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Can't get MS2Extra to idle under 1500RPM


Xnke

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I've got this posted up over at MSextra.com as well...JSMCortina keeps pushing this off as ignition timing being stupid high. He hasn't said much after I started posting timing maps from here showing that it's not unusual for L28's to be running 18-24* of ignition timing at idle.

 

Anyway, I am running high impedance "520cc" injectors, at a reduced fuel pressure (they are 520cc at 3.5bar pressure...) which makes them 480cc/min. The opening time supplied with the injectors is 0.85ms at 14V. The engine will idle at 1500RPM and 35kPa at 12.5:1AFR's, injector PW 2.0ms, and ignition timing of 26*. This is the "best" idle I can get...close the throttle plate any further and the idle first becomes unstable, then oscillates wildly, and eventually stalls out on a downswing. It doesn't appear to follow manifold pressure, AFR, or ignition timing, as I can vary all of those things and it will still die out or become very unstable below 1500RPM. I got it to idle at 945RPM (my desired idle speed!) ONE time and if you gave it any throttle it was fine...but when releasing the throttle the engine would immediately die.

 

The engine appears to immediately become unstable and stall out with any injector pulsewidth shorter than 2.0ms...which corresponds to about a 1500RPM idle. I think I have an injector range problem, but since most people on MSextra that have answered are so hung up on ignition timing, I can't get an answer about how to work around this problem.

 

I am currently running alternating, two squirts, and am reading that simultanious, 1 squirt will not result in any change in pulsewidth, according to the manual. However, there are other people on the 'net that appear to have better luck with it that way. It's been raining for four days so far, and shows no sign of stopping, so I will not have any results or any tuning time for at least a week now.

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I went through a cycle where my car died every time I lifted the throttle.

I was idling at 750 RPM with timing at 22 degrees.  I backed the timing

down to 17 degrees and no longer stalled on throttle lift.  I also have a

'catch' column at 500 RPM where I bump timing up to 19 degrees.

 

I'd be concerned that your dead time, or voltage correction are not

quite right.  I idle with a .95~1ms pulse with using 475cc low-z injectors.,

with a 13.5 AFR target   I'm on the B&G code which is very limited

on setting the voltage correction, so you should have an easier time

tuning the correction curve on Extra

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I've tried everything from 8* to 32*, so i'm not sure it's timing related...hence my asking here. As soon as it stops this torrential flood outside I'm going to try playing with the dead time to see how far off it is. Battery correction Is pretty close; I spent a year chasing it down, unless it changes with injectors or something.

 

Req_fuel is 6.3; so (6.3*0.51)-0.850=2.363, so I don't understand why I'm getting injector pulsewidths of 2.0 and less at that VE...

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Is it possible that the data really is for opening time, not deadtime (more or less opening time - closing time)? That might explain where your missing 0.35ish ms went, but it won't explain why the car won't run at lower pw.

 

Do you have the small injector pulsewidth table active and zeroed out by any chance? 'Cuz that would impact 2ms and lower pulsewidths.

Edited by bradyzq
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Injector small pulsewidth table?? WTH is that? This isn't MS3, just MS2Extra. I have no idea what you're talking about there, but if it's in the code I better find out!

 

Alternator output is good, it's an overdriven CS140 amd can supply +22A at idle, and only goes up from there. O2 is calibrated and smack on, timing has been verified with a light and is trimmed in exactly. The timing IS locked; I have tried timing values from 8 to 32* advanced with no change...anything under 2.0ms and the engine gets unstable. It decided to snow tonight, so I didn't go out and play with the car tonight.

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spark and compression tests come back fine, no problems there. ignition is edis, wires and coil pack are fine, edis module is good, plugs are ok.

 

I can idle the car at about 950rpm if I really fatten it up, but we're talking off-the-scale rich.

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Is this 2ms PW when warmed up? Is TPS accell enrich on? I would turn it off until this is sorted.

 

How far off-scale rich would it take to stall it? How lean can you go? I guess what I'm saying is are your plugs black if you get it to idle nicely at the desired RPM?

 

You have an L28, right?

 

My 3L V6, with lo-z 550cc injectors, set at 44 psi base pressure, idles at ~14.0 AFR with 1.9-2.0 ms of PW, once fully warmed up. Cold it's much higher.

 

I'm leaning toward faulty O2 sensor/controller.

Edited by BLOZ UP
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Can you post your msq and a datalog.

Follow up questions; is the high idle the only symptom? is the engine running rough?

I had a similar issue, turned out I spaced the VR sensor wrong and it wasn't reading teeth right.   

Edited by AkRev
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Set MAP sample angle to 55* and window to 10*. O2 sensor checked against two others, all read the same. This engine and this car idled and drove perfectly fine with MS1Extra, and idled poorly with MS2Extra with a single failing fuel injector. After replacing the set of injectors and rebuilding the exploded intake manifold, setting valve lash and checking ignition timing, i cannot achive the proper idle speed.

 

It's still 20F and now snowing, so there has been no progress today.

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  • 3 weeks later...

Worked on the car again. Runs just fine from 1500RPM up. if engine speed drops below 1500RPM, engine will begin oscillations until it swings too low to run and cuts off.

 

Here's a MSQ and Datalog.

 

Rename the file to "2014-02-23_15.08.57.msq", HBZ will not allow files of that type so I just changed the extension.

 

same with the log, it needs to be ".msl"..."2014-02-26_16.45.52.msl"

 

2014-02-23_15.08.57.zip

 

2014-02-26_16.45.52.zip

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So why is it when I pull the MS2 daughterboard, unplug the extra 12V lead for the MS2, and plug in my MS1extra processor I can idle the engine wherever I want? This ONLY occurs with MS2.

 

I'm not giving up yet, I'll give it another shot...I think I've got some settings messed up somewhere.

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