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Thread: Tuning for idle AFR-realtime

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Posts: 1-10 of 27
2011-08-23 22:52:41
#1
Tuning for idle AFR-realtime
I've been battling an issue with my car not idling when the motor is cold since day one of the motor swap, 3 years ago. I've been over everything so many times including rigging the AAC valve open. I literally have to hold my foot on the throttle till the motor comes to temp for it to idle, or she stalls.

I've finally decided it is a tuning issue as my AFR's between a hot and cold motor are basically backwards. Cruising is slightly richer than I'd like and WOT is perfect where I want it. With the morning turn of the key and a cold motor, AFR bounces around up over 14.5. As the motor warms the AFR drops to bouncily settle around 12.

I've raised rpm for a cold motor as well as cold idle enrichment. Nothing works at all. It's gotta be in the fuel map. My fuel map is extremely "plateauish" whereas an unofficial expert, friend of a friend, says he doesn't even know how my cars runs with the map after I emailed him the .bin to inspect. (unofficial expert tunes at a local dyno shop when he's not flying airliners) no time for me without buku $$$

Any help and or suggestions would be great!

The bin is the original from calum with a mild street tune. A bin I acquired here on the forum that has a 2 step also has this plateau of a fuel map.
2011-08-24 01:19:44
#2
Is the IACV air regulator plugged in?
2011-08-24 02:40:43
#3
Your car should be idling around 15 not 12 when warm.

Something isn't right with your tune and/or your iacv/aac valves.

Engine Start Tuning | Tuning Cranking | Engine Starting

and

How to tune Air Fuel A/F Ratio Values on EFI engines
2011-08-24 16:21:14
#4
Is your temperature sensor working fine? I think you need to start working on the injector latency.
2011-08-25 15:34:04
#5
Took a screenshot of the target afr table I am working on with BenFenner right now. You want to use this as a guideline for your tune but this is approximately how you want to have your afr look throughout the table. Disclaimer: Keep in mind, this is a tune for my car, yours may vary. Use this at your own risk.

I use kpa as my values along the vertical side. 0-100 is serious vacuum (coasting down a huge hill) to atmospheric (wot n/a). 100 - 240 is atmospheric to approx 23psi. Obviously rpm is self explanatory.

Last edited by blairellis on 2011-08-25 at 15-41-04.
2011-08-26 02:22:13
#6
curious why iacv came up right off the bat? I'm running no iacv on my car and have no issues at all with cold idle or warm. As long as your warm up enrichment is set right when the motor is cold and your ve is right when the motor is warm. Have you datalogged anything on start up?

Curious if you're using the afr target table all the time blair, or at a set point?
2011-08-26 10:07:51
#7
Originally Posted by nsusammyeb
Curious if you're using the afr target table all the time blair, or at a set point?


You should only use it up to about 700-800 mbar and below 5000 rpm or so.. there is a certain point where it becomes counter productive to keep the o2 feedback turned on. Especially if your sensor starts to freak out or go bad and it makes unwanted corrections to your fueling!

You should really only use it for cruise and idle portions of the map.

On a side note.. depending on how the car likes it you might NOT be able to idle the car that lean. I would still shoot for a 14.5-14.7 idle and then lean it out to the 15.3-15.5 during light cruise and very light throttle. This all depends on your setup, specifically your injectors and fuel pressure to how lean you are able to run the car at idle and light cruise without any issues.
2011-08-26 12:45:02
#8
I have been tuning my VE without any o2 corrections at all. After I get things where I want them, I'll let the o2 have a little say so again. Megasquirt only has an 8x8 target afr table though...very impressive that the aem has a table that large for afr's.
2011-08-27 12:55:03
#9
The AEM is nice in that I can turn on o2 feedback but yet tell the ecu that I am not giving it any ability to make changes to the fuel map. If I have the right parameters open I can datalog and it will overlay the intended afr over the actual so that I can see where my tune is off. It's a pretty nice feature to have and makes modifying the fuel map a lot easier. I wish I would have started using that initially Wish I had experience with the realtime boards so I could say if and or how to do that with them.

Originally Posted by nsusammyeb
I have been tuning my VE without any o2 corrections at all. After I get things where I want them, I'll let the o2 have a little say so again. Megasquirt only has an 8x8 target afr table though...very impressive that the aem has a table that large for afr's.


This! Absolutely make all the changes to your fuel map first. THEN let the o2 have its way with things.

I posted the graph so I could show my simplistic version of the intended target AFR throughout the entire map rather than show the o2 feedback screen.
Originally Posted by JKTUNING
You should only use it up to about 700-800 mbar and below 5000 rpm or so.. there is a certain point where it becomes counter productive to keep the o2 feedback turned on. Especially if your sensor starts to freak out or go bad and it makes unwanted corrections to your fueling!

You should really only use it for cruise and idle portions of the map.

On a side note.. depending on how the car likes it you might NOT be able to idle the car that lean. I would still shoot for a 14.5-14.7 idle and then lean it out to the 15.3-15.5 during light cruise and very light throttle. This all depends on your setup, specifically your injectors and fuel pressure to how lean you are able to run the car at idle and light cruise without any issues.


Also this
Last edited by blairellis on 2011-08-27 at 13-01-31.
2011-08-27 16:27:03
#10
I have been over all mechanical possibilities leaving me to imagine it's gotta be the tune...especially since my first post states my backwards AFR upon start up. Currently the tranny is next to the car awaiting a clutch with a 1.6 shipped not a 2.0, so I'm delayed further diagnosis at this time.
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