Maybe a dumb question but.....
04-07-2006, 09:29 PM
#1
Maybe a dumb question but..... How do I change AFR only at idle while in SD open loop mode before the temp gets high enough to go into closed loop SD? What does the VCM use to fuel open loop before closed loop?
Do you guys just lower the Closed Loop temp so you are in Closed Loop SD mode right from startup?
Do you guys just lower the Closed Loop temp so you are in Closed Loop SD mode right from startup?
04-18-2006, 09:44 AM
#4
Originally Posted by HumpinSS
Use the Open Loop Fuel Air table
My AFR on initial startups is very high 17-18.0:1 and then slowly after a couple of minutes comes back down to around 15.0:1
04-18-2006, 09:51 AM
#5
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Originally Posted by 99whitews6
Is this the ONLY thing the computer using for fueling on open loop startups before closed loop is enabled? If I change all the values in the table to 1.0 as a multiplier shouldnt I see 14.7 AFR on my wideband at idle? How would it achieve this AFR without using O2s for a feedback loop? or does it use O2s on open loop?
My AFR on initial startups is very high 17-18.0:1 and then slowly after a couple of minutes comes back down to around 15.0:1
My AFR on initial startups is very high 17-18.0:1 and then slowly after a couple of minutes comes back down to around 15.0:1
The engine needs more fuel when it is dead cold. That's what this table is for... to compensate for engine temperature.
If your normal operating range is say 160*F to 210*F then it is okay to make entries in that area 1.0
but you will need more fuel when colder.
Then engine isn't going to be happy at 14.7 AFR during a dead-cold start.
Even if the entry was 1.0 you would still be leaner than 14.7 on your wideband because the engine simple needs more fuel for a cold start. The chamber and plugs don't have enough heat yet, so the burn is much slower and often incomplete.
The computer does not use the O2's during open loop.
04-18-2006, 09:54 AM
#6
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Originally Posted by white2001s10
NO. Don't change that table to all 1.0
The engine needs more fuel when it is dead cold. That's what this table is for... to compensate for engine temperature.
If your normal operating range is say 160*F to 210*F then it is okay to make entries in that area 1.0
but you will need more fuel when colder.
Then engine isn't going to be happy at 14.7 AFR during a dead-cold start.
Even if the entry was 1.0 you would still be leaner than 14.7 on your wideband because the engine simple needs more fuel for a cold start. The chamber and plugs don't have enough heat yet, so the burn is much slower and often incomplete.
The computer does not use the O2's during open loop.
The engine needs more fuel when it is dead cold. That's what this table is for... to compensate for engine temperature.
If your normal operating range is say 160*F to 210*F then it is okay to make entries in that area 1.0
but you will need more fuel when colder.
Then engine isn't going to be happy at 14.7 AFR during a dead-cold start.
Even if the entry was 1.0 you would still be leaner than 14.7 on your wideband because the engine simple needs more fuel for a cold start. The chamber and plugs don't have enough heat yet, so the burn is much slower and often incomplete.
The computer does not use the O2's during open loop.
That is the job of the afterstart enrichment table
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04-18-2006, 09:58 AM
#8
Originally Posted by HumpinSS
That is the job of the afterstart enrichment table .
.
So I should jsut change them all back to stock, then leave all the values above 160F at 1.0?
What/When is the difference between OFLA table and Afterstart Enrichment initial adders tables?
Last edited by 99whitews6; 04-18-2006 at 10:06 AM.
04-18-2006, 10:01 AM
#9
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I guess i shouldve been a little more clear. You can set the OLFA table to 1.0 all the way across the board and use the After startenrichment table to add fuel in the colder temps. The stock values work great when you set the OLFA table to 1.0. I think at the colder temps you get 1.70@40* (1.0 + .70 from afterstart enrichment) and so on an so forth. 1.70 is way more than enough fuel to keep the car running while cold
Edit @ 25* it is .70 + 1.0 form the OLFA table will give you 8.6:1@ startup. Can you say black smoke
Edit @ 25* it is .70 + 1.0 form the OLFA table will give you 8.6:1@ startup. Can you say black smoke
04-18-2006, 10:07 AM
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Looking at my afterstart enrichment decay delay table, it looks like the enrichment only lasts for <100 engine revolutions. Or am I reading something wrong? Isn't this too short to help open loop fueling very much??
04-18-2006, 10:08 AM
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Yes you have a decay rate a delay rate and a factor that you can mess with. I have left these alone though. This Afterstart Enrichment table acts like a choke and as the engine warms up or is warmed it leans itself out going solely off of the OLFA table.
04-18-2006, 10:11 AM
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Originally Posted by muncie21
Looking at my afterstart enrichment decay delay table, it looks like the enrichment only lasts for <100 engine revolutions. Or am I reading something wrong? Isn't this too short to help open loop fueling very much??
Next time you log the car log commanded AFR from a dead cold and watch how long it takes for the car it transition fully to the OLFA table. It will be a little clearer if you set the olfa table to 1.0 though. If you want you can always up how fast it decays and how long before it starts to decay.
04-18-2006, 10:54 AM
#19
Originally Posted by HumpinSS
are you having an issue going from P/N to in gear. And if you do make sure you raf tables are close for both scenarios. then move from there
04-18-2006, 11:03 AM
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Originally Posted by 99whitews6
Is this the ONLY thing the computer using for fueling on open loop startups before closed loop is enabled? If I change all the values in the table to 1.0 as a multiplier shouldnt I see 14.7 AFR on my wideband at idle? How would it achieve this AFR without using O2s for a feedback loop? or does it use O2s on open loop?
My AFR on initial startups is very high 17-18.0:1 and then slowly after a couple of minutes comes back down to around 15.0:1
My AFR on initial startups is very high 17-18.0:1 and then slowly after a couple of minutes comes back down to around 15.0:1
Do you still have your air pump installed/enabled ?
That will cause it to read lean on the wideband until it turns off, as it's pumping air into the exhaust at startup.
Otherwise OLFA table accompanied by startup enrichment tables control A/F at startup (prior to falling into closed loop).
Rob (Bad30th)