[s-cars] Car runs like crap under load

[Jason Butler]

The way the car runs it does not react the same as a boost leak, I have had 
numerous ones of these before.  It will creat full boost for a bit then miss 
a little and get worse from there until the engine cuts out completely then 
it will fire again the cut out then fire and so on.  Almost like the fuel 
pump can't keep up.  Could this be from a failing coil that is dumping 
unburned gas in the exaust causing the O2 sensor to lean out the engine and 
cause further cylinders not to fire? Thus making the exhaust even richer and 
so on.  I have my wifes S6 so I will be swaping parts today.  Thanks all for 
the advise

Jason


----- Original Message ----- 
From: "chris chambers" <fastscirocco_2000 at yahoo.com>
To: "Jason Butler" <jwbutler at wispertel.net>; <s-car-list at audifans.com>
Sent: Friday, January 19, 2007 7:21 AM
Subject: Re: [s-cars] Car runs like crap under load


> Jason,
>
> if it only happens under load I can think of two things to check.
>
> 1. boost leak - fix is to find boost leak and fix. In order to do this
> you will want to build a boost tester, which is basicly household PVC
> fittings with an air pressure valve on it. Here are pics of my first
> one.
>
> Basicly it's a pvc cleanout -
> http://img.photobucket.com/albums/v48/chrisanjenn/Audi%20S4/Press_Test_1.jpg
>
> Assembled with your choice of air inlet valves, be it a tire stem or
> air tool coupler.
> http://img.photobucket.com/albums/v48/chrisanjenn/Audi%20S4/Press_Test_3.jpg
>
> With this version of the tester you disconnect the house that attaches
> to the outlet of the MAF and clamp the hose to the tester. This allows
> you a way to pressurize your boost hoses and look for leak(s). Now I
> found that the MAF hose tended to leak, and not being a pressurized
> hose that didn't matter. So I added a reducer to the cleanout with a
> section of ~2"pvc pipe and connected mine to the hose that normally
> is connected to the outlet of the turbo. Sorry I don't have pics of it.
>
> 2. failing coil - What is happening here is that the coil is weak, it
> puts out enough spark to fire with no boost, but when under boost it
> missfires and the car develops a miss. If it feels like the car is
> missing you will want to check your coils. The easiest (non pro) way
> I found was by using a adjustable spark tester (as pictured below)
>
> http://www.thegrillstoreandmore.com/image/products/big-pics/375319b.jpg
>
> What you do is remove the bolts holding the coil pack in place and
> flip the coil pack over, I placed mine on a piece of wood. It's also
> been advised to pull the fuel pump fuse to prevent washing your
> cylinders with fuel. Connect a ground cable to the end of the tester
> and press the other end into the cpark plug connector. What you will
> be doing is have a partner then turn the engine over and check for a
> spark jumping the gap. Check each cylinder and then increase the gap,if
> you have a bad coil eventually you will get a gap large enough that one
> of the coils won't have a spark and the other 4 do, at this point you
> have determined which coil is the weakest.
>
>
> Obviously other more informed S-car gurus will point out any error(s)
> in my suggestions, which I welcome.
>
>
> HTH
> Chris
>
>
>
> --- Jason Butler <jwbutler at wispertel.net> wrote:
>
>> I have somehow pissed the Audi gods off, within the last three weeks
>> I've
>> had a timming belt that slipped three teeth a blown tire a bad fuel
>> pump and
>> now this.  The car is a '93 S4 with stock everything.   It Idles fine
>> and
>> drives ok with no load on it but if I get over 5 PSI boost it cuts
>> out and
>> stumbles.  I get a code of 2342 which is O2 sensor, ignition problem,
>> fuel
>> tank empty (it's not this one), air leak etc..  anyone have any BTDT.
>>
>> things I've done in the last three weeks
>>
>>     Replaced timing belt.
>>     Replaced water pump.
>>     Replaced Spark Plugs.
>>     Replaced Fuel pump.
>>
>>
>> Any advise would be apreciated
>>
>> Jason
>>
>>
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>
>
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>
>
>
>
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