Discussion
ukhsv said:
That shows that your VE table is a bit lean and should be trimed a bit -1 to -2 is a good area for your LTFT..........
"VE table" - volumetric efficiency - how efficient (in %) the engine is, at sucking in air and pumping it out again, dependant on rpm and manifold pressure (or vacuume) ?? This is the "Primary VE vs RPM vs MAP" table under engine airflow in the VCM editor? So making changes to the air intake system (maf/maf pipe/air filter/2nd air box hole etc)affects the efficiency... altering the table will bring the LTFTs into line?
ukhsv said:
The main problem is your maf is not tuned to the car so you need to scale the maf table after you have sorted the VE table......
"maf table" - this is the MAF airflow v frequency under the engine airflow tab? So the table thats in it at the moment represents the airflow for the standard MAF ..... I assume the "S2 MAF" flows more air (it's ported and the screen has been removed) so assuming nothing has been done to its electronics, we need to scale the MAF table airflow g/sec up, for each frequency step?
ukhsv said:
When logging you are disconecting the Maf? (electric supply) if not your not getting a true set of figures to tune the VE .....
Haven't disconnected the MAF. Why do I need to?
ukhsv said:
The big problem with the GM PCM is the fact that any one table has 5 or more other tables effecting it!!!!!!
Its like playing 3 dimensional chess!!
ukhsv said:
Don't mess with your IFR or any fuel tables until you have a good base tune and then only if you have a Wideband O2 setup (best done on the dyno)
Don't worry, I will not be making ANY changes until I am a lot more confident!
Re the wideband 02 sensor - the standard sensor output swings between 0 & 1v - with nothing in between - so the PCM then takes an average ?? What is a wideband sensor - a more accurate version?
So many questions! I just need to know that I'm on the right line .... How about running an HP Tuners seminar sometime?
>> Edited by GSE on Thursday 2nd December 22:02
This looks to me like a hand ported standard MAF. The kind of thing you do with a dremmel @ home. I think you should talk to the company you bought it from for advice of what to do next. Unless they tell you the characteristics of the MAF it will be very difficult to tune you car to this mod. 
The standard O2 sensor is only accurate at the correct A/F ration for emmision, approx 14.7 for the UK.
So it will go rich and then tell the PCM to lean out then it will lean to much and the O2 will tell the PCM to add fuel.
This is why you see the sensors bounce up and down in HP Tuners, so half your A/F figure to get a rough figure.
a wide band sensor can record at any A/F ration so you can tune to an exact figure (a must for WOT running!!!!!)
>> Edited by uk hsv on Friday 3rd December 17:41
So it will go rich and then tell the PCM to lean out then it will lean to much and the O2 will tell the PCM to add fuel.
This is why you see the sensors bounce up and down in HP Tuners, so half your A/F figure to get a rough figure.
a wide band sensor can record at any A/F ration so you can tune to an exact figure (a must for WOT running!!!!!)
>> Edited by uk hsv on Friday 3rd December 17:41
island boy hsv said:
This looks to me like a hand ported standard MAF. The kind of thing you do with a dremmel @ home. I think you should talk to the company you bought it from for advice of what to do next. Unless they tell you the characteristics of the MAF it will be very difficult to tune you car to this mod.
OK I've been investigating the "S2" MAF.
The internal diameter of the air funnel is 75mm, same as the standard unit.
The black part in the centre (that houses the electronics) is identical on both mafs. Part numbers are the same, only difference is a different year stamp (02 instead of the 04 on my original maf) and a different serial number.
The air funnels either side of the black part, are plastic, rather than metal.
The "S2" maf has been modified by cutting out the black plastic bar (by 'hand', by the looks of it..) that runs between the electrical elements, and the outside perimeter of the maf opening. Presumably, this is to further open up the airway, and allow more air into the engine. On the standard maf, the bar sits inside the 'wing' that splits the air intake in two.
The box that houses the electronics is sealed, and it is not possible to open it up.
Looking on the CAPA website, my conclusion is that this MAF is the "Large Bore MAF ends (use with original electronics)" option.
www.capa.com.au/ls1_induction.htm
Whilst it might let a bit more air into the engine, I'm not so sure about the removal of the central 'wing' and gauze - these are supposed to smooth the airflow, lessen turbulence, and provide a more consistent maf reading.
At the moment, all this MAF seems to be doing for my car, is to push the LTFTs up to max - i.e it's making the car run too lean. So for the time being, I've removed it, and put the original MAF back in. LTFTs are still generally positive - max i've seen so far is +12 (headers and exhaust probably causing this) - but not stuck on +25 as they were before.
>> Edited by GSE on Friday 3rd December 20:31
Here is another example of such a thing....
APS's Cold Air intake kit for a classic shape Impreza.
It consists of new piping and airflow meter housing, and new filter.
Actual airflow is increased a bit using this setup, but not drastically.
But what it does do, is cause such a change in the air the airflow actually measures due to either more/less turbluence or poor air distribution over the MAF, that unless the ecu is re-mapped to suit, the car will run dangerously lean, and in many cases, has actually caused engine damage.
Im not saying this wil be the case when altering anything to do with the LS1 MAF, but you do need to be cautious when doing such things, and even more so if you arent monitoring fueling, and/or re-mapping afterwards to suit the changes.
APS's Cold Air intake kit for a classic shape Impreza.
It consists of new piping and airflow meter housing, and new filter.
Actual airflow is increased a bit using this setup, but not drastically.
But what it does do, is cause such a change in the air the airflow actually measures due to either more/less turbluence or poor air distribution over the MAF, that unless the ecu is re-mapped to suit, the car will run dangerously lean, and in many cases, has actually caused engine damage.
Im not saying this wil be the case when altering anything to do with the LS1 MAF, but you do need to be cautious when doing such things, and even more so if you arent monitoring fueling, and/or re-mapping afterwards to suit the changes.
In the stuff I have seen people have hand ported their original MAF's or bought Billet ends. The calibration of the MAF will have been affected by the modifications. On later MAF's on the 2002 LS6 and upwards GM have done away with the screen and the wing. I would have left either half the wing or the support bar so that the sensitive electronics had some protection. Best thing to do is get your car working with the updated exhaust first and then look into if you wont to add in the MAF. I agree with steviturbo the amount of modification your car has had it desperatly needs to be retuned. The engine management will do its best to keep things within the emissions rules but as UKHSV says it will have a tough time at it.
The wonderful world of MAF's !
Just for info the VZ comes with an even bigger MAF! I think it is the truck one from the states!
MAF's used to be ported down here before Edit and HPtuners came along, then people started to leave them alone or nowadays mainly retire them to the shed completely.
I too have one of those MAF's, in my spare room stock pile of goodies! Although I think this one has modified electronics as well. It used to mess around with the signal back to the PCM and throw up error codes all the time. I therefore cut and shut the original electronics and no more codes much the same as the picture above.
motomk
Just for info the VZ comes with an even bigger MAF! I think it is the truck one from the states!
MAF's used to be ported down here before Edit and HPtuners came along, then people started to leave them alone or nowadays mainly retire them to the shed completely.
I too have one of those MAF's, in my spare room stock pile of goodies! Although I think this one has modified electronics as well. It used to mess around with the signal back to the PCM and throw up error codes all the time. I therefore cut and shut the original electronics and no more codes much the same as the picture above.
motomk
Further to what motomk said,
The consensus in Oz is that modified maf-meters don't work.
Even just fitting maf-ends is not recommended.
(Same deal with bigger throttle bodies and lower temp thermostats).
The stock maf isn't the restriction a lot of people thought it might have been.
The screen is there because the pipework before the maf is very short, the Camaro and Vette don't have this problem so went de-screened in 2002.
The only way -according to "Delco" at chipmaster.com.au -to improve on the stock maf-meter is to fit a correctly calibrated 85mm unit from the Vette or LQ4/LQ9 (6.0litre) engine.
The consensus in Oz is that modified maf-meters don't work.
Even just fitting maf-ends is not recommended.
(Same deal with bigger throttle bodies and lower temp thermostats).
The stock maf isn't the restriction a lot of people thought it might have been.
The screen is there because the pipework before the maf is very short, the Camaro and Vette don't have this problem so went de-screened in 2002.
The only way -according to "Delco" at chipmaster.com.au -to improve on the stock maf-meter is to fit a correctly calibrated 85mm unit from the Vette or LQ4/LQ9 (6.0litre) engine.
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