Audi 100 (5000 in US?), 5-cyl 10v engine troubles... Help!

[Phil@sievers.com (Phil Payne)]

In message <199703091820.SAA25214@richmond.premier.co.uk> Mike Walder writes:

> >Check warm-up regulator and full-throttle enrichment, in that order.  The warm-
> >up regulator check requires a Bosch or compatible "continuous injection"
> >pressure gauge, but a competent garage should be able to do it in 1/2 hour.
> >The full throttle enrichment issue is a bit more complicated - see if you can
> >get the appropriate Haynes manual from your local library.
>
> By this do you mean the Thermo-time switch that controls the cold start
> valve.  This has given problems in the past, and is now operated by a
> switch, before the problems, it was just disconnected for several years,
> without problems.  Or do you mean the Warm-up valve.  From the Haynes
> manual, I can check this with a multimeter which I shall do.

There are two braided petrol lines going from the fuel metering head
across the top of the engine and down to a contraption bolted to the
side of the block.  That's what I mean.  As I said, you need a
specialised pressure gauge to test it.

> With your method, of all plugs out:
> Cyl     PSI     BAR
> 1       200     13.8
> 2       210     14.5
> 3       220     15
> 4       212     14.6
> 5       190     13
>
> Using method from tester, with one plug out at a time:
> Cyl     PSI     BAR
> 1       203     14
> 2       214     14.8
> 3       210     14.4
> 4       210     14.4
> 5       208     14.3

Looks like a little bit of cross-leakage from 1-2 and 4-5.  Probably
not enough to worry about.

> But they are all way over the
> 128 to 185 PSI new pressures!  How can this be?

Get the gauge checked.

>>> Also, when the engine is revved to 5000+ rpm, a cloud of grey smoke comes
>>> from the tail pipe.  I was told that this was because of over fuelling, but
>>> others say it may be head problems.

> Definately grey or whiteish (bit like a knackered turbo only less smoke),
> smells of normal exhaust smoke, not particularlly oilly.  Perhaps a bit of
> petrol vapour.  This only happens after being revved.  ie. when the engine
> is returning to idle.  Doesn't last very long, most noticable when comming
> of a motorway, to a roundabout.  Or after overtaking, which I cannot do very
> well any more.

Valve guide oil seals.  Not expensive.

> This was ok for a while, but then I started loosing power, until the engine
> no longer pulled at all.  I had to take this to my local garage.  After
> three weeks I eventually got the car back.  They had changed the fuel pump
> with a new one, switched around the injectors, and hoses for tested second
> hand ones, changed the metering pump, and Warm-up valve for second hand
> ones.  He had also previously changed the sender in the distributor, the
> spark plugs, the rotor arm, and cap.  This resulted in a car that went much
> faster than before, and smoothly.  I was told that after getting
> "specialists" to look at it, they could do no better, and the injection
> system was now overfuelling, and they could give no guarantee.  This
> resulted in a very fast audi!  Unfortunately this only lasted for a few
> days, where the performance started to drop to normal, then below normal, to
> where it is now - pretty bad.

It's not uncommon to find the adjustment ranges in the CIS system used
to cover up problems that a garage lacks the skill to diagnose properly.

There's no substitute for taking the thing to someone who knows what
they're doing and cares.

In your private copy of this email, I've suggested who you might call.

-- 
 Phil Payne

 Phone: +44 385302803  Fax: +44 1536723021  CIS: 100012,1660