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Old 07-14-2012, 01:17 AM   #1
Oni
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Default Is this normal AFR behaviour?

Hi all

Ive posted a few times on AFR but id like to narrow down if what im seeing is an issue / normal / hardware or tune related. Some days my AFR seems stable sitting arround -+0.2 in a steady state others it can be -+0.8 or so. I found the Gve setting in megalog viewer and my understanding is that if its sitting at a stable Gve then the AFR should be pretty much rock solid.

90' miata
Reverant MS2
mtx-l getting power and grounding via additional MS harness ( have tried a few differnt grounds / power locations )

Changing the wideband response speed from 1/12 to 1/6 doesnt seem to make any difference.

In the pic below i have a stable VE or 46, but my afr ranges from 14.4 to 15.2

Is this normal AFR behaviour?-stable-ve.jpg

Ive seen some other peoples logs and they sit at a steady ratio or vary -+0.1 but mine seems alot more jagged and varied. Can someone post a log of there own if they think this is normal so i can have a look please . If this is normal how are people tuning? steady state and a 0.8 AFR change how do u know if your 14.4 or 15.2, you could just guess that your in the middle but that seems like going backwards.

Thanks
Scott
Attached Files
File Type: msq 14-7.msq (88.0 KB, 77 views)
File Type: msl 2012-07-14_13.16.40 wideband change - Copy.msl (1.81 MB, 82 views)
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Old 07-15-2012, 02:55 AM   #2
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I have a similar problem...will run some logs and post them.
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Old 07-15-2012, 05:27 AM   #3
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injector size, quality and AFR neighborhood will affect AFR 'stability'. for example, idling at 16:1 AFR I'll get more variation than at, say, 14:1.

Also sequential vs batch injection. Going sequential made my AFR more stable.

Finally, it only really matters under load conditions. So if your AFRs are solid under load, you're golden.
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Old 07-15-2012, 06:16 AM   #4
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Cheers for the reply soviet. I do seem to have a more stable ratio when over 70kpa. One thing i forgot to mention is that i have mine located in the stock NB hold ATM as im still NA. Could it also be that people with it further down stream are getting a more "adveraged" reading as the gas' mix as they travel further?.

The next thing that i thought was that since it seems better at higher loads, perhaps its insufficient exhaust flow using the stock exhaust but i dont recall this being an issue with my older wideband.

Doesnt seem like that is likley to me but worth a mention.

Im using RX7 460cc injectors that were cleaned and flow tested about 6 months ago.
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Old 07-15-2012, 06:44 AM   #5
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Quote:
Originally Posted by Oni View Post
Im using RX7 460cc injectors that were cleaned and flow tested about 6 months ago.
Which would explain everything.
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Old 07-15-2012, 06:55 AM   #6
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Would you think a change would help mate?. i know they arent fantastic but if the general consensus is that a change will help out im happy to give them a try. Its a budget build thats what i went with those injectors ( lots of people using / cheap ). i have all my parts ready for turbo install this is the last thing holding me back, i want to get a good NA tunes first before throwing anything else on the car as variables.

Again thanks all

Scott
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Old 07-15-2012, 07:45 AM   #7
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If you are looking for budget injectors, the yellow RX-8 injectors are decent, certainly a lot better than the RX-7s! However, I ALWAYS recommend the FIC 650cc EV14s. Yes they are expensive, but they never cease to amaze me, as they completely transform the way the car idles and behaves in general.
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Old 07-15-2012, 08:24 AM   #8
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So in your opinion Rev its the out dated injectors that are contributing to the problem above?. My afr at idle is usually quite stable ( more so that the rest of my map ). Rather than an issue with my tune / install / noise?.
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Old 07-15-2012, 09:52 AM   #9
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regardless, the AFR is never going to be perfectly flat. but you should be able to keep it within a +/- .5 window.
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Old 07-15-2012, 12:54 PM   #10
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Quote:
Originally Posted by Reverant View Post
If you are looking for budget injectors, the yellow RX-8 injectors are decent, certainly a lot better than the RX-7s! However, I ALWAYS recommend the FIC 650cc EV14s. Yes they are expensive, but they never cease to amaze me, as they completely transform the way the car idles and behaves in general.
I want two sets of those, lol.
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Old 07-15-2012, 01:08 PM   #11
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This isn't your issue, but worth a mention for others. Back when I used MAP-based accel enrichment, I would see rhythmic injector duty cycle (and matching AFR) readings. This was due to the accel enrichment getting triggered due to MAP-sensor noise. Switched to TPS-based enrichment and effect went away. The TPS signal is rock solid.

Not sure what's causing my MAP-sensor noise (still there). May dig into it someday. It's not much, but it was enough to trigger accel enrichment. Doesn't cause a problem now, so not worried about it.
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Old 07-15-2012, 05:46 PM   #12
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Quote:
Originally Posted by Oni View Post
So in your opinion Rev its the out dated injectors that are contributing to the problem above?. My afr at idle is usually quite stable ( more so that the rest of my map ). Rather than an issue with my tune / install / noise?.
Its not really a "problem". At least not enough "problem" to buy better injectors.
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Old 07-15-2012, 07:25 PM   #13
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ok thanks guys. i might just suck it up and call it a "normal issue" and if i find some rx8 injectors at a bargin price / FIC 650cc EV14s. Its strange that i didnt find any other threads like this since the 460's are used alot. im not against spending the additional money but wanted to be sure it would make a big enough diference to justify spending the extra.

You all would be happy to tune with this variance at cruise aslong is its more accurate at higher loads?

Thanks
Scott
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Old 07-15-2012, 11:02 PM   #14
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yeah who cares about what your gauge says as long as a) you're safe at load b) you get decent MPG in cruise

Also ID1000 or bust. Although FIC 650 are probably considerably cheaper.
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Old 07-16-2012, 05:13 AM   #15
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You gays are right again.

Higher loads are much more stable ( 75kpa + 8DC or more ). I need to stop being a bitch slap the turbo gear on and know that its ok.

Ill tune with the rx7 460's untill a station near me gets E85 ( in the next year ) then get ID1000's.

i dont think ill ever want massive power so ID1000's should be ok for up to 300rwhp on E85 i think

ID1000's - $500 PP
FIC 1100 - $495 PP

Thanks again all, Ill also try some fuel injector cleaner and see if that helps any ( i have some free samples ).

Cheers
Scott
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Old 07-23-2012, 02:46 AM   #16
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Back again, buying injectors in the next day or so. Getting ID1000's from 949. They come with clips so i should be able to pull my 460's shove these in.

Change REQ fuel, plug in deadtimes / voltage correction and be a happy camper.

Any objections?
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Old 07-23-2012, 10:23 AM   #17
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none. everyone should have IDs.
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Old 08-12-2012, 04:44 AM   #18
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Not Trying to be a necro, just posting for others future reference. I wasn't ever able to find anyone that said "I run ID1000's in my 1.6 at base fuel pressure without issues / super rich idle".

I got my ID1000's and put them in. They were a little more painful to install than the RX7 460's, the bigger clip on the injector pigtail was a pain to get in the correct orientaion on the rear most cylinder, Still only an hour job for a novice ( including putting the fuel harness back in).

I plugged in the settings below



Car fired up fine but died a few secs after, i needed to increase my VE table from about 35 to 65 to get the AFR's to a resonable level. I thought this was weird but i did a search and someone (Brain or Sav or some guru) said that when going from EV1 to EV 14 VE would need a dramatic change.

The injectors seem quite loud compared to my old 460's.

After playing for 10min i got to the below screenshot, Arround 950rpm and 14.2 AFR. Its not perfect i know but im really happy with the stability of the AFR and with some reading / work im sure i can get it better.



I do need to read more on the battery voltage correction though as when i first start up my voltage is arround 12 untill i rev it to 1500rpm to make it kick up to 14.7-15.1 volts. when this happens the AFR leans out from 12.7 to 14.7, i think that the voltage correction is suppose to keep the AFR stable with voltage change.

Thanks for all the advice, and if anyone has issues with my settings etc just let me know, happy for feed back.

Cheers
Scott
Attached Thumbnails
Is this normal AFR behaviour?-oni-11419-albums-id1000-s-523-picture-id1000-settings-need-some-work-battery-correction-area-261.jpg   Is this normal AFR behaviour?-oni-11419-albums-id1000-s-523-picture-id1000-idle-not-great-but-im-stoked-how-stable-afr-etc-no-.jpg  
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Old 09-05-2012, 05:50 AM   #19
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Just an update on this, im still fighting issues with AFR's being Awesome and then shithouse. I know most of you think im imagining things so ive taken a log from today, all in a 10min drive of the issue im fighting with. Please have a look and tell me im not crazy and that its not normal it will take 30secs of your time.

First part of the log is what id say is great, really happy with how stable it is. first interupt is where i pulled over, turned the car off left it a few min then turned the car on and it was horrible, not useful at all. then i did the same again, pulled over shut off left it a bit and restarted, and this time it was reasonable, usable for sure but not good.

The log i cut off about 5min at the start and then about 30min at the end so it was a size that would fit.

Any comments would be great, i hope someone can point and laugh at how ive missed something obvious so i can fix it.

Thanks
Scott
Attached Files
File Type: msq AFR Tune.msq (88.2 KB, 55 views)
File Type: msl AFR Stability.msl (1.75 MB, 79 views)
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Old 10-29-2012, 01:08 AM   #20
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Not sure how your MS is set up BUT--
What made my idle go from doing what yours is doing to perfect was switching to timed injection. I'm still running batch injection, its just timed now so the injection events happen at the same time every revolution(in my case its called semi sequential).

Alot of the people who can pull off the rx7 460/550's in the 14's (and have a smooth no-hiccup idle at 750 rpm) run full sequential injection. Full sequential allows one squirt per cycle rather then two (like batch fire or semi sequential). This =
one long pulsewidth instead of two short ones per cycle. Then the injectors deadtime affects it less. Also, most likely the deadtime input into ms by the user is off by a small amount, so that will affect a long pulsewidth less than a short one when corrections take affect.
The ultimate would be some ID or FIC injectors with full sequential injection. Those two would make a perfect tune muuuuch closer imo.
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