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63-70C Strange lean out

Old 06-07-17, 02:51 PM
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63-70C Strange lean out

Just wondering if anyone else has noticed this with their microtech and has any idea what it is so I can sort it. In case you have not seen my other posts I have a 20B with LTX-12. I have got my idle 12.5-13 AFR when hot and running lovely. From cold start I am around 12 AFR at the moment but might try and take more out once I get the main map finalised and this little niggle I have. So car idles fine through the temperature. My water correction curve is a nice smooth drop of and zero by 82degsC. Currently I have it at 4% for 68 but mainly to try and work around this issue a bit. Basically as the water temp hits 63degs as best as I can tell it suddenly leans off too much and dies unless you give it throttle. If it stalls you need to give it throttle and hold it to keep it going. again as best as I can tell wen the temp hits 70degsC it seems to normalise again and be fine. It is like something else switches off that has been adding correction or possible rpm drops causing the same effect. But I also added fuel to the idle rpm cell below my resting idle cell in the matrix to try and catch it. It helps and maybe if I added loads in it would stop it stalling but I suspect that will impact my AFR for normal idle as I am kind of sitting between the cells a bit?
Any thoughts or pointers gratefully recieved.. I have look all through the tables and cannot see any other correction that would drop out around a similar time to cause this. It would have to be a step down as well as it is litterally fine then bam.. splutter stop!
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Old 06-10-17, 09:52 AM
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What changes in injector pulsewidth do you see when this happens?

Can try increasing the water curve for that area and see if it clears the issue. That would at least prove it is the water table as the cause.
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Old 06-10-17, 02:32 PM
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Hi Arron,
having driven the car a couple of days ago and run it up to see this issue, I ran it up today with my tuner to log it and guess what it didn't do it.. It had a momentary stumble or two around this temp but ran through it fine. Totally confused. it has done it the last few times since I pulled the main map down. I will have to check again next time I run it up now. All I can think is I maybe added a touch of fuel in the 68deg water table last time after it did it. It was only 2% I think I put it up to 4% or maybe 6%. Could also be where I have been tweaking cells around that idle and off idle area in the matrix it has inadvertently fixed it!? Watch this space!
I need to tweak up the crank map a bit for sure I think as it keys over quite a bit to start from cold. Hot seems fie but as it cools a bit again it takes some keying over and I was finding around 75deg water temp an heat soaked 39deg AIT you had to give it throttle for about a minute after starting for it to run smooth other wise is was farting about. Lean I think but hard to say when you have to give it throttle as it then is running okay with throttle at a reasonable AFR.
Now I feel like I am making progress at last it is nice. Went for a 30mile drive so my tuner could finish off the low end tweaks I had done and starting adding in some map so I can get some miles done at 4000rpm. Drives nice and smooth up to about 3500rpm. then we seem to be getting some injector staging fun! 3500rpm there are a few lean bits still to tweak out but as soon as it hits 4000rpm AFR's are 9-10! Was pulling fuel out but still needs more. Seeing more 10's now and less 9's but way still way rich! Ran out of time! Would you expect the fuel table to look a bit odd around the staging point or can it be improved by playing with the staging settings? I seem to recall if you do that the rest of the low end map gets affected? If it is a point you are not really going to cruise in which I assume it won't be as it is on boost do you just accept it will be rich there and live with it and just get the best compromise? Any tips would be nice as I gather you have played with this a bit because I used the rough settings you gave me as a guide for my staging settings!

Cheers
Lee
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