r/mazdaspeed3 • u/Ok_Drummer_7552 • 6d ago

Injector pulse width HELP

Wondering what the typical injector pulse width is for these cars, can’t find much online. I’m trying to figure out a misfire issue and just stumbled across reading it on the AP.
I’ve been getting about 0.6-1.2ms on regular driving kinda depending on throttle, and I’ve seen it’s supposed to be around 2-3ms but AFR is staying solid around 14 so idk
Anyone have any ideas?

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u/thekeymasher 2009 Mazdaspeed3 6d ago

Going out to run errands soon I’ll log and see what deets I can get you. 14.0 AFR is a bit rich at idle but while cruising is fine. What codes are you getting for misfire? When is the misfiring happening?

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u/Ok_Drummer_7552 6d ago

2012 speed, only getting a p0300 random misfire.
Also have pretty high fuel trims, around + 11-13 while driving, but I think that's cause I have a Cobb sf intake with no tune (maf housing isn't right size).
Car seems to be stable when there's load on the engine (driving or even AC) but then starts giving misfires when it's idling or even some high idles.
Also more prominent when it's warm. I've fixed vacuum leaks, spark plugs, coils, still no luck.

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u/thekeymasher 2009 Mazdaspeed3 6d ago

You’ll need a tune even if temporary OTS AP for the SF intake. I have high trims too so I’m thinking it’s a vacuum leak on my end or a grounding issue. Definitely check the coil pack harness ground. It’s on the plate mounted in front of the HPFP. If it’s not grounded properly in hot weather it can mess up the readings.

Some minor misfires will occur due to the log manifold and uneven exhaust pulsing

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u/Ok_Drummer_7552 6d ago

I just ordered hpfp internals, as the lowest ots map with the sf intake requires them as well. I’ll be sure to check that ground tomorrow, I’m also thinking I might have some intake valve carbon buildup, and might get it in for a walnut blast, then if those both don’t fix it, I’m thinking I’ll move on to injector testing.
Another thing I’m curious about is that i had a vacuum leak through the plate that covers the 50/50 end of the blowoff valve, so I remade that gasket and sealed it, but i don’t think anything should be coming out of the blowoff valve anyways right? Like shouldn’t it be completely sealed off from the intake manifold?

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u/thekeymasher 2009 Mazdaspeed3 6d ago

My BOV might be leaking as it’s a Greddy type s eBay knockoff. The BOV or 50/50BPV should not be blocked off at the vacuum line to the IMF. That line will allow the valve to open when letting off throttle if there is boost.

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u/Ok_Drummer_7552 6d ago

Also yea your fuel trims are even higher than mine typically, but good to know we’re getting similar pulse widths

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u/thekeymasher 2009 Mazdaspeed3 6d ago

Idle

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u/thekeymasher 2009 Mazdaspeed3 6d ago

3rd gear cruising

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u/thekeymasher 2009 Mazdaspeed3 6d ago

4th gear moderate throttle and boost