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Old 11-30-2007, 03:39 PM   #1
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Default Big cold start improvement

Since it's been cold, I've had a little tougher time with cold starts. Now, part of that was due to the fact that the lower temperature enrichments were not tuned, but the values were assumed as it wasn't cold enough to actually hit those cells, and not until today have I tried to actually tune them. My main problem was that each time I would cold start the car, it would run for only a few seconds then stall. I would start the car again, it would run for a few seconds, then act like it wanted to stall for a few seconds, but it would typically clear up and then go to cold start high idle.

Inspired by my "new" tuning laptop from DropTopDrifter, I decided that today is the day to clear up my cold start issue. Here's the fix:
In MegaTune, go to Crank/Warmup and open ASE Settings. Make sure the ASE Mode is Fixed Then Decay, MAP Mode During ASE is set to Fixed MAP, and set the Time Period to 15 seconds. My previous setting for Time Period was only 5 seconds, so the problem I was having was that when the Fixed MAP period was ending, the actual MAP was not stable enough to appropriately fuel the motor, and my car was going lean and stalling out. Now that I have MAP locked for 15 seconds after start, I am getting good, stable cold starts.

As it gets colder, I'll get my settings locked in better. But for your benefit, here's what I'm running for now:
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Old 11-30-2007, 03:59 PM   #2
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Since it's been cold, I've had a little tougher time with cold starts. Now, part of that was due to the fact that the lower temperature enrichments were not tuned, but the values were assumed as it wasn't cold enough to actually hit those cells, and not until today have I tried to actually tune them. My main problem was that each time I would cold start the car, it would run for only a few seconds then stall. I would start the car again, it would run for a few seconds, then act like it wanted to stall for a few seconds, but it would typically clear up and then go to cold start high idle.

Inspired by my "new" tuning laptop from DropTopDrifter, I decided that today is the day to clear up my cold start issue. Here's the fix:
In MegaTune, go to Crank/Warmup and open ASE Settings. Make sure the ASE Mode is Fixed Then Decay, MAP Mode During ASE is set to Fixed MAP, and set the Time Period to 15 seconds. My previous setting for Time Period was only 5 seconds, so the problem I was having was that when the Fixed MAP period was ending, the actual MAP was not stable enough to appropriately fuel the motor, and my car was going lean and stalling out. Now that I have MAP locked for 15 seconds after start, I am getting good, stable cold starts.

As it gets colder, I'll get my settings locked in better. But for your benefit, here's what I'm running for now:

I found with a fixed MAP setting the idle after *any* start was absolute bobbins as soon as I turned it off everything was fine

Apart from my cold start, I've never been able to get it to consistently start 1st time from cold, and generally the ASE looks *far* too rich (PW's at 5-6x normal), it idles really rough, but never stalls but as soon as the ASE ends it idles fine. leaning out the ASE just means that it won't stay running.
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Old 11-30-2007, 05:17 PM   #3
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I'll check mine. It does not stall, but takes a quite a bit more cranking than normal to get started, and acts like it will stall.
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Old 11-30-2007, 05:21 PM   #4
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I fixed mine. I put it in a garage and haven't started in in three weeks.
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Old 11-30-2007, 05:25 PM   #5
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Yeah I hadn't touched mine in 2 weeks. Might man up and change my front brakes tomorrow.
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Old 11-30-2007, 07:08 PM   #6
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Phewww, its a good thing i don't have to worry about that stuff!! Coldest it'll ever get here is the mid 50's!!! All that sounds like a pain in the ****.
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Old 11-30-2007, 07:15 PM   #7
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I had a little dilemma one night. Parked the miata behind my truck. 4 hours later the temp dropped close to 30*. Colder than i had ever tuned the cold start to. Kind of a pita when you have to tune the car just to move it. Now my cold starts are great though. I have my map lock on for 3 seconds though. I'll try 10 for the heck of it.
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Old 11-30-2007, 08:19 PM   #8
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Good heads up Ben, thanks!

supersuk - add your location to your profile so we know where "here" is.
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Old 11-30-2007, 08:27 PM   #9
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Phewww, its a good thing i don't have to worry about that stuff!! Coldest it'll ever get here is the mid 50's!!! All that sounds like a pain in the ****.
Here it was 59in the garage today , but the day the MS was installed it was probably 80. You can't nail the enrichment at low temperatures without it being cold out. You can only ballpark it. Likely, I'll give it one more go one morning that's really cold out (like the 1 day a year it gets into the upper 20s), and I'll be good for forever.
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Old 11-30-2007, 08:49 PM   #10
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Don't have my msq on this computer, but I've noticed that the car likes it on the really rich side on cold mornings. I think my low temp ASE enrichments are a good 10-20% higher than yours and no cold start issues down to 30 or so degrees.
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Old 12-01-2007, 07:55 AM   #11
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Ben,

Since it's been cold here I have been having the same problem, I'm going to give this a try

BTW: it's suppose to be zero degrees here today... So I get lots of cold start practice...
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Old 12-01-2007, 07:57 AM   #12
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Don't have my msq on this computer, but I've noticed that the car likes it on the really rich side on cold mornings. I think my low temp ASE enrichments are a good 10-20% higher than yours and no cold start issues down to 30 or so degrees.
I didn't have any issues til it got to be around 20 or so, before it would start like stock.
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Old 12-01-2007, 08:34 AM   #13
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Ben, would you mind posting up your Cranking and Prime table? Your ASE settings are similar to mine, but my May fixed MAP value is only 3 seconds.

My car runs pretty good when it is finally started, but when temps are in the 30's I have to crank it forever... I'm thinking I should open up my cranking PW
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Old 12-01-2007, 11:21 AM   #14
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Stealth, best practice is to use the Cold Start Wizzard, and not to modify the table directly. None the less, the table is below. And FWIW, all the cold start default settings were way lean for my car. I don't know how my base settings compare to what DIY is offering now. But I think Tom's comment pretty much confirms that the base settings are indeed super lean.

Since my car is garaged, I haven't yet been able to start the car where CLT was below like mid 50's.
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Old 12-01-2007, 11:29 AM   #15
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Thanks for the info. I'm still a n00b at this stuff, but I'm figuring it out.
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Old 12-01-2007, 04:22 PM   #16
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15 seconds fixe dmap will ensure you're getting enough fuel... but that's ALOT of fuel more than likely as the fixed map setting is probably high, 80 or 100 kpa, and I bet the VE up there is much higher than at idle, meaning it's pumping the fuel in. This will be fine when it's super cold, but when it's 70 degrees out it will feel super rich.

Was it dying immediately after 5 seconds or sometime a bit later? I'd think it's an afterstart enrichment thing, but that fixed map may not be the 'best' answer. I use it for 5 seconds on these cars and that's it...


BTW Ben, notice the sig update.
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Old 12-01-2007, 06:48 PM   #17
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Well it's 8.4 degrees and my car starts w/o stalling, by Am it should -5 or so I'll try again then and see... Yeah it's F'n cold out...
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Old 12-02-2007, 07:37 AM   #18
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Quote:
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Stealth, best practice is to use the Cold Start Wizzard,

Where's the Cold Start wizard? I have a Warmup wizard, but those settings aren't related to the cranking and priming table afaik?

is there a hidden menu somewhere that'd make my life a hell of a lot easier?
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Old 12-02-2007, 10:34 AM   #19
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Originally Posted by richyvrlimited View Post
Where's the Cold Start wizard? I have a Warmup wizard, but those settings aren't related to the cranking and priming table afaik?

is there a hidden menu somewhere that'd make my life a hell of a lot easier?
There and the cranking PW/Priming PW's, the afterstart enrichments, and the warmup 'wizard'. No cranky wizard, I mean cranking wizard.
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Old 12-02-2007, 12:31 PM   #20
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I must have been mistaken.

Jerry, good job! I may indeed now have the second fastest miata in the county. But not for long. I have a trick or two up my sleeve for the 1.6 (I'll probably create a thread about that later)
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