Well, @!#$ this pcm. I randomly this week figured out the cold startup super rich issue and how to fix it. I was trying to figure out why my idle map was super rich in the top left hand corner. I remember I put it there to fix some stalling and lean issues when I first started the car. So this week I pulled that back down to be like the rest of my idle map. Low and behold I was idling at ~20:1 afr when the engine was warming up. Added some more fuel back in the same spot, went to 17:1, added even more and was back to seeing the 12:1 i should be seeing on cold startup. Why is just that random part of the map controlling this? I have no clue because its not actually on that part of the map.
Below is the circle part of the map that I think effects it.
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Double check your target idle speed table. Maybe when your engine is cold it is calling for 1300-1600 rpm.
It is, but its not hitting those cells. its in the 40-50 kpa of vac.
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I know it's in the 40-50kpa of vac. That is what Idle is, and that's what you circled in that weird black shape thing.
I'm assuming that you are meaning that you added fuel in all the cells ranging from 1300-1600 rpm, and 40-80kpa of vac?
Either way, tables reference each other and if you happen to have values that are conflicting, it causes weird issues. Increasing the 80 or 70kpa Idle cells won't increase your idle AFR. Simply because you are idling at 40-50kpa.
Double check your Low RPM single and double tables. The 0.0% throttle cells (the ones that range from 600-1600) should cross reference with the idle VE table.
(eg. If your car is pulling 40kpa at idle, then the 40kpa cells on the idle table (a bit of general smoothing required) should be the same as the 0.0% throttle cells on the Low RPM tables, in reference to engine RPM)
Ninja post. That 2nd paragraph should state "Increasing the 80 or 70kpa Idle cells won't RICHEN your idle AFR. Simply because you are idling at 40-50kpa"
Yes it shouldnt and it doesnt effect idle once warm. But its made a distinct impact on the cold startup that everyone complains is too rich and they cant fix.
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2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
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Sponsored by:
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weird mine's not like that... and i too have the rich cold start... its because of that missing IAT multiplier...
Weird. one more reason to hate this damn computer.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
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WPI SAE Risk and Sustainability Management Officer
Leafy (Club Jeffie FEA man) wrote:Yes it shouldnt and it doesnt effect idle once warm. But its made a distinct impact on the cold startup that everyone complains is too rich and they cant fix.
I hate stooping down and doing what everyone else does, which is call you out, and say you give false advice.
But, I had this same 'extremely rich' (10:1 or 11:1) cold startup issue that everyone else is having.
I fixed my cold startup issue in HP Tuners, as well as a few others on here with the 03/04 PCM....maybe you should double check everything again, or may I suggest you take your car to a real tuner to do it for you.
Well you fixed yours. And now you've tuned 3 cars, would it really surprise you if the computer in this car was this fake? I mean come on, only obdii production car with alpha-n, the spark advance is always more than what you command if you run anything but a 1 bar map, I'm surprised the tune doesnt work with injector pulse width and not VE.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
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WPI SAE Risk and Sustainability Management Officer
Erik Nyman wrote:Leafy (Club Jeffie FEA man) wrote:Yes it shouldnt and it doesnt effect idle once warm. But its made a distinct impact on the cold startup that everyone complains is too rich and they cant fix.
I hate stooping down and doing what everyone else does, which is call you out, and say you give false advice.
But, I had this same 'extremely rich' (10:1 or 11:1) cold startup issue that everyone else is having.
I fixed my cold startup issue in HP Tuners, as well as a few others on here with the 03/04 PCM....maybe you should double check everything again, or may I suggest you take your car to a real tuner to do it for you.
So what's different in the 03/04 pcm? Only thing i've found is cranking ve.
I'm just going to keep my mouth shut...... Carry on!
P&P Tuning
420.5whp / 359.8wtq
Slo-Ryan is not adding to the thread because it's made by leafy. He's waiting for further amusement.
I was hoping he'd add something. I'm puzzled as to why changing only those cells only effected cold startup and nothing else. Especially when my log data shows that I never see 60 or more kpa of vac. I cant figure why tuning cells it never sees makes such a large change, and its cant interpolation from nearby cells, for how large of a change I was seeing.
Also note that some/all 02 pcms have the idle tables in manifold vacuum and all the 03+ pcms I've looked at have the idle table in the normal absolute manifold pressure.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
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WPI SAE Risk and Sustainability Management Officer
During cold start up, the Commanded AFR are modified by the PCM. He drop to 2:1 in very cold ECT and IAT just before start up. With Hptuners, we don't have acces to this table of AFR Cmmd modifier start up vs IAT and ECT. AFR commanded are the base of injection with the Injector constant. Try this, change your base AFR target value in PE to 8:1 afr and you will see your AFR PE with the same VE are not the same. If you change the AFR base target cmmd value you change the AFR in PE without any change of the VE. If you understand that, it's the same @!#$ with your Cold start too rich because of AFR cmmd by the pcm.
Boost Lover
No, at lot of people were having an issue of it being richer than commanded. I know what a commanded afr table does, and why its awesome.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
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WPI SAE Risk and Sustainability Management Officer
Leafy (Club Jeffie FEA man) wrote:No, at lot of people were having an issue of it being richer than commanded. I know what a commanded afr table does, and why its awesome.
please read.
Quote:
With Hptuners, we don't have acces to this table of AFR Cmmd modifier start up vs IAT and ECT
The fact we do not have this table is the issue. This has been known for a long time, and is not that big of a deal really.
FU Tuning
Leafy (Club Jeffie FEA man) wrote:No, at lot of people were having an issue of it being richer than commanded. I know what a commanded afr table does, and why its awesome.
Datalog your cold start and look your commd AFR low res or SENS.121 and you will see what i say. You can't modify your cmmd afr during cold start then you can't have issue. That the lower cmmd afr control by PCM during cold start who richen up the cold start.
Boost Lover
I KNOW. I'm saying that I and some other people (seemed like at lot of people) were still commanding normal cold start afrs but were getting retardedly rich ones instead. I know we cant adjust it. Like I said before, I would see a commanded afr of like 11 but get getting like 10 on the wideband, now I have a cmd afr of 11 and see around 11. (numbers are +/- e)
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Sponsored by:
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WPI SAE Risk and Sustainability Management Officer
Be explicit man ! why you change your cmmd AFR on Cold Start. ? mine always go below 5:1AFR wend IAT&ECT are near 0C. I try to up the Cmd afr vs ECT (PE Table) on lower ECT but nothing have change for WB afr
It's why i think he don't have issue with this...
Boost Lover
No member edit : Be explicit man ! how you change your cmmd AFR on Cold Start. ? mine always go below 5:1AFR when IAT&ECT are near 0C. I try to up the Cmd afr target vs ECT (PE Table) on low ECT but nothing change for WB afr. It's why i think he don't have issue with this...
Boost Lover
your commanded afr on startup is 5:1? Optionally it should taper from 9:1 - 12:1 depending on how cold it is to stoich until the coolant gets to 80-100 or so. Gm commanding 5:1 would make the car not run. That much gas would put the fire out, and make the car fail the epa tests.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
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WPI SAE Risk and Sustainability Management Officer
Leafy (Club Jeffie FEA man) wrote:your commanded afr on startup is 5:1? Optionally it should taper from 9:1 - 12:1 depending on how cold it is to stoich until the coolant gets to 80-100 or so. Gm commanding 5:1 would make the car not run. That much gas would put the fire out, and make the car fail the epa tests.
I can send you a log of that if you don't believe me. On -20C IAT condition, i've seen 2:1 cmmd AFR for few seconds... my WB AEM stay @ flash 10.0AFR for long time Idle lol. When ECT gets to 50-55C like you say, the cmmd always are stoich. If your does the same, it's normal.
Boost Lover
