Weirdest Problem Ever 1997 Miata

I sure hope someone can help me.

I drive a 1997 Mazda Miata. I bought it twelve years ago and drove it everyday for about six.
But then life happened and it sat for about five years in Southeast Alaska and had numerous problems as a result. I have fixed all of the problems save one that has even my engineer friend puzzled.

It idles fine, it runs fine for about an hour; then it just starts to loose power every time I push in the accelerator. if at this point, I engage the clutch, the engine revs normally. Once I put the load back on it starts to hesitate again. Sometimes this goes away and sometime it keeps happening to the point where it is a little scary. It has never actually died on me. Once I let it sit for an hour or so it runs fine again for a while.

I have changed the plugs, plug wires, fuel filter, air filter and drained and flushed the fuel tank...

Any thoughts?

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Originally Posted by Iconoclast

I sure hope someone can help me.

I drive a 1997 Mazda Miata. I bought it twelve years ago and drove it everyday for about six.
But then life happened and it sat for about five years in Southeast Alaska and had numerous problems as a result. I have fixed all of the problems save one that has even my engineer friend puzzled.

It idles fine, it runs fine for about an hour; then it just starts to loose power every time I push in the accelerator. if at this point, I engage the clutch, the engine revs normally. Once I put the load back on it starts to hesitate again. Sometimes this goes away and sometime it keeps happening to the point where it is a little scary. It has never actually died on me. Once I let it sit for an hour or so it runs fine again for a while.

I have changed the plugs, plug wires, fuel filter, air filter and drained and flushed the fuel tank...

Any thoughts?

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Just curious. Fuel filter before or after the tank flush? Do you have E-10 or 15 up that far?

Ask because dead gas would be my first guess. Gasoline gels down here (Lower south-east continental) over years. But with your temps. and lack of humidity it could go sooner. If it sat that long with an alcohol mix gas then you have to think that there might be rust flaking in the fuel lines. Clogged injectors?

You 'Palooza bound?

Hope this helps,
Rick

If you have no codes, as stated, no fuel or a blocked exhaust, like a bad cat seems probable.
No fuel from a clogged filter or injectors, bad TPS, leaking lines or a bad gas cap.

I would also suspect the coil packs and/or plug leads; losing power as they get hot.

Quote:

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Originally Posted by NCGreasemonkey

Just curious. Fuel filter before or after the tank flush? Do you have E-10 or 15 up that far?

Ask because dead gas would be my first guess. Gasoline gels down here (Lower south-east continental) over years. But with your temps. and lack of humidity it could go sooner. If it sat that long with an alcohol mix gas then you have to think that there might be rust flaking in the fuel lines. Clogged injectors?

You 'Palooza bound?

Hope this helps,
Rick

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Rick:

Everyone has said bad fuel. I changed the filter before I flushed the tank. I can change it again. The only problem with the fuel idea is that it revs and idles fine when there is no load on the enginer? I have thought about pulling the injectors, but wouldn't that cause problems all the time, not just under load?

Iconoclast

Peter:

My best friend keeps saying it is the cat, but once I told him it only happens under load he scratched his head and said that doesn't make any sense?

Iconoclast

...sorry got to ask; what is "Palooza"?

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Originally Posted by Iconoclast

...sorry got to ask; what is "Palooza"?

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http://mazdaroadster.net/showthread....L-Event-Thread

https://www.facebook.com/Miatapalooza

Same situation happened with my friends MG Miget & Porsche. I helped him clean out the old fuel out, and basically did a tune up. We got it to finally run, but the idle was still inconsistent for a while, until we added fuel system cleaner and drove it some more.

Quote:

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Originally Posted by Iconoclast

Peter:

My best friend keeps saying it is the cat, but once I told him it only happens under load he scratched his head and said that doesn't make any sense?

Iconoclast

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Actually if the cat was clogging the issue would be most apparent under load because if the cat was clogging as the load increase, exhaust flow/velocity increases thus making it more apparent.

If driving on the highway does it not want to accelerate at certain speeds? Or after driving on the highway check the exhaust manifold to see if it is unusually hot, could be bad enough to even cause the manifold to start to glow orange/red.

Maybe buy a infared temp sensor and check to temperature of the cat after some spirited driving or extended highway speeds. I'm sure you could locate what a properly functioning catalytic converters temp should be at. Not saying it is the cat but if it is those are things to check. :)

I'd venture to say it's a coilpack issue based on the fact it only happens after things are nice and warm.... That said, it could also be a bad sensor of some sort (air temp sensor?) Check for vacuum leaks that might arise once the plastic/rubber gets nice and warm, you can use a can of carb cleaner to spray lightly around the intake and vacuum lines. My corvette had a misfire that I finally diagnosed as a vacuum leak in a hard vacuum line that only leaked when it was warm and pliable.

Dump some Marvel Mystery Oil in the gas tank to help clean things out. Maybe try replacing the fuel pump.

I'm in agreement with AirBrush1 on the fact that "if it only happens warm" part. Electronics breakdown under heat. Coil, plug wires, cam sensor. Do you or a friend have an ignition scope so you can see the firing lines? Or when it is acting up pull one plug wire and see if you can tell that a certain cylinder is the dead one. Be very careful! Man bit close to fender metal and a removed plug wire. The spark jumps from somewhere. :frantic: