Your right to a point but there is always cause and effect. A properly tuned engine in this country is suppose to be safe for all available fuel grades ranging from 87-93 octane. A bad tank of gas can easily be a tank filled with 87 octane by mistake because the truck driver filled the wrong tank with the wrong grade of fuel.

It's like this, when manufactures program the ecu's for a specific regions, they do so so that the engine will be safe for all available fuel grades in that region. Yes Mazda recommends 91octane on a stock fd but Mazda can't put out a product that can ONLY run on 91 octane otherwise they go broke because of warranty claims. They had to make it safe for 87. Why do you think the factory A/F is so pig rich during WOT? This is so you won't detonate with 87 in the tank or its what Mazda found as the safe zone for 87 octane at 10 psi and their power goals. I personally drove around with 87 in the tank for the last 1-1/2 yrs with my own fd that had 90k+ original miles and have zero problems with boost or anything. It wasn't until I over boosted that I blew my engine at 108k.

Personally I "THINK" Mazda tuned the engine to the lowest knock thresholds with 87 octane as the fuel. IMHO this is the safest way to tune any engine because it's the lowest grade available and if it's tuned safe with 87, you will have more of a safety margin with the higher grades and zero need for bandaids.

Most after market tuners don't tune this way. They will take a customer's vehicle and have them put in the highest grade of fuel available (91 or 93) and then tune to the ragged edge of safety with that particular fuel. Some will set A/F at 11-11.5 and began to increase timing to the earliest knock readings and then back the timing off 2 degrees and call it good. Now as long as you have 91 or 93 your safe however, this isn't good if a lower grade of fuel somehow enters the fuel system later down the line because now you have ZERO margin of safety.

 

i agree with you, not the other guy. he is basically saying there is no such thing as bad gas causing issues, just people being lazy.

i understand that manufactures build cars that can tolerate different drivers.. they have no other choice which is also why you can tune a stock car and get more power out then from the factory.

all i know is that right now im working on a diesel bmw x5 and the check engine light is on and running like **** because it got a tank full of bad diesel. mold in the fuel, also jelled due to environmental stuff like the cold weather. bmw is telling me to replace the entire fuel system because of the bad gas. customer filled up with BP diesel. also if you remember, BP had to pay a lot of repair bills for cars that were running rough/ not running at all because of the bad gas they received from the factory. didnt matter if it was 87,89,93 it just all caused problems. it was a very big issue here in illinois and indiana. dont know how far it spread.

there is also tests you can do on gas to see the quality of it. so if your trying to diagnose a car and do that test and it comes back as bad then thats your issue. have to always start with what you know is broken/ defective.

 

Very sorry for your luck man. Been there.. threads like these are why people are dropping in V8s.

 

True however, most people who swap out the rotary don't know how to properly work on the rotary and rely on others who are not as skilled as they should or claim to be. So they install something more familiar. You can never argue against a larger displacement engine making the reliable power NA V8's do.

 

Sorry it's been a while. Here is an update on my car. I've been driving it with the stock ecu. It's been driving really strong and sounds deep and rich haha. It starts right up when it's hot or cold. I still need to get a datalogit. I've put about 2k miles on the car since the last rebuild.

 

^^ umn ok... wow bro... I wouldn't dare drive it care free until I figured out was caused the issue in the first place. Given that your car has failed twice under similar conditions, I also suspect the problem is with your car and not the builder nor tuner. Injectors stuck, OMP, engine harness, could even be something that fails intermittently. Fix the problem and not the symptom... Just saying man...

 

Neptune speed---irvine/orange

Lucky 7 racing---duarte

my picks

 

faulty injector or bad wiring. They are the only parts that were not changed.

 

Maybe I missed something, but do you have an AFR gauge? If the timing is right and your AFRs are good then that can rule out a lot of things. But it does sound like you have a wierd fuel delivery gremlin. Based on your experience with this in the past few years, I'd say you're a much more patient man than myself and applaud you for sticking with it.