Modified URS6 running rich

[twoqu]

Think that particular brand was discontinued leaving only Chinese knockoffs!
The plan was just to put the car back to stock injectors and run the prjmod just to get past the emissions for the mot test here rather than attempt to map it.
I appreciate that would give someone with the skills, equipment and experience to map the ecu more easily than before but I suspect like most people on here, its not something I would be comfortable with. In fact I haven't seen any reports on here outlining peoples experiences good or bad or perhaps more importantly for beginneers the processess involved even though it is fascinating!

[newsh]

Which says absolutely nothing about the MAF.
You should compare block 000 values between one MAF and another. Also "known working" means nothing, unless it's been bought in the last 5 years it's probably junk

As I’m working away at the moment I sent him the MAF from my coupe which is fairly new, the tune is similar and the car just passed an MOT.

[prj]

Well I'd rule the MAF out then.

Don't know what to say really. Fit stock injectors and stock ECU and see if it passes MOT, if it does, it's the tune.

[S4Marc]

Well I'd rule the MAF out then.

Don't know what to say really. Fit stock injectors and stock ECU and see if it passes MOT, if it does, it's the tune.

Strange how the dyno i previously posted in this thread (page 3) shows the car was able to keep 14.7 AFR upto 3000rpm

What could have changed? can the mapping get worse over time?



Definitely putting stock ECU and injectors looks like the next logical step or reducing the fuel pressure and see if closed loop returns

[diesel des]

Kinked fuel return hose or pipe some place?

Sent from my Moto G (5) using Tapatalk

[newsh]

What could have changed? can the mapping get worse over time?

No. If the mapping was right and is now wrong it’s because something has changed with the hardware.

[S4Marc]

No. If the mapping was right and is now wrong it’s because something has changed with the hardware.

This is now the Millon dollar question of has it ever passed a UK MOT legitimately on emissions, if I knew this it would make my job much simpler

An Audi tuner (don't want to name drop) from "up north" has suggested the raised fuel pressure and 630cc injectors are quite probably a large factor in the rich running

MRC have completely washed their hands of these engines now


However the Dyno printout suggests closed loop was functioning

[prj]

If it was properly mapped with them in then no, it's not a factor. And on the dyno it's indeed in closed loop until ~3000rpm.

7 pages of thread, but the solution is simple. Get a 2nd stock ECU and a set of stock injectors, fit them and do the MOT.

[S4Marc]

If it was properly mapped with them in then no, it's not a factor. And on the dyno it's indeed in closed loop until ~3000rpm.

7 pages of thread, but the solution is simple. Get a 2nd stock ECU and a set of stock injectors, fit them and do the MOT.

After the MOT?

[prj]

After the MOT you'll know if it's the mapping or not. If it is, you need to get a standalone or ... prjmod and someone to map it.
I can sell you a standalone pnp kit (ecumaster based), there are other ecu's as well which will drop in.

You're still gonna have to spend $ though.

[twoqu]

The only difference betwwen the dyno and the MOT test is that for the former it is effectively being driven whilst for the latter it is stationary!
So what are the parameters for closed loop operation and what does the ecu monitor? That would be useful to know.
What would be the solution to the increase in fuel pressure from the 044 without factoring it from mapping? Increase in return line diameter, adjustable fpr or something else? I have read something that suggests the fuel rail return lines are different sizes on the S4/S6 which is the braided/rubber difference. However the S6 got the rubber one which is supposedly larger anyhow.

[S4Marc]

The only difference betwwen the dyno and the MOT test is that for the former it is effectively being driven whilst for the latter it is stationary!
So what are the parameters for closed loop operation and what does the ecu monitor? That would be useful to know.
What would be the solution to the increase in fuel pressure from the 044 without factoring it from mapping? Increase in return line diameter, adjustable fpr or something else? I have read something that suggests the fuel rail return lines are different sizes on the S4/S6 which is the braided/rubber difference. However the S6 got the rubber one which is supposedly larger anyhow.

Could it be something to do with the injector pulse/duty holding off the closed loop? The injectors are quite large at 630cc @ 3bar (this increases as it's 4.2bar in my car)

Also the car was mapped without a wideband as they opted for EGT

I could be chatting plop though



I reduced the fuel pressure earlier and it got down to a level which would pass UK emissions, I used a 1:1 sytec adjustable unit....... obviously this masks the issue and could not be driven like that, it was just my intrigue

[twoqu]

It would be a crude solution but perhaps a 3bar fpr installed in the rail would be an easy way to get the presure back to 4bar, at least if you are going back to stock injectors. Might even be a VAG drop in .
Looks like its the maf load and rpm with a 3000rpm threshold for the lambda if I have understood it properly. Presumably there is no advantage to testing at the higher rpm allowed in the MOT as the load will be higher than that at the lower 2500rpm limit. Its a bit odd that they have that spread!

[S4Marc]

It would be a crude solution but perhaps a 3bar fpr installed in the rail would be an easy way to get the presure back to 4bar, at least if you are going back to stock injectors. Might even be a VAG drop in .
Looks like its the maf load and rpm with a 3000rpm threshold for the lambda if I have understood it properly. Presumably there is no advantage to testing at the higher rpm allowed in the MOT as the load will be higher than that at the lower 2500rpm limit. Its a bit odd that they have that spread!

I have asked the previous owner to check if they have the standard injectors, I've got all fine her and toes crossed

Does the CO reading go hand in hand with the AFR? Could it be 14.7 AFR but high CO?

[twoqu]

Thats the chemical ideal so anything numerically less is richer and vice versa.
Still a bit confused why its pulling so much vac compared to stock specs of 0.5bar difference between atmo and vac. Although that does help somewhat.
The point I was making earlier was how the test is conducted. You would have more chance at lower revs to pass if the maf is out of whack although I am not sure how much influence you can have on the testing procedure.
As you have said its a bit frustrating if you have evidence it has been capable of holding the correct value via the dyno print out. It appears to be leak free, the maf has been swopped with a relatively fresh one, can't see there being an issue with rpm sensing so that leaves the lambda itself which you have replaced and appears to be functioning. The mapping cannot go bad and ultimately relies on the signals already mentioned unless I have misunderstood how it works.