Stumble

[John Larson]

On 11:59 AM, Dan DiBiase wrote:
>
> On 11/3/11, Dan DiBiase<d_dibiase at yahoo.com>  wrote:
>> I've noticed a slight stumble during acceleration in my car over the past
>> week or so. Basically, in most gears, when the car is
>> warmed up, there is a slight hesitation or stumble while accelerating - it
>> always occurs around 2,000 - 2,300 rpm, regardless of
>> which gear I am in. It feels like an interruption in the engine power, or a
>> hesitation. No CELs have come on, and the TB was replaced
>> at 75k miles (currently have 109k). Any thoughts on what could cause this
>> stumble?
>
> Ok, I finally got around to doing some additional diagnostic work. None of the local auto places will pull codes
> without a CEL, and when I loosened my gas cap to try and generate one, it never came on! Since several suggested
> the MAF sensor (and Google suggested same) I disconnected the wires and drove a bit and it seemed to drive a lot
> better. So I ordered one from Chris at Force5 and replaced it last Friday. Car DOES run better but still a little
> 'stumbly' although not as definitively (i.e., not always at the same rpm level as before).
>
> So Sunday I was leaving to drive an hour and a half for a Christmas lunch with my family and the CEL came on a
> mile from my house. Went back and we took the Odyssey instead. Today I went to Autozone and they pulled up a
> P0118 - Engine Coolant Temperature circuit fault. Googling indicates that it is the G62 coolant sensor at the
> back of the had. So guess I will pick one up and replace it. I also read somewhere that it could cause a stumbling
> condition, so perhaps that is the true culprit here.
>
> Dan D
> '04 A4 1.8Tq MT-6
> Central NJ USA
A word of advice from a well seasoned Audi wrench (29 years this 
spring!).  Buy the sensor from the dealer.  The iATN archives are full 
of "fixes" that detail removing the new aftermarket CTS and replacing it 
with a dealer sourced part.  Same for the thermostat.  I can't say why 
there's a difference, or what that difference is, but it exists.

John