[SOLVED] Sudden drop to AFR 10.0 at idle

[Beastlee]

Tuesday I noticed the car was a little sluggish when I set off to work but thought nothing much of it. On wednesday we went to a restaurant for dinner and I noticed the car was again a little slugigsh at first and ocassionally seemed funny as we slowed. As we pulled onto the forecourt the car dipped then lurched and nearly sent us into a concrete plantpot. On the way home it stalled at the entrance to camp which was the final straw. When we arrived at the house I noticed an AFR of 10.0 as it was idling and it stank of fuel so Iput it in the garage and left it.
Yesterday I did a re-calibration of the LC-1 and at first it seemed to cure it but once I revved the engine it seemed to settle back to 10.0. I checked everything I could and there were no apparent issues, nothing logged wiht the ECU and Evoscan didn't highlight anything either. I wasn't able to do another re-calibration so I left the car until today.
This evening I did another recalibration which reset the idle to 15.2 and clean air to 22.2 as I expected but again it dropped to 10-11 after the first time I revved it. Further attempts to rev the engine resulted in the car stalling and making a 'not veru nice' groan. After restarting the car it would again revert to 10-11AFR. I drove around the block and at all times during closed loop it was sitting at around 15.2 but WOT (Only did this once) it dropped to 9-10. As I stopped at the garage again it again tried to stall and returned to 10-11AFR. I returned the car to the garage to ponder why it wants to cause me trouble!
I did notice that, whilst the ingition was on but the engine was not running, that the AFR was still reporting as 11 which I found odd but assume is due to residual exhaust gases in the car. Whilst I left the ignition on there was a clicking noise like a relay coming from around the inlet plenum, perhaps near the throttle body, and I wondered if it could be the stepper motor, which may be causing the idle issue.

So answers on a postcard please, what should I be looking for?

Thanks
Lee

[Wodjno]

This could still be just a duff 02 sensor ? Or possibly your TPS is shot? Or Temp sensor? I would be checking your TPS 1st as it seems you have the issue after going to WOT. Maybe it it's sticking ? But then on another note it resets after a sensor calibration, which would point to the 02 sensor!
I take it your calibrating the sensor in the exhaust! Take it out and have a look at it, it could be all crudded up, and do a free air calibration that way..

Wodj

PS.. If you still have a standard 02 sensor then i would connect that back up, in case it could be an LC-1 fault?

[Beastlee]

Glenn,

Thanks, going to take it over to the club along with the new sensor that came with the gauge set for the RVR. Hopefully it will be as simple as needing a clean or even a simple swap of sensor.

Just for clarity, you don't have to go WOT before it starts doing it, simply revving it to 2-3000 RPM triggers it.

[Mark 4]

This sounds very much like the same issue that I am getting. I've put a brand new sensor in, did a proper free air calibration and it still seems to be doing the same thing. I am wondering if the earths are acting up so I will be checking that later today. Also hoping to get a call from Apeman 69 cos he seems to understand these things pretty well.

[Beastlee]

Mark, it is a possibility but why after 18 months would the earths suddenly play up? They were soldered properly and sealed up, I also used the stock sensor connector to ensure it worked like the OEM unit. Why too would it only happen only at idle?
Do you post a thread on your issue, would like to review what you've done.

EDIT: Found your thread - http://www.clubvr4.com/forum/showthr...te-LC1-problem.

Shoudl point out my only soldering is the LC-1 wiring into the stock connector.

[Wodjno]

Glenn,

Thanks, going to take it over to the club along with the new sensor that came with the gauge set for the RVR. Hopefully it will be as simple as needing a clean or even a simple swap of sensor.

Just for clarity, you don't have to go WOT before it starts doing it, simply revving it to 2-3000 RPM triggers it.

2-3000rpm, but at what Throttle position ?

Also in answer to earlier questions..

Yes there will be risidual exhaust gases in the Zorst with ignition off.. These will last for some ours..

The clicking you can here is the the stepper moror. This is also normal..

[Beastlee]

Sorry Glenn got distracted whilst posting and lost my train of thought.
Throttle never went above 50%, I literally just raised the revs slowly with partial throttle. Incidentally I have some Evoscan logs and will get them from the laptop shortly. The TPS seemed to be logged as normal on the E-01.

[Beastlee]

OK, found the issue.....it was the Bailey VTA BOV.

I noticed on the way to the workshop that it was easy to keep the valve open so, after doing a free air calibration of the O2 sensor, I set about removing it. Unplugging the bung from the end of the return pipe left me sopping wet and a nice puddle on the floor. Swapped back to the alloy one I bought off Glenn a couple of years ago and voila, all was back to normal. Even the throttle had smoothed out considerably.

Did a quick run up the autobahn and logged it, AFRs under WOT in 4th are about 10.5-11, slowly climbing as the revs increased.

Could a friendly Mod please add [SOLVED] to the front of the thread title?

[Mark 4]

So it was a boost leak in the BOV ?

[Beastlee]

Seems to be, only at idle though. Gues it was ac ombination of the Bailey design and the low location of it under the bumper.

car drives better with the recirc on too, just doesn't make hat lovely wooshing noise now