Downside to a maf only tune

[Maxspeed96ct]

A friend of mine just purchased a camed T/A .
He asked me to look at the tune for him and I did . Made some minor changes .
The car is on a maf only tune , pretty much enables at 500rpm.

I've always kept my tunes a blend ve and maf , or speed density on cam cars .

I must say his ta seems to run good , What are the downsides to a maf only tune ?

[RonSSnova]

I've run my C5 MAF only since I began tuning it. I logged countless runs at the dragstrip zeroing in on ET and mph.
If there is any drawback I'd have to say it is in that initial whack of the throttle leaving the line.
I was not able to get the fueling to accurately follow commanded in that region.
Perhaps due to the somewhat "slow" response time of the MAF itself?
Auto trans btw.
Drive around response is excellent btw.
Mine being a 2000 has the dual VE table setup and I just haven't gotten the calibration correct there.
My belief is that blended when both are calibrated would improve fueling at the hit of the throttle.
But I need to prove that.

All said and done though, MAF only netted me a 10.99 ET.

Ron

[MikeOD]

I've run my C5 MAF only since I began tuning it. I logged countless runs at the dragstrip zeroing in on ET and mph.
If there is any drawback I'd have to say it is in that initial whack of the throttle leaving the line.
I was not able to get the fueling to accurately follow commanded in that region.
Perhaps due to the somewhat "slow" response time of the MAF itself?
Auto trans btw.
Drive around response is excellent btw.
Mine being a 2000 has the dual VE table setup and I just haven't gotten the calibration correct there.
My belief is that blended when both are calibrated would improve fueling at the hit of the throttle.
But I need to prove that.

All said and done though, MAF only netted me a 10.99 ET.

Ron

You could write entire with a 2002 OS, giving you a single VE table. The only difference is less copy and paste headache when tuning the VE. The 2002 OS is also a better OS to work with for speed density tuning.

I highly advocate tuning the VE table when you can...it does make an improvement in how the vehicle behaves at lower RPM.

[Maxspeed96ct]

What's the proper way to write a entire os from another year ?

[RonSSnova]

That is exactly my plan Mike. I'd like to just get a different PCM unless it's possible to keep the same VIN which I'll need come emissions testing.

Ron

[mowton]

One other more obscure knock against MAF only tuning (other than it is simpler and tuners make more money :-) ), is the VE is actually the backup airflow modeling should and when you have a MAF sensor failure. If you don't at least "rough in" the VE, moderate to heavily modified engines could find themselves running very lean......especially if open loop tables are left at 1.0 which I have seen more times than I can count.

Ed M

[MikeOD]

That is exactly my plan Mike. I'd like to just get a different PCM unless it's possible to keep the same VIN which I'll need come emissions testing.

Ron

It might be worth reaching out to support on that one. In the past other tuning solutions could put the 2000 VIN into the 2002 OS and HPTuners couldn't, but I've heard that things are changing with 2.25.