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-   -   Help with Idle MS3X (https://www.miataturbo.net/megasquirt-18/help-idle-ms3x-97388/)

mrelia100 07-08-2018 09:05 PM

Interesting, I put the timing light on the #3 spark plug wire, and it seemed to be ok. I'll try removing 2-3 degrees of timing and see if anything changes. Could it be non firing fuel injectors?

mrelia100 07-09-2018 12:59 AM

Yeah it's very down on power and removing timing did not change anything. Any recommendations on how I should test for a non firing cylinder(s)? I watched one video where after running the engine for a minute you spray water on the headers and check for abnormalities in the vaporization on different cylinders. At idle it runs pretty smoothly, rich (10.5 AFR) but overall ok. Running rich could possibly be because of unburnt fuel but that's just a guess.

Braineack 07-09-2018 08:20 AM

output test mode.

you need to lean it out.

SpartanSV 07-09-2018 11:43 AM


Originally Posted by mrelia100 (Post 1490427)
Yeah it's very down on power and removing timing did not change anything. Any recommendations on how I should test for a non firing cylinder(s)? I watched one video where after running the engine for a minute you spray water on the headers and check for abnormalities in the vaporization on different cylinders. At idle it runs pretty smoothly, rich (10.5 AFR) but overall ok. Running rich could possibly be because of unburnt fuel but that's just a guess.

A misfire puts unburnt fuel AND oxygen into the exhaust. Your wideband measures oxygen not fuel. A misfire will always register as lean since it's seeing extra oxygen.

mrelia100 07-09-2018 03:26 PM

Ah I see SpartanSV, that complicates this a bit more! I pulled the spark plugs and did an Output Test Mode - INJ/SPK on Coil A and then B, both batches spark fine.

Braineack how do I do an output test mode to lean it out? Am I running the engine, disabling cylinders and seeing if it affects anything? If so is that that INJ/SPK Disabling test mode?

Braineack 07-09-2018 03:41 PM

two statements.


1. use output test mode to test outputs.
2. lean the damn thing out so you're not idling at freaking 10.5 -- which is the max some WBo2 sensors even read at.

mrelia100 07-09-2018 04:23 PM

Oh damn that is pretty rich! I was so preocuppied about "leaning out" and damaging my engine that I stopped tuning the idle once it stopped stalling and oscillating. I just fine tuned my idle VE table so it's much better now at a pretty steady 14.1-14.9.

So how should I go about testing injectors?

mrelia100 07-09-2018 10:30 PM

Alright coils are good, and for injectors I disabled them one by one using the INJ/SPK Disabling test mode, each time the motor vibrated significantly so I don't suspect either of them is causing any problems

mrelia100 07-10-2018 01:10 PM

I have been comparing the base tune I'm using from Trubokitty to the DIYAutotune's 01-05 MS3PNP base tune. The injector timing is pretty different, any reason for this?
https://imgur.com/Nes4Wqv

SpartanSV 07-10-2018 01:17 PM


Originally Posted by mrelia100 (Post 1490671)
I have been comparing the base tune I'm using from Trubokitty to the DIYAutotune's 01-05 MS3PNP base tune. The injector timing is pretty different, any reason for this?
https://imgur.com/Nes4Wqv

That DIY basemap has several issues. Injector deadtimes, timing map, and now apparently injector timing.

https://www.miataturbo.net/megasquir...5/#post1490066


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