Just fired up the "new" engine...O2 sensor tables...
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From: 600 yds out
Car: Bee-Bowdy
Engine: blowd tree-fity
Transmission: sebin hunnerd
Axle/Gears: fo-tins
Just fired up the "new" engine...O2 sensor tables...
I remember reading a few things about tweakin the O2 sensor tables for a big cam. I think it was JeffC1500TBI or Low C1500
who mentioned it. I did a search but could not find the topic. He said something about turning the rich O2 at low air flow down to keep it form going rich at idle.
My engine combo is in my sig. The cam seems to idle around 45 kPa and it jumps to 50-60 kPa when I stomp on the brake (in neutral) or put it in gear. This of course screws the ECM all up and it backs the IAC out all the way. I'm about to go out and set minimum IAC and see what the gets me.
I've been tweaking the VE#1 table but I know I'm going to have to do something with the proportional terms soon.
thanks
who mentioned it. I did a search but could not find the topic. He said something about turning the rich O2 at low air flow down to keep it form going rich at idle.
My engine combo is in my sig. The cam seems to idle around 45 kPa and it jumps to 50-60 kPa when I stomp on the brake (in neutral) or put it in gear. This of course screws the ECM all up and it backs the IAC out all the way. I'm about to go out and set minimum IAC and see what the gets me.
I've been tweaking the VE#1 table but I know I'm going to have to do something with the proportional terms soon.
thanks
Last edited by V8Astro Captain; Jan 25, 2003 at 04:26 PM.
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Re: Just fired up the "new" engine...O2 sensor tables...
Originally posted by V8Astro Captain
I remember reading a few things about tweakin the O2 sensor tables for a big cam. I think it was JeffC1500TBI or Low C1500
who mentioned it. I did a search but could not find the topic. He said something about turning the rich O2 at low air flow down to keep it form going rich at idle.
My engine combo is in my sig. The cam seems to idle around 45 kPa and it jumps to 50-60 kPa when I stomp on the brake (in neutral) or put it in gear. This of course screws the ECM all up and it backs the IAC out all the way. I'm about to go out and set minimum IAC and see what the gets me.
I've been tweaking the VE#1 table but I know I'm going to have to do something with the proportional terms soon.
thanks
I remember reading a few things about tweakin the O2 sensor tables for a big cam. I think it was JeffC1500TBI or Low C1500
who mentioned it. I did a search but could not find the topic. He said something about turning the rich O2 at low air flow down to keep it form going rich at idle.
My engine combo is in my sig. The cam seems to idle around 45 kPa and it jumps to 50-60 kPa when I stomp on the brake (in neutral) or put it in gear. This of course screws the ECM all up and it backs the IAC out all the way. I'm about to go out and set minimum IAC and see what the gets me.
I've been tweaking the VE#1 table but I know I'm going to have to do something with the proportional terms soon.
thanks
RBob.
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From: 600 yds out
Car: Bee-Bowdy
Engine: blowd tree-fity
Transmission: sebin hunnerd
Axle/Gears: fo-tins
oh yeah...sorry. I'm running a 747.
I did some tuning since the first post. The new engine combo wanted ALOT more timing. Wow. It wouldn't hardly idle and tip-in throttle was horrible. I cranked the timing way up and now it idles nicely in park...
...not so well when I put it in gear. It thinks about it...then it starts having a fit. It starts doing that stuff where the engine sounds like it's bogging down and then the IAC starts to go to its max position.
I did some tuning since the first post. The new engine combo wanted ALOT more timing. Wow. It wouldn't hardly idle and tip-in throttle was horrible. I cranked the timing way up and now it idles nicely in park...
...not so well when I put it in gear. It thinks about it...then it starts having a fit. It starts doing that stuff where the engine sounds like it's bogging down and then the IAC starts to go to its max position.
Last edited by V8Astro Captain; Jan 26, 2003 at 03:33 AM.
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Originally posted by V8Astro Captain
oh yeah...sorry. I'm running a 747.
I did some tuning since the first post. The new engine combo wanted ALOT more timing. Wow. It wouldn't hardly idle and tip-in throttle was horrible. I cranked the timing way up and now it idles nicely in park...
...not so well when I put it in gear. It thinks about it...then it starts having a fit. It starts doing that stuff where the engine sounds like it's bogging down and then the IAC starts to go to its max position.
oh yeah...sorry. I'm running a 747.
I did some tuning since the first post. The new engine combo wanted ALOT more timing. Wow. It wouldn't hardly idle and tip-in throttle was horrible. I cranked the timing way up and now it idles nicely in park...
...not so well when I put it in gear. It thinks about it...then it starts having a fit. It starts doing that stuff where the engine sounds like it's bogging down and then the IAC starts to go to its max position.
As for the O2 at idle the gist of the post was that the overlap allows air past the valves tricking the O2 sensor into believing it was lean. The fix was to lower the O2 mV targets levels. On the '747 there are two places to do this.
For 'while in idle' location $2F7 has a value that is added to the desired O2 mV target. That will enrich the mixture during idle.
Then there are the three tables @: $494, $499, & $49E. These three tables define the desired O2 mV target window. They are by airflow.
RBob.
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Transmission: sebin hunnerd
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Alright. So the term at $2F7 offsets the O2 mV in the rich direction?
Is it possible to say at what point you NEED to modify the proportional terms? I have all the papers, and have printed out alot of threads from this board concerning those things. I still don't firmly understand them...mainly because I haven't NEEDED to know it yet.
Thanks RBob. I'm so anxious to tune but it's 17*F outside. Yesterday was a balmy 38*F so I had to take advantage of that!
Is it possible to say at what point you NEED to modify the proportional terms? I have all the papers, and have printed out alot of threads from this board concerning those things. I still don't firmly understand them...mainly because I haven't NEEDED to know it yet.
Thanks RBob. I'm so anxious to tune but it's 17*F outside. Yesterday was a balmy 38*F so I had to take advantage of that!
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Originally posted by V8Astro Captain
Alright. So the term at $2F7 offsets the O2 mV in the rich direction?
Is it possible to say at what point you NEED to modify the proportional terms? I have all the papers, and have printed out alot of threads from this board concerning those things. I still don't firmly understand them...mainly because I haven't NEEDED to know it yet.
Thanks RBob. I'm so anxious to tune but it's 17*F outside. Yesterday was a balmy 38*F so I had to take advantage of that!
Alright. So the term at $2F7 offsets the O2 mV in the rich direction?
Is it possible to say at what point you NEED to modify the proportional terms? I have all the papers, and have printed out alot of threads from this board concerning those things. I still don't firmly understand them...mainly because I haven't NEEDED to know it yet.
Thanks RBob. I'm so anxious to tune but it's 17*F outside. Yesterday was a balmy 38*F so I had to take advantage of that!
Proportional terms, like changing the tables to look like this:
Code:
;*==================================================== ;* Proportional Gain Value vs Slo O2 Error ;* ;* For Selecting Bin Val To Adjust Proportional Gains ;* ;* This table gets multiplied by gain table: LPrpGanOff ;* ;* Prop Correction: ;* ;* L00BC = (PrpSloO2 * PrpGanOff) / 256 ;* ;* Tbl = Bin * 1 ;* ;* The ERR value used for the lookup is from ;* the O2 ERR VAL, this is calc'd from the SLO ;* FILT O2 & R/L O2 thresholds. It is the term ;* of how far from desired we are. ;*==================================================== LPrpSloO2: ;-------------------------------------- ; Bin ; ; O2 Error ;-------------------------------------- FCB 16 ; ; 0 0 mV FCB 16 ; ; 8 35 FCB 16 ; ; 16 70 FCB 16 ; ; 24 104 FCB 16 ; ; 32 139 FCB 16 ; ; 40 174 FCB 16 ; ; 48 208 FCB 16 ; ; 56 243 FCB 16 ; ; 64 278 FCB 16 ; ; 72 312 FCB 16 ; ; 80 347 FCB 16 ; ; 88 382 FCB 16 ; ; 96 417 mV ;*==================================================== ;* Proportional Gain Flow Factor vs Air Flow ;* ;* Used to modify prop gain count. ;* ;* This table is multiplied into tbl: LPrpSloO2 ;* ;* (Skip if in idle conditions, use LD2F9) ;* ;* Tbl = Mult * 256 ;*==================================================== LPrpGanOff: ;-------------------------------------- ; Mult ; Air Flow ;-------------------------------------- FCB 16 ; 0 FCB 16 ; 16 FCB 32 ; 32 FCB 32 ; 48 FCB 32 ; 64
Hmm, 17 out, good time for cold start and cold driveability tuning. Only problem is that you need the normal operating temperature tuning done first.
RBob.
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I understand the math behind what you posted. But I'm not too sure what it will do for me. I read from another post (one that I did save) that this keeps the O2 sensor/integrator logic happy. Is this commonly done to keep the ECM from wildly adding and subracting fuel?
If I understand things right this will still allow the ECM to make fuel adjustments...but they will take longer. Effectively keeping the ECM from oscillating the inj pw.
Am I close?
thanks
If I understand things right this will still allow the ECM to make fuel adjustments...but they will take longer. Effectively keeping the ECM from oscillating the inj pw.
Am I close?
thanks
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Originally posted by V8Astro Captain
I understand the math behind what you posted. But I'm not too sure what it will do for me. I read from another post (one that I did save) that this keeps the O2 sensor/integrator logic happy. Is this commonly done to keep the ECM from wildly adding and subracting fuel?
If I understand things right this will still allow the ECM to make fuel adjustments...but they will take longer. Effectively keeping the ECM from oscillating the inj pw.
Am I close?
thanks
I understand the math behind what you posted. But I'm not too sure what it will do for me. I read from another post (one that I did save) that this keeps the O2 sensor/integrator logic happy. Is this commonly done to keep the ECM from wildly adding and subracting fuel?
If I understand things right this will still allow the ECM to make fuel adjustments...but they will take longer. Effectively keeping the ECM from oscillating the inj pw.
Am I close?
thanks
While tuning w/a locked BLM and using the INT these tables prevent you from chasing your tail. It is common for the INT to be in one direction while the proportional gains are in the opposite. IE: INT of 124 with a proportional term of +8. By the INT it appears to be a rich spot in the VE table. However the proportional term is actually adding fuel above and beyond the neutral point.
RBob.
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From: 600 yds out
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Transmission: sebin hunnerd
Axle/Gears: fo-tins
Now I'm beginning to understand. Now that I'm comfortable with that...
Would it be wise to assume that proportional duration is how long the proportional term is used? Or is the proportional duration a sort of "sampling rate" used by the ECM to capture info?
thanks again
Would it be wise to assume that proportional duration is how long the proportional term is used? Or is the proportional duration a sort of "sampling rate" used by the ECM to capture info?
thanks again
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