mattruhland

Having issues getting my new engine started. I suspect a timing issue, but I am not certain. I'm hoping that someone with more knowledge than me knows what's going on here. Tune is the same as my last engine which was very similar. Have confirmed fuel and spark are working properly.

Info: Ms3Pro, 99 chassis, ATI damper, 36-2 trigger wheel.

I have attached a video of the attempted start and all the funny noises it made during the start. Additionally I have attached a datalog from that start attempt as well as the composite log of cam and crank sensors. Hopefully with this information, someone can help me get a better idea of what the heck is going on here.

Video: https://www.dropbox.com/s/w1ja6xe9p5...08-12.mp4?dl=0
Datalog: https://www.dropbox.com/s/80zga69hne...58.39.mlg?dl=0
Composite logger: https://www.dropbox.com/s/lz7sieht40...00.29.csv?dl=0

More than happy to provide any additional information that may be useful! Thanks in advance!

mattruhland

Here is an image from a composite log, maybe something is immediately obvious

mattruhland

A video of the mechanical timing can be found here: https://www.dropbox.com/s/k3w59zj3wh...iming.MOV?dl=0

Everything looks completely accurate to me, but it's still not starting and it's sending puffs of air out of the intake, making me think that the timing is way off. I'm completely at a loss and would love another set of eyes on this.

mattruhland

Hello everyone. This issue is solved for me. I had some great suggestions from other miata communities around the web, but ultimately it ended up being something else.

On the back of an NB coil pack, there are two identical wire plugs that fire two sets of spark plugs in a wasted spark configuration. I have no idea why the Mazda engineers allowed these two wire plugs to be identical, but they are and can be interchanged.

With the wire plugs backwards, the spark plugs fire in reverse order, leading to the perfect backfire exhibited for my engine. Swap the wire plugs on the back of the coil pack and the engine runs perfectly.

Hopefully everyone can read this update and help someone else in the future. It seems like a very easy mistake to make and I'm surprised that it is not more well known in the Miata community.

Part of me is very frustrated that I spent 20+ hours checking every single other thing, but I'm also very relieved that it was such an easy fix when all else failed.

Hopefully in the future, this log can help someone else in need.

All the best!! -Matt

SpartanSV

Thanks for reporting the solution. I labeled the connectors after the first time I made that mistake on my NA8.

PReddy

quick question. although the connectors are identical, the wire colors should be different right? one side is brown the other is brown/yellow.

also ​​​​​@mattruhland can you send me your tune file? I have a similar setup and having issues with my first start as well :/
hopefully comparing mine to it will help remove settings as a problem.