90q missing on cyl. 5...more help needed

Kneale Brownson knotnook@traverse.com
Mon, 18 Feb 2002 06:36:53 -0500


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At 11:15 PM 02/17/2002 -0500, Dave Hord wrote:

>Car: 1989 90 quattro.
>
>I posted this problem last month, in the last two weeks of January.  Car is a
>2.3L non-turbo.
>
>When it's wet out (raining, snowing) the car starts to miss on one or two
>cylinders.  In January the miss seemed specific to cylinder #5.
>
>I have replaced, at the recommendation of the list, the following:
>
>Spark Plugs
>Rotor
>Cap
>Spark Plug Wires - Installed with di-electric grease.
>
>I have checked the hall sender wires, and connection...and these _seem_ okay,
>though I'm not 100% positive of this...how can I be without replacing them?
>
>The problem seemed to be MUCH better, but not perfect the first week...mind
>you, it never got that wet.  In the past week we've had rain, snow and
>then wet-
>snow turning into rain.
>
>Problem was present.  Car will miss and run really rough at idle. Pushing on
>the gas will cause the engine to stumble and miss further, back-fire into the
>exhaust manifold and such.  Give it FULL throttle and the car will stumble for
>a quarter of a second and rev right up smooth for you.  Keep it above 2500rpm
>and it's the smooth 5cyl I remember.  Let it drop to idle, and it's ugly.
>
>If the car sits overnight, problem is gone in the morning...UNLESS the air is
>still damp. Then problem _might_ remain.
>
>Given the above..what ELSE could it be???


Before my 200q20v's fuel pump died, I had similar intermittent poor
operation in really damp circumstances.  I bought new wires, plugs, cap and
rotor but didn't get them installed before the pump coughed its last bit of
fuel.  Since completing the pump replacement, there's been no such poor
performance in the wet.   Have you checked fuel pressure?

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