Lambda regulation stays off (mblock 099)

[RieS]

Hi,

We are having problems with a 1.8T Cupra engine (AYP) in an older model Seat Ibiza Cupra (from 2001).
The car doesn't pass it's emissions test as it may only have 0.5% CO and it has over 2.5% CO.
So it's running way too rich and the O2 sensor doesn't seem to do anything.

Engine is rebuild to k04-023 specs using the turbo, maf and injectors from an Audi S3.
After being in contact with Revo a stage 2 program for an Audi S3 is installed (most basic version of the software).

Car now has only 1 O2 sensor which is a narrow band sensor.
The wiring loom from the AYP engine actually has 2 O2 sensors but as the ecu is using the most basic Audi S3 management (which only has 1 O2 sensor) the second O2 sensor is disconnected.


We checked several measuring blocks (030-040) using vag-com.
The O2 voltage should change between 0-1 volt but it hardly changes at all, both idle and while driving (perhaps from 0.780 to 0.790V).
We also noticed that the lambda regulation stays off (measuring block 099, column 4).


Things we tried so far:

- Replaced the O2 sensor with a brand new one : no difference
- Checked wiring to O2 sensor : all ok
- Checked the ecu to see if on the correct pins there was either a ground or 12 volt : all ok
- Checked wiring to maf sensor : all ok
- Checked wiring to intake manifold pressure sensor : all ok
- Checked wiring to intake temp sensor : all ok
- Checked wiring to coolant temp sensor : all ok
- Checked wiring of several ground connections : all ok
- Used the O2 sensor from another car : no difference
- Used the map sensor from another car : no difference
- Used the intake temp sensor from another car : no difference
- Used the n249 valves from another car : no difference
- Used the throttle valve from another car : no difference
- Used the accelerator pedal from another car : no difference
- Used the n75 sensor from another car : no difference
- Used the maf sensor from another car : no difference
- Lowered fuel pressure from 4bar to 3bar : no difference
- Replaced ecu, first with the original Seat Ibiza AYP mangement : no difference
- Replaced ecu, now reflashed to Revo's Audi S3 stock mangement : no difference


It's not that the car is undrivable but it's not at 100% either so it's hard to tell if it's in limp mode or not.

We have no idea why this lambda regulation stays off. We believe that first priority is to get this on again and than see what happens....but how?

Does anyone have an idea what can cause this as we have run out of options what else to try?

Thanks a lot.

 

[ibizacupra]

both precat and post cat lambda's are electrically plugged in?
no activity on block 001 on vag-com?

any N112/N249 type resistor or bypasses? or SAI or EVAP?
what faultcodes? if any?

I know adaptions are prevented when N112/N249/EVAP is disconencted.. seen it on a local S3

also, S3 MAF.. MAF housing or sensor element also? ibiza mk3 is 040 sensor last 3 digits, and later S3 would be 049 sensor... (wrong for a narrow band ecu)

 

[RieS]

Hi,

Pre-cat lambda is plugged in.
Post-cat lambda isn't there anymore. Wires are still in the loom but no connector. As said in first post, as it is running on a S3 management there was no need for the post-cat lambda because the first Audi S3 didn't have that either.

N249 vacuum valves have been removed. They are reported in the ecu as error. We hooked them up again and did some tests and the errors were gone but the lambda regulation stayed off.

SAI and EVAP are gone as well and are reported in the ecu. We haven't reconnected them yet.
Not sure if they are still part of the wiring loom; we'll have to check it.

Removing these kind of sensors behaves so differently among the 1.8 20VT engines that maybe all these sensor must be connected, not only a few.


S3 MAF is both housing + sensor. Ordered for a 1999 Audi S3 with engine code APY so it matches the Revo software flashed in the ecu.



The strange part is that the car passed it's previous MOT with exactly the same setup as now.
The MOT station where we brought the car won't pass a car while failing the emission test so obviously. But as there is no print-out of the last emission test, we can only assume it was OK back then.

 

[tom w]

It's not decatted is it? Or 100 cell sports cat?

 

[cuprawill]

if im right in thinking you need a mk3 ibiza air flow sensor but the housing from an s3.

 

[tom w]

You do indeed on a hybrid not sure on a ko4 set up

 

[Nexus_french]

Maybe a miss of info from the lambda, and you need a wideband instead of a narrow band.

When you got 2 lambda, pre cat is for checking the AFR mostly! Second one is used to regulate the CO2 level, and make sure the cat converter is working well
Now, you only have 1 lambda as there was on first gen injection car! So it only manage the AFR.

To me, using a wideband lambda should be a big step forward and see clean in your problem!
If you want to be sure, install an AFR gauges and see the result, you will see quickly how you run!

 

[RieS]

Hi,

Good news, the problem is solved.
In the end we connected all the valves for N112, N249, SAI and EVAP; the faults were gone in the ecu and the lambda regulation turned on.

So thanks for thinking with us.


One last question:

If we want to replace all 4 valves with resistors, what values do they need to be (how much Ohm) ?
I'm sure it will be here somewhere on the forum but maybe someone can tell it immediately?


Thanks,
Richard

 

[chris_200120vt]

330 omh resistor or you can have them mapped out to fault codes

 

[joehirth]

Rich suggests too much air, I had richness problems was faulty MAF. I would start there, block 031 should be immediate fuel trim IIRC. Check this too.

As for MAF you can't just plug Ibiza sensor into S3 housing, it needs to be calibrated as it will read incorrectly.

Have you got a boost gauge? 6-7psi is limp mode and it will pop and bang more than usual if running rich, probs some flames too...

Post the VAG-COM results may be able to see something there.

Joe

 

[joehirth]

Just read you sorted the problem

 

[RieS]

Hi,

Yes it was a relief that it works now.

But we don't use the Ibiza sensor in the S3 housing.
Engine is basically a complete S3 engine now, so with the S3 software (management) and all the S3 hardware (turbo, maf housing+sensor, injectors).

The original Ibiza ecu is overwritten with the Audi S3 management so when you hook it up to vag-com, you'll get the ecu id of an Audi S3.


But we'll probably replace all the valves with resistors so thanks chris_200120vt for the correct Ohm values.

 

[joehirth]

Make sure they're 10w too

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0160297

These are what you want.

Joe

 

[ibizacupra]

Hi,

Good news, the problem is solved.
In the end we connected all the valves for N112, N249, SAI and EVAP; the faults were gone in the ecu and the lambda regulation turned on.

exactly what I said

dont use resistors FFS, just tuck the solenoids away if you dont want to see them when doing bypasses.

 

[p34ch3y]

the more time gos by the more issuse i read that end up pointing at these poxy resistors


when are people gunna listen





RESISTORS

 

[joehirth]

Lol resistors, the bane of Bill's life, although saying that I haven't had any problems with them....yet!

 

[SeatR]

330 omh resistor or you can have them mapped out to fault codes

How exactly do they map out the fault codes?