a MAP sensor of a MAF or whatever it uses to >> measure airflow in. I'm not familiar with the setup on this engine >> though. > > It's got one. The normal plug it into Vag-Com applies butodds are it's an > air or fuel flow restriction. Thanks for the replies, it does sound like a fuelling problem. I'll get hold of a fuel pressure gauge and check the correct pressure is reaching the injection unit. Autodata says to manually trigger the pump and reading should be between 0.8 & 1.2 bar and hold at 0.5 bar after 5 mins. Should at least rule out any filter, blockage or pump probs. It's got good pick up if, for e.g, I knock it into 2nd gear to turn into a side road with a steep incline. As soon as I press the throttle it will pull very well up hill from low speed but get to a certain point and nothing much happens at the top end of the throttle range. |
#14
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Could this be a lambda issue?
In article >,
Redwood > wrote: > Thanks for the replies, it does sound like a fuelling problem. I'll get > hold of a fuel pressure gauge and check the correct pressure is > reaching the injection unit. Autodata says to manually trigger the > pump and reading should be between 0.8 & 1.2 bar and hold at 0.5 bar > after 5 mins. Should at least rule out any filter, blockage or pump > probs. The fuel pressure effects the entire engine range. If it were wrong it wouldn't idle properly either. I suppose a blocked filter could have more effect at high demand, though. The range of 0.8 - 1.2 bar seems awfully wide to me - on mine a couple of PSI makes a big difference. Although of course the pressure does change depending on engine vacuum. But I'd expect the static pressure to be much more accurate than that. -- *Real men don't waste their hormones growing hair Dave Plowman London SW To e-mail, change noise into sound. |
#15
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Could this be a lambda issue?
On Wed, 15 Jul 2009 14:45:06 +0100, Dave Plowman (News)
> wrote: > In article >, > Redwood > wrote: >> Thanks for the replies, it does sound like a fuelling problem. I'll get >> hold of a fuel pressure gauge and check the correct pressure is >> reaching the injection unit. Autodata says to manually trigger the >> pump and reading should be between 0.8 & 1.2 bar and hold at 0.5 bar >> after 5 mins. Should at least rule out any filter, blockage or pump >> probs. > > The fuel pressure effects the entire engine range. If it were wrong it > wouldn't idle properly either. I suppose a blocked filter could have more > effect at high demand, though. > Yup, if the filters clogged they're fine at low demand & bad at full bore. > The range of 0.8 - 1.2 bar seems awfully wide to me - on mine a couple of > PSI makes a big difference. Although of course the pressure does change > depending on engine vacuum. But I'd expect the static pressure to be much > more accurate than that. > 1 bar sounds low anyway. |
#16
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Could this be a lambda issue?
In article <op.uw38osczhaghkf@lucy>,
Duncan Wood > wrote: > > The range of 0.8 - 1.2 bar seems awfully wide to me - on mine a couple > > of PSI makes a big difference. Although of course the pressure does > > change depending on engine vacuum. But I'd expect the static pressure > > to be much more accurate than that. > > > 1 bar sounds low anyway. Indeed. My old SD1 runs at 36 psi - and most modern vehicles are higher. -- *You sound reasonable......time to up my medication Dave Plowman London SW To e-mail, change noise into sound. |
#17
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Could this be a lambda issue?
"Duncan Wood" > wrote in message
newsp.uw38osczhaghkf@lucy... > On Wed, 15 Jul 2009 14:45:06 +0100, Dave Plowman (News) > > wrote: > >> In article >, >> Redwood > wrote: >>> Thanks for the replies, it does sound like a fuelling problem. I'll get >>> hold of a fuel pressure gauge and check the correct pressure is >>> reaching the injection unit. Autodata says to manually trigger the >>> pump and reading should be between 0.8 & 1.2 bar and hold at 0.5 bar >>> after 5 mins. Should at least rule out any filter, blockage or pump >>> probs. >> >> The fuel pressure effects the entire engine range. If it were wrong it >> wouldn't idle properly either. I suppose a blocked filter could have more >> effect at high demand, though. >> > > Yup, if the filters clogged they're fine at low demand & bad at full bore. > >> The range of 0.8 - 1.2 bar seems awfully wide to me - on mine a couple of >> PSI makes a big difference. Although of course the pressure does change >> depending on engine vacuum. But I'd expect the static pressure to be much >> more accurate than that. >> > > 1 bar sounds low anyway. Got a fuel filter ordered for tomorrow. I'm assured it's had all filters changed at every yearly service, but with the fuel filter hidden away under the back end somewhere I will make sure & fit a new one anyway. The 1 bar figure is the regulated pressure when measured with the gauge fitted inline between the fuel inlet pipe & the injection unit - if that sounds more feasible. |
#18
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Could this be a lambda issue?
On Wed, 15 Jul 2009 18:30:22 +0100, "Redwood" > wrote:
>"Duncan Wood" > wrote in message >newsp.uw38osczhaghkf@lucy.. >> 1 bar sounds low anyway. > >Got a fuel filter ordered for tomorrow. I'm assured it's had all filters >changed at every yearly service, but with the fuel filter hidden away under >the back end somewhere I will make sure & fit a new one anyway. The 1 bar >figure is the regulated pressure when measured with the gauge fitted inline >between the fuel inlet pipe & the injection unit - if that sounds more >feasible. > One Bar is about right for a SPI system. They run much lower than MPI. Graham |
#19
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Could this be a lambda issue?
In article >,
> wrote: > One Bar is about right for a SPI system. They run much lower than MPI. Didn't realise Audi ever used a SPI system - although the OP did say so. -- *A woman drove me to drink and I didn't have the decency to thank her Dave Plowman London SW To e-mail, change noise into sound. |
#20
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Could this be a lambda issue?
"Redwood" > wrote in message ... > 1993 Audi 80 2.0 single point (ABT engine). > > It's my dad's car, had it from new & been well serviced over the years. > I'm trying to diagnose poor top end performance and thinking it may be the > lambda sensor, or any other suggestions welcome. > > Starts & drives well but gutless at top end. Up to about half throttle it > has plenty of pull but put your foot down for overtake or approaching > inclines and there isn't much there and takes a long time to build up > speed - usually have to knock it down the gears. Feels as though it wants > to go but a lack of fuelling at top end is holding it back. In fact if > your cruising along say at half throttle and plant your foot down it feels > like it actually slows down before very slowly starts to build up speed. > TPS & various other sensors appear ok (within Autodata spec) & checked for > any vacuum, air leaks. The injector unit to manifold rubber flange looked > a bit worn & cracked but I've replaced that. > > Only thing I can think of is the lambda sensor as the cars done about 120k > miles on the original so was wondering if that could be on its way out and > slow at sending the correct signal to increase fuelling at top end? I'd thrash the hell out of it for a while and see if it picks up... |
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