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Old 07-22-2011, 03:39 PM   #1
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Default hot starts, lean at idle

ORginally I heard this problem was caused by ideal gas law causing the ecu to run lean from iat heat soak. Now though I think there maybe something else causing this issue. I used brains anti ideal gas law correction table to keep GAIR at 100. that works great but the problems is still durning hot restarts, say let the car sit for 10-30 minutes or so and come back and restart. She'll end idling very lean.

But if you start going after a certain rpm it seems to stop leaning out and goes back to running off the ve fuel map fine. Its not timed based as much or if it is after a certain rpm value it stops but will keep going till certain ammount of running.

Any ideas at what I should look at. I just hope this isn't something hardcoded.
thanks
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Old 07-22-2011, 03:44 PM   #2
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are you sure gAIR is still at 100%? also where is your AIT sensor?
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Old 07-22-2011, 03:58 PM   #3
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well my logs are long and not enough space here to upload, but yes gair is at 100 durning hot starts.
the IAT though is here, hard to tell but where the brass fittings are. There is a T coming off the itnercooler piping. So its not in the direct airflow to the engine unfourntaly. I've been meaning to move it more in the flow, just haven't gotten around to it.


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Old 07-22-2011, 04:01 PM   #4
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move it just past the IC. IN airflow.
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Old 07-22-2011, 04:04 PM   #5
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reguardless it shouldn't idle so lean like this
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Old 07-22-2011, 04:06 PM   #6
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make sure the gammae is really at 100% when this is happening.
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Old 07-22-2011, 04:11 PM   #7
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Quote:
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make sure the gammae is really at 100% when this is happening.
I will recheck again but I"m pretty sure it is at 100% these hot starts
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Old 07-22-2011, 10:26 PM   #8
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Quote:
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make sure the gammae is really at 100% when this is happening.
when it happens gammae is near 115 due to afterstart enrichment, but comes down to 100 really quickly. Still even if its back at 100, lean as hell. IAT placmenet should not be an issue at all.
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Old 07-26-2011, 07:24 AM   #9
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Any progress on this?

I've noticed something similar with my DIYPNP. I have attached a log that I took on startup (log begins shortly after the engine starts)

There is a drop in RPM and the AFR gets a bit richer. I'm not sure what is causing the drop in RPM though as the idle valve PWM isn't changing and I can't find anything else in the log that explains the drop in RPM.
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hot starts, lean at idle-graph.png  
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Old 07-26-2011, 09:49 AM   #10
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was the car just started?
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Old 07-27-2011, 03:37 AM   #11
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Quote:
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was the car just started?
If that's directed at me then yes. Although I thought this log was with the engine fully warmed up but it looks as though that's not the case.
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Old 07-27-2011, 08:25 AM   #12
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yeah, looks like you need ase and warmup enrichments.
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Old 08-03-2011, 11:39 PM   #13
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restructing my dead thread
Here is a data log of a hot lean start

http://www.mediafire.com/?23rzszb4gwanxa2

you can notice that its around 18+ afrs after reving it around a tad it will come down to 17~s and finally driving it around a tad it will be come down to where it should be low 15s high 14s


the sensor was relocated to in airflow and it reads 103-104f at hot start and while running between 102 and 104.

You will notice though I'm actually have higher PW at lean hot start idle than I do at normal idle

Yeah I think there is some other variable in the system that needs to be figured out.
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Old 08-04-2011, 01:32 AM   #14
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How are your injector parameters? What is the voltage doing?

Are you sure that your voltage compensation for injector dead time is close?

You could have a situation where your battery voltage is low after a hot start and then later it becomes normal.

-Raj
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Old 08-04-2011, 04:55 AM   #15
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I don't know if this has anything to do with it,. but looking at your log it seems that when it's lean at idle your MAP is ~40 and later on when it's better the MAP is ~30, perhaps you should try adding fuel to the cells around 40kPa / idle rpm?
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Old 08-04-2011, 09:16 AM   #16
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Quote:
Originally Posted by giblets View Post
I don't know if this has anything to do with it,. but looking at your log it seems that when it's lean at idle your MAP is ~40 and later on when it's better the MAP is ~30, perhaps you should try adding fuel to the cells around 40kPa / idle rpm?
if you notice though at one point its at idle at map 33 rpm around 950~ and gve 31 and its still 16 to 17s idling, PW at 1.7-1.8

later on gve is 30, map is around 30 and rpm is 950~ and i'm idling around my normal 14.x to low 15.x

PW between 1.6-1.7
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Old 08-04-2011, 10:15 AM   #17
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The more I question the more I think it has to do with the fuel injectors at this warm up time and the current ecu injector characerstics not being correct until a certain point in time after it has been runing for a bit
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Old 08-04-2011, 10:17 AM   #18
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Quote:
Originally Posted by redrider706 View Post
How are your injector parameters? What is the voltage doing?

Are you sure that your voltage compensation for injector dead time is close?

You could have a situation where your battery voltage is low after a hot start and then later it becomes normal.

-Raj
I'm using the diyautotunes ms2 460cc startup map injector settings. I probably should get confirmation that this 460cc startup map was for the rx7 460cc high imp injectors.

battery voltage looks normal at hot start
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Old 02-09-2014, 11:28 PM   #19
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Resurrecting a dead thread. Did you ever figure this out? I have the same issue. My GAIR is fine. IAT located right after intercooler.
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Old 02-10-2014, 08:24 AM   #20
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you have MSI?
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