Sick '91 Miata

[flyin94m]

This morning, I fired up my Miata as I prepped for the drive to work. Cranking was sluggish and I attributed it to the cold. It idled fine. I drove out of the neighborhood and it still seemed okay. As soon as I hit the highway and gassed it, it bogged way down -- complete loss of power.

I pulled to the side of the road and it died shortly after hitting idle.

I started it back up and noticed that I cannot rev past ~5000 RPM. I limped home and parked it.

Observations:
1) I think this actually started happening yesterday on the way home from work but more at highway speed
2) There's a high-pitched whine (almost a whistling sound) at high RPM (>5000).

Recent changes:
1) Oil filter and RP 10w30 2 weeks ago
2) Filled the tank with gas right before I got home (after I started noticing symptoms)

Outside of that, there's nothing major that I can think of.

Things to check out:
1) Fuel filter/fuel pump (courtesy of Dave04) -- I ran the tank a bit low before this last fillup. Perhaps there's some sediment that I picked up because of the low level in the tank. This doesn't explain the sluggish cranking (which really might just be attributed to weather anyway).
2) Check the oil -- Looking for level, color, shiny stuff, etc

I'm looking for any other suggestions that you guys might have or anyone who's seen this before.

Thanks.

[Miatamaniac92]

Clogged maybe?

Chris

[MadMerv]

a vacuum leak?

[POS Racing]

Plugs and plug wires??

[cam76034]

Fuel filter is first suspect

[Sharpie]

I'm gonna guess with Chris the maniac. Checking the cat is easy unless it's been welded on in the past.

[flyin94m]

I'm gonna guess with Chris the maniac. Checking the cat is easy unless it's been welded on in the past.

The same thought has crossed my mind. I've been talking to the wife about picking up another FM cat and replacing the O2 sensor with it.

[flyin94m]

I just had a thought... I've heard a rattle over the last couple of days that I assumed was the heat shield on the cat. This rattle was missing this morning. Is it possible the cat broke up and clogged up the exhaust???

[Miatamaniac92]

I just had a thought... I've heard a rattle over the last couple of days that I assumed was the heat shield on the cat. This rattle was missing this morning. Is it possible the cat broke up and clogged up the exhaust???

Doesn't sound unlikely (how's that for an internet diagnosis?).

What do you mean another FM Cat? Is the one on there already an FM Cat?

I wish you luck with getting bolts off, using plenty of penetrating spray and use some Copper Anti-seize on the new one.


Chris

[creek]

I always check the easy things first.
1. air filter
2. alternator charging?
3. fuel filter
4. stubborn cat

Before I get flamed I would like to point out about the alternator that the coil pack can pull down the voltage at high rpm if the car is running on the battery only. My money is on #3 but like I said, the easy things first.

[flyin94m]

What do you mean another FM Cat? Is the one on there already an FM Cat?

I wish you luck with getting bolts off, using plenty of penetrating spray and use some Copper Anti-seize on the new one.


Chris

I had an FM cat on the 94M -- Really liked it. I know what you mean about the bolts. I ended up just cutting the bolts on the old cat on the 94M.

[sammm]

I ended up just cutting the bolts on the old cat on the 94M.

Spray'em down with PB Blaster and let them soak overnight. You may get lucky.

[Snowdoggie]

Take the car immediately to MT for a new engine, a new transmission and a full chassis alignment. Don't forget your checkbook.

[flyin94m]

Take the car immediately to MT for a new engine, a new transmission and a full chassis alignment. Don't forget your checkbook.

Don't feel the today.

[onething]

Where is the whistle coming from? I'd open the hood and see if I could hear it there before soaking everything overnight and buying a At 17 YO, you could just have on old vacuum hose leak.

from a guy who pays for oil changes

[flyin94m]

I haven't had much time to look at it today but I did the following:
Removed the air filter -- Yes, needs to be replaced, but not the problem spot.

Checked the battery -- Read 12.76v. Threw it on the trickle charger anyway and it said it was done in about 5 minutes.

Fired it up again (sans filter). It turned right over and idled, but really looks rough under the hood.

While I was there, I throttled it a little until it bogged and noticed smoke around the exhaust manifold. I also smell gas.

After it died, I tried turning it over again and it seemed to really struggle. It's not turning as quick as the first time and the starter sounds like it's trying harder than when I first started it. I'll let it sit for a while and try again.

I'm still leaning toward a backed up exhaust, but will grab a fuel pressure gauge later today and try it out.

Where is the whistle coming from? I'd open the hood and see if I could hear it there before soaking everything overnight and buying a At 17 YO, you could just have on old vacuum hose leak.

I'm not even sure where to begin looking for a vacuum leak

[flyin94m]

After sitting a while it started again.

I also crawled under and checked out the cat. It has puked -- I'm certain of it. I sprayed the bolts down with WD-40. I'll crack them loose tomorrow and run the engine without the cat to see if it makes a difference.

Hopefully I'm not looking at both a cat and muffler.

[onething]

I'm not even sure where to begin looking for a vacuum leak

Listen

[flyin94m]

Okay. It's the cat. Pulled it. Ran down the highway full bore. Scared horses. Looks like I'm off to FlyinMiata