What do YOU do about this High BLM condition?

[Jerryl]

Yesterday 93F here and had the BLM’s at 129. They stayed there all day (140 mile cruise). Today, it is 78F and BLM’s are at 138 after a 20 mile cruise.

I realize that the cooler air will permit more fuel and that the ECM does not compensate for temp changes thus incresing the BLM's. Just did not think it would affect it that much.

So, what is everyone doing when the temp and BLM changes? Anything?

 

[Gary Wells]

Reading the "helpful hint thread" on high BLM's that used to be in your signature up until at least last night.

 

[vacuum 6]

Raise your fuel pressue.

 

[TurboDave]

Yesterday 93F here and had the BLM’s at 129. They stayed there all day (140 mile cruise). Today, it is 78F and BLM’s are at 138 after a 20 mile cruise.

I realize that the cooler air will permit more fuel and that the ECM does not compensate for temp changes thus incresing the BLM's. Just did not think it would affect it that much.

So, what is everyone doing when the temp and BLM changes? Anything?

One of the many primary reasons that the BLM's exist in the first place is to compensate for changes in weather, etc. They're doing exactly what they're supposed to be doing.
People should never be lulled into a false hope that, a. they can achieve the ideal number, nor b. that it will stay at that value.
They're working, leave it rest.

 

[Jerryl]

Reading the "helpful hint thread" on high BLM's that used to be in your signature up until at least last night.

Yeah, I removed it. Not sure anyone read these GREAT threads I stumble on.
The real question (with the suspected answer) was;
Don't chase the "perfect BLM" change that is a direct result of weather changes.

Anyone second that?

 

[Mike Licht]

I don't think 138 is anyting to worry about and like Dave said it is doing what it is supposed to do. One thing to add. I get guys that call me all the time and say "my car is tto rich, my BLM is at 120" They don't seem to understand that their car is going to run the same at 120 or 128 that is only shows how much the ECM had had to adjust to get to the target programmed into the chip. It is the ecm telling you "hey you were a little rich but I fixed it" It is when you get to the upper or lower limit that you really have problems. Of course closer to 128 is better when we transition from cell to cell so we do not have stumbles from sudden fuel changes but overall guys get too excited about this sometimes
Mike

 

[Jerryl]

.......... They don't seem to understand that their car is going to run the same at 120 or 128 that is only shows how much the ECM had had to adjust to get to the target programmed into the chip. It is the ecm telling you "hey you were a little rich but I fixed it"

GREAT explanation!

 

[Gary Wells]

Yeah, I removed it. Not sure anyone read these GREAT threads I stumble on. The real question (with the suspected answer) was;
Don't chase the "perfect BLM" change that is a direct result of weather changes. Anyone second that?

---------------------------------
Not trying to be as smartazz, but I was in the process of reading the threads referenced in your signature. I did read all of them. Allthough I do not necessarily agree with every statement in the threads, I think that they are great references and very worthwhile reading. Sorry if my statement was taken for anything else. I think that you have/had some very interesting threads there.

 

[VadersV6]

If your temps sway from 50 degrees in winter to 100 in summer, just tune it for 128 BLM's in 75 degree weather and it will adjust. But, this kind of sounds silly to me. I havent seen any difference in BLM's from weather...well nothing significant. Ive always been more concerned with getting idle BLM's and cruise BLM's as close to each other as possible, with 128 being the target. Took some time to figure it out, but I did it, and driveability is great. No off idle stumble or anything funky going on from the fueling having to change when I raise the rpms.
It sounds like something is starting to open up and leak after the long cruise...not a 10 point drift from weather changes.

 

[Jerryl]

....... Ive always been more concerned with getting idle BLM's and cruise BLM's as close to each other as possible, with 128 being the target. Took some time to figure it out, but I did it, and driveability is great. ........It sounds like something is starting to open up and leak after the long cruise...not a 10 point drift from weather changes.

How do you get idle and cruise BLM to 128 without a chip reprogram?
INT's are right at 128 and stay there at cruise, but, BLM's are 112 at cruise and 129 in P.

As far as something opening up ........ I would tend to agree since this is a major shift IMO for that small of a temp change.

 

[tenright]

Hey Jerryl...May I add an overlooked point here???

78 degrees is a much better temp to have 128 blm then 90+. I would suggest tuning it for 78 degrees....In other words tweak the fp up a couple of points. I would say 128 at 70 degrees would be ideal.


T

 

[Jerryl]

Hey Jerryl...May I add an overlooked point here???

78 degrees is a much better temp to have 128 blm then 90+. I would suggest tuning it for 78 degrees....In other words tweak the fp up a couple of points. I would say 128 at 70 degrees would be ideal.

Understand. :biggrin:
Working with TT to get things finalized. (actually TT working with me ..... :tongue: )

 

[VadersV6]

How do you get idle and cruise BLM to 128 without a chip reprogram?
INT's are right at 128 and stay there at cruise, but, BLM's are 112 at cruise and 129 in P.

As far as something opening up ........ I would tend to agree since this is a major shift IMO for that small of a temp change.

I used to be at about 100 at idle and 140 at cruise, and this was with the extender's BLM adjustment on 1. That's a big adjustment! It took alot of figuring out. Took like a year to finally get there. The biggest change came from getting the updated 6.22 translator chip, and setting it to 3" MAF, even though I have a 3.5. You need to clear the memory every time you make a change to the translator or it will never be right. With this, I was able to bring my BLM offset up to the default of 8. Now the spread was only about 25 points. Like 110 at idle and 135 at cruise. I added a couple of filtered, intentional leaks in the intake tube after the MAF. I used little exhaust mufflers for pneumatic valves. At idle, the 2 leaks add up to a larger percentage of the total air being used at idle. At higher rpms, its a much smaller percentage. This brought my idle BLM's up about 10 points. I replaced all the hoses that were leaking and used a real AC Delco PCV valve. I pulled the intake manifold off and replaced the intake gaskets. By the looks of it, the old steel shim gasket was leaking pretty bad. I also replaced the PCV grommet which was really loose before. I hooked my charcoal canister solenoid up to a power supply here in the lab at work, and found it was sticking. I used pneumatic oil, poured it in and blew it out with an air gun, and then hooked it back up and cycled it till it didnt stick any more. I made my own check valve going to the charcoal canister cause the ones on the car sucked. Deleting the EGR reduced the BLM spread betwen idle and cruise by about 5 points. The extender shuts EGR off anyway, so why deal with the exhaust pressure forcing the EGR valve open and screwing everything up. I installed a Bosch O2 sensor. People like the denso cause it holds up to lead better. But I dont run leaded gas. Ever. The Bosch O2 is wayyyy more active. It cycles 0-255 in about 10-15 seconds. The rest was a matter of fuel pressure, sealing up all exhaust leaks and sweating little details. Now my BLM adjustment is on default (8), and the spread between idle and cruise BLM's are about 5 points at worst. Its usually closer. Naturally I got all the sensors adjusted properly, IAC at about 15, TPS at .44, etc. Now the BLM's got a little screwed up cause I cracked another header, but it only moved it by about 5 points.

 

[Jerryl]

I used to be at about 100 at idle and 140 at cruise, and this was with the extender's BLM adjustment on 1. .............

Thank you for the reply.