S3 APY lambda issues

[Gtech]

Hi There, I have a S3 with APY engine with strange issues.

Little background info, when I got the car I found a lot of issues with the engine.
-MAF sensor was turned 180 degrees (yes I'm not kidding)
-Intake turbo hose hanging loose, fixed it.
-Changed boost actuator into newer revision
-Placed OEM diverter valve since the aftermarket spring was weaker then the original.
-Changed broken vacuum hoses
-Only fault code left is secondary air pump solenoid but that's not relevant for the issue.
-N249 and N112 systems are bypassed by previous owner/tuner
I also found a dynograph in the car so we found out it has stage1 tuning map from 'ziptuning'

Now the last issue that I cannot resolve, the car is running OK now but for our yearly check MOT/APK we need to have a working emission system (lambda and katalysator.)
Since the catalysator was missing I placed a new one and is working. Also the lambda sensor wasn't working as it suppose to do so I changed that also. (afterwards I tested the old lambda sensor but it was actually working properly)
Only the strange thing is it seems that the engine is not using it's lambda input. Almost looks like the engine is running open loop and don't use it's lambda input at all. I tried unplugging the lambda and feed the ecu 0V to see if it responds but no change in exhaust readings.



So I called the tuner and ask if they removed the lambda parameters when they tuned the car and they say they never do that. They could bring the car back to original but they don't think it will fix my issue. Could my engine ECU be broken? What do you guy's think how to tackle this? How to check or restore the engine lambda settings?

Thanks for reading my story.

 

[<tuffty/>]

Its a narrow band lambda on APY's... they are generally only in play for cruise/part throttle applications... does the lambda reading change if you increase the revs?

APY's are open loop on full throttle though

The ECU won't be broken I very much doubt... if it couldn't see the lambda sensor for whatever reason then it will throw a fault code

<tuffty/>

 

[Gtech]

Its a narrow band lambda on APY's... they are generally only in play for cruise/part throttle applications... does the lambda reading change if you increase the revs?

Yes, the yearly check is in idle and with 2500rpm stationary so that's why lambda needs to be between 0.97 and 1.03. Also CO is way to rich even with a working catalysator.

When I increase the rev at a steady rpm it will stay around 0.83 so way to rich.

APY's are open loop on full throttle though

The ECU won't be broken I very much doubt... if it couldn't see the lambda sensor for whatever reason then it will throw a fault code

<tuffty/>

Will see if it triggers a fault when I remove the lambda. It runs exactly the same exhaust values with and without the lambda, even when I short the signal wire to ground. I also measured fuel pressure it is 2.5bar (36psi) idle and 2000rpm.

Also the tune does something with the readiness test, it passes directly even after 1 sec after disconnecting the battery, I find that strange also.

 

[Gtech]

I have some new data points, If I disconnect the lambda it will trow a fault code so it is detecting it but for some reason it won't go in closed loop.

 

[Stuart B]

Generic stage 1 maps do very little. They usually just up the allowed maximum load.. especially on a narrow band lambda. (apy / apx)

With all the leaks you found and fixed, there's maybe more.. or was the car mapped with faults and now you have fixed them, is running crazy

 

[Gtech]

Generic stage 1 maps do very little. They usually just up the allowed maximum load.. especially on a narrow band lambda. (apy / apx)

With all the leaks you found and fixed, there's maybe more.. or was the car mapped with faults and now you have fixed them, is running crazy

Thanks for your reply.

I am one step further, since they deleted the N112 and N249 I thought maybe it affects the closed loop so I placed 2 random solenoids I had laying around to fool the ECU and what do you think? We have a working closed loop lambda now.

After clearing this issue myself I found this topic that confirmed my suspicion, to bad I found it afterwards lol.

Loss of adaptive fuel trim when removing SAIC/N249/N112?

www.vwvortex.com

So I tested exhaust gasses at our local garage and lambda and CO is ok at 2300prm and 0.2% CO so that's good, only stationary it still isn't correct.

At Idle lambda says 0.96 and CO 3% so need to work on that. Also found out PCV valve is broken, will replace it but not sure if that's the issue.

Now I think about it maybe injector cleaning could help since the car was standing still for about 2 years.