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Leaky Injectors, Long cranking times, Long story
After I bought my used 89 200TQ last year with 75K miles
I noticed it had the annoying habit of requiring 2-3 seconds
of cranking before it would start after it was warmed up
and then shut off for about an hour (lunch break). It also
took 2-3 seconds to start in the morning cold. After it
started after this 2-3 sec of cranking it always ran smooth.
Audi indicates that up to 10 seconds of cranking time is
considered OK. I didn't think it was acceptable as my
previous 5000 started quicker than this car.
The previous owner of my car had the injectors replaced
30k miles before under warranty so I didn't "think" the injectors
could be leaking again already. (This car uses the higher pressure
Viton rubber tipped injectors mentioned previously) On a
few occassions, I noticed that the car would sometimes
start right up after it sat for 3-4 days but it was not
I replaced the fuel pump check valve and
reinstalled the fuel pump that was incorrectly
mounted (rubber mount was twisted and
the fuel pump was making noise)
The fuel pump had been replaced under warranty
for the previous owner.
I pulled the injectors and looked at the spray pattern
which was fine and they didn't drip after lowering
the air flow fuel distributor plate. I didn't have the
bench mounted injector pressure tester that
should be used to leak test and clean injectors.
I replaced the injector O-rings/brass inserts and adjusted
the idle CO% . I checked all the breather hoses and
turbo plumbing but found no vacuum leaks. I
checked the fuel system pressure and it was
ok at 6.5 bar. The warm control pressure
was at 3.8 bar and the cold start control
pressure was at 1.6 at around 52 F.
The residual (shut off) control fuel pressure
was fine at 3.3 bar at initial shutoff, it actually
went up to 4.1 bar after 20 mins and then
back down to 3.4 bar after 1 hour. Energizing
the fuel pump relay before starting the car did
not help the cold/warm starting time.
I connected a test light to the
cold start valve and pulled it to check for
correct spraying. The cold start valve was
functioning as expected. I noticed that the
ECU actually turns on the cold start valve
briefly during acceleration when the
engine is very cold (around 30F).
I checked the air flow plate resting position
and it was ok.
This last month the car began to run rough
briefly after starting the car warm with
the 2-3 sec cranking time and I could smell
FINALLY, I bit the bullet and replaced all the
injectors last weekend. NOW the car starts
instantly when cold and within a second when
warm. I just did not want to believe that the
previously replaced injectors were causing the
problem. Yes, I am a stubborn old fart............