J-Rod

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...

Bink

J-Rod is this a near stock 2002 Z06?? Cam and heads?? Very interesting stuff...I've been amazed by HumpinSS and his Speed Density tuning progress.
joel

HumpinSS

iTrader: (1)

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......

Magnus

iTrader: (4)

That is definately one very nice LTFT map.

Plan B

It's a pleasure to help you out J-Rod, looking forward to catching up with you at the Thunder Shootout... Sam say's G'day.

HumpinSS

iTrader: (1)

How is throttle response now that the MAF is gone. Better I assume

J-Rod

Initial testing was on a stock 2002 Z06.

We will be testing on a max effort car very soon.

maddboost

iTrader: (11)

Very interesting. Why is Speed Density so popluar down under and virtually unused up here?

WS6snake-eater

Man that histogram is absolutely sick. What kind of driving characteristics are you using to touch that many cells?

J-Rod

Because most folks don't know how to do a SD tune in the states.

SideStep

Good question!!!

I can never hit that many cells at part throttle or WOT...

J-Rod

That was about a 5 minute drive. To hit those cells with a 6spd is easy. You simply use part throttle (say 10-20%) and then carry 1st all the way to redline. Then you roll in the next few gears and cary your revs up to redline, but don't go WOT. Each gear (and the load on the motor) will affect you manifold pressure, so you can hit all the cells. Its pretty easy to do in a stick car. You can alos watch, and vary throttle opening while the motor is under load in various gears to hit all the cells. For instance while in 3rd shift to 6th load the motor, and vary the gas a bit to hit the cells.

maddboost

iTrader: (11)

Would you consider a SD better setup for high output setups than a MAF setup?

HumpinSS

iTrader: (1)

I think because most tuners follow the pack and that is partly the reason why tuning has changed so much in the last few years. Abandoninig the old and try new things since we now have a better understanding of how things work. Also with the MAF plugged you can scale the MAF table or the IFR table get your trims - so they lock at 0 at WOT and then proceed to dial the car in on the dyno. That method takes about an hour where SD you have to drive the car around and still use the WB for WOT tuning. I fprefer the latter hence me running with no MAF.

HumpinSS

iTrader: (1)

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

P Mack

iTrader: (6)

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.

P Mack

iTrader: (6)

That would be interesting to get some before and after MAP numbers at wot to see how much of a restriction the maf is, even though it's probably not much. Or dyno numbers.

HumpinSS

iTrader: (1)

I will try and get this done tonight

CHRISPY

I'd love to have a proper SD tune done on my car. I have a bunch of part throttle irritants

it would be nice to get rid of the MAF and do up a nice solid tube ram air kit for the track

J-Rod

Well, I am still testing, but all looks good thus far.