92 CPI Blazer BLM cells

American Delco GM ECUs and PCMs, ALDL, OBD 1.5.
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cidium
Posts: 21
Joined: Wed May 25, 2011 4:06 pm
cars: 92 s10 blazer

92 CPI Blazer BLM cells

Post by cidium »

Hi,

This is my question, from what I have read there are 16 BLM cells. In addition there are 3 more cells used for idle, braking and CCP. Starting with cell 0 - 15 these are used for normal driving conditions, 16 is used for idle, 17 is used for braking and 18 for CCP. So, here's what I have noticed, my truck is in cell 4 during idle not cell 16. I have compared data with a 93 CPI and his truck idles in cell 16. I know the 93 uses a different eprom from my 92 but should my truck be idling in cell 16? If so what could be causing this problem?

EPROM type: 27C256



thanks
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VL400
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Re: 92 CPI Blazer BLM cells

Post by VL400 »

You would need to get a log of it. In the aussie vehicles the engine idling flag must be set for it to use the idle cell. Maybe yours is not going to idle properly? A log should show what is happening.
cidium
Posts: 21
Joined: Wed May 25, 2011 4:06 pm
cars: 92 s10 blazer

Re: 92 CPI Blazer BLM cells

Post by cidium »

well, I am using TP4 and there is nothing showing idle flag. Here's what I do know from looking at the data. My 92 blazer idles in cell 4, so it makes me wonder if the truck should be in the idle cell which would be cell 16. I have looked at data logs from a 93 blazer and his idles in cell 16. From what I understand the computer goes into cell 16-idle cell if the truck isn't moving and the 0% TPS is showing @ idle rpm. So I should see if the TPS is reporting a percentage at idle, this would confuse the computer. I was wondering if anyone knows if the 92 blazer 4.3l CPI uses the idle cell?

" Cells 16, 17, and 18

Brace yourself, because things are always a little more complicated than we might like. It turns out that there are three more BLM cells than the 16 discussed above. Cells 16, 17, and 18 are considered to be closed loop cells because they do not use the open loop AFR table. But my understanding is that "learning" is turned off in these cells, which means that the BLMs for these three cells won't be adjusted, even if the O2 sensor feedback indicates that the mixture is not as good as it could be. This means that the term "closed loop" is not an accurate description of what's going on, but we use it to remind ourselves that the PCM is using a fixed value of 14.7 instead of the AFR table. Also, PCM scanners will report that the PCM is in closed loop.

Based on looking at tons of logged PCM data, it appears that cell 16 is used only while the engine is idling (0% TPS and idle RPM), cell 17 is used during engine braking (0% TPS and any RPM [?] above idle), and 18 can be used at any MAP and RPM as long as the TPS is not 0%. So how does the PCM decide to use cell 18 (which "covers" the same conditions as cells 0 through 15? It appears to be related to the charcoal canister purge (CCP)."

I got this from: http://para.noid.org/~lj/PCM%20Tutorial/PCMtutorial.htm

Well I just looked at an old log file and the TPS is 0% at idle....

here's a recent adl file maybe someone can look at it?
http://www.4shared.com/file/VeFIcpDM/test005.html
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