Hey I was wondering about the BLM locker. Do you use it to calibrate your maf at high gms/sec readings. Because the only way to get to the higher numbers like 250 gms/sec is to floor it. Does this allow you to tune the blms to 128 at the high airflow numbers.

Also, does this allow you to tune your WOT a/f ratio more precisely, by more accurately calibrating your MAF?

 

Good question im curious to know also

 

There are some setting in Tunercat's constant tables that you can set to prevent "enable WOT". This will prevent going into PE mode at high rpm.

 

you do not need to get your blms at 128 at high rpms. how often do you acctually drive at that high rpms and map for a significant time to even let the pcm learn the fuel map.

the best thing to do would be to, get the blms where you want them under all your noraml driving condition, for example if you dont see 100mph but once every 2 weeks dont worry about your blms there. and use the blm locker for your wot stuff that way anytime you go wot and enter pe mode the blms will lock at 128 and give you the exact program A/f ratio.

and by the way if your blms are say 132 and 135 or 125 and 123. it doesnt matter if you are using the blm locker. because you are not running lean or rich. as long as you are not below 108 and above 160 you are at 14.7 a/f ratio. remember the blms are a correcion factor that the pcm is using to keep the a/f ratio at 14.7, the number is showing that the pcm is making a corection and if it wanst you would be lean (at say 135 or rich at say 122) THAT IS IF IT WASNT MAKING A CORRECTION FOR YOU.

so long as your blms are between 108 and 160 and your using the blms locker the pcm will give you a your predetermined a/f ratio in pe mode at wot.

hope this helps.

 

Thanks alot. I have one question though. If the blms are merely a correction factor, meaning its just how the computer is compensating to get 14.7:1 then whats the purpose of tuning your fuel mixture at part throttle if your blms are already between 108-160?

 

because if you have blms above 128 (a correction factor for a lean condition,) the pcm will use the corection and add the correction to the pe tables. so therefore you will not see the predetermined a/f ratio in pe mode that you have programmed it to hit. it it is still compesating for a lean condition that it saw under normal conditions,

if you have have datamaster or something you can that if you go into pe mode and you have a blm above 128 then the pcm will use cell 15 and the correction that comes with it. so instead of your EX.12.8 to 1 that you are trying to hit it might be 12.2 to 1. becuse it is trying to compensate for a lean condition that it thinks will damage the engine, when its probably a exhuast leak.

now if you go into enrichment mode with a lower blm of say 125 then the pcm uses cell 18 and locks the blms at 128 to show no correction, this is a open loop cell used at high load. but without a corection faction, remember you are not in open loop when you go wot. you are in pemode and the cell used is what you need to worry about. becuse there is where to ruber meets the road, the cell determines if you are adding fuel or not.

hope this helps

 

So I want to be in cell 18 at WOT? What A/F ratio is good for a car with my mods? I know it varies but just an ideal range please.

 

yes cell 18

and anywhere from 12.8 to 13.2

 

Thank you, you have been the most helpful so far. Ok I checked what cell my car is using, at WOT it uses cell 15 in first gear and cell 18 in the rest. Is this ok or do I want to get 1st gear in cell 18 also? Do I richen the mixture up to correct this? My long term BLMS show 128 average through out the power band at part throttle. Although, short term does run lean and rich within the same cell at times. Is this normal or is there a way to correct this?

Let me ask you this question. If I made all my BLMS run at say 110 long term wouldn't that keep it from adding fuel in PE mode? Or would it have the same ill effects just on the other side of the spectrum I.E. run leaner

 

ok.

the short term values are only used once and tossed away the O2s make measurement again well that measurement was its last correction, and this lets the pcm know if the last short term was correct or not. if not it makes another short term correcetion and then the cycle starts over agian, so theres no need to worry about the short term stuff. IMO.

now long term....the long term is used everytime the engine fires, the long term is average of all the short term counts. if you notice the short term operate the same as longterm from 108 to 160. if you have a short term of 122 and the next is 136 the long term will be 129. but the next short term will be small maybe 126 or so to try and get back to 128.

now about the 110 idea if you tune to 110 and over time your car starts doing something you didnt know about and it starts running lean well its almost reach its boundries to correct for that. and now theres no telling how long youve been running lean. so no dont do that. so people tune to 128 some tune to 124 125 area to try and accomplish the same thing your trying.

ok now the the thing about the car in cell 15 in first and 18 in the others is that the pcm looks at the very last longterm it used. so when you let off the gas for a shift theres alot of things that happen one is the throttle closes so the next reading will be rich becuse it addign fuel and the tb just cut the air of to it. noe its loaded on fuel. there are so many thing that hapen during a shift as far as fuel goes you will never get the car to go into cell 18 everytime. so what i would do in your case is tune for a 128 blm at idle and everyday driving. and use the blm locker that way your at 128 all the time (at wot)and dont have to worry about what cell its using and if its adding fuel.


good luck

 

Thanks. Why didn't GM make them with the BLM locker from the factory? I'm going to the dyno in a few weeks, any tips on tuning? I should probably begin by getting the A/F right first, correct?

I'm getting false knock I think. With MADZ28's tuning I found spark knock above 4000rpm. I've tried using the stock spark tables and 94 octane and I still get knock at 180 coolant temp. Should I try a LT4 knock module? Should I just tune the WOT to where I get max hp then just disable it above 4000rpm?

 

if you are sure its fasle then you can go to the max knock VS rpm and tune some knock out. do not buy the lt4 KM when you have tuner cat. go to the table max knock VS map and put the wholle table at zero.

the reason they didnt come with the blm locker is becuse like i said above if your blms are correcting for a lean condition (above 128) it will not have the correction added to the pe tables when you go wot. so you may have a lean condition at wot using the blm locker but if you monitior you car and know what its doing then you should feel safe using the locker.

as far as dyno tuning IVE NEVER DONE IT but if i were i would probably set the pe mode at say 12.9 to 1, and and dyno. then if you have no knock add say one degree of timing, then dyno again, if you get knock. try adding a little fuel and dyno again. and see if the knock goes away. do all this using the blm locker. like i said ive never done it so maybe some people will chime in. it may be something that you post a new thread about.

 

I agree I feel these discussions help people to learn more about this. This is one of the most technical areas. The web should have a better "search" program. They could break it down to ignition, MAF, dyno tuning, etc. and put detailed threads in there.

How do I tune out the max knock vs rpm? Do I add or subtract? How much? I heard a guy with tuner cat say an LT4 knock module helped get rid of his knock problem.

Hey I just realized something. When I increase the numbers on my high flow maf tables the injector % goes way up at WOT. Instead of 70% it went over a 100%. What should I do here?

Do you have LCA relocation brackets?

 

Hey what is the formula to convert the PE table numbers? I see someone post it before, I believe there are 2 of them.