RomRaider

Just wondering if anyone knows how the logic works when the MAF is disconnected with a 16 bit ECU.
Specifically bugeye if its different.

What does it use to reference load values for timing and fuel?
Does it run on the failsafe tables or still on the normal tables if IAM is still 16?

I broke my MAF and I've been running and tuning with no MAF plugged in at all, and it runs really well. I just want to make sure I'm on the right track...

I've made the whole IAT table read 70 degrees to prevent any timing and fuel errors.
I've gotten it to hold 14.3 to 14.7 very consistant in closed loop fueling, and by working with the OL fueling table, I've gotten a solid 11.2 AFR from spoolup all the way to 28 psi.

I'm kind of upset I didnt try this a long time ago.. it runs great.
Is there any downside I'm missing?

It calculates load based on a multiplier and offset applied to MAP. Failures like this will have very specific effects (not a general limp-home mode which I don't think exists). I believe that it disables feedback correction in this case and has some other impacts that I haven't looked at.

Is IAT part of the calculation for MAF-less fueling? Seems like the weather is going to have an effect on the AFRs if not.

It disables feedback? Thats not good..

If you have a chance to check into what it does, that would be awesome..

Is it like (literally) 32-bit ecus? I mean topic1127.html
When beeing able to look at bugeye DTC procedures, I've noticed this:
- with failure of MAF sensor circuit manual "promises" poor performance and bad idling;
- with failure of MAP sensor circuit it says you'll be unable to start the engine;
Wondering what trims look like...



Are these single values?



Yeah, what if IAT sensor left connected?

There's no IAT compensation. The general concept is the same across both ECUs, although I have not looked into detail what the effects are (other than coming across the FBKC disable before). With the 32-bit ECU, at least, the multiplier/offset did vary by model (haven't checked the 16-bit ECU). I'll look into it further after I'm done working on the canbus stuff.

Did some more testing last night.

It wont run if I turn the MAF and IAT CEL's off. Probably some kind of issue that prevents it from going into "speed density" mode.

It does, however, still use FBKC..... but I think it might not use fine learning...

I checked again and I remembered incorrectly. It prevents the disabling of FBKC, which means that changes to FLKC will not occur nor changes to the IAM (at least within the FBKC rpm range). This particular failure is active with ANY of the following CELs -> P0102, P0103, P1141, P0101 (with the 02 wrx ROM I am looking at).

It would be easy to add to RomRaider a "fix" that would prevent this from happening and any other effects individually.

EDIT: or a better plan would be to force speed density and then you would be able to disable the CELs and, in this particular case, would eliminate any effects.

So then, it falls back to a speed-pressure system and not a speed-density system, because you need pressure AND temperature to calculate density.

Well thats not so bad then.. I tune my car a couple degrees below the "gray area" normally, so IAM and FLKC are never active anyway. I turn off FLKC and IAM at the track to prevent LC and rev limiter negative learning, so I guess it automatically is in that state now.

A forced speed density would be great so IAT comp could still work, since the IAT needs to be unplugged to do it with the current method..

well, there is no IAT comp. So by forced, I mean forcing the load calculation based on MAP alone without any of the side effects (and without having to unplug the MAF sensor).

I meant the table that pulls timing based on higher IAT (which I use to prevent knock after intercooler heat soak since the MAF is in blow through setup)

That would be functional if the IAT was plugged in right?

Yes.

Went to the track yesterday running with no MAF. This is definately something that needs to be followed up apon. The car performs and launches so much more consistant than with MAF. Ran 11.56 with a 1.7xx 60' twice in a row. Launch at 6200 on LC, shifting at 7800. Made a 3rd pass, again 1.7xx 60', tried shifting lower at 7300 and ran 11.70. Running with no MAF is really the way to go on the more highly modified/front mount cars it seems...

Wow this is interesting!