I'm going to KC this weekend to get a tune. And with this tune I won't even use my front 02 sensors. This guy knows his **** so I trust him. I guess my car will run in open loop all the time. He said he gets 28 city and 35 hwy. The reason for the awesome gas mileage is he is also going to tune my car for lean cruise. When i'm on the highway my car will lean out. So I am pretty excited about the tune. But not many people tune like this.

ps he checks his wideband periodically and his tune is perfect everytime.....


A quote from him "I chose to run open loop because having 2002 vette o2's didnt help me..my o2's were still sleepy...
just requires a little more tuning for full time open loop to be accurate"

He said the 02's don't get hot enough in the long tubes....

I've also talked to a couple people that he has tuned and they are very pleased! Opinions?


(oh yea he will also have to convert my 2000 OS to a 2001 or 2002 OS which isn't to hard he said)

 

It really depends on how you use your car...28 MPG in city driving is a bit of a stretch IMO...20-22 would be more like it. Since mine is a daily driver, I run mine in closed loop for reliability. It runs better in open loop though (go figure). I haven't done any long term study on how my open loop tune would vary with changing weather conditions, but every time I tune it, it has drifted a bit (not much to be of concern, but enough where I correct it).

It will definitely unlock some HP for you...if it was me, though, I'd just learn how to do it myself (which I have done). Then you wouldn't have to worry about the tune drifting at all, since you could fix it yourself. It really isn't hard to learn how to do, and you'll learn a ton in the process...

 

I plan on watching and learning from him. Thanks for the response. Anyone else?

 

actually I said I got 25 city and 33 highway...LOL


and I still usually try to do a regular closed loop tune...unless they are "sleepy"
teh problem is that many tuners are just going about the tune with closed loop with no regards to the actual air fuel...
they do it by trims...which are only as accurate as your O2's
and if your O2's are sleepy, then fueling can be Way off...
in my case they were off by -12 when I knew from my Wideband LC1 that Air Fuel was dead on 14.63 stoich...
by the car learning -12 it threw my stoich tune very lean....so I went back to an open loop tune where I have told teh car exactly what to do with the air fuel.
I have also used the OL vs ECT table to get it to command proper fueling at cold starts...
everybody that tunes SD in open loop has a method..one of the common methods is to set the OL vs ECT table all to 1.000
well, at colder than normal Operating temperatures it needs different fueling to get the same results.....
since I have my VE tuned in in teh "normal operating temp range" by an OL ect value of 1....it stays the same at every map for that temp....
my previous rows all get adjusted via wideband and a custom histogram that is for the most part AFR Error except that I tell it that commanded is stoich instead of letting it tell me what commanded is....teh OL ECT table will tell it to command a different AFR than stoich so I wont get anywhere by using a normal AFR Error setup as it would follow the multiplier in that table and every log no matter how much I adjust it would show the exact same result and show no progress....henceforth a contsant # instead of a variable #...

the other thing to remeber is with a MAF...if you tune the VE in Correct with a wideband....and then tune th eMAF in with a wideband....
no matter what you throw at it.....it measures the air density...by doing a cooling of the wires math function...reports a frequency in HZ.... checks a table..and puts exactly the fuel you tell it to.....
so it will always be right...even if you throw a huge dry shot at it...as long as you dont max out the MAF HZ...you are all good..

 

I had a open loop tune from a good tuner and he told me i would lose MPG and i did Now my car is getting tuned for a 408 and i'm going back to the old way.

 

the only reason you lose MPG in open loop is because in closed loop your car will report Rich... (negative trims) and lean out the fueling... and in open loop you get exactly teh right amount of fuel....
which may be rich by measurement of your stock O2's but its correct by wideband.

and with tuning in lean cruise you can regain MPG....

 

thanks for the replies

 

Can you explain this part again...I kinda got lost on what EXACTLY you are doing with your OLFA table and histograms...screen captures might help too.

 

Oh, and another question...I'm assuming you are tuning in the MAF in all of your tunes that are still in open loop? I might try to tackle that next to see what I can come up with for a decent, open loop tune that I can run every day. I love how my car runs in open loop, but have been afraid to try with my car being a daily driver and all.

 

I have been in open loop now for almost a year and a half. I won't go back to O2's unless the President tells me to.

PS I drive mine daily

 

I think with enough attention to the various environmental
adder / multiplier tables you can make an open loop tune
pretty robust to IAT, ECT and get decent performance
and base mixture stability. The open loop table can be a
poor man's lean cruise if you tailor the "sweet spot" for
highway running to be less than 1.000 fuel air multiplier.
The main trick I expect is making it transition cleanly out
of this "pocket" without ping etc. from the over-lean
initial condition.

If your kittens wandered off the farm then there's no
particular reason why you want to be at 14.7; most
likely leaner or richer would suit you better (power or
economy; who wants to be "average" anyway, other
than bureaucrats?).

 

Can you post up a pic of what your OLFA table looks like just for reference? What do you have your PE come in at? Just looking for some new direction...I'm tired of the narrow bands and always being skewed -4 (or worse) trim-wise...

 

I am using a custom EFI Live OS so I don't have a normal open loop table like you guys. This is setup like this and pe has been disabled.

 

That's a pretty nifty little trick...I could probably emulate something really close with the OLFA table and PE tables in HPT. Thanks man...do you find that this has advantages over the PE table?

 

I dunno. Throttle response seems really nice with it. I haven't really had a chance to get on it that much cause I am missing 3rd gear.

 

Been there... *sigh*

Definitely sounds interesting. I think I'm gonna switch over to a full time open loop tune within the next month or so...might even try screwing with the MAF stuff again for giggles.

 

Just put a new chip in and be done with it.

 

Nah...I already have the Corvette chip

 

simply put..we tune with the OLFA tabel put at 1.000...
well at full operating temperature all map values will be corrected according to how we tune... so we know that that row can remain at 1.000 from 15kpa all the way up to 100kpa
when we start up cold the car requires differnt fueling to get stoich fuel ratios.....
and because of how we tuned above...we dont really need to pay attention to MAP in teh OLFA table any more....
we now just ned to pay attention to teh temperature... and correct according to how much leaner it is at those temperatures....
I'm working on a write up...I will post it eventually...I just have been working so much I havent had any free time..and the little bit that I do have is being spent with my 2 month old....

 

No worries man...I'll bet I can figure it out from the screen captures you put in the other thread...there are more important things in life than this stuff