2000 Miata breaking up under boost
 

Having an issue where the car doesn't want to accelerate in boost. Makes a like a rapid fluttering or popping sound from the exhaust. AFR looks like it is leaning out too. Out of boost it seems to drive like a normal Miata. I've had three different tuners look at the car but no solution. Two of them were new to Megasquirt and more familiar with LSx. The most recent one was from Begi turbo. Only place near me willing to look at it. Did a compression check and leak down test just incase which all checked out. Still new to Megasquirt and tuning myself and wondering where to go or test next.

Car is an Exocet using a 2000 Miata donor. FM turbo kit and exhaust, 750cc injectors, Walbro 255 fuel pump, DIY Megasquirt 2. Rebuilt engine with Manly rods and everything else stock. Using the stock coils with BKR7E spark plugs tried at several different gaps from 0.20-0.30.

Searching I found similar issues resolved with CoPs. I tried the Fab9tuning Denso CoPs and plugs, but it didn't change anything. Perhaps I need LSx coils? I'd like to get some other opinions before I go changing more things.

:laugh:

That "tuner" from BEGi is probably a worse tuner than you, and I'm only slightly exaggerating.
From that screenshot, your car is leaning out so bad that I'm impressed it hasn't blown up yet. Needs more fuel. It's like your fueling is inverted.

Make sure you don't have any boost cuts enabled. Also curious why your CLT in the logs is so low?

his wideband is pegged lean the whole way through. that aint no boost cut

LOL. I didn't even notice it was a log because the first half of it isn't even present. But now i see that's because it's pegged up top with no deviation. That's special.

"Well there's your problem right there!"

Is your wideband broke? You're full lean everywhere except at idle.

Fix that then come back.

Can we get a picture of your engine bay, and a full list of parts on the car?

That is what I've heard and was hesitant to take it there, but like I said I can't find anyone else who will touch a turbo Miata. I figure there has to be someone Texas that tunes something besides LS engines.
It does seem like it is inverted doesn't it? It appears rich at 11 idling and then pegs at 17 under load. One of the LSx tuners claimed the injectors were maxed out and simply couldn't give it any more fuel. Doesn't sound right.


I'll try to get a picture later tonight.

2000 Miata engine rebuilt stock except Manly rods.
FM Voodoo II Turbo kit.
Amsoil cone filter.
DIYPNP MS2.
Bosch EV14 750cc Injectors.
Walbro 255lph.
Exomotive fuel line kit.
AEM Wideband. This isn't connected to the Megasquirt.
FM Turbo catted midpipe and silencer. No muffler.
Coolant Reroute.
Fab9tuning CoPs and Denso plugs / Stock coils with Magnecor 8.5mm wires and BKR7E plugs 0.25 gap right now.
Odyssey PC680.
No P/S, No A/C, No Heater.

Found it. Fix that, then tune the car.

Also: What re-route does it have? Those CLTs kinda make me think it has a Begi "Racer" Reroute. If so, that needs to be removed and thrown in the trash where it belongs.

then what are we looking at in that log screenshot?

That is a good question. The AFR gauge in Tunerstudio is reading off of something.

It is the Begi rear thermostat reroute. Not the racer one.

oh boy. I wish you the best of luck, this needs a whole lot of diagnosing by someone that knows what they're doing. no one can help you if the information you're providing is completely worthless/useless because no one knows how your car/ecu is wired up.

until the data is accurate, we may as well be exchanging photo's of kittens

I understand. I'm going to try to backtrack my steps and start over. And go ask the previous tuners what exactly they may have done/changed.

Where are you located? You need to find a good tuner asap.

first thing you need is a proper diagram or at least list of exactly how the unit is built and wired in. start there

I'm in Corpus Christi.

There are a bunch of guys on here that can remote tune with you, but you'll need to find them and pay them. Pretty sure one already commented on this thread...

If you're willing to drive to Houston, we have a highly reccomended tuner over here. If not, he also does Remote tunes. Join the Houston Miata Page and Ask for Brett. He'll respond pretty quickly

No-one can remote tune if the WB O2 is not even connected to MS.