Hey guys,

 

I'm having a nightmare trying to diagnose my Octy VRS and I wondered if any of you could help.

 

My car started juddering whilst driving. I could not accelerate smoothly. The car would either jump forward or barely move at all. Pulling out from junctions was a pain as you didn't know if the power would suddenly drop. Also, and perhaps most alarmingly, the car is suddenly stalling at speed. It usually happens at around 70-80mph. The EPC light suddenly flashes on and off once, and the car loses all power. The ASR light also comes on and stays on. As soon as I stop the car and restart the engine, the ASR light is gone. The car does not appear to be logging any fault codes related to this. The same issues occur whether ASR is on or not.

 

I was reading the fault codes and noticed that it was reporting issues with the MAF sensor and temperature sensor. I had these both replaced and it appeared to be fine. A couple of days later and the issue is back. This time it is reporting bank 1 sensor 1 lambda sensor. Replaced that and again seemed to fine. It is no longer reporting any fault codes, but the issue is still there. It is especially worse when the engine is cold.

 

Any idea what could be causing this? It's a real shame as I am running out of money to diagnose this car and I haven't got a clue what it is. My mechanic doesn't seem to have any ideas either. I really can't chuck any more money at this without having a better idea of what is wrong.

 

The car has been remapped (several years ago and has worked fine since then). It also has a Forge Intercooler, Jetex sports cat and exhaust, uprated CRT turbo and limited slip diff.

Edited 3 March, 20179 yr by Gumble

Did you fit a genuine MAF and temperature sensors? People on here have reported problems with non-genuine ones.

 

What are you using to read fault codes?

11 minutes ago, vrsTom said:

Did you fit a genuine MAF and temperature sensors? People on here have reported problems with non-genuine ones.

 

What are you using to read fault codes?

 

Yup, always use genuine VAG parts. Fault codes were read with Snap On SOLUS Ultra.

Have you checked the intake pipe between the airbox and turbo for splits?  If you have a bluetooth OBD and Torque you can check MAF, fuel trims, air temps etc on the fly to see if there is anything suspicious.

3 hours ago, vrsTom said:

Did you fit a genuine MAF and temperature sensors? People on here have reported problems with non-genuine ones.

 

What are you using to read fault codes?

 

Spoken to the mechanic and he doesn't think a genuine part was used after all.

 

If it was not a genuine part and it was causing an issue, would it not still trigger an error code?

6 hours ago, Gumble said:

 

Spoken to the mechanic and he doesn't think a genuine part was used after all.

 

If it was not a genuine part and it was causing an issue, would it not still trigger an error code?

 

Not sure, but when my MAF was past its best I didn't have any lights come up on the dash.

 

You could try unplugging the MAF and see if that makes a difference.

Mine did this for ages, change the brake switch fella. Mine had the new green switch, a temperature sensor and I cleaned the maf and its not done it since, it still has issues regarding boost but thats something else, I have a boost leak! Not had the lights come on in ages. Also whilst looking into it people suggested abs sensors but I would have thought that would throw a code.

 

From what I gather the brake switch tells the ecu your on the brakes hard when at speed and it confuses everything as the speed sensors don't show a lose in speed.

 

Hope this helps, sorry if it dont