[s-cars] Help - Stumble, stall, and no start condition

[Dave Ellis]

Yep, and therein lies the dilema.... where to start checking.  :o)

It's really the engine controller not being found by the VAG-COM that's 
throwing me for a loop.  Otherwise the other symptoms seem "usual" for 
various things.

Dave


Robert Myers wrote:
> 
> Dave,
> 
> There are _SO_ many possible causes.
> 
> Fuel pump.  Fuel pump relay.  Cam position sensor.  Short in the 
> ignition wiring where it enters the engine under the valve cover.  Blown 
> or missing "extra" fuse in the fuse bo in front of and below the 
> windshield in front of the driver.  Probably 20 other possibilities.
> 
> 
> At 11:17 PM 7/17/2008, you wrote:
> 
>> I have on odd set of symptoms I'm hoping the group wisdom can assist with.
>>
>> They just started yesterday and I'm supposed to start a week vacation
>> tomorrow driving with our kayaks on the roof racks.  Needless to say my
>> wife is none too pleased.
>>
>> The last couple of months the car would intermittently drop a cylinder,
>> sometimes for a few seconds, sometimes for minutes.  This behaviour
>> seems to get worse as the ambient temperature rose.  Higher octane fuel
>> seemed to help (97 as opposed to 91/92), but may have been co-incidental
>> or placebo-like.
>>
>> As of yesterday, when driving with the engine cold everything is good.
>> As soon as the engine warms up and the engine bay gets heat soaked the
>> stumble comes back *bad*, the car feels like it wants to stall, and if
>> left to go to idle will actually stall.  Once stalled it will not start
>> unless it's let sit for several minutes, and then will usually start,
>> only to stall once more as soon as I remove my foot from the gas.
>>
>> To add to this set of symptoms, the Engine Controller reports "No
>> Response from Controller" after stalling when the engine's hot.  Other
>> controllers I can talk to fine, so it's not the laptop or cable.
>>
>> When I hooked the VAG-COM up right before my test drive tonight (engine
>> cold) it connected just fine and was able to scan for fault codes (none
>> found).  I'm going to try connecting it after things cool down tomorrow
>> morning again and see what happens.
>>
>> Any ideas?
>>
>> I've replaced the spark plugs and gapped them small (0.030) just in case
>> the ignition coils are getting weak (original with 240,000kms).  The MAF
>> looks ok though I haven't yet checked the resistance on it (tomorrow
>> morning).  I just replaced the N75 valve two days ago and have checked
>> all hoses for leaks (haven't pressure tested though).
>>
>> Once more thing to add, I had swapped in the 1.8bar wastegate spring
>> which lead to some bucking at WOT and threw maximum boost exceeded
>> errors so I swapped back the original spring.  It was while driving with
>> the new spring that the car stalled for the first time and things got
>> really bad.  Co-incidental?  The car is not chipped, just stock.
>>
>> Any insight or suggestions welcomed!
>> Dave
>> _______________________________________________
>> S-CAR-List mailing list
>> S-CAR-List at audifans.com
>> http://www.audifans.com/mailman/listinfo/s-car-list
>>
>> No virus found in this incoming message.
>> Checked by AVG - http://www.avg.com <http://www.avg.com/>
>> Version: 8.0.138 / Virus Database: 270.5.1/1559 - Release Date: 
>> 7/17/2008 6:08 PM