Spei

I just put together my 2554R build on my 1.8. I've been street tuning it for the past few days and have been getting the hang of things. As I get more and more into boost like 5spi+ I notice the car starts to stumble and "puff" out. It's sort of like hitting a wall, it just stops pulling, no bangs or pops from the exhaust, just seems like puffing, kind of like a fuel cut limiter or something. I don't see AFRs go lean either. I've gapped the plugs to .030" which helped a bit. (I'll be trying to gap 0.25"). I've recently fixed a huge boost leak and now the turbo is spooling how it should and now, even more, boost is being thrown at it. Logs say about 13psi and fueling seems good, about 9-10 AFR.

What should I look for in the logs? Is this a spark issue? I'm running NGKBKR-7E plugs like a lot of others. Running stock coils and NGK blues. Blues were replaced in June 2019. Plugs are brand new. On the log I see that I was running 9.5AFR at fuel map cells 136-170, could that 170 just be putting too much fuel in and causing it to sputter out? I see large jumps in the fueling values compared to the tuned values. Not sure if that's it though. I've also pulled some timing out of the map in the boost cells just out of paranoia. The maps is based on Braineak's base map for a 94. As far as the turbo build stuff, 640cc Flow Force injectors, 2554r, Kraken Mani 3" DP, custom IC piping stuff, but I don't think those matter too much.

The log (.zip) and the current tune is attached. The tune is pretty rough right now, haven't been able to touch certain parts of the map due to this issue. Even though there is this issue I'm excited to see the car spooling to 13psi at 3300rpm with 3" exhaust mated to 2.25" exhaust. 2554r's are nuts.

borka

iTrader: (1)

9.5 afr?? You are drowning the engine with gas. No wonder its misfires.

Adjust fueling to 12 afr light boost to 11.5 afr heavier boost.

Then report back if it's still missfiring

pdexta

iTrader: (17)

What year 1.8? 99-00 cars had some notoriously weak coilpacks. If it clears up, or improves by closing the spark plug gap check out: https://www.miataturbo.net/useful-sa...writeup-12704/

The writeup may look intimidating at first, but take your time and it's really pretty straight forward. Toyota Cops are cheap, easy, and will hold more power than the rest of your drivetrain and still run stock plug gap.

yossi126

iTrader: (6)

My coils are misfiring with a 2554 at 12 psi and my fuel is where it should be at 11.5-11.8
Same plugs and gap as you. I have ordered a Hawley kit and LS coils. Should solve the issue.

borka

iTrader: (1)

On my 99 I had my 2560 up to 14 psi on stock ignition with no misfires.

Spei

Yep, taking out fuel fixed the issue. And holy **** does it pull.

1994. Yeah, I'm planning on upgrading the ignition system soon. I thought LS2 coils were better?

Spei

Yep pulling fuel out fixed the issue. Pulls smoothly now. Thanks!