RotaryRevivalist

Alright so before I explain what’s going on I need to lay out what I know before we try to figure out what isn’t correct lol. The car has 90k miles on the odometer, a K&N typhoon intake (gross I know it’s from the previous owner and will be swapping the oem one back in once I have a bit more free time), I just replaced coil packs plugs and wires earlier this year, the car has a gutted cat (also previous owner), and the car starts hot or cold after 3 bops no matter what. Now for what is confusing me, I had a misfire on start up before changing the ignition system which was really bad and I only let it happen once before ordering the parts garaging the car and swapping it all out. Since then the car has ran great but the other day I took it out for about 150 mile drive about 40% highway 60% twisty hooning. Upon start up I had a slight misfire that immediately went away. During this drive only in 1st or 2nd gear WOT after relaxed driving for a while it’ll hesitate ~7-7.5 or 8k and every other gear and every other pull afterwards is fine until I drive it easy for about 30 minutes and begin hooning again. Immediately after experiencing this I started trying to recreate it on a back road, included shutting the car off letting it cool off and starting it warming it up and ripping. It ONLY happens after driving easy (shifting around 4-5k) for an extended period, and I haven’t had the misfire even once since then. This was the first really long drive I have taken in the car since my purchase late last year. I don’t believe the car is on the verge of an engine grenade due to hot starts being so effortless. My imagination is saying that it’s something with the gutted cat causing flow and back pressure issues or the fuel system not flowing correctly until WOT builds up some pressure after low demand driving. I’d love to hear some brainstorming and ideas on how I can test this stuff. Not new to working on cars at all but somewhat new to rotary power. Any help is greatly appreciated. Thanks all!

DannyR3

What kind of coils, plugs and wires did you buy? If they aren't OEM, I'd start there. I'd replace that gutted cat ASAP for a proper midpipe. Put in a proper intake as well, be it OEM or the AEM intake.

RotaryRevivalist

NGK wires and plugs with OEM coils from the homies at mazmart. It was their kit they offer. I’m gonna get the cat cut out and a piece of pipe welded temporarily until I can afford an agency power exhaust. The intake I’ll do this week end. I just gotta pick up a filter from Mazda. I hate this intake. It’s wide open pulling air from the hot AF engine bay lol. It’s so dumb. Heat is a rotary cars worst enemy. Any experience with the fuel systems on these cars?

DannyR3

Don't have to cut it out. 5 nuts and a hanger and it comes right out. Go do some searching on Ebay or whatever. Used midpipe can be had very cheap, especially since the AP one came free with a catback if my memory serves me right. It's raspy crap though. If you want a good one, go with BHR or Racing Beat.

RotaryRevivalist

I’ve got friends at local shops so it’s basically free to cut out and weld. Online reviews of the AP set up were good. Racing beat was my second choice but I hate the thick rounded tips that look very similar to oem. I may go with that and just replace the tips. I’m mostly concerned with replacing the massive chamber the cat has created. If anyone online has a midpipe for the right price I would entertain it but with the corona crisis cheapest right now is best just in case it hits the fan.

sinkas

Misfire on startup ,
particularly cold start,
need to rule out water seal failing

RotaryRevivalist

what are some things that can rule that issue out? Line I said I have a general mechanical knowledge but not a lot specific to rotaries. The water seal for a rotary is still the coolant jacket to the combustion chamber correct?

sinkas

best to probably take it toa shop that can pressure test it,
pump up the radiator to about normal op , or higher
,
see if it leaks and or gets worse

could also try start it on front only then rear only rotor,

TeamRX8

iTrader: (25)

you’ll be chasing unicorns on here because nobody can guess over the internet what this problem or multiple problems are, but guaranteed for people to muddy the water with irrelevant stuff. Which you can scratch out your own crackpot theory right off the bat. The gutted cat is irrelevant.

in all honesty, without some way to monitor and log the OBD2 data stream you’re just left guessing.

always start at the basics; did you go back over everything and make sure you have all the connections seated/tightened properly?

without other symptoms I’m doubtful that it’s a leaking coolant seal letting coolant into the rotor housing, but you can either pressure check it or send an engine oil sample to Blackstone etc to be tested.

cleaning the MAF is easy enough and you might as well put the OE intake box on to eliminate that as well though I doubt it’s the issue, but when it could be anything you’re left guessing at everything.

Not sure if your front end crash is before or after either and might be contributing in some way. Internet diagnostics don’t usually render results imo. .

The proper method is testing from the most basic point and eliminating, but that requires the proper equipment with time and patience.

RotaryRevivalist

I don’t disagree with you, however the people here have knowledge. I didn’t even consider coolant getting into the rotor housing potentially causing a misfire issue. Maybe it isn’t that but only having the car for a short time any and everything I can learn will help me not need to come here if future issues come up. As far as my “crack pot theory” I know that gutting a cat on a piston engine specifically on motorcycles creates turbulent exhaust flow characteristic and on engines that are sensitive anyway it can cause minor hiccups and rob you of power. I purchased a cbr1000rr that was running like garbage for cheap replaced the gutted cat and viola perfectly running CBR for almost half the price. As far as OBDII I check my OBDII periodically. My only codes I’ve thrown were for the misfire before the coil replacement, and cat efficiency. I’m not an idiot lol. As for the front end it was done by a chain link fence. No air bags deployed, no issues. Pardon me if this sounds rude at all but it seemed like you were treating me like I’m an idiot and that frustrates me greatly.

TeamRX8

iTrader: (25)

You’re not an idiot, but your theory is bunk and you have more to learn still. There’s nothing shameful or embarrassing about that. You’re also being too sensitive and focusing on the wrong thing with that kind of talk. Even if you are rude I probably won’t notice so don’t sweat it. Emotions aren’t going to fix your car, they’re only going to get in the way and will most likely mislead you. Try focusing on what matters instead and you might get this figured out.

RotaryRevivalist

I’ll be testing this and update the thread once I know more. In the mean time I think I’m going to order a second engine with my savings just incase I need a rebuild. Anyone selling a second gen renesis? 😅

TeamRX8

iTrader: (25)

Well you’re not going to help yourself any making decisions to throw out money on a whim without any data and/or facts to back it up. Technical problems aren’t resolved with feelings and emotions. You have to get your mind around establishing a methodical procedure to start at A, then move to B, and so on by collecting data, testing, getting a result, and then let that lead you on to the next step. I know it’s frustrating if not overwhelming, but patience and determination are your best path to victory.

I’ve been on here 16 years and seen this kind of mistake happen over and over again. A misfire could be any number of things, maybe multiple things combined; fuel delivery, internal engine issue, non-ignition electrical/sensor issue, etc.. Which the biggest issue with internet auto repair analysis is just trying to get an accurate accumulation of all the facts from the person having the problem. That’s the only reason I asked about the front bumper. Because it’s not personal at all, rather it’s not unusual for someone not to mention something they *feel* isn’t important that might be. Assumptions lead people astray.

Just so you understand, people on here have run gutted OE cats for more years than you’ve probably owned a drivers license. It’s extremely unlikely that you just suddenly have a problem out of the blue that nobody else in the hundreds or maybe even thousand plus never had happen in the last 15 years or so. You have a Renesis engine and it’s a unique engine above all other engines. I’m not discounting your past experience, it’s just not likely to be relevant here based on my own.

Are you actually continuing to have a problem? Because that’s not clear to me. Perhaps you should clarify again what the exact problem right now is. Just try to be as brief and to the point and as emotionless as possible on what the actual facts are about what is happening right now. Thank you.

Loki

iTrader: (1)

Don't buy an engine "just in case". For one thing, if the 2011 car was sold in 2012, you're still within the 8 year/100k engine warranty. Call Mazda, get your warranty facts, and see if you can get a comp test at the dealer. If for whatever reason it fails, Mazda can buy you a new engine. If it doesn't, at least you know where you stand. For another thing, it's not particularly good for a built engine to sit dry for a long time, especially if you live in a humid climate.

Get data. The OBD port can give you many clues, like fuel trims, airflow volume, lambda, etc. You can try to repro the issue and see what the data says. Make your decisions from there.

Let's also go back to the K&N intake and it's path toward the garbage bin. Those things can easily cause issues.

What did you replace the coils with? Not all coils are born equal, unfortunately.

TeamRX8

iTrader: (25)

...



if he takes it to the dealer for an engine warranty it better have a cat converter and the OE airbox on it.

but look, if you’d like to pm me I’ll do my best to try and help you work through it.

.