Maf and custom op. sys. 3

[hpcubed]

If one wanted to use the maf with cus. op. 3 and 2 bar map, is it possible? Meaning if you wanted to use the maf and set the fail freq to say 8000. When the frequency is surpassed, would it default to SD mode and use the boost VE table etc. for fueling? Sort of a hybrid system. Any issues that come to mind?

[ringram]

Hmmm interesting concept. I think if you did that it would "fail" and never get reset until power cycle and/or codes were cleared. So it would work until it failed, then it would stay failed. Maybe someone else can confirm either way.

A recent thread on ls1tech shows there is no benefit from maf over sd. SD is better for boost and cams. Maf is good for flexibility. If you have a 75mm maf then you are better off in SD.

[hpcubed]

Hmmm interesting concept. I think if you did that it would "fail" and never get reset until power cycle and/or codes were cleared. So it would work until it failed, then it would stay failed. Maybe someone else can confirm either way.

A recent thread on ls1tech shows there is no benefit from maf over sd. SD is better for boost and cams. Maf is good for flexibility. If you have a 75mm maf then you are better off in SD.

The accepted method to cause the computer to go into SD mode is to set the fail frequency to 1. This causes no reset etc as you speak of. I don't think it matters as far as functionality if you set it to 8000 instead. Am I missing something?

[hpcubed]

Any more thoughts??

[ringram]

Why not try it then.
I think you will find that the maf will work until you go over 8000 hz, then it will fail and you will be in SD from then on. It wont start working again when you drop below because it has "failed" based on your hz setting.
You are better off just to dump the maf in your instance.

[joecar]

What ringram is saying is that the MAF will be ignored for as long as DTC P0103 is present, even if you go back down below 8000Hz;

what we don't know is how long it takes to self-clear the DTC.

[hpcubed]

Oh, yes I see what you are saying now. That could be a problem. I was asking about it because someone said they were doing it this way.

My maf will be on the shelf but I might light the motor off for the first time with it.

[hpcubed]

Now wait a minute. Then how do people tune a forced induction motor with the maf? They use PE vs RPM. But at some point the maf maxes and I suppose defaults to sd mode (or something). Or what is the PCM using for airflow calculations at that point? Is it just stuck on 512g/s?

[joecar]

If they peg their MAF, they are advised to toss it.

[vetteboy2k]

In the Corvette C5 you can reset codes right from the DIC, I will test around with this for you during the week and let you know what I find

[hpcubed]

If they peg their MAF, they are advised to toss it.

People have been tuning forced induction (LS1) with the maf and pegging it for the last 4 or 5 years. SD is the new kid on the block :) Seems to make me think that the maf sets a trouble code and when the frequency drops back below the cutoff, it uses the maf again. The trouble code is set but that does not mean it stays in SD mode.

[hpcubed]

Ok, I have more info. If you exceed 512 g/s the computer won't know how much more air is coming in but will not set a code. If you exceed the fail frequency, code is set and program defaults to using SD. So I'm still not sure if this will work. The question still remains, how long does ECM stay in speed density after the maf reads below fail frequency?

[joecar]

Hi hp³ :wave:

I was just thinking about this today after reading a post by kp on ls1tech.

If airflow exceeds 512 g/s and no DTC is thrown, what does PCM use for airflow/airmass (does it just use 512 g/s...?)...?

I thought the fail freq would be hit before the airflow hits 512 g/s (so the DTC would be set)...

Yes, the question still remains, when does the PCM revert back to MAF (does the DTC get cleared when this happens...?).

Good comment in prior post... :rockon: people have been pegging their MAF, but now they can use the 2/3 bar VE table provided by a COS, so they can toss their MAF.

Cheers
Joe
:cheers:

[Highlander]

The DTC must be cleared before the PCM can revert to MAF functioning... I guess it will depend on how many trips it takes to clear it

[Highlander]

My question:

If you are going to use the MAF sensor why are you using a Custom Operating System??? It defeats the purpose of boost assisted fueling...

My suggestion. If you want to keep the MAF... is.. buy a pro M maf. IT will cost you around 600 bucks and its pretty darn big. It will read to 900g/s (1000rwhp a guesstimate) and you can calibrate it to whatever hz with its computer aside. That is what i have.

[hpcubed]

Hi hp³ :wave:

I was just thinking about this today after reading a post by kp on ls1tech.

If airflow exceeds 512 g/s and no DTC is thrown, what does PCM use for airflow/airmass (does it just use 512 g/s...?)...?

I thought the fail freq would be hit before the airflow hits 512 g/s (so the DTC would be set)...

Yes, the question still remains, when does the PCM revert back to MAF (does the DTC get cleared when this happens...?).

Good comment in prior post... :rockon: people have been pegging their MAF, but now they can use the 2/3 bar VE table provided by a COS, so they can toss their MAF.

Cheers
Joe
:cheers:

Joe, you can set the fail frequency to 15000 Hz so it will hit 512g/s before it hits the fail freq. It will be stuck on 512 g/s thereafter. And yes you don't need the maf but some tuners want them on street cars for legality reasons. I talked to a guy at Lingenfelter about this. They don't speed density tune any car with an electronic throttle body because they said they loose the safety features. Although I believe you can retain them if set up properly but a lot of people disable them. They have a calibrated 100mm maf which will not hit the fail freq. but will max the computer at 512 g/s. However with this maf you could scale the maf table and injector table (and spark etc.) so that you will never hit 512g/s.

[hpcubed]

My question:

If you are going to use the MAF sensor why are you using a Custom Operating System??? It defeats the purpose of boost assisted fueling...

In the end I will probably not use the maf. When I drive the car with the turbos initialy on low boost I am going to use it. I just heard someone say they were tuning like this and I wanted to confirm that it was possible.

My suggestion. If you want to keep the MAF... is.. buy a pro M maf. IT will cost you around 600 bucks and its pretty darn big. It will read to 900g/s (1000rwhp a guesstimate) and you can calibrate it to whatever hz with its computer aside. That is what i have.

Interesting. Do you have a link to this. I looked and only saw them for mustangs and they were only 80 mm.

[hpcubed]

My question:

If you are going to use the MAF sensor why are you using a Custom Operating System??? It defeats the purpose of boost assisted fueling...

My suggestion. If you want to keep the MAF... is.. buy a pro M maf. IT will cost you around 600 bucks and its pretty darn big. It will read to 900g/s (1000rwhp a guesstimate) and you can calibrate it to whatever hz with its computer aside. That is what i have.

In the end I will probably not use the maf. When I drive the car with the turbos initialy on low boost I am going to use it. I just heard someone say they were tuning like this and I wanted to confirm that it was possible.

Interesting about the maf M. Do you have a link for it. I just saw them for mustangs and 80mm.

[joecar]

The DTC must be cleared before the PCM can revert to MAF functioning... I guess it will depend on how many trips it takes to clear itFrom what I read, the PCM may clear the current DTC (and promotes it to history) within the same current drive cycle, question is what are the conditions which trigger this.

[hpcubed]

From what I read, the PCM may clear the current DTC (and promotes it to history) within the same current drive cycle, question is what are the conditions which trigger this.

I think that if the maf falls below the fail frequency, the PCM uses its input immediately and sets a history code. Still need to confirm this though.

[ls1mike]

so the question remains, can you run a 2 bar and a maf with a cos (on a ls1b) and everything will play nice? mine is a low boost application, full throttle is fine but 75% throttle spikes in the 10.5 AFR range, would be nice to slim that down for economy's sake as well as minimizing gas wash

[joecar]

Yes, you can run a MAF with and without boost.

You would have to tune both the Main VE and the Boost VE tables using a wideband, and you would set PE to be suitable for boost (11.7 say) and make sure that PE enables easily...

post your tune file.

[ls1mike]

sure, this is based off of one you gave me i believe. i think it is a segment swapped 6.0 file? 13559

to go COS i'd have to switch to another OS, i have a 04 Escalade file with the right OS i believe.

this is my daily driver so there's been a lot of edits.

13560 recent long log from a single day.