Optimal BLMs for performance vs. optimal BLMs for economy... some Qs and comparisons.
So I found out that the BLM value of 124-128 is optimal for pure high performance driving/racing while the BLM value of 134 is for economy. Is this correct?
Is there a way to translate/interpolate/transliterate BLM values into a/f ratios without a wide band O2 sensor? What are the BLM ranges from least to greatest?
Another thing, ever since I had my chip tune from Alvin @ PCMforless and just filled up with a tank of gas today, I was noticing my before even my SRI, 24# Bosch injectors, I have been consistantly getting 12 mpg in the city vs 16 mpg 100% bone stock. Highway gas mileage is the same @ 22 mpg cruising @ 80 mph. What made me lose 4 mpg in the city even though my driving style is the same way as always?
Nevertheless, my Vette's performance off the line and from a roll is far more superior and more stellar than ever before because of the ablity to keep pulling past 5000 rpms with no tapering of the power. I noticed manually shifting my automatic @ 5500 rpms made me pull a best of 12.60 @ 107.47 using my G-Tech. So far that is the best 1/4th mile ET on my newer G-Tech. Looks like this translates into 288 hp @ the crank assuming my Vette weighed exactly 3050 lbs with me at a local truck weighing station. What do you think?
Did he change the injector constant? I'm pretty sure the CCM uses that to figure out fuel consumption. You might have been getting a false high reading before..
depending on HOW the tuner increases fuel delivery, the ECM can be giving you acurate or completely false MPG readins. the only way to really know is to monitor your own mileage and fuel use - and do the math.
FWIW - most people tend to change the Injector Constant to "trick" the ECM in to widening or shortening the pulse width for more or less fuel delivery. this will probably give eroneously low MPG readings in your case.
Or, the MPG readings could be accurate and your vette simply uses more fuel for all the newfound power you're making. Around town is where you'll see the biggest changes anyway with all the start/stop-ing and whatnot.
So does that mean if my mpg is lower, it also could be I am running richer? I still keep on hearing for n/a motors a 13:1 a/f gives the most power and performance and a 14.7 gives the most economy, e.g. lean burn engines. Someone back me up on this one...
So does that mean if my mpg is lower, it also could be I am running richer? I still keep on hearing for n/a motors a 13:1 a/f gives the most power and performance and a 14.7 gives the most economy, e.g. lean burn engines. Someone back me up on this one...
Thanks!
There is no standard. Tune 5 different motors, you might get 5 different answers. The Tuner should be looking for power as the goal, not an AFR.
I've been out of town for the past week so I didn't see this.
Thanks, for the kind words. How does the chip feel?
In alot of the vettes there is a "fuel delievery display rate" or something like that. Its sole purpose is to make the displayed MPG to show up right. I may have forgotten to calibrate yours, in any case your more than welcome to send it back and have me go over that portion of your chip.
I do not just change the injector constant to change fuel delievery. If you would like you can check your MAF tables to see that they are changed after the injector constant is changed to the appropiate amount depending on injector size.
If your are a email program customer you can even watch the evolution of your MAF tables as I calibrate the car to run closer and closer to ideal between iterations.
Also, I do not put anyones car into open loop without thier asking.. even so I have different ways of preventing a closed loop operation than just locking it into open loop
Also, I do not put anyones car into open loop without thier asking.. even so I have different ways of preventing a closed loop operation than just locking it into open loop[/quote]
I wasn't assuming that the chip was set for open loop, but rather something else is causing it. You gotta admit that "BLM's are EXACTLY 128 at idle and cruise" is a little suspect....
A car will not stay in open loop due to a fault. It can have overly long states of staying in open loop but it should never stay in open loop.
I can't think of any DTC's that would default the car to open loop. A o2 sensor fault will just set a DTC and ignore the o2 readings.. It doesn't kick it back in open loop though.. you see what I mean?
I thought he meant that its staying very close to 128.
I'll be more than happy to review any .uni files. That way I can see if theres any power left in the chip.
to think that an ECM would be seeing "128" across the board without fail is awefully tough to believe. Without questioning the "tune," it does sound like the car is in open loop since the BLMs are listed as "128." Hooking up datamaster or any scanning program should be able to tell the poster if he has other issues he needs to address (coincidentally, remaining in open loop would explain the drop in MPG) in addition to easily reading any DTC codes.
But sounds like you've got great customer support, Alvin.
I think too many confuse 128 with Open loop. Open loop is when closed loop flag is 0 (not equal to 1). Open loop has several adders as far as fueling so its not smart to ever lock a car in "open loop" you can do it in a smarter way by removing the O2 feedback from fueling logic essentially making it Open loop.
I hardly ever lock any car, if I do its only on the customers request and only if I approve (some people request strange things that shouldn't be done in thier best interest)
I just assumed again that the guy ment that the car spent most its time around 128.. not that it was exactly 128.
I can't speak for every model, but my car is a SD car and the ecm requires some amount of crosscounts from the O2 sensors showing they are warm and working before entering closed loop.
Corvette Store
Optimal BLMs for performance vs. optimal BLMs for economy... some Qs and comparisons.
That sounds like open loop.
