Suggestions...MAF sensor is maxing out above 5100 rpms!
05-03-2005, 01:38 AM
#12
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Originally Posted by 02sierraz71_5.3
Im new to tuning but couldnt you just retune for SD and eliminate the maf all together.
05-03-2005, 01:48 AM
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Originally Posted by 02sierraz71_5.3
Im new to tuning but couldnt you just retune for SD and eliminate the maf all together.
05-03-2005, 08:24 AM
#14
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you must have copied the program you had in the truck when you started. some of the tuners do this. here is one from another guy who had programming from mach performance (i believe actually done by westers).
it was in the way he scaled it. the 99 tahoe i was running the procharger on last year was showing as high as 420+gms and never maxed out the maf. this was with ed wrights programming. i'd recomend flashing the pcm back to stock and editing the software from there using tunercat. this will get your maf tables back to stock. many tuners will have the maf flatline at a lower hz reading because they figure the fmu is going to add the extra fuel so the pcm doesn't have to. there should be plenty of room if you have the stock maf table back in place.
it was in the way he scaled it. the 99 tahoe i was running the procharger on last year was showing as high as 420+gms and never maxed out the maf. this was with ed wrights programming. i'd recomend flashing the pcm back to stock and editing the software from there using tunercat. this will get your maf tables back to stock. many tuners will have the maf flatline at a lower hz reading because they figure the fmu is going to add the extra fuel so the pcm doesn't have to. there should be plenty of room if you have the stock maf table back in place.
05-03-2005, 08:41 AM
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Originally Posted by rcfast
as far as increasing the HZ that was something im thinking might be problem in the tunercat software and that they might be able to extend that for us. as far as changing the gm/sec to 512 that will skew the reading and cause problems. The table needs to be accurate to what the maf is reading, that table is the measurement the maf is reading for the hz value. If you where to put 512 in there at 11000hz it would think the maf is reading 512 gm/sec when in reality the maf is probably reading the 324 at 11000hz where its maxed out. There isn't programming that will fix this. the only thing that will is a different maf such as the 2001 c5 maf. I also found that casper electronics makes the adapter to adapt the five wire maf to a 3 wire for the maf and a 2 wire for the iat which would plug into our trucks part number CAS108100
Ken
05-03-2005, 09:15 AM
#16
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when you go into tables/fuel tables/maf sensor air flowvs. output frequency. what does it show in them tables? i'm going to get the files from a 96 and compare them to a 97 i have programmed. i believe everything on that scaling goes X2 which would make 11,000hz 457.86 even though it may show it at 228.93@11000.
the 96 files show the stock scaling to 11000hz@256.xx which would be 512. obviously this is odd, but as is most of the numbers in tunercat. i believe you'd have considerably less trouble going into that setting though and loading it to a stock maf reading.
the 96 files show the stock scaling to 11000hz@256.xx which would be 512. obviously this is odd, but as is most of the numbers in tunercat. i believe you'd have considerably less trouble going into that setting though and loading it to a stock maf reading.
05-03-2005, 01:40 PM
#17
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Originally Posted by zippy
when you go into tables/fuel tables/maf sensor air flowvs. output frequency. what does it show in them tables? i'm going to get the files from a 96 and compare them to a 97 i have programmed. i believe everything on that scaling goes X2 which would make 11,000hz 457.86 even though it may show it at 228.93@11000.
the 96 files show the stock scaling to 11000hz@256.xx which would be 512. obviously this is odd, but as is most of the numbers in tunercat. i believe you'd have considerably less trouble going into that setting though and loading it to a stock maf reading.
the 96 files show the stock scaling to 11000hz@256.xx which would be 512. obviously this is odd, but as is most of the numbers in tunercat. i believe you'd have considerably less trouble going into that setting though and loading it to a stock maf reading.
ok, i did some more research on this. according to the gm service manual the stock maf will read up to 512gms on the stock programming @ 11000hz. this also indicates as i suspected that the tunercat maf tables are in 1/2 just as the v/e tables are X2 instead of normal. all of this information is directly from the shop manual for a 96K1500 truck. i work for a dealer and have access to all of this at hand. if you're maxing it that low, you need the maf tables from a stock truck put back in there. i can get that for you if you'd like. i have a full scan from a stock 96k1500. if you no longer have the stock file for that i can probably get you yours even with the vin. i'm assuming at this point though that you started tuning with tunercat using the previous tuner's input. i tuned a procharged S10 recently from stock to a heads/cam with other mods and 3 weeks later with the procharger. all of this from the stock files and the truck went 13.18 so far. (if i recall this is a 97) you'd be much better starting right from a stock tune and re-doing all of it yourself.
05-03-2005, 04:56 PM
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Per John at TC...
Hi Ken,
At least theoretically you should be able to use any MAF sensor whose output
signal is compatible with the PCM. What you'll need to find is a MAF sensor
that flows more air for a given output frequency since the PCM limits the
useable max frequency of the MAF signal. In the case of the Vortec PCMs this
is limited to 11216 Hz so if you use a MAF sensor that goes past this to
12000 Hz for example, you still won't be able to measure any air flow values
that correspond to frequencies above the 11216 Hz limit.
BTW, I took another look at the MAF table in the Vortec PCMs and I had them
scaled incorrectly. I originally used the same scalar as the LS1 but they
are actually different. I've corrected the Definition File to reflect the
correct scalar for this table. (attached).
You might try an experiment before sinking a lot of money into a new MAF
sensor. Try increasing the air flow values in the MAF table that correspond
to the highest frequencies and see if you get any more fuel at the upper
end. Its going to make the engine run rich when the air flow actually
corresponds to these frequencies but you may be able to get through the
range fast enough with the supercharger that it won't be a problem. Since
once you reach the limit of the MAF sensor frequency, the PCM will use the
last value in the MAF table, you should see additional fuel.
The other obvious thing to check of course is to make sure you're not
running out of injector.
John"
Ok...updated my program..it now reads 400gs at 11000Hz max...what do you think now? I'm going to call him tomorrow morning...any other questions you want me to ask...I hate using email on smothing as detailed as this is turning out to be.
Took screen shot....
Ken
Hi Ken,
At least theoretically you should be able to use any MAF sensor whose output
signal is compatible with the PCM. What you'll need to find is a MAF sensor
that flows more air for a given output frequency since the PCM limits the
useable max frequency of the MAF signal. In the case of the Vortec PCMs this
is limited to 11216 Hz so if you use a MAF sensor that goes past this to
12000 Hz for example, you still won't be able to measure any air flow values
that correspond to frequencies above the 11216 Hz limit.
BTW, I took another look at the MAF table in the Vortec PCMs and I had them
scaled incorrectly. I originally used the same scalar as the LS1 but they
are actually different. I've corrected the Definition File to reflect the
correct scalar for this table. (attached).
You might try an experiment before sinking a lot of money into a new MAF
sensor. Try increasing the air flow values in the MAF table that correspond
to the highest frequencies and see if you get any more fuel at the upper
end. Its going to make the engine run rich when the air flow actually
corresponds to these frequencies but you may be able to get through the
range fast enough with the supercharger that it won't be a problem. Since
once you reach the limit of the MAF sensor frequency, the PCM will use the
last value in the MAF table, you should see additional fuel.
The other obvious thing to check of course is to make sure you're not
running out of injector.
John"
Ok...updated my program..it now reads 400gs at 11000Hz max...what do you think now? I'm going to call him tomorrow morning...any other questions you want me to ask...I hate using email on smothing as detailed as this is turning out to be.
Took screen shot....
Ken
05-03-2005, 08:17 PM
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Originally Posted by zippy
here is a table from a stock L31 K1500 96 suburban.
[]
[]
Yeah, that's what mine looked like before the update on the DF file...remember you are viewing it with the older DF which is using an LS1 table cal....if you plan on changing this table you would need to contact John at TC and get the update fix for this...even though the table goes to a higher number it is still limited to how high the MAF can read...mine maxes out at 327gs. Some guys run a bit higher numbers but this is on 98+ trucks.
I may play with the maf gs settings...but I have decided to install a wideband LM1 meter/data logger and my MF2 fueler (2D or 3D fuel/boost curve) with two extra injectors below the TB as just playing around with the stock 19-21 lb injectors may be enough for 7psi of boost but not any more than that....
Ken