Changed my exhaust now I have a stutter
 

Ok to start with I am running a 94 with stock internals, and a Flyin Miata turbo II with a hydra nemisis. I got my initial tune after the turbo kit installand the car pulled like a mofo up to redline. It was making about 230 hp and about 210 tq. It had a 3 inch exhaust with a high flo cat, and a backwards glass pack at that time at about 12 psi. Again the car drove great, and pulled really really nice all the way up to 7 grand.

My only real complaint was that it was just too loud. I was not a big fan of my neighbors giving me the eveil eye as I drove past them, not to mention the fact that it was a great reason for the highway patrol to mess with me. So I had a racing beat 3" can installed to quite it up a little.

After the install I would get a hesitation from about 6500-7000 rpm. Not horrible but defiantly noticeable. My guesses that it richened things up and that was my problem. Soo I took it to get another tune this last weekend. Umfortanatly I went to a guy who has never tuned with a hydra, and actually tunes rotaries for a living. He claimed that I was getting some knock and that was my problem. He also shaved a crap load fuel from 6-7k, and took some timing out. Now granted he made it better but there is still a stutter at 6600 rpm up. He kept saying it was a spark issue and even replaced the plugs and gapped them down to .25. My ignition is also still stock by the way. He also said the boost was only holding about 11 psi now.

Again he helped it out, but I want it back to the way it was. Spark is not the issue as it drove great before the addition of the can. What do you guys think? Is it still that I might be too rich and I need to take more fuel out and put a little more timing back? The tuner kind of gave up due to the fact that there was another customer waiting and, and he made like twenty pulls that got only slightly if any better with each one. I just got a battery for my laptop so now I can start to do some of my own data logging and tuning, but I am the ultimate noob when it comes to this tuning thing. I appreciate the advice, and like always can't wait for the snide comments to pile up. That's what forms are really for after all. Thanks.

If you can, post a datalog of a pull and also post a screen shot of your fueling and spark.

Wait, your tuner said you were knocking and shaved " a crap load" of fuel from 6-7k rmp which happens to be the same spot were you're having the hick up? Wtf O_o

What AFR and what level of boost are you seeing at the hick up?

Yeah, wtf is right! Let's say the AFR's were good...who would shave fuel out of it to keep from knock? Is that what they do with rotaries? If so, no wonder they eat apex seals all the time...
Everybody knows, knock = retard timing, Power= advance timing. Goal is to advance timing to make the most power before knock occurs.

That's not all OP says the "tuner" ran the car for an additional 20 times and the issue persisted. O_O

I guess I wasnt really all that clear. The first thing he did was pull timing. Then he did a pull. Shaved more timing. Did a pull. That went on for like five pulls. Then he started to trim fuel. Sorry if I wasnt clear enough. I will try to get a data log in tomorrow if I have the time, as well as some screen shots for you guys. The afr's were staying at like 10, even as he pulled lots of fuel out of the top end towards the end. I think he got it to around 10.5 when he finished. Again I think he just gave up on it. He kept claiming that the hydra was really slow to tune with. My guess is it's a learning curve thing.

I don't see how you went from a "perfectly" running car to extremely rich AFRs from an exhaust change.

10 and 10.5 is really rich. I'd say at 11psi, it should be 11.5 at the very richest. What turbo is on your car?

OP do you know how to datalog and export the log in the hydra?

If you do, then please upload the .csv of a pull. Make sure your default hydra log data profile shows RPM, AFR, advance (timing, knock voltage, knock retard, boost.

This is a pull:

Floor it in 3rd or 4th gear all the way to redline.

Upload that here, along with your hydra map.

I'm going to post a FAQ on tuning soon.

This just in:
Most people who own dynos are fully retarded with sometime 3-5 extra chromosomes.

Actually I can't knock the guy. When it comes to rotaries he is really good at what he does. Again I kinda feel like he was behind the learning curve and kinda gave up because of time. Do you think spark could possibly be my issue? I will try to get some shots up tonight for you guys. Just gotta figure out how to do it. Again I'm a noob so Please bear with me.

I'm not sure if a stock ignition, even with gapped down plugs, is sufficient for a FMII at 12 psi. :confused: I'm thinking the wideband reading stupid rich could be a symptom of a misfire rather than too much injected fuel. That would explain why it's still stupid rich even after pulling a bunch of fuel, and why you can't hold 12 psi.

We stuck in his wideband to make sure mine was reading ok, and they were both dead even. He thought maybe mine was miss reading. Again though it ran great at 12 psi with no hints of missing at all before. It's a GT2560R by the way.

This. Your tuner sucks.

If you don't upload a data log and your hydra map i'm going to unsubscribe.

First thing I would have done would have been to put the other exhaust back on just to make sure.

Ok so here we go. I got a couple of pulls in today, and actually what I previously thought was wrong. It looks like the AFR's are way better than I thought. The boost is way lower than I thought as well. What do you guys think? It seemed like when I got to the fourth pull it started to buck and hesitate more at 6500 up. Lame. I realize that being in the 12's afr wise at 6700k might not be all that great for the motor. I need to put some more fuel in right? I did talk to Jeremy today at Flyin Miata, and he told me I might want to try bumping the dwells up one. Again thanks guys. I really appreciate it. And faeflora chillax my friend. Some of us have jobs. And the can is welded in so i can't exactly remove it that easily.

Where's your hydra map???????

What map do you mean man? I thought the fuel and timing were what you were looking for. Sorry please elaborate.

The .s26 file.

Looking at the logs it doesn't look like you are having spark misfire. That would be characterized by lean or rich spikes in your AFR.

Your timing is very very wussbuckety but that wouldn't cause stutter.

Your AFRs look rich from 3000-6500 and then a little lean above that. 12:1 or even 12.5:1 AFR won't break your motor at that boost level and high RPM.

You are down 2.5psi at redline. That means your power will fall off. In the driver's seat, that will feel like you lose power, or power feels flat, or the motor feels weak in that RPM. That could have been caused by your exhaust system change.

lol @ your fuel table. Ask your tuner why you're squirting more fuel at 5200rpm than 6500rpm, then tell him to fuck off, pull the head, inspect the pistons, call your attorney, then drive the car to one of the MiataTurbo trusted member/tuners and pay them. There is absolutely, positively no excuse for a fuel table that looks like that from anyone...from a "professional tuner" it's criminal. Again, no excuse for tuning that looks this bad.

This one? Sorry, again Im such a noob I can barely see the light at the end of my moms vigina.

The attorney is not gonna help due to that piece of paper I signed releasing all liability. Hustler I kinda don't want to fuck with tuners anymore. I am bound and determined to figure it out on my own at this point. I mean what's the worst that can happen? I blow my shit up? Oh well, it's gonna happen sometime. So now then what do you suggest? Any pointers for a dumb ass like me to start with? Other than trimming some at 5300k or so.

I was in the same place, I paid for two shit tunes then did it myself and it was great the first time out.

No, you won't ever blow it up if you tune it right.

Read this.
I'm by no means a pro, nor do I have a respectable understanding of how these small computers work, but this is the way it's done by those in the know.

Use arithmetic to reach the required AFR target.

For instance

If you are at 10.7 AFR and your target AFR is 11.7 AFR then you're 8% too rich for your target AFR.

Use the hydra math operators on the appropriate fuel cells to multiply by the appropriate integer. Then interpolate. Then log, then look at log, then repeat process.

If you have difficulty doing this, then I will tune your shit for nudes.

Nudes? Elaborate please. So about the stutter on top. See anything that looks obvious? As far as target afr's go I think 11.7 is about what everyone shoots for right? Also when it comes to the timing, should I put some more in, or just leave it and tune the fuel map for now? Also in the target afr table what happens when i start messing with that? Does that actually change the timing and fuel tables if i mess with that? Oh and one more thing. What exactly is bad when it comes to the knock. I guess I mean what numbers do I start to worry my shits gonna blow up?

Do you have a smoking gf or sister? well take nudes of her and send them to Fae. Or send them some spread ass cheeks from a male friend any of those should suffice.

I am assuming Hydra does have a feature like Autotune or tunerstudios correct?

No, I want nude pictures of dwood11.

Hydra does have autotune but it may be to slow to respond properly under WOT. Only one way to find out though. Also, from "the factory", meaning the FM base map, autotune is disabled if TPS is over 70% or whatever.

Uhhhhhhh did you buy the Hydra? You may want to start by downloading the Hydra tuning manual from the FM website.

AFR target table is only used for closed loop. And autotune.

Don't tune timing until you understand what timing does, how to look for knock, where MBT is, blah blah.

BTW your shit is not fucked up as it is. Not the best at all, but not horrible. As I said, your power takes a shit because your boost takes a shit.

The hydra manual sucks ass. I read a lot of it, but I wouldnt exactly call it user friendly at least not for a moron like me just starting out. Guess I missed the spot about afr's and auto tuning. I get the gist of timing, but looking for knock is something I still would like to educate myself on. So the knock ramp table tells me I'm doing it wrong?

Read the FM Manual and the Hydra User Manual. The Hydra User Manual explains what every map and setting is.

Yes, it is not user friendly.

Man, I hate reading. It makes me feel stupid. Especially the hydra manual. Oh well. I'm gonna start messing with my fuel table and turn my dwell up a smudge as per Jeremy's recommendation. He did give me another really good piece of advice. He said that in general with that much boost if I were having a spark issue that it would show up at a much lower rpm. Really wish I knew what the problem was.

My spark problem showed up at 5500rpm a while ago, I took the gap down to .025"

They are at .25 right now. I guess I will try .20 to see what happens.

I told you that I would remote tune your car for nudes of you.

Don't turn up dwell everywhere. Only turn it up for the RPM range that you're having your stutter.

Remember to make change, log, look at log, adjust, repeat. Also use the math functions like I said.

Ok Faeflora pleas elaborate for me on the dwell for me. I see a dwell setting, and excuse me as I'm not at home and dont have the program in front of me. But i know there is a dwell rpm setting that I'm pretty sure is blank on my map as I think you can see, and the other dwell that just has voltage not associated with rpms just volts. I take it I dont turn those up? Do I add dwell in the rpm map?

Yes just add dwell in the dwell RPM trim map

Thanks man. I really appreciate the help. Do I add one whole number or just use the plus button to bump it up? And one more thing, do you prefer twinks or bears? I have a plethora of both for your nudes.

I only want you.

Ok I get it. Are you a bent over ass spread kinda guy, or a demure cup the balls while blowing you a kiss dude? So do I add a whole number or what?

Curious, did the same guy do your baller initial tune and the FUBAR tune?

When you do get around to messing with timing, you'll need det cans to listen for det.

Cupping is good. Make sure we can see your face so we can use the pictures against you in your upcoming political career. Based upon your demonstrated competence with tuning, I would say a run for Congress can't be too far off.

Actually I was thinking of getting on the presidential GOP ticket in a couple of elections from now. With my brains or lack of, and my good looks I will be a shoe in. Not to mention the fact that I love groping men women and boys more than a Penn state bench couch.
So I fucked with the dwell tonight after I got home and guess what? Problem is looking to be getting better. I shaved some just ever to slightly at 6800 rpm, and what do you know. The car pulls almost like it used to. Thanks for all the help guys, I think. I am working on some really classy frontal shots by the way for you faeflora. Hope you like ungroomed bush.

This thread is getting like this:

I like this OP though, he's a good sport. Seems like another prestigeous member of MT.net society!

I appreciate it thirdgen. These guys are nothing compared to the Subaru boys. Plus I have a weakness in my heart for guys that act gay to cover up the fact well that they are gay. Sometimes that closet is really hard to find your way out of.

So I'm going to build some detcans in the next day or so and keep reading more threads. Again I wish that the hydra manual explained things just a touch better. That way I wouldn't have to keep asking questions, and having to explain to my wife why I keep locking myself in the guest bedroom with the camera.

If the hydra does start to see knock and pulls timing will it be fairly evedent from the data log?

I would think you'd see the timing change in the log...so, "yes".

None of that. I just want a pic of you full frontal. You can put a piece of paper with "dwood11" over your face and pee pee if you'd like. If you want to show your face, please look sad.


Good job. Dwell can be a real fucking bitch to tune. Sometimes.

If you have the hydra log KNOCK RETARD then yes, you will see the amount of *s the hydra pulls in the KNOCK RETARD column. Always log knock retard.

So what's the worst thing that can happen if I take too much dwell out?

spark is weak and you get misfire hiccup shit

Word. So what's your best guess why after the addition of the can that it started to stumble and taking some dwell out helped it?

Reread thread. I already said because your boost took a shit. Who knows, maybe backpressure caused combustion chamber shittiness and spark said fuck you?

Ok now I got another question for you. I turned the boost up and lowered the dwell a touch more, as well as shave more fuel. Now Im holding around 12 psi, but my afr's went back down. Is it because of less spark? Check out my last pull I just got done with. Its 4th gear by the way.

Nice. Need pic for more answers. Sorry.

wife with dwood11 would also suffice

You 02 sensor is looking for Oxygen in the exhaust. You will have excess oxygen (AFR high/lean) two ways:

1. You are actually lean.
2. You are misfiring and the Oxygen is not consumed.

So, if you were misfiring and that misfiring stops, you should expect AFR to drop to the real value.

You still owe Fae that pix.