Fw: No start condition - 1988 90Q - SECOND UPDATE

[Vincent Gelinas]

This sounds exactly what I went through with my beloved 89 90q. Which
incidentally was built exactly 10 years before my jetta. This is good info!

-V
On Aug 2, 2011 11:41 PM, "Huw Powell" <audi at humanspeakers.com> wrote:
> I'd check what the timing actually is. The second butterfly does open
> rather "suddenly" at WOT, but should close fairly smoothly if you
> gradually pull off the throttle.
>
> Luckily, you can get to the ECU connector by "assuming the position",
> and it unclips fairly easily. Don't forget the ignition ECU behind the
> passenger right foot kick panel as a possibility.
>
> Check the idle switch is still good.
>
> Unplug knock sensor, OXS (separately).
>
> Unplug control pressure actuator.
>
> Pull spark plugs and examine.
>
> Check IM ground wires (I guess you did when you pulled the IM top...)
>
> Check engine fuses in fusebox under the big red clip.
>
> On 8/2/2011 10:47 PM, Radek wrote:
>> Played with fuel pressure regulator (attached a vacuum pump to it) - no
difference.
>> Changed idle stabilization valve - no difference.
>> Advancing ignition timing seems to help - instead of a single fire we get
two or three, but still does no start.
>> An observation - does not fire at all with fully depressed throttle, but
will fire with throttle off.
>> When firing, sometimes loud knocking can be heard, seems to come from the
intake manifold - backfire?
>>
>> Also, throttle body butterflies seem to be weird. The small one opens and
closes smoothly, but the large one only opens fully in one shot at WOT then,
when slowly released, snaps back with a loud ping. Is it supposed to work
like this? All levers and springs seem to be in place.
>>
>> Planning to switch ECU tomorrow, hate to think about contortions
necessary to get deep into the passenger well.
>> Cheers;
>>
>> Radek.
>>
>>
>> ----- Original Message -----
>> From: Radek
>> To: quattro at audifans.com
>> Sent: Tuesday, August 02, 2011 12:21 PM
>> Subject: Re: No start condition - 1988 90Q - UPDATE
>>
>>
>> Fully charged battery overnight. Blinked out codes - nothing.
>> Replaced ignition cap, rotor and wires with good looking old set - got
car to sputter a bit. It seems to catch a bit initially and then no more. It
is actually catching when cranked with foot off the gas - with throttle
open, nothing at all.
>> Any ideas? Is there a way to check fuel pressure on these engines (NG)?
>> Radek.
>>
>>
>> ----- Original Message -----
>> From: Radek
>> To: quattro at audifans.com
>> Sent: Monday, August 01, 2011 9:46 PM
>> Subject: No start condition - 1988 90Q
>>
>>
>> In need of help again, my son's 90q is out of commission again.
>> Here is what he reported:
>> when trying to start the car, at the first or second crank he heard a
bang (a snap, something sounding mechanical) and smelled something weird
under the hood. The smell, he said, smelled of friction.
>> The car kept cranking, but no start. Came back home on a flatbed.
>>
>> Here is what I checked till now:
>> - starter cranks the engine
>> - timing belt is OK
>> - valve train is moving (took rocker cover off to see if sprocket is not
sheared)
>> - has good compression
>> - timing belt alignment is OK (crankshaft to camshaft)
>> - distributor turns
>> - smells of gas when cranked
>> - seems to have spark (checked with wire touching enging block)
>> - coil resistance checks out OK
>> - Hall sensor works (blinks a diode)
>>
>> Where to look next? I'm going to blink out error codes tomorrow,
mosquitoes chased us out tonight.
>> TIA
>>
>> Radek
>>
>>
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