Ok, FINE! The answer is Miata, but now what?

SO i bought one. its a 90, stick shift, red, lots of custom (some good, most bad). i wasn't even looking, but i came across it, and i liked it, and i needed a decent MPG DD, so i got one.

Impressions: I like it. its too loud (ricer pipes and header), and its a little too small for me (6'2", 305 lbs), but GOOD GOD ALMIGHTY its a blast to drive. It really is a GoKart with doors.

Questions:

1. Should it 'warm-up' really fast? It seems I'm at operating temp REALLY fast, like, the end of the drive way fast. It doesn't overheat, and only one of the two fans work, but man does it get warm quick...

2. What fuel mileage should one expect from a 1.6 with 165k on it and a 5 speed? Mods that matter include a tubular header, cone filter, 15 inch wheels with 205's, and i think it has a posi. Oh and the top doesn't go up unless its parked. My drive is all highway, 60-70mph, and at 70 mph, I'm turning roughly 3800, so please infer my final drive ratio if you can...(I'd simply like to know).

3. Wheres the free power? I know its a 1.6 and 'free' and 'power' don't usually belong in the same category, but if one had say, under $100 to spend on making slight HP increases, where would you guys put it? I've heard timing adjustments make a difference, but I know almost nothing else about this motor. Also keep in mind i need decent mileage, so losing 10% in fuel economy for 2HP isn't feasible, and it already has exhaust and intake filter upgrades.

4. Is there anything i NEED to know? For instance, I'm a big Turbocoupe thunderbird fan, and the 'thing to know' on those is the TFI module fails at the worst possible moment, and replacing it with a ford unit and rewiring it to the firewall completely eliminates this as a possibility. This bit 'o knowledge saves many a t-bird owner from a $200 tow over a $40 part.

So, is there anything like that i should know about for this car? Easy fixes or "do this now so it wont bite you later"?

I guess thats it for now. Thanks in advance GRM!

Oh, BTW, fell free to impart ANY Miata wisdom you feel i might need to know. Again, I know VERY little about these cars.

thanks!

-J0N

turn the ignition timing ahead if it hasn't been done already.

my '94 (different engine, but whatever) also warms up faster than any car i've ever owned.

I know I don't know alot either, but approaching 30mpg is easily obtainable.

As to the t-stat, I have had diesels have heat in under 1/2 mile of turning the key, putting it into drive, and driving. Then I have had others that take 10 miles plus. As long as it doesn't overheat, it is OK. But, I would be flushing the coolant out and put in a new t-stat.

I'm listening as well to what others say too.

Full exhaust, intake and a stand alone ECU with a good tune will net you in 15whp range.......about the most you can expect without opening the motor.

Your final drive is 4.30 (all 90-93s are).

Weird, because mine seems to warm up really slow, even before the coolant reroute. I suspect because it's running pig rich.

The big thing to know:

http://www.miata.net/garage/hsue/LoctiteCrank1.html

1) Should it 'warm-up' really fast?

Yes, yes it should. That tiny engine goes from zero to toasty heat before I even leave the road I live on. As long as your radiator isn't freakishly green, you should be failure-free for some time. If your car fails to heat up rapidly, look into your thermostat being stuck open.

2) What fuel mileage should one expect from a 1.6 with 165k on it and a 5 speed?

Hooning, I get around 26. Driving responsibly, I get 29-30. I'd expect you to be in the 28-32 range depending on your engine condition and whether or not the header/exhaust keeps you off the loud pedal!

3) Wheres the free power?

Turbo? Seriously, there's not a whole lot you can do to add power easily and that includes intake/exhaust which is already done on your car! I'd look into getting an STS-appropriate tune with rev limit increase, but I have zero experience in that department.

4) Is there anything I NEED to know?

If the radiator is vivid green, rumor has it it might be ready to crack and go Vesuvius on you. I personally don't believe such nonsense, but that doesn't stop me from having a brand new radiator in my garage ready to go. I'd consider a pre-emptive replacement.

The timing belt should be replaced every 60-100k miles (60 if you trust the manual, 100 if you trust Mazda using the same belt for all 50 states since California required a longer belt-life). It's easy to do yourself with the right tools (cough Flyin' Miata cough). I'd replace your water pump at the same time and, if you're feeling extra special, your radiator too (see above). Our engines are non-interference so you'll just need a tow if it breaks, but yours is old enough that it's probably due for job #2 (or #1!!!).

Check under your parcel shelf carpet for ridiculous rust (neglected shattered rain rail). The panel replacement is cheap and so is POR-15 for the frame, but if it's there, you want to fix your roof fast.

Have fun!

By the way, Keith, you should sell me a super discount bundle (timing belt kit with tools, all radiator hoses, and water pump). Say, include a free built engine!

2. What fuel mileage should one expect from a 1.6 with 165k on it and a 5 speed?

With mostly highway driving, 28 to 33.

i think it has a posi.

If anything, it's a viscous limited slip. I think it transfers 25% of power from one side to the other when it's new. To check if you have one, jack up the rear end and spin one of the wheels while watching the other. If they spin in the same direction, it's a limited slip. If they don't, it's not (or it's worn out). I can't remember if you have to do that with the car in gear or not, so try both.

3. Wheres the free power? I know its a 1.6 and 'free' and 'power' don't usually belong in the same category, but if one had say, under $100 to spend on making slight HP increases, where would you guys put it? I've heard timing adjustments make a difference, but I know almost nothing else about this motor. Also keep in mind i need decent mileage, so losing 10% in fuel economy for 2HP isn't feasible, and it already has exhaust and intake filter upgrades.

You've got most of the good stuff done, but feel free to get rid of the ricey exhaust. I made 110 whp on stock exhaust pipe.

Set ignition timing at 14 degrees BTDC. I did this and still ran regular gas (and I did it for 80k miles), but I've heard some people say they heard pinging and switched to premium gas. This should improve fuel economy, but not enough to make up the cost of pricier gas. Stock setting is 10 degrees.

With 160k miles, I'd consider getting new fuel injectors or sending yours out to get serviced. RC Injection, Marren Injection and Cruzin Performance all do this service.

If you want to go to a dyno, you can gain a few horses (and slightly better drivability and economy) by adjusting your Air Flow Meter. You can pop that plastic cover off it and adjust the clockspring wheel to tune. Look up how to do it first so you don't bust the thing.

If you get more than 100 hp at the wheels, consider yourself lucky.

4. Is there anything i NEED to know?

I've read something about the reverse switch or neutral getting jammed and the car acting like it won't go in/out of gear. Your trans won't be broken, but you'll have to replace that switch. Backing that sensor out a bit (big crescent wrench) should allow you to shift again so you can get home.

The radiator will crack eventually. Plastic end tanks. I've been lucky every time mine failed (twice total, once at an autocross) that a nearby parts store had one in stock. Replacement takes a 10mm ratchet, if memory serves, whatever you need to remove your hose clamps, and about half an hour. There's nothing you can do to prevent this from happening unless you want to spend big money on an aluminum radiator.

jmthunderbirdturbo wrote: SO i bought one. its a 90, stick shift, red, lots of custom (some good, most bad). i wasn't even looking, but i came across it, and i liked it, and i needed a decent MPG DD, so i got one. GOD ALMIGHTY its a blast to drive. It really is a GoKart with doors. Questions: 1. Should it 'warm-up' really fast? It seems I'm at operating temp REALLY fast, like, the end of the drive way fast. It doesn't overheat, and only one of the two fans work, but man does it get warm quick... 2. What fuel mileage should one expect from a 1.6 with 165k on it and a 5 speed? Mods that matter include a tubular header, cone filter, 15 inch wheels with 205's, and i think it has a posi. Oh and the top doesn't go up unless its parked. My drive is all highway, 60-70mph, and at 70 mph, I'm turning roughly 3800, so please infer my final drive ratio if you can...(I'd simply like to know). 3. Wheres the free power? I know its a 1.6 and 'free' and 'power' don't usually belong in the same category, but if one had say, under $100 to spend on making slight HP increases, where would you guys put it? I've heard timing adjustments make a difference, but I know almost nothing else about this motor. Also keep in mind i need decent mileage, so losing 10% in fuel economy for 2HP isn't feasible, and it already has exhaust and intake filter upgrades. 4. Is there anything i NEED to know? For instance, I'm a big Turbocoupe thunderbird fan, and the 'thing to know' on those is the TFI module fails at the worst possible moment, and replacing it with a ford unit and rewiring it to the firewall completely eliminates this as a possibility. This bit 'o knowledge saves many a t-bird owner from a $200 tow over a $40 part. So, is there anything like that i should know about for this car? Easy fixes or "do this now so it wont bite you later"? I guess thats it for now. Thanks in advance GRM! thanks! -J0N

Based on 6 years of owning 1.6 here are my answers.

1. Mine warn warms up quickly. Not quite that fast but certainly within 5 minutes the gauge is middle of the range.

2. 25 to 30 mpg. The gearing is short. It doesn't have slipperiest shape. The EFI is not the most advanced that was available in the early 90's.

3. Intake made the the biggest difference on mine. The shock one is restrictive and breaths hot air. I had a chance to get a used Jackson Racing intake and exhaust header. The butt dyno could feel the intake. The header I not something I would bother with if i had another 1.6. The stock header works pretty well.

4. On a 1990 crank nose wobble can be problem if the the last timing belt replacement was done wrong. There are plenty of explanations of the problem online. Other than that there is not that much that regularly bites people. Here are some problems that come with age. Cam angle sensor o-rings can fail and leak oil on the back of the engine. The heater the rubber hoses harden and fail after 20+ of baking at the back engine compartment. A lot drivabilty problems can be traced to old plug wires and sometimes the coils. Again they bake in hot part of the engine compartment.

I get 27mpg doing 70 on mine, but it's running a bit rich and needs an o2 sensor I think. Doing 80 the mpg drops to low 20s (once you get over that 4k rpms point where the engine starts making more power)

Mine warms up super fast also so seems normal to me

Get some good tires if it doesn't have them and take it to an autocross you have no idea how much harder the car can turn until you do :P

Must be the answer, I just snagged me one also. 2001 SE, 52000 miles. Really CLEAN car. I think I will like it

Marty

I got 24-28 in my '94. I'd expect slightly better, but not much from a 1.6. You will get better mileage with top up.

Free power: Timing adjustment as mentioned. Usually you can swap out the trap-door air-flow meter for a standard type MAF Sensor from an RX-8.

Radiator and engine rubber are the only things to worry about. Well, and the potential of the short-nose-crank issue.

Yeah, they do warm up fast. BTW, only one fan runs via temperature. The passenger's side fan is for the AC. You can wire them together pretty easily so that the main fan triggers the secondary as well. This is a 1.6-only thing.

Free power: timing. The RX-8 MAF only helps above 6500 or so, but it does help up there. A Randall Cowl intake (from Flyin' Miata) will add 5 hp for under $200, and from that point it starts getting difficult. If you have the head off, give it a shave to bump the compression and tweak the cam timing, they like that.

They respond much better to handling mods. A set of sway bars and some upgraded bump stops will improve the ride and the handling far out of proportion to the investment.

20-year-old rads do crack if you run hard. If you're going to run the car on the track, I'd recommend changing it ahead of time to a metal one. Also, the timing belt should be done every 60k. Mazda recommends "inspecting" the belt every 60k for the California cars, which means R&R. I've seen them break at 80k, and they never break when you want them to. So do it if you're not sure. The engine won't be hurt if it breaks, but it will ruin your day.

Excellent info gentlemen, thank you.

ONE BIG QUESTION: at about 4k, in any gear, including neutral, even free revving, i have a NASTY rattle inside the trans. What do you all think it is and what can i do about it? The PO did a clutch the morning i bought it, and swears under oath he put fluid in it, and i know they guy, so i trust him. Maybe under full? leaked out in a few weeks? i don't see much fluid under there...

Things to note:

• I just replaced the brakes. Every pin and guide was rusty and dry. Its quite amazing how much pedal feel i gained, and with the upgraded Wagner Thermo Quiet pads up front mated with drilled and slotted rotors, WOW she stops hard.

• The radiator is new, and i replaced the bad fan. They were wired together, and i left them that way. I did notice that the fans run all the time, however. Am i looking at a bad coolant switch? when i unplug the connector from it, the fans stop, so the relay isnt stuck.

• the timing belt was done recently.

• the radiator is new, as are most of the hoses in the engine bay. Someone must've had that one already.

• i know the ins and outs of the air meter, and intend to screw with it. the turbocoupe i know and love has one just like it.

• ill set the timing as soon as i can to 14.

• ive already looked into upgrading the injector from the gen 2 boschs to the gen 3's. i have a guy that builds them.

Thanks for the info!

• J0N

I'd probably get rid of the drilled rotors ... slotted = ok .. but drilled just weakens the rotors (makes for less mass and more likely to crack under hard use)

disclaimer: this is just my opinion ... YMMV (waiting for Angry Corvair to step in)

jmthunderbirdturbo wrote: ONE BIG QUESTION: at about 4k, in any gear, including neutral, even free revving, i have a NASTY rattle inside the trans. What do you all think it is and what can i do about it? The PO did a clutch the morning i bought it, and swears under oath he put fluid in it, and i know they guy, so i trust him. Maybe under full? leaked out in a few weeks? i don't see much fluid under there...

Can't imagine what that sound would be. Here's a question: What if you press in the clutch and rev it to 4000? Still make the sound? If it does it with the clutch in, you can rule out the transmission.

Maybe it's the header vibrating and hitting the transmission or bell housing.

It's easy enough to check the trans fluid. get it up and relatively level on 4 jack stands. On the passenger side of the trans is the fill hole. It's got a square-head plug on it. Unscrew that plug and stick something in there (a finger works). The fluid should be up to the bottom of the fill hole.

^Probably wouldn't be a bad idea to go ahead and change it (the transmission fluid).

That rattle is likely to factory exhaust manifold heat shield. It has happened to many, many Miata owners. Just remove it and see if the rattle persists.