3.0 M54 tinkering, ECU adaptation query...

[Mr Whippy]

I'm going to do some performance testing on my car soon. I am going to be changing out different exhaust combinations and then want to test the change in the cars sound level, accelerative performance etc.

However, I wonder if the ECU will do adaptations due to the change in exhaust flow. Ie, less back pressure means cats on manifolds run cooler, altering fuelling!? I have no idea really if the ECU will even care about changes post cats, or if it will all come down to pumping loss benefits, but I want the tests I do to be as indicative of reality as possible.

Is the best thing to do to run the car on the road for 20mins prior to re-testing to make sure the ECU has got used to any changes? If it even cares?

Thanks

Dave

[TheEnd]

Any changes from gasses out will be picked up by the MAF and accounted for.
The cat won't be part of any adjustments, although the ECU is clever enough to figure out the dewpoint.

The post cat sensor just has to see a slight drop in O2 levels and it'll be happy. If anything changes there, it will just flag up a light and not try to fix it.

The adaptations are mainly aiming for a target, you set the targets, and the ECU will do its best to hit them, making short term and long term adjustments to suit.

Now, it may be the case that if you make fueling changes, the ECU already has the data available in adaptations to hit that target first time, or it may need to adjust its program to suit, so to get something a bit more accurate, try letting the car run around for 30-40 mins of mixed driving to re-adapt, or always clear the adaptations on each new version so you are on a level playing field.

If you are making adjustments from a wideband, you'll need to bear in mind that the ECU can also being making adjustments and will slowly change to hit the new targets so both may be twiddling with knobs at the same time.

[Mr Whippy]

I can probably reset the adaptations via INPA... pretty sure I did it before while having a tinker with INPA but it made no real difference to driving.


In this case though, I'm simply altering exhaust post manifold cats... the first step will be removing the secondary cats, checking MOT pass-ability, sound level change, and engine performance change.

I just want to make sure what changes I see are not short term/sporadic due to other forcings etc... I guess before each test I should reset adaptations, drive a fixed course doing mixed driving for 30mins, and then test. Then alter exhaust config, reset adaptations, re-mix drive, then test again...


I'm assuming what I change will make very little difference to the ECU's operation in this regard, but since the changes might also be very small in torque output from reducing pumping losses, I don't want to jump to conclusions based on some other variable having changed in the ECU for instance.


Just want to work start to finish on an exhaust and generate a proper pro/con matrix so others can get useful info from it.

Dave

[zek]

I would leave the secondary cats in and remove the cats on the exhaust manifold, unfortunately no one makes an aftermarket manifold for RHD cars so you will have to cut them out.

[Mr Whippy]

I'm trying to keep the changes to things you can do for under a few hundred quid tops, but to get the best from the system you can...
Removing the manifold cats would require moving the lambda sensors, tapping for them into the secondary cat housings etc etc...

I'm also skeptical about the benefits of gutting the 3>1 manifolds, they seem like a bad design irrespective of back pressure due to the matrix inside them (ie, they are designed to have cats there, so may as well keep them there)


I'd agree a proper tubular tuned manifold would be the way to go, but now these cars are worth maybe £8-9k tops it just seems a bit overkill... Z4M would be the way forward if you have a budget that would cover such jobs... or an ESS TS2 kit

Dave