Cold start AFR

2kCivicSi · Post by **2kCivicSi** » Mon Jan 14, 2008 8:53 am

Cold weather is a rarity here and when it hits it doesn't stay cold for long.. When it hit 30's F here my car had trouble starting and staying running for about 1-2 minutes until it warmed up a little. I didn't have my laptop at the time. My friend couldn't even start his car (He is OBD0) both are B16 N/A setups. What AFR should we be aiming for in freezing temperatures? I may only get 1-2 more chances this month... if I'm lucky. Is there any way to simulate the condition (IE connect the ECT/IAT to a trimpot dialed down to match the correct resistance at 30F)?

borat · Post by **borat** » Mon Jan 14, 2008 5:37 pm

Because fuel doesn't atomize well at low temperatures, the ECU needs to inject more fuel to get the engine to idle well. You shouldn't really aim for an AFR when it's cold, it's more of an experiment to find what values let the engine run well enough until everything is warmed up. Thus you can't just \"simulate\" a cold start, since the problem is caused by cold fuel trying to burn correctly. Cold-start is one of the hardest things to tune, since the only way to do it is when the engine is stone-cold. Currently mine is running lean (16.5:1 AFR) when starting in temps right at freezing. The engine is running fine at this AFR, but I figure I can richen it up a little for peace of mind. Most engines run rich during cold-enrichment due to the extra fuel needed to idle correctly, so if you find that you need a 13:1 AFR to run well during warmup, so be it.

Almighty-Si · Post by **Almighty-Si** » Mon Jan 14, 2008 5:58 pm

Unfortunetly I get many freezing cold days being in the Northeast but my B16 on initial startup to about a minute in is 13.0-13.2 after the minute 14.0. What I need to fix is ECT right around 100deg gets 12.3's

2kCivicSi · Post by **2kCivicSi** » Mon Jan 14, 2008 11:32 pm

100F is easy to hit because you can just idle it and hit that temp gradually. I only get 1 shot with 30F unless I pull an all-nighter when it is supposed to hit cold.. by 9am it is already 50-60's and high of 70's by 3pm

non-vtec · Post by **non-vtec** » Tue Jan 15, 2008 5:57 pm

its below freezing here most winter days. my a/f goes from 14:1 to around 11:1 about 5 seconds after it starts.....it will start and idle fine between 11:1-14:1 i was having an issue trying to get it to idle/start correctly as it was dumping so much fuel that it would flood/stall (below 9:1a/f). i had to play around with the cranking trim in the fuel trims and post fuel maps to get it right. since you are having trouble keeping it running look into the post start maps or maybe even the ECT/IAT correction. you want it to run a little richer on cold starts...

2kCivicSi · Post by **2kCivicSi** » Tue Jan 15, 2008 7:22 pm

on start today it was running in the 11's. I waited for the O2 heater to fully heat before I started so I got an accurate idea. I tried to reduce a few of the ECT trims but I think this is not where it needs adjustment. I also noted that with ECT at 180 and IAT at 50's I was idling in the 14's where in the 70+ IAT I am idling at 15-16, where we tuned it to..

2kCivicSi · Post by **2kCivicSi** » Sat Jan 17, 2009 4:00 pm

Back to working on this. After I met up with Dave at PRI, I made a few changes to my ECT trims. I'm not sure if I'm headed in the right way or what may be too much correction.. is there a limit to it? Of particular concern/problem is when my ECT is between 30 and 60F. The car barely idles around 500rpm or tries to surge (1100rpm) and dip(200rpm) almost to stalling. Once ECT's get up about 70F, the car smooths out, idles up and runs better. I tried putting the ETC fuel correction in the affected cell progressively higher up to about 80 units but it only moderately helped. AFRs in the 10-12 range.

2kCivicSi · Post by **2kCivicSi** » Wed Jan 21, 2009 10:42 pm

I don't know if it's fixed, but I changed the ECT timing from 3.00 to 28.00 for the temperature I was having trouble, and when I started today at 45F, it ran much better. I made a few other tweaks to IAT compensation for same temperature.. if it works, I'll post the new cal..

elevation · Post by **elevation** » Thu Jan 22, 2009 4:01 pm

the ect correction doesnt look like it has been changed much. timing is going to be more for fine tuning the cold start. I run way less fuel in the ect corrections.hope this helps

Post by **Gaskleppie** » Thu Jan 22, 2009 4:30 pm

Ervin has made a nice solution for this problem. Calvin is working on it. In the mean while you can try this:

Many people have problem with idle when car (engine) is cold in winter time. Today i discovered how to fix this. It is not the correct way it should be, but if you make it you will never got a call from your customer that car can't idle (or it is idle rough) when it is cold (or it dies when you touch gas pedal and release it). I discovered if ECT is below 12c (54F) )in winter days it idles at around 10.5 to 11.2:1 AFR which is too rich and the car idles rough or even dies if you touch gas pedal. To avoid this problem i made it this way: (step by step) 1. copied primary maps to secondary maps. 2. secondary fuel maps made 20% leaner 3. in parameters/secondary maps i made them Condition based 4. in parameters/output1 i made Enable GPO1 and \"switch to secondary maps on output\" enable 5. GPO activation conditions i put: engine speed 30-2000rpm MAP 11-600mbar coolant temp -26C(min) to 12C(max)this was the most important) IAT (the same as ECT) TPS -5% (if you put it as 0 it won't work, i tried, believe me This setup makes your car idle around 13.5-13.7:1 AFR at start up in very cold weather (on secondary map) and it switches to primary map when ECT reaches 12C (54F), this is usually after 120-150 seconds after start-up. i tried this on 5 cars and i got zero complaint. Before that i received many complaints from my customers. I know this is not the right way to make tuned program, but it fixes all cold idle related problems in cold winter days. i spoked about this with Calvin and he told me he will fix this one day, but for now he admit i discovered great \"tool\" to minimise this problem. i hope this will help somebody and i hope you understand me somehow as English is not my native language. Regards, Ervin.

elevation · Post by **elevation** » Thu Jan 22, 2009 9:05 pm

Gaskleppie wrote:Ervin has made a nice solution for this problem. Calvin is working on it. In the mean while you can try this:
Many people have problem with idle when car (engine) is cold in winter time. Today i discovered how to fix this. It is not the correct way it should be, but if you make it you will never got a call from your customer that car can't idle (or it is idle rough) when it is cold (or it dies when you touch gas pedal and release it). I discovered if ECT is below 12c (54F) )in winter days it idles at around 10.5 to 11.2:1 AFR which is too rich and the car idles rough or even dies if you touch gas pedal. To avoid this problem i made it this way: (step by step) 1. copied primary maps to secondary maps. 2. secondary fuel maps made 20% leaner 3. in parameters/secondary maps i made them Condition based 4. in parameters/output1 i made Enable GPO1 and "switch to secondary maps on output" enable 5. GPO activation conditions i put: engine speed 30-2000rpm MAP 11-600mbar coolant temp -26C(min) to 12C(max)this was the most important) IAT (the same as ECT) TPS -5% (if you put it as 0 it won't work, i tried, believe me This setup makes your car idle around 13.5-13.7:1 AFR at start up in very cold weather (on secondary map) and it switches to primary map when ECT reaches 12C (54F), this is usually after 120-150 seconds after start-up. i tried this on 5 cars and i got zero complaint. Before that i received many complaints from my customers. I know this is not the right way to make tuned program, but it fixes all cold idle related problems in cold winter days. i spoked about this with Calvin and he told me he will fix this one day, but for now he admit i discovered great "tool" to minimise this problem. i hope this will help somebody and i hope you understand me somehow as English is not my native language. Regards, Ervin.

Did you see his ect corrections? @ 30 deg F he has 40, I have 25. @167 deg F he has 12, I have 2. Why is it that I don't have a problem with this?

2kCivicSi · Post by **2kCivicSi** » Thu Jan 22, 2009 9:54 pm

Did you see his ect corrections? @ 30 deg F he has 40, I have 25. @167 deg F he has 12, I have 2. Why is it that I don't have a problem with this?

Originally, that's what my ECT corrections were.. but I made a small improvement by adjusting my ect corrections with those changes. Before, when temps were in the 60s even, it was surging and the colder it was the worse... now it is stable above 55F and surges when below. You're saying to reduce AFR by 20%...? What do you do about the table differences? My 2nd table the RPM jumps to 3500 RPM in the 2nd row... so without losing high-rpm scale that doesn't seem like a good solution...

elevation · Post by **elevation** » Fri Jan 23, 2009 11:39 am

2kCivicSi wrote:
Did you see his ect corrections? @ 30 deg F he has 40, I have 25. @167 deg F he has 12, I have 2. Why is it that I don't have a problem with this?
Originally, that's what my ECT corrections were.. but I made a small improvement by adjusting my ect corrections with those changes. Before, when temps were in the 60s even, it was surging and the colder it was the worse... now it is stable above 55F and surges when below. You're saying to reduce AFR by 20%...? What do you do about the table differences? My 2nd table the RPM jumps to 3500 RPM in the 2nd row... so without losing high-rpm scale that doesn't seem like a good solution...

Not the 2nd cam map, the secondary set of maps. copy and paste your primarys and turn them on under 60 deg with less fuel.

xenocron · Post by **xenocron** » Sat Jan 24, 2009 8:21 am

Good idea for a fix Ervin...I'll try and do the same on my car and see if it helps the similar issues I have been having here

civic4g · Post by **civic4g** » Sat Jan 24, 2009 10:59 am

In relation to Ervin fix, wouldn't be enough to just tune ect correction tables? Or is there something wrong with ect fuel compensation?