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Okay, got BLMs down.....now too low

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6SENSE

Member
Joined
Jun 3, 2001
Messages
1,635
Problem was at the charcoal canister. It was pretty much empty and probably had a messed up solenoid since there was no cv installed on the vac line. One BIG vac leak right out the bottom of it. Replaced with another that I found I had sitting around. Installed a good cv after testing it with mityvac. Now BLMs are no longer high 140s at idle but fell way down to the low to mid teens. No higher than 117.
Ive tried lowering FP, but no difference. Got the fp at 40 static now. Had it down to 37-38 also.
Have always had a ATR brass cv inline with the GM pcv valve (like the instructions showed to do). I know guys have looked this direction for high BLM issues, but what about low BLM #s? Should try a new GM pcv valve, with and/or without the ATR cv?
Or try switching 3" MAFs. Maybe even throw on a known good stock MAF (I think I have one around) and see what happens? OR should I just switch the MAF translator to 10% lean at idle?
 
I had the same problem with my blms going to low about 115 after fixing a high blm problem, just set your translater to 10% lean at idle, and then you should be pretty close , after that just play with fuel pressure to get it as close to 128 , that should do it, at least that is what did it for me. good luck.
 
Yes, make your adjustments with the Translator, NOT adjusting fuel pressure. This is afterall what it's for!
Get your base (static) fuel pressure back up to around 42-43 where it belongs, and then use the Translator to make your adjustments.
 
Thanks guys. I set the translator to 10% lean/base. Now BLMs sit at 122. Is that good enough??
FP is still at 40 right now.

Justin
 
Originally posted by Razor
Get rid of the check valve.
I was thinking of experimenting with that ;) see what happens.
May not have to though: this evening I swapped chips. Put in my JL street chip that was burned for my car. BLMs went from 122 to 130s. As high as 136 or 138, cant remember. Usually settled around 134 or a tad lower. So now I guess, I could probably stand to change the translator base setting back to normal :rolleyes: , probably put #s at 128~.
This is the only chip that I have that was actually burned with 37lb Del Phi injectors in mind. All my other chips are actually for 36lbers. If I wasnt so curious (anal :p ) and looked up the #s on my injectors I never would have known they were 37lb. They were sold to me as 36lb from Poston. Maybe just enough difference between 36 and 37lb to make a noticeable change in block learn readings when fine tuning?
 
Easiest way to change fuel pressure, is change injector constant on the chip. Aside from turning the allen screw on top of your FPR :D

So dont go by the "has to be 43 lbs" all the time..unless you can fudge with the IC inside the chip. Also dont get too caught up with chasing that number, you will go nutz.. just get them close..your there. Me 124-132 as an average.. i'm done messing with it.

Bet your gas mileage will soar now :)
 
line off on my car is 37psi static line on is about 32, and i dont have any problems with KR or anything of that sort, bigger injectors flow much more fuel than stocker, the 43psi static all the time is a myth it mostly applies to stock injectors not bigger injectors , just think about it for a minute if you have bigger injectors you dont have to have as much FP to give the car what it needs, unless your having fuel problems on top end, if i was you i would set your FP down to 37/38 static and that should put you right around 126 blm range if you have any problems with KR just lower the boost, it worked for me i am sure it will work for you.

BTW i have 42.5 bosch inj.
 
Thanks everyone. I think its getting there...."I love it when a plan comes together". Aint nothing like getting ever so closer to wright. Should have the car 100% before the end of this decade :eek: :rolleyes: :D ;)
 
Originally posted by wiked87gn
line off on my car is 37psi static line on is about 32, and i dont have any problems with KR or anything of that sort, bigger injectors flow much more fuel than stocker, the 43psi static all the time is a myth it mostly applies to stock injectors not bigger injectors , just think about it for a minute if you have bigger injectors you dont have to have as much FP to give the car what it needs, unless your having fuel problems on top end, if i was you i would set your FP down to 37/38 static and that should put you right around 126 blm range if you have any problems with KR just lower the boost, it worked for me i am sure it will work for you.

BTW i have 42.5 bosch flouresent green tops they flow really nice.

There's nothing mythical about it. When injectors are flowed, they are done so at about 3 bars of atmosphere. That's about 42.5psi.
That's the reason it's always best to get the best state of tune at or around that fuel pressure. And if your chip is set up right then the BLM's "should" be in the ball park (118-138) at that fuel pressure.

What is a myth is always chasing the perfect BLM. Unless the cell(s) are locked or open loop, it can't be achieved all the time. That's the reason they're there, to compensate for various changes, like atmosphere, weather, driving, etc. etc.
 
Originally posted by TurboDave
What is a myth is always chasing the perfect BLM. Unless the cell(s) are locked or open loop, it can't be achieved all the time. That's the reason they're there, to compensate for various changes, like atmosphere, weather, driving, etc. etc.


Exactly! Chasing the "128" is a waste of time. If the BLMs are maxed out like you first had, there is a problem and you need to find it. If not, it's not that the car is running bad. The computer still made the fuel ratio correct, it just had to go a little more than "people like to see." 10 +/- is fine, even more is fine. As long as it isn't maxed out or close to max, the computer is still able to achieve the correct air/fuel ratio. If it is close to max, a differant program might help, a little less/more here or there depending where your car needs the help. If it runs good, LEAVE IT!

Unless it's running bad, stick to the WOT tuning and let the computer take care of itself for the drivability. That's what it's there for. It's nice though to know what you regular BLM #s are in case of a drastic change, telling of a broken vacuum line or other problem.
 
Originally posted by wiked87gn
<snip> so far i got my FP line off set at 38 static and my blms are 128 132 range at idle and Drive, if i move FP up to 43psi my blm's shot straight up to 138-140 range, and the car runs rich on top end, i guess every car is different my is probably one of those where you dont need tons of FP to make run right.

wikedGN


Huhh???? :confused:

You have good BLM's and you increase FP and your BLM's go up???????

When did the laws of fluid dynamics take a 180° turn?? ;)

There are lot's of us around that have been around turbo Buicks for far more years than even I'd like to remember. That's all I'll say on that matter.

As for going up in injector size and them liking lower fuel pressure, well, actually it's nothing to do with the fact they're larger. It's all in the way the chip's cut, injector constant, and maf tables, etc. That's like buying 55# injectors and running them below 40psi static, just to shoot for good blm's. All you've managed to so is turn those 55's into 50's or less. Could save some money and buy smaller injectors and run them at the proper fuel pressure.

But enough of that, I really don't care to argue that point. I've been around these cars way too long to change my mind on the fueling aspects and how it should be accomplished.
 
I am searching on BLM issues and came across a thread.....this was a post in that thread. It seems to be contradicting the above information. I am not trying to flame anyone...just trying to solve my BLM problem.

http://www.turbobuick.com/forums/showthread.php?s=&threadid=101901

Originally posted by wiked87gn
this is my personal experience, my blm's were hitting upwards off 152 and sometimes close to 160 , problem was my fuel pressure was too low it was set at 36 static, i move it up to 43 static and my blm's went down to 130 range, with no other change made, you should try increasing the fuel pressure see what happens. good luck.
 
Originally posted by BlownZ
I am searching on BLM issues and came across a thread.....this was a post in that thread. It seems to be contradicting the above information. I am not trying to flame anyone...just trying to solve my BLM problem.

http://www.turbobuick.com/forums/showthread.php?s=&threadid=101901

High BLM means ecm thinks car is lean and is adding fuel. So low fuel pressure means its lean and the ecm is adding fuel. Vacuum leak same thing.

O2 says lean, ecm adds fuel to richen it up.

Dont know why it thinks its lean.. this is the problem posted and resolved.

HTH
 
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