Timing is a much bigger contributor to power production than AFR's..
The SAFC indirectly affects timing by reducing the MAF sensor's reported reading to the ECU, so it runs in a different portion of the ECU's maps, so you are also altering timing.. The problem is, at certain MAF readings, you can see as much as 22 degrees of timing at high RPM and 7 or 8 degrees of timing at peak boost.. potentially a problem if you are running high boost levels and are slightly lean..

Not that the S-AFC is bad, I used it with the buschur stage 1 components and ran approx 12.42.. I think the SAFC in combination with a good ECU flash is a great budget combination. Drag racing really isn't my thing, but its a good representation of power output.

 

Xede.

 

How have you confirmed that you are experiencing this MAF anomoly?

Shiv

 

Hmm.. any way to gather a data log of the MAF reading vs Boost and RPM? Should allow you to compare the tunes side by side and see if the MAF really is anomolous.. You could be experiencing a high-rpm misfire, that can have a devestating affect on your trap speeds....

 

I haven't, thus this thread.
Shiv,
The purpose of this thread is not to "rag" on you or your Xede. Your tuning abilities are reputable and your product (Xede) great for 95% of EVO owners.

Most tuners agree ,however, that the factory MAF has its limits and I wanted an objective opinion where those may be.

 

BTDT... it's not anomolous

 

True, if it can be reproduced consistently then it can be compensated for.. I'm just wondering if maybe something is being overlooked..

 

But the info your presented is shrouded in testing inaccuracies. For instance, what boost did you run when you ran the c16 map? You don't know. Furthermore, a new wastegate pill the night before as you remember without ever confirming that old boost restrictor was of the same diameter. If the new pill is of smaller diamter (even by just a few thou), boost will be several psi higher than it should be. And it boost goes much above 30psi, there isn't enough spark energy to bridge the spark plug gap. Isn't this a more likely scenario than implying that the MAF is misreading when simply analysis would prove that it is not?

Shiv

 

I have to agree, I was actually pondering in an earlier message that this actually sounded more like a misfire..

 

No, because the same thing happened on my previous trip to the track. (with the old pill) and 30lbs. of boost.
Low traps and inconsistency was the name of the game then also.

 

If you are now running 123-124mph traps (fuel cut 4th gear) with the 100oct map (26-27psi) and slower with the 30psi c16 map and complaining of misfire, then what you are experiencing is most likely due to ignition limitations, not MAF limitations. No stretch of the imagination here.

Shiv

AFAIK, everyone appeciably faster than you in the quarter mile are running higher rev limits (no need to shift into 5th) and ignition upgrades (no misfire at high boost).

 

I NEVER complained of misfire. (got me confused w/ another customer)

 

Shiv,
Don't take this personally, please.
Once again your tuning is great and your products are awesome (incld. Xede)
I have never blamed you for any of these.
I am a hardcore/very demanding racer that expects absolute performance.

If something stands in the way of me achieving my expected results, I endeavor to track it down and correct/replace it. (in this case the suspected MAF)



Cheers

 

Even if you are not hearing misfire through your helmet, doesn't mean that you are not experiencing improper combustion for some reason or another. 30psi on a GT35R is pretty close to the limit of what the stock ignition system can handle. I think this has been proven on a number of ocassions but I could be wrong.

And you are tracking it down how? My suggestion is to grab a mulitmeter and measure MAFin (the green/white wire on the XEDE's grey connect). Log the frequency runing a successive 30psi runs and see if they are anything but consistent. If they are consistent, you are experiencing a limitation in the ignition system. If they are inconsitent, you found your culprit. I've done this test myself a number of times and I'm reasonably satisfied with the results. But it can't help to get some independant verification from users. Don't worry, I'm not taking anything personally as a dig towards me or my products but I do want to offer a little scientific basis to the matter at hand. This stuff is pretty easy to prove or disprove. We're not exactly hunting for the Loch Ness monster here

Shiv

 

BUT, you still run the stock ignition on YOUR GT35R equipped shop car. Don't you?
I assume that car is not misfiring.

Agreed, however, that those power levels could use an upgraded ignition.