Speed Density tune in and working...
Thread Starter
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
Likes: 13
From: Texas
Speed Density tune in and working... Sam of Sam's Performance, and Pete (PlanB) were gracious enough to work with me to test a speed density tune on a U.S. car. Specifically a 2002 Z06 Corvette which is equipped with a drive by wire throttle.
Of course Sam's response to the challenge of a car he had never seen was was "Oh that won't be a problem, send me the stock tune...".
Anyhow, I had been logging a tune from a noted U.S. tuner in another vehicle. This post isn't meant as a bash, so I'm not specifying what type of vehicle, or who the tuner in question was. But the results were certainly informative to say the least.
First off, we have the U.S. MAF tune on car X.
Now we have Sam's tune having never seen this particular car (2002 Z06, not the same car as above), and being 12,000+ miles away...
For those of you not familiar with HP tuners software, these are the LTRIMs (long term fuel trims). This is where the computer decides if the air fuel ratio at part throttle is off of the 14.7:1 (stoich) ratio which is the ideal air fuel ratio. From the histogram of the U.S. tune the numbers in RED mean that the tune is not adding enough fuel, and the computer is forced to compensate by adding fuel. This is less than ideal.
On the other hand you will see that Sam's tune out of the box is spot on, and is virtually perfect throughout the entire range. Green means the car is a bit on the rich side, and the computer pulls a bit of fuel out.
HPtuners considers LRIMS of 0 to -4 to be about perfect. As you can see this tune is about perfect out of the box. On the other hand, the other car in question really needs to be looked at...
Just thought some folks might find this informative...
Of course Sam's response to the challenge of a car he had never seen was was "Oh that won't be a problem, send me the stock tune...".
Anyhow, I had been logging a tune from a noted U.S. tuner in another vehicle. This post isn't meant as a bash, so I'm not specifying what type of vehicle, or who the tuner in question was. But the results were certainly informative to say the least.
First off, we have the U.S. MAF tune on car X.
Now we have Sam's tune having never seen this particular car (2002 Z06, not the same car as above), and being 12,000+ miles away...
For those of you not familiar with HP tuners software, these are the LTRIMs (long term fuel trims). This is where the computer decides if the air fuel ratio at part throttle is off of the 14.7:1 (stoich) ratio which is the ideal air fuel ratio. From the histogram of the U.S. tune the numbers in RED mean that the tune is not adding enough fuel, and the computer is forced to compensate by adding fuel. This is less than ideal.
On the other hand you will see that Sam's tune out of the box is spot on, and is virtually perfect throughout the entire range. Green means the car is a bit on the rich side, and the computer pulls a bit of fuel out.
HPtuners considers LRIMS of 0 to -4 to be about perfect. As you can see this tune is about perfect out of the box. On the other hand, the other car in question really needs to be looked at...
Just thought some folks might find this informative...
Another testimonial. woot mine is comming through nicely. I do have some cells that are rich (-5 STILL GOOD) but that is due to my operating system and year (I have have two ve tables the second one having less resolution is used when the maf is unplugged) other than that the car smells good drives well (no surging and bucking) and I am overall pleased with it. I use my WB for WOT tuning realtime at teh track......
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Thread Starter
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
Likes: 13
From: Texas
Originally Posted by maddboost
Very interesting. Why is Speed Density so popluar down under and virtually unused up here?
TECH Fanatic
Joined: Mar 2003
Posts: 1,946
Likes: 1
Originally Posted by WS6snake-eater
Man that histogram is absolutely sick. What kind of driving characteristics are you using to touch that many cells?
I can never hit that many cells at part throttle or WOT...
Thread Starter
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
Likes: 13
From: Texas
Originally Posted by WS6snake-eater
Man that histogram is absolutely sick. What kind of driving characteristics are you using to touch that many cells?
Originally Posted by maddboost
Very interesting. Why is Speed Density so popluar down under and virtually unused up here?
Originally Posted by maddboost
Would you consider a SD better setup for high output setups than a MAF setup?
SD density cleared a lot of my problems up. Car stinking, no responsive to throttle changes, loading up and a bunch of other symptoms mainly PT situations. my cam isnt big at all 230/232 Fm13 and I wouldnt consider it hight output. The driveablitly issues the MAF caused were enough for me to dump it and since i seen the manners of the car while running SD i am not looking back. I will get some PVC pipe from home depot and run it straight to my TB and call it a day
Just thought of something. It seems like the pcv setup could contribute some to bad driveability because it is after the maf. You'd think that the amount of fresh air going to the valve covers would be the same as the air entering the intake through the pcv so it would all even out, but that's not always the case as the pressure in the crankcase changes. The maf can't account for this cause the pcv setup is after the maf, but a speed density tune would account for it because the map sensor is downstream of the pcv.
Originally Posted by HumpinSS
I will get some PVC pipe from home depot and run it straight to my TB and call it a day
