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Old 05-25-2012, 03:50 AM   #1
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Default Strange Boost control / AFR problem

Dear MS friends,

I got a very strange but not very nice problem.

When I switch on my EBC (I put a switch inside the line to the boost control solenoid) at 5000 rpm my AFR is going bonkers...

- My setup 1.6l MX-5 NB 99, Garrett GT2560R, 460CC RX-7 injectors, GM boost control solenoid, MS3+MS3X

Here is a screenshot of a run with wastegate boost control:



AFR are very steady and go rather a tad rich at the end (VEanalyze live is running - so next time it's going to hit the target nicely)
kPa is at ~155

Here is a screenshot with EBC working.



At 5000 rpm the AFRs go crazy (worse, they go crazy lean - you can notice the stumble) - VEanalyze is also running, same log
kPa is ~170

This is the VEtable that VEanalyze gives me


I attach my actual MSQ, the log is ~11MB so it's too big to attach...

MSQ


- Could it be something EBC related (I have installed a Diode at the solenoid to keep voltage feedbacks out)

- May my fuel be dying and just don't give enough juice at that spot (though this was working with the DIYPNP last year no problem)

- injector timing?

-What else could it be?

Thanks for your help...!
Attached Thumbnails
Strange Boost control / AFR problem-vetable_afrproblem.jpg  
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Old 05-26-2012, 12:23 AM   #2
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It would be useful to log your injector duty cycle.

Note that the AFR is going up at the same time that your MAT is climbing. The MAT climb seems to also be driving Gair. I'm guessing that you are seeing some coupling there and Gair is leaning you out too much.
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Old 05-26-2012, 03:45 AM   #3
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I will take a look at that, I never had problems with it. MAT correction factor is at 50% and I am adding ~4% every 15deg. The correction seems so big in the log, because of the small change, only about 6deg.

@all
I had the problem, that I lost sync at ~5k rpm when I build the new Ms3+mS3x due toa wrong set poti at the MS3X. Could there be another poti be causing my problem?
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Old 05-26-2012, 10:31 AM   #4
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Looks like secondary ignition grief to me (spark blow out).
The lean spikes are signs of misfire. Check plugs, coils, wiring, etc.
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Old 05-26-2012, 11:10 AM   #5
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I am going to check all this.

BTW with the Toyota COPs should I set the ignition to "Wasted spark" or to Wasted COP" ?

Greets
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Old 05-26-2012, 12:34 PM   #6
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depends how wired. wasted spark if still in wasted mode, wasted cop if wired for seq but you still want to fire them in pairs for some odd reason.

iirc.
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Old 05-27-2012, 08:30 AM   #7
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Quote:
Originally Posted by Braineack View Post
depends how wired. wasted spark if still in wasted mode, wasted cop if wired for seq but you still want to fire them in pairs for some odd reason.

iirc.
So wasted spark is correct for me...

I checked the COPs and spark plugs today. Color of the plugs looks perfect.

One more thought - I did build my MS3 according to Franks instructions as a PNP unit with the connector inside the MS3 case. Could the wire size for my ignition outputs be too small?
What kind of size would you be sufficient? (Problem here is, that the holes in the MS3X board after removing the DB37 connector are not very big...).

Thanks

Last edited by Zaphod; 05-29-2012 at 03:35 AM.
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Old 05-30-2012, 11:26 AM   #8
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Today I took apart my MS3 to have a look - because yesterday I thought about the MS3 daughtercard pin I broke during my build (I resoldered it then) - The pin was still tight and nice. (It was pin 40 (FB1 - fb_inj1) ) and I am using the MS3X injector outputs, so it wouldn't have mattered anyway.

But I realized that my R56 was not correctly set (reading 0.85V between R54 and pin3 of U7) - I set it to 2.5V now. Could that have caused my problems...?
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Old 05-30-2012, 11:27 AM   #9
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that could cause sync issues, yeah.


otherwise the wire size for the spark outputs shouldn't matter, think about how small the traces are.
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Old 05-30-2012, 02:17 PM   #10
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Didn't help. Fitted the Walbro 250 fuelpump today, will seetomorrow if this helped...

I still have the feeling that it has something to do with the MS EBC because all isfine, when I run wastegate pressure.
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Old 05-30-2012, 02:44 PM   #11
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I dont see how. your settings are very close to mine.


try copying you injection timing table from the 100Kpa row and apply it to all the boosted rows?

or it could be your include AFRTarget under general setting > load parameters. I dont use that...cant remember off hte topic of my head how that calculation works, but iirc it causes pretty high valued VE% numbers in boost.

http://msextra.com/forums/viewtopic.php?f=122&t=44819
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Old 05-30-2012, 03:12 PM   #12
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I'm still going with ignition grief. Plus or coils.
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Old 06-02-2012, 12:53 PM   #13
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http://www.msextra.com/forums/viewtopic.php?t=45125

Could this be related to my problem?
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Old 06-02-2012, 12:57 PM   #14
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No, this only affects engines with distributors.
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Old 06-02-2012, 01:00 PM   #15
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did you trying removing "include AFRTarget"???
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Old 06-02-2012, 01:37 PM   #16
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I have the include AFR running since years with MS2 and the DIYPNP...
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Old 06-02-2012, 01:50 PM   #17
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oh okay, nevermind. its something most people dont use.
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Old 06-04-2012, 02:29 AM   #18
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As it is bloody raining outside and I can't go to check if my new walbro pump helped - I'd like to do some theory with you guys..

Before I swapped in my MS3/MS3X in the car I changed my injector dead times (460CC high-imp, RX-7 injectors) from the setting I got via testing (different squirts per cycle - until I got the same AFR) which was 1.185ms to the setting that Techsalvager implied and got through his MAF setup, which is 0.75ms.

What would happen if lets say the setting is at 0.75ms but the real dead time is 1.185ms... Would that have effects that could cause problems like mine? I see that the wrong dead time can have ill effects at low rpm/idle etc. but at high rpm?

Thanks for your input...
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Old 06-04-2012, 10:04 AM   #19
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No, you would "tune around" that with the VE table.

Still going with ignition.
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Old 06-04-2012, 10:43 AM   #20
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Quote:
Originally Posted by Ben View Post
Still going with ignition.
Dang! I did really check everything ignition related...

O.K. it's dry outside, so I will get my lazy *** up and see if the new fuelpump brought any change...
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