Timf91

So a fast background
bought my evo 8 late March w 100k miles. Ran nice and pulled nice when I test drove it. Drove 2 hours home w/o a hiccup out of it. Parked it but would drive it every few days around the block a few times. Never gave an issue to me. I then left for vacation mid April and was gone for 2 weeks. Coming back from vacation I did a timing belt job and replaced all timing components, serpentine belt, serpentine tensioner, and did a a.c delete (used gates a.c. delete belt) also after changing the belt I removed the spark plugs because I got tired of fighting compression when I was hand cranking motor to check to make sure the timing makes kept aligning. After that o replaced them with brand new ngk copper plugs gapped to .28. I reconnected everything else, cranked the motor a few times w/o the coils plugged in, the plugged them in and cranked, it turned right over and ran like complete crap (lots of miss firing), nd the battery and brake light where on. I turned it off, and Check for immediate vac leaks and plugs that o may have missed, didn't notice anything. A little later i started again and This time it ran better, but was still missing. The battery and brake light where not on at this time. A few days went past and on my next day off i came out and started it again. No issue starting, idled fine for a few moment, they started missing really bad and brake/battery light was on. Again I turned it off, this time I went and lined up all the timing makes to tdc and they where still lined up, so it didn't jump timing. Turned it on again later and it still miss fired, but again not as bad as the first turn on, and no lights on the dash. Now I also noticed if I gave the car gas it would not miss fire, and held rpm relatively steady. Yesterday i took it for a drive around the block a few times (I have no plates and insurance at the moment so i can't go on any major roads) same as before at idle it miss fires, but while driving it ran fine even going heavy on the gas (not flooring it ) it gave no issue. But today on another trip around the block at a stop sign the battery / brake light came on and it started missing again really bad , then went away and it cleared up a bit but still has the slight miss fire at idle.

I checked codes and the only one I am getting is p0441, which the car had when I bought it as well (along with the code for rear cat as the car is catless )
current mods are straight pipe exhaust, open dump off stock Wastegate, aem intake and aps blow off valve (recirc)
I seen no immediate signs of boost leaks but I don't have a way to actually test (trying to get my air compressor this weekend as I just moved a few months ago and a lot of my stuff is at my mom's)
no smoke in exhaust
car has been on the battery the whole time. The battery never lost power and always started up the car and still does
Other than factory dash I have no gauges

I'm wondering if anyone can tell me what I should look at that is maybe causing this. I read that battery/brake light is typically a electronic issue (possible bad alternator )

Timf91

Update:
Boost leak tested the car and intake track is holding pressure. Car is still missing at idle, and almost stall when driving and depressing the clutch to stop (yes bov is recirculated ). Any help?

Biggiesacks

Too much gap, close them down to .024 at the widest. .022 is more standard. Also timing belt jobs on these motors can be tricky, i would double check all your timing marks still line up.

Evo9_Dubai

Yes, the problem does somewhat sound like an alternator problem. I would test the voltage to make sure.

Timf91

I thought stock gap was .32? I'll try a closer gap. And I double checked marks they are all lined up still.

Timf91

had a lose battery terminal I tightened it and the lights are no longer coming on.

Biggiesacks

Stock gap from the evo 8 fsm is .028-.031, but that's with stock iridium plugs and a stock motor. I have tried to run .028 with copper plugs and a C.O.P. ignition and it was very unhappy and threw codes. It did ok at .026 but .024 is what felt the best to me overall. I didn't get any improvement going to .022 either in logs or in general engine behavior so i have settled out on .024 for my setup. Like i said though .022 is a much more common or even a .02 if your really running some boost. These plugs are cheap and ridiculously easy to change so don't be afraid to experiment.

Timf91

thanks for the info. I got the plugs out now so I will shorten the gap. Did a compression test and got 150-160 psi across the motor that was a big sight of relief (I was dumb for not initially doing it when I boughtthe car) ima let the motor cool and then regap and retorque the plugs

Timf91

thanks for the info. I got the plugs out now so I will shorten the gap. Did a compression test and got 150-160 psi across the motor that was a big sight of relief (I was dumb for not initially doing it when I boughtthe car) ima let the motor cool and then regap and retorque the plugs


I might just get some iridiums and try those. I always rancopper plugs in all my other turbo cars and never had an issue, so I thought they would work fine here to unless the car is that picky

Biggiesacks

Unless you really don't like gaping plugs then just run the copper plugs and save money. If/When you start modding your going to want to run copper anyway. Copper is a better conductor then iridium, it just doesn't last as long.

You don't have to play around with the gap, just run a .022 and it will be fine.

Timf91

I set them at .22

as far as driving goes will the car be ok to drive with it missing a bitat idle? Like I said the car seems fine driving and under heavy throttle, no codes or anything but i have been buming rides and borrowing cars for a few weeks now and people are starting to get annoyed.

Biggiesacks

Without really knowing what the problem is, or observing it running first hand its really hard to say. Also there are other things that factor in, do you have free towing through your insurance etc. I personally don't like driving the car with unresolved issues, but you do what you gotta do.

Timf91

This is what the spark plugs looked like when i pulled them to check compression. The old ones, which were iridium, had a dark tan color, and looked normal. These look like the car is running lean

Timf91

https://youtu.be/dxNkGsYt2no
there is a video of it running. You might need headphones to hear it but it hiccups every once in a while

Biggiesacks

That sounded totally normal to me. Nothing in that video tingled my grease monkey senses. If you log timing i bet you will see whats happening, the ecu will dance the timing around a little and it makes the engine lope a little bit. Its just dialing itself in adjusting the Idle air and timing to find a happy place for the current conditions. Thats my guess as to what you are picking up as miss firing anyway from what i have seen. One tried and true method to detect a miss fire though is while the engine is running unplug a spark plug and see what happens. If there is a change it was good, if nothing happens it was miss firing.

Edit: that method will only work if you have a C.O.P. as the stock system needs both plugs hooked up to complete the ignition loop (i think anyway).