On Wed, 15 Jul 2009 08:21:34 +0100, Chris Bartram
<news@delete-me.piglet-net.net> 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.

 

"Redwood" <not@home.net> wrote in message
news:7c347tF255srkU1@mid.individual.net...
> 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.

>

 

"Duncan Wood" <nntpnews@dmx512.co.uk> wrote in message
newsp.uw3p5xwrhaghkf@lucy...
> On Wed, 15 Jul 2009 08:21:34 +0100, Chris Bartram
> <news@delete-me.piglet-net.net> 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.

 

In article <7c63p2F269lidU1@mid.individual.net>,
Redwood <not@home.net> 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 dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

On Wed, 15 Jul 2009 14:45:06 +0100, Dave Plowman (News)
<dave@davenoise.co.uk> wrote:

> In article <7c63p2F269lidU1@mid.individual.net>,
> Redwood <not@home.net> 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.

 

In article <op.uw38osczhaghkf@lucy>,
Duncan Wood <nntpnews@dmx512.co.uk> 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 dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

"Duncan Wood" <nntpnews@dmx512.co.uk> wrote in message
newsp.uw38osczhaghkf@lucy...
> On Wed, 15 Jul 2009 14:45:06 +0100, Dave Plowman (News)
> <dave@davenoise.co.uk> wrote:
>
>> In article <7c63p2F269lidU1@mid.individual.net>,
>> Redwood <not@home.net> 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.

 

On Wed, 15 Jul 2009 18:30:22 +0100, "Redwood" <not@home.net> wrote:

>"Duncan Wood" <nntpnews@dmx512.co.uk> 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

 

In article <9hds55ps83p266ll8c9ev7o4dqm4eb8es2@4ax.com>,
<ng@hglmotors.com> 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 dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

"Redwood" <not@home.net> wrote in message
news:7c347tF255srkU1@mid.individual.net...
> 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...