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RE: mysterious 5kcstq problem
Thanks for the reply. re: your suggestions...
The ECU checks out with no fault codes for either the memory, or the sensors
(second pass codes). As mentioned the belt timing (including the
distributor) are dead on checked by mechanic, 2nd mechanic, independent
third mechanic and myself.
I'll check the WG, but the buck starts at a noticeable low point in power.
I'm defenitely not getting up to positive pressure when the car's warmed up.
Regardless, I'll check the diaphragm per your suggestion, thanks.
( ()()() )
86 5000cs tq 140k Pearl/Black Sports (his)
86 5000cs tq wagon 170k Grey/Black Comforts (hers)
72 911e Oak Green/Black Sports IROC bumpers ducktail
>From: "Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>
>To: "'Richard Reed'" <firstname.lastname@example.org>
>Subject: RE: mysterious 5kcstq problem
>Date: Fri, 17 Dec 1999 12:57:37 -0800
>I think the first thing to do is to pull codes from the ECU after getting
>the engine to misbehave. I don't know why it would cause a boost related
>problem, but I'm thinking that when they put your timing belt on it was one
>tooth away from nominal, and this has put your distributor timing right
>the border of the acceptable window. Spin the engine until the crank and
>cam are set up to TDC compression on cylinder #1 and take of the
>cap. The rotor is supposed to be pointing directly at a mark on the
>of the metal part of the distributor that the distributor cap seats.
>Another possibility is that even though the gauge is not reading high that
>you are getting into an overboost situation due to a broken line to the
>lower chamber of the wastegate or a cracked diaphragm. You can check for a
>cracked diaphragm by removing the hose from the WGFV to the upper chamber
>the WG and seeing if the upper chamber can hold a vacuum.
>San Jose, CA (USA)
> > -----Original Message-----
> > From: Richard Reed [mailto:email@example.com]
> > Sent: Thursday, December 16, 1999 1:29 PM
> > To: firstname.lastname@example.org
> > Subject: mysterious 5kcstq problem
> > My Audi Friends,
> > Please help with this mysterious 5000 TQ problem.
> > Problem.
> > Car starts fine, idles fine, and runs out fine until you come
> > into boost.
> > On boost the car begins to buck and breakup. The behaviour
> > is temperature
> > sensitive, in that, if ambient is below 40 deg F, no breakup
> > until say 1.2
> > bar. If ambient is above say 65 deg, occurs around 1.0 bar,
> > and as car
> > heats up to full operating temperature the threshold drops to
> > as low as 0.7
> > bar.
> > History.
> > 1986 5kcstq 130k miles. Car has always been a strong 1.4 bar
> > car, and was
> > until a service early this summer. Mechanic is Audi and
> > Porsche certified,
> > and is local dealer's shop foreman (not a hack). Early this
> > summer car was
> > serviced for timing belt and basic CIS setup. I was told
> > that car had been
> > set rich and was leaned out. At this point problem began.
> > Timing belt
> > setting was triple checked and is OK (have checked myself as
> > well). We
> > reset mixture to rich but problem persisted. Mechanic and
> > associates (other
> > dealer wrenches) felt it was ignition related. I've always
> > thought fuel
> > mix. Replaced the following:
> > plugs
> > cap & rotor
> > plug wire loom
> > fuel filter
> > air filter
> > Nothing. Still breaks up. Checked all vacuum lines, OK.
> > Pressure tested
> > intake system w/ no critical leaks. Injector seals were
> > thought to be a
> > little leaky, and so were replaced and resealed. WOT switch
> > tested and
> > declared OK (I've double checked this, as well as followed
> > Scott Mockry's
> > test routine, is OK). Swapped the following parts from
> > wife's 86 5kcstqw:
> > ECU
> > ISV
> > coil unit
> > frequency valve
> > No change. Checked spark to all cylinders with road test
> > equipment. All
> > fine but with unusual spark maps (acting lean). Checked fuel
> > pressure.
> > Found delivery pressure was fine, but control pressure from
> > differential
> > regulator was bad (no control of pressure) and so replaced.
> > We all thought this was it. High pressure from regulator
> > back to CIS would
> > press down on plate and lean out mix (more noticeable under
> > boost and when
> > warmer). Reset base CIS settings, and test drove.
> > Nothing. At 0.8 bar buck and breakup.
> > At this point we are all stumped. Next step would seem to be a full
> > teardown of the CIS system.
> > Seeking BTDT's and suggestions. Please reply.
> > Regards,
> > R.H. Reed
> > ______________________________________________________
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