Fuel Problems?

[zoominmx5]

Okay, I have a 1996 Miata with the original 1.8 in it & 5speed trans. It still has just under 100k(99,xxx). Has a brand new plugs, wires, air filter, oil, oil filter, new fuel pump & filter. It's all stock(mechanically) right now.

Honestly, I really can't even say that I know exactly what is happening. It doesn't give me any codes. All I know is that it cranks fine, but when I accelerate I drastically lose power where I can't even go the speed limit. Even when it's idling and I rev it, it won't reach redline. It will start to rev past 2500k, but then right before 3k, the needle falls.

I really don't wanna take it to a shop because of the hassle of getting it towed there(I don't think I could drive it:cry:). So if this has happened to you and you found a fix, please help.

Yes, I searched, and found NOTHING specifically relating to this. PLZ HALP!:sweat:

[DK Wolf]

Get AAA, have them tow it fo' freeeeeee



But on some serious levels, what comes out the exhaust? Black smoke? Nothing? Do you hear knock? It is running rich or lean? You need to provide more evidence.


But my first guess is to either clean to MAF with pressured air.

[kung fu jesus]

So, is it slow to accelerate too? Is it down on power or does it hit the RPM freely and just die?

Right now I am leaning towards plugged cat, clogged fuel injectors. Can you post a video of the behavior?

[Flyin 92]

I know it's a long shot, but maybe his throttle body/linkage isn't functioning right. DK's theory is probably closer to being right though.

[DK Wolf]

Clogged CAT more likely than clogged injectors. What are the odds that multiple injectors will be clogged? And he should still be able to freely rev to redline with one dead cylinder. I'm ruling that out.

Two most likely culprits are the CAT or MAF.

[kung fu jesus]

I thought about MAF, but OBD2 cars are super sensitive about those and chuck the code pretty easily.


I might consider this more if the symptoms came suddenly. Bad grounds too.

[zoominmx5]

Okay, I used all my tows with them, hence why I stated. I have to have my mom present w/ me to get a tow for her w/ my car. -__- Nothing unusual comes out of the exhaust. No knock. I have also cleaned out the MAF with air when I did the filter. YES It is slow to accelerate too. It doesn't smoothly climb rpm's. I've checked the cat, and had a friend check it and tap on it with a rubber mallet. and it sounds solid. No clogged cat. What else?

[zoominmx5]

I thought about MAF, but OBD2 cars are super sensitive about those and chuck the code pretty easily.


I might consider this more if the symptoms came suddenly. Bad grounds too.

Exactly. No cel/no codes(stored). Checked grounds and terminals, all seems normal.

[DK Wolf]

Okay, I used all my tows with them, hence why I stated. I have to have my mom present w/ me to get a tow for her w/ my car. -__- Nothing unusual comes out of the exhaust. No knock. I have also cleaned out the MAF with air when I did the filter. YES It is slow to accelerate too. It doesn't smoothly climb rpm's. I've checked the cat, and had a friend check it and tap on it with a rubber mallet. and it sounds solid. No clogged cat. What else?

How does nothing come out of the exhaust? That's so bizarre.

It's unlikely, but it looks like it's fuel or tuning.

check to see if your injectors are getting signal while revving. Also, find another stock ECU to swap out just to see if yours isn't buggy.

[kung fu jesus]

yeah, that's how to check for a BUSTED car, not a clogged one.

[zoominmx5]

How does nothing come out of the exhaust? That's so bizarre.

It's unlikely, but it looks like it's fuel or tuning.

check to see if your injectors are getting signal while revving. Also, find another stock ECU to swap out just to see if yours isn't buggy.

If you read it, it says "nothing unusual". So before getting smart, read. Thanks! I'm thinking it might be relating to timing?
Also, cat was removed and a shined a LED light through it. It still seems to be intact on both sides. Looks like a block of fine mesh screen.

A buggy ECU? It was fine when I first had it. I don't see how an ECU would just randomly decide to act weird? It's not like I keep it parked outside or anything(garage kept).

[DK Wolf]

If you read it, it says "nothing unusual". So before getting smart, read. Thanks! I'm thinking it might be relating to timing?
Also, cat was removed and a shined a LED light through it. It still seems to be intact on both sides. Looks like a block of fine mesh screen.

A buggy ECU? It was fine when I first had it. I don't see how an ECU would just randomly decide to act weird? It's not like I keep it parked outside or anything(garage kept).

Slow your roll cowboy, when I said nothing comes out I meant smoke of any color.

Cant be timing.. otherwise you'd have smoke.

Its a fuel or ECU problem hence the lack of smoke.


And ECUs can go bad. Mine did on my FD and swapped it out and it worked just fine.

[zoominmx5]

Now, who wants to sell me an ECU for cheap? Any offers at this point? Haha!

[kung fu jesus]

I would get a diagnosis before throwing parts at it.

[zoominmx5]

So just take it to a shop....? What should I tell them?

[kung fu jesus]

I would suggest a Mazda dealer.

[riefdaddy]

Have you checked to ensure no vacuum leaks? You could have a leak that impacts the fuel pressure regulator.

[zoominmx5]

I was told it was timing. Crank pulley keyway is worn causing wobbly crank, which causes retarded valve/cam timing. That was one of my initial thoughts but everyone here shot that down.

[kung fu jesus]

Ooof! someone installed the woodruf key wrong, didn't torque the front crank bolt correctly or both. I suppose you know the way most people fix this is with a another engine?