8v GTI stutter/flatspot

[Andy!]

Hi all, long time no see.
Had a search but via a sh!tty Nokia I'm pissing in the wind.
My car is occasionally faultering, it will do it when cold or warm and when cruising or under acceleration.
I have noticed a drop in the mpg reading from the mfa too.
I have examined the vac lines and can find no obvious damage.
The plugs, leads, cap and arm were new maybe four months ago.
Does anyone (help me rj!) have any clues for me.

[Andy!]

Just tried a poke around with the search function and wonder about the coil.
I replaced everything but that a while back when the leads disintegrated.

[Sam]

16v, 8v kjet/digi? 

[Andy!]

Pb iirc? Its a 91J. I mentioned the lack of valves in the title.

[Andy!]

Pb iirc? Its a 91J. I mentioned the lack of valves in the title.

[Sam]

Pb iirc? Its a 91J. I mentioned the lack of valves in the title.

Ha ha, I thought I read 8v somwhere but re-read and re-read what you put and couldnt find it. One simple solution is to clean the throttle body out carefully, It may not be responding properly

[DeanO.72]

could it possibly be the fuel side? like an old filter that's disintegrating and causing intermediate blockages?

[Andy!]

Ta, thats something to look at for sure.

[Andy!]

A mechanic I saw today suggested it could be the crank sensor, anyone have any thoughts on that?

[Sam]

Stolen from wikipedia 

Most of driveability issues can be traced back to a few issues:
Bad ECM earth/ground
Bad o2/lambda sensor earth/ground
Faulty Engine Coolant Temperature sensor (ECT)
The engine coolant temperature sensor is located in the coolant flange,(under the distributor on the Polo Fox Coupe) on the front of the cylinder head (on transverse-engine vehicles). The bad earth/ground can be traced to an essential ground strap on the front upper transmission bolt. Without this, the ECU tends to earth/ground elsewhere, causing a specific trace to burn out on the circuit board and killing the ECU. This causes the injectors to stay open constantly, flooding the engine.


1990 Jetta GL with Digifant engine management
Common issues that are indicative of a failed ECT are:
Vehicle idles poorly
Engine sputters, might stall
Higher than normal fuel consumption
The part number for this sensor is '025 906 041 A' (always check with your Volkswagen dealer for the most updated part number). The resistance of this unit is appriximately 3.2 Kohm at 10 degrees C. If it measures open circuit this will explain erratic idle and throttle speeds especially when the engine is cold.
When replacing this sensor, it is important to also replace the clip that holds it in position ('032 121 142') and the O-ring ('N 903 168 02').
Once the new sensor has been installed, start the engine and disconnect the blue coolant temperature sensor. Rev the engine through 3,000 rpm three times, each time allowing the throttle to close completely. This clears the Digifant ECM fault memory.