Recently detected a bit of a surging/hesitation feel through the rev range whilst driving my 98 A3T. The car also feels like it’s down on power. Build up is slower and in situations where my wheels would spin (such as in the wet) they don’t at all. Furthermore I am sure fuel consumption is down.
So from my past of reading such issues on this site I knew it could be down to a multitude of reasons – great!
In April I did a bit of DIY servicing – cleaned the Throttle Body and MAF. I also had my lambda probe replacing. The probe I bought (as advised by the local motor factors staff) was a cheaper alternative to the OEM one. When I popped round to my mechanic and asked him to swap it, he said the cheaper ones were indeed cheaper for a reason, and not as good as the OEM. Anyway we fitted it as I needed the car on that day.
Ran a vagcom this morning and low and behold the following few errors:
16515 - Oxygen (Lambda) Sensor B1 S1: Signal too Low
P0131 - 35-00 - -
17967 - Throttle Valve Control part (J338): Fault in basic settings
P1559 - 35-10 - - - Intermittent
17973 - Throttle Actuator (J338): Lower Stop not Reached
P1565 - 35-10 - - - Intermittent
Lambda probe – again!! Great! I monitored some of the measuring blocks (007 & 008) as advised through advice from helpful forum members. At 80+ degs the results I logged showed the voltage initially fluctuating from 0.0 to + 0.3ish, this as I am led to believe meaning the car is running lean – this would equate to my fuel consumption.
I cleared the codes, and the voltage sat at 0.0 – it didn’t budge at all. So maybe it is totally duff? This may need replacing again (this time for the OEM part of course), but I also have worries about the Throttle Valve Control part / Throttle Actuator. When I cleaned the Trottle Body I did not do a Throttle Body Alignment – I just let the car do this (as I read on here somewhere with the procedure).
The hesitation through driving seems to be around the 3k mark. Sitting still and reving the engine is fine, but when letting off the accelerator at 1800 revs there is a little bit of a jolt.
I’ve cleared the codes but yet to take her out for a drive. Should I try performing a TBA with vagcom? Obviously I need to monitor this lambda probe and indeed replace it if it continues to prove to be duff, but would these problems be the direct cause of power loss also? It didn't seem to be affected like this in the past when I first replaced the probe.
Any other ideas / suggestions?
Apologies for the long winded post – but I figured it may be helpful for other simpletons like me searching for similar info in the future.