Running a gutted stock MAF with the flash ECU.

[Greg E]

This is actually quite easy to tune! Well when you gut the MAF, quite literally more air goes around it. This means that each pulse stands for a greater airflow number. All you have to do is adjust the MAF Adder value for this extra air. Leave the MAF Scaling table alone.

To keep your injectors and fuel table accurate, you just need to adjust the MAF comp values. How much or little can be calculated easily with the fuel trims and a wide band.

Live tuning would be very helpful for this... :(

[Blackmount]

Subbed- Also This is why alot of people who "gut" their maf's usually end up having running issues later down the road? (Because of scaling)

[Greg E]

Well... When you gut the MAF you should be able to fine tune it with any 1% increment piggy back. The thing is though, who know what air turbulent effects this has on the MAF. The reason this only works "okay" is because you're not telling the ECU to add/take away fuel, you're increasing or decreasing the HZ value the ECU sees so you have to speed it up or slow it down into an area in the MAF scaling table where the look up has the correct value you need.

To further complicate the issue, remember there's is the MAF smoothing table which is yet again another correctional value multiplied after the scale and adder are combined....

The only reason people have had decent luck with it is because closed loop works well enough at fixing all the airflow errors you get as a result of this setup.

[futurevr4man]

So do you think people running blow thru with a maf-t may need to rescale our mafs slightly? Maybe the lower resolution is off which is causing our lean spike? Maybe I should post in the other thread...

[Greg E]

Yes. You must do this even when running the stock MAF. Hard intake pipes, innercooler, bigger turbos, exhaust, head work... All those things change your engines particular VE. Not even getting into engine wear... This is why no tunes can be copied into another car and keep the fuel trims happy. Every engine has a different VE curve.

[Greg E]

In the case with the MAFT, the GM sensor reports much less airflow than a stock MAF meaning your HZ numbers are usually lower than what you would see out of the stock MAF. So right off the bat, your scaling numbers aren't accurate anymore.

[futurevr4man]

Hmm. I haven't even touched the maf smoothing table yet.

[futurevr4man]

Would a logical test be:

Hook up stock maf, datalog and record airflow from a constant source (hair dryer) then do the same test with GM maf/maf-t and compare/adjust?

[Greg E]

What I did was leave the stock MAF, ran a 3rd gear pull (on the road in front of my house), then let the car idle.

Then I swapped in the MAFT (draw thru) left it zeroed out, ran 3rd gear on the same exact stretch of road, logged idle again. The HZ readings were lower.

With Toni's car (MAFT in blow thru) his car sees even less airflow than mine did. For reference my 9b car was pushing 220load when I did the 12.87. Toni's car was seeing only 190 load and his car ran a 12.5.

There is no way his car is pushing less air than mine. It put down 450whp...

[futurevr4man]

But I cannot run on stock maf, not really an option on my build. I figured comparing maf values to maf values is reasonable though

[Greg E]

Its too bad we only have one pulse counter on board the ECU. Would be easy to tune if you could hook up both MAFs and tune one using the other. That's how the 5V Hotwire MAF setup is going to work.

[CoopKill]

What if any is the Montero maf an advantage over oem 3s? I know they have a faster pulse? rate. I need to do something soon if I am to need a different setup to achieve ~600 whp. I've not seriously looked into a solution yet. I have the Montero, but not gotten a definite idea if it will work.

[Greg E]

What if any is the Montero maf an advantage over oem 3s? I know they have a faster pulse? rate. I need to do something soon if I am to need a different setup to achieve ~600 whp. I've not seriously looked into a solution yet. I have the Montero, but not gotten a definite idea if it will work.

It can count more air before the signal breaks up.

[ChargerX3]

Any luck on the Evo sensors?

[Greg E]

Any luck on the Evo sensors?

Evo sensors work awesome. Always have....

[ChargerX3]

Maf???

[Greg E]

Maf???

Yes...

Where have you been??? I've been running both an EVO MAF and MAP sensor since before chrome V1 came out.

[ChargerX3]

I know that. Im talking... "X".

[Keyan]

So do you think people running blow thru with a maf-t may need to rescale our mafs slightly? Maybe the lower resolution is off which is causing our lean spike? Maybe I should post in the other thread...


the weird part is that i didnt have the lean spike before i switched to chrome. now it's there. so i dont know if we can blame the maft for it, directly. unless the way it computes all the numbers is so radically different that the chrome ecu gets freaked out by the lower Hz from the maft. or something.

[2fnloud]

Yes...

Where have you been??? I've been running both an EVO MAF and MAP sensor since before chrome V1 came out.

I was under the impression that these two MAF's are the same?

[Greg E]

the weird part is that i didnt have the lean spike before i switched to chrome. now it's there. so i dont know if we can blame the maft for it, directly. unless the way it computes all the numbers is so radically different that the chrome ecu gets freaked out by the lower Hz from the maft. or something.

...or a stock VE table isn't adequate for that setup...

[Greg E]

I know that. Im talking... "X".

No. Still having issues with switchable maps. Been pounding my head on the table trying to figure this out for 3 nights in a row. Doesn't help that I don't have my own car to test it on...

[ChargerX3]

What about the SL?

[Greg E]

What about the SL?

I am using that for more Chrome SL mods/testing but its looking more and more like that will need to be put on hold. The issue with using the SL is its not exactly a TT therefore many stuff can't really be tested.

[ChargerX3]

True, hardware is not exactly the same, but you should be able to play with switchable maps there too, correct?



While we are talking about SL's. Should i get a hold of an intake manifold. Enough progress made there yet?

[Greg E]

The code to drive the switchable runners isn't in the turbo ROM. I have quite figured out how it works yet.

[futurevr4man]

the weird part is that i didnt have the lean spike before i switched to chrome. now it's there. so i dont know if we can blame the maft for it, directly. unless the way it computes all the numbers is so radically different that the chrome ecu gets freaked out by the lower Hz from the maft. or something.

I assume its because I have 1200cc injectors so even a small issue will make a big difference. I also think my lean spike is load based... once I get past a certain load it comes back to life no problem.

[Greg E]

I assume its because I have 1200cc injectors so even a small issue will make a big difference. I also think my lean spike is load based... once I get past a certain load it comes back to life no problem.

You've got a monster engine compared to a stock VR4... I'm sure a lot of tweaking needs to be done. Didn't look like you changed much of anything in the ROM you sent me.

[KeithMac]

I assume its because I have 1200cc injectors so even a small issue will make a big difference. I also think my lean spike is load based... once I get past a certain load it comes back to life no problem.

Have you got PTE 1200s?. I run these and they are not perfectly linear low down, you may also have to slow 02 correction down and run richerer than stoich in some low load conditions.

Throttle tip in, accel enrichment is also vastly different to the 360 stockers.

[futurevr4man]

You've got a monster engine compared to a stock VR4... I'm sure a lot of tweaking needs to be done. Didn't look like you changed much of anything in the ROM you sent me.

yeah, i am not trying to be real ballsy though. give me some time. i dont dive headfirst into everything haha


Have you got PTE 1200s?. I run these and they are not perfectly linear low down, you may also have to slow 02 correction down and run richerer than stoich in some low load conditions.

Throttle tip in, accel enrichment is also vastly different to the 360 stockers.

no, they are deatschwerks 1200's. i will look at accel enrichment and throttle tip in, which are probably my issues.

for reference, here is a picture of a section of a log. TPS stays relatively the same, my rpm goes up, my VE sticks on one spot (which seems to be consistently happening on my lean spot issue), and my airflow goes up and down repeatedly. and the strangest of all is my load goes DOWN and then its like it catches itself and everything is suddenly fine. its really wierd.

https://sphotos-a.xx.fbcdn.net/hphotos-prn1/544400_10200116390291529_1493079674_n.jpg

[futurevr4man]

cant find a throttle tip in table, but changed the accel enrichment table, and it is better now. i lowered the values which as far as i understand it will richen up the areas i richened up. its not fixed, but it is better.

i believe you had said that changing those values would help mask the issue. im not sure what else to change to try and fix this? it makes sense to me that the accel enrichment table is the issue. any other ideas? i am still trying to soak all this up.

i know this will take time, and i will figure it out. im just posting my findings as i go. maybe i should make a thread so i can ramble and not kill other peoples threads haha

[Greg E]

Throttle tip in is the TPS delta table.

Looking over your tune Nate, I see you are adding fuel all over the place. Accell, VE, fuel map... This is going to sound a bit crazy but I would almost suggest either switching the MAFT MAF setting (believe its dip switch #1 in the MAFT box itself) or adding a click or two to the base knob. This will make the MAFT show more air which the ECU will then sort itself out. Everywhere you're adding fuel with Chrome is only masking the issue with the MAFT not showing an accurate count of the air.

[futurevr4man]

Well I do actually have the maf-t set to a 3.5" maf even though I have a 3.75" maf. I did that because it ran significantly smoother when I was tuning with the safc but I didn't think that would cause this issue. Maybe it is?

[Greg E]

Nah, telling the MAFT you have the smaller MAF always seems to work better.

In that case, give the Base knob a click or two till things start to get a bit rich, then lean out your tables.

[futurevr4man]

im not being argumentative, just question(ative?).

what is the difference between turning the base knob a click compared to increasing the fuel tables up to the point i like it? i have been tuning all morning long, just with the fuel tables, and i think it has worked well. 11.0 afr's and messing with the accel enrichment is working to get rid of the lean spot. may not be the best tune, but im learning and its a start. starting to mess with timing a bit.

[Greg E]

Absolutely nothing is wrong with that approach. When other people run into this issue, I'm now more knowledgeable about the quick and easy solution. Most people aren't as patient as you are with tuning and want an easy solution. Thanks to your feed back, I now have one for them. :)

[Chris@Rvengeperformance]

Since most of the flash threads get OT anyway I just wanted to mention that the latest ecuflash worked perfect on my new windows 8 pro machine. Just flashed some startup changes, no issues at all.

[RealMcCoy]

I don't have a flashable ECU yet, waiting on some funding before I make that leap, but I am running a gutted and ported stock sensor. I can offer a bit of insight into what direction the scaling is going to go, so you can at least start out in the right time zone....

I'm somewhat guessing what my WOT high RPM correction "would" be without all the meth I'm spraying, but I believe I'm gaining about 15% up top. Which means I've increased the limitation of the stock sensor by about that amount. If common wisdom says the stock sensor gives up around 450AWHP, then running a sensor like mine you should get well over 500. (which will more than cover the capabilities of my 13T's, so I've been more than content to leave it as is...)

It's down around idle that it gets interesting... Mathematically, with the injectors and fuel pressure I'm running, I should be around -39% correction.(maybe a little less with the E10 they make us run in Oregon) at idle my correction is +30.

It does appear to be a pretty linear progression as it goes up...

Here's a pic of my sensor... If you've ever seen Matt Monet's posted pics of his, you'll recognize that it's a near exact copy:

http://i90.photobucket.com/albums/k252/lnmccoy/ForumPics/mafs.jpg

[Greg E]

Finally got around to testing this. It was a lot easier than I thought. All you need to do to make the ECU more aware of the extra air is play with the MAF Adder value. On my SL, I just kept increasing the numbers in small steps till the engine ran like stock. Over time, a little bit of fine tuning with the MAF Comp table brought the fuel trims back within spec.

I suspect the MAF Size number will also need to be increased to keep the engine load calculation accurate, but I have no way to measure this. The car runs great as is so I'm going to leave it alone.

My MAF is gutted like the picture McCoy posted above.

[Stealth_RT]

Finally got around to testing this. It was a lot easier than I thought. All you need to do to make the ECU more aware of the extra air is play with the MAF Adder value. On my SL, I just kept increasing the numbers in small steps till the engine ran like stock. Over time, a little bit of fine tuning with the MAF Comp table brought the fuel trims back within spec.

I suspect the MAF Size number will also need to be increased to keep the engine load calculation accurate, but I have no way to measure this. The car runs great as is so I'm going to leave it alone.

My MAF is gutted like the picture McCoy posted above.

Do you think that we'd have to increase the MAF adder value when running bigger than stock cams as well?

[Greg E]

Do you think that we'd have to increase the MAF adder value when running bigger than stock cams as well?

You'd adjust the MAF Comp (VE) tables for that.