Hi,

I have a 1998 Mk3 GTi 8V, picked it up a few months back, and other than a few old car rattles, the only real issue is pretty much identical to this: MK3 Golf stuttering under load at 3000rpm

Usually occurs under load, say on the motorway, and generally going uphill - just under 3000RPM, feels like it's coughing/spluttering, but if you push through it's fine.

I also suspect that I'm not getting full power out of it, and getting about 32MPG (running on Super Unleaded).

Don't have the fully-detailed history (receipts etc.), but it has been serviced regularly at a main dealer with all the appropriate stamps.

Since getting the car it's been serviced and MOT'd, with the only issues being exhaust and tyres (now resolved).

The plugs and HT leads look new-ish - the distributor cap and rotor arm have been replaced, and the ignition timing adjusted.

The crankcase breather hose was replaced by the dealer I bought the car from as apparently it was cracked.

The Air Flow Meter is a Hitachi AFH60-10A.

To the best of my knowledge, it's a 2.0l, AGG engine, with a SIMOS 4S ECU.

I've picked up an OBDeleven dongle with a view to getting some useful information out of it.

It is showing the following fault:

Oxygen Sensor Control - Upper Limit Stop Value / 00537

This fault was originally showing as "Intermittent", but after clearing it and going on a test drive, it has come back and showing as "Static".

I was hoping to graph the air flow vs RPM, and find out the fuel trim values, but the data I'm getting back from the OBDeleven doesn't quite match up with any group details I've seen elsewhere. I have no idea if this is a restriction of the dongle, or just the age of the car, but from other posts I've read I was expecting more.

I've only managed to access 8 groups when trying to read the Live Data, this is at idle (Group 000 having 10 values, 001-007 with 4 values each):

000: 93 || 129 || 134 || 42 || 14 || 14 || 6 || 14 || 2 || 27
001: 896 /min || 90°C || 0.3 V || 10100010
002: 864 /min || 2.0ms || 13.4 V || 46 °C
003: 864 /min || 16% || 6.50 <° || 25%
004: 864 /min || 16% || 0 km/h || 01000000
005: 864 /min || 0 % || 0.0 ms || 00000110
006: 0.4 ms || 1.10 || 1.05 || 1.00
007: 60 || 6 || 0.78 || 00000000


The values are exactly as returned by the OBDeleven, including the units.

Any advice would be much appreciated.

Thanks in advance!