High BLM's during cruise
- Thread starter 87T
- Start date
PE is not used during cruise, so that's absolutely the WRONG thing to be tweaking for that problem.
It's very complex, but the MAF tables for the load/rpm range you're talking about are about the only way to tweak up cruise BLM's.
Making your own chips is not for the faint of heart!! Trust me, you can spend the next several years learning to get it right.
It's very complex, but the MAF tables for the load/rpm range you're talking about are about the only way to tweak up cruise BLM's.
Making your own chips is not for the faint of heart!! Trust me, you can spend the next several years learning to get it right.
maf count// gm/sec ????
Using the TunerCat program when I look at any of the [6] maf tables at the top I see "count" on the left side and "gm/sec" on the right side of the table, gm/sec being the part of the table that is adjustable.. what does "count" and "gm/sec" mean ???? And which way do I go when I adjust the gm/sec scale.... I tried increasing all the tables a +5 on the "increment selected table value" and saw no changes to my cruise BLM of 105,,,,do you know of any printed information that I can read that would help explain what each Table does to a chip???? thanks for the info....Robert
Using the TunerCat program when I look at any of the [6] maf tables at the top I see "count" on the left side and "gm/sec" on the right side of the table, gm/sec being the part of the table that is adjustable.. what does "count" and "gm/sec" mean ???? And which way do I go when I adjust the gm/sec scale.... I tried increasing all the tables a +5 on the "increment selected table value" and saw no changes to my cruise BLM of 105,,,,do you know of any printed information that I can read that would help explain what each Table does to a chip???? thanks for the info....Robert
It's difficult to explain, but I'll try a short version, and I just figured it out trying different things, although I haven't figured out how to adjust the first value in the table out of specific ranges, its seems to be limited somehow...and I havent spent much time trying to figure it out.
But essentially, the gms for a given reading from your MAF converts to a "count" which is used for fueling...the more counts for a certain gms, the more fuel.
With that in mind, to make a leaner mixture at a certain gms reading, the "coutns" need to be lower, so you would shift the gms readings in the table down some so that a corresponding gms reading would now correlate to a lower "count" #.
As you shift the table in the "area of concern", be sure the next table starts with nearly the same gms reading as the previous table ended on. (This is where you will find a limit on what that starting entry in each table is limited by some value somewhere.)
Luckily, mine weren't to far off so I havent been concerned with it.
Also, you can try raising the flow rate constant for the injectors to lean it up some across the board, then adjust the PE fueling when in Power Enrichment mode by RPM.
But essentially, the gms for a given reading from your MAF converts to a "count" which is used for fueling...the more counts for a certain gms, the more fuel.
With that in mind, to make a leaner mixture at a certain gms reading, the "coutns" need to be lower, so you would shift the gms readings in the table down some so that a corresponding gms reading would now correlate to a lower "count" #.
As you shift the table in the "area of concern", be sure the next table starts with nearly the same gms reading as the previous table ended on. (This is where you will find a limit on what that starting entry in each table is limited by some value somewhere.)
Luckily, mine weren't to far off so I havent been concerned with it.
Also, you can try raising the flow rate constant for the injectors to lean it up some across the board, then adjust the PE fueling when in Power Enrichment mode by RPM.
That makes sense
okay, that makes sense, lower the number of for a leaner mixture,,my car has always been on the rich side,,,,,I was trying not to change the constent from 42.5 but it seems to be what most people do to get better BLM's or at least closer to 128,,,,105 at cruise is to much fuel being removed,,,,,,Do you ever change the "closed loop enable cool temp threshold" in the consteant table ????? thanks
okay, that makes sense, lower the number of for a leaner mixture,,my car has always been on the rich side,,,,,I was trying not to change the constent from 42.5 but it seems to be what most people do to get better BLM's or at least closer to 128,,,,105 at cruise is to much fuel being removed,,,,,,Do you ever change the "closed loop enable cool temp threshold" in the consteant table ????? thanksRe: That makes sense
As far as the closed loop threshold, I can't recall what it should be set at, but I have not changed mine, but then again, I started with an aftermarket chip that was already tweaked for a 160 thermostat, that would be the only reason I could see for changing that value. I'll check this evening when I get home and see if its any different from a stock chip.
And make sure you don't have another problem that's causing the low BLMs before trying to correct it in the MAF tables, like bad O2, bad MAF, stuck injector. Use only an AC Delco O2, I've had bad luck with Bosch sensors, and make sure the Cross-counts are very active, cycling 0-255 in 90 seconds or less.
Remember, your injectors may not truely flow 42.5#/hr, its not uncommon of the ECM to be programmed with a lower number for the constant than what the injectors are advertised to flow, even a totally stock program for alot of GM cars will have a lower constant.Originally posted by 87T
I was trying not to change the constent from 42.5 but it seems to be what most people do to get better BLM's or at least closer to 128,,,,105 at cruise is to much fuel being removed,,,,,,Do you ever change the "closed loop enable cool temp threshold" in the consteant table ????? thanks
As far as the closed loop threshold, I can't recall what it should be set at, but I have not changed mine, but then again, I started with an aftermarket chip that was already tweaked for a 160 thermostat, that would be the only reason I could see for changing that value. I'll check this evening when I get home and see if its any different from a stock chip.
And make sure you don't have another problem that's causing the low BLMs before trying to correct it in the MAF tables, like bad O2, bad MAF, stuck injector. Use only an AC Delco O2, I've had bad luck with Bosch sensors, and make sure the Cross-counts are very active, cycling 0-255 in 90 seconds or less.
Also, with the stock maf tables and most chips larger than stock, the idle blm (top left on direct scan) and blm15, used at wot (bottom right on the ds table) tend to be higher than the cruise blms (second and third from the top, rightmost column on ds) by as much as 20-30, so what lots of people do is adjust the injector constant so that these all kind of average 128 even though none of them are perfect. For example, get the idle and wot to maybe 135-140 and the cruise ones to maybe 115-120.
I have replaced the o2 with a GM one,had a bad MAF sensor so I put in a Translator, cross counts seem to be okay they go the full range... Is there ANY POSSIBILTY that a bad SPEED SENSOR could cause any problems,every one in a while I get a CODE 21 'bad VSS" is there a chance that it is confusing the ECM ???????? I need to check my injectors they are farily new but one could be stuck open and I don't know it
To check for the stuck injector, while running either try the screw driver on the injector technique and it will magnify the clicking noise, or use a small piece of rubber tubing, or I use one of my wife's old stethoscopes with the end removed and replaced with a piece of steel tubing, and listen for the clicking.
Anyway, the fan on/off and closed loop threshold temps are adjusted in the aftermarket chips. Stock the values are 92/89 and 32 C respectively, and my JC chip had them at 76/73 and 24.5 C
Anyway, the fan on/off and closed loop threshold temps are adjusted in the aftermarket chips. Stock the values are 92/89 and 32 C respectively, and my JC chip had them at 76/73 and 24.5 C
Mike Licht
I was here first
- Joined
- May 23, 2001
You can adjust fuel with a translator as well the + will adjust timing. That is the difference
Mike Licht
Mike Licht