Next in line NOOB
 

Just picked up a 1990 with a turbo installed. I've turned a lot of wrenches in my time but mostly on Jeeps and trucks. Looking forward to learning how to make this car run better.

What's the setup?

Welcome to the Wonderful World Of Boosted Miatas. (Miatae?)

You've come to the right place to learn, there is no better repository of information on Forced Induction Miatas anywhere on the planet, and nowhere else will you find as many true experts on the subject as you will here. Good bunch of guys, without a doubt. Read as much as you can, and use the search bar to try to answer your own questions before asking stuff that's been covered in depth a bazillion times already, and you'll enjoy your time here on MT.

Best of luck with the new car. Post up some details on what you've got.

I have no idea what the step up even is, let alone how much it's got. lol I picked it up off of ebay for a decent price. I know it's got a whole laundry list of upgrades the PO did.
My daughter wanted one and this one is in pristine condition with extremely low miles (25K miles on a 1990). My original intent was to take the turbo off and just run it factory, but it's not overly powerful so I'll probably leave it on. The only issue it seems to have is that it misses unless you're really getting into the gas pedal. Probably something to do with the ECU. I have a good friend that is into Buick Grand Nationals and he's really good with turbo chargers. Between him and this forum it should be running perfect soon. It actually does run perfect if you act like you're at the track.

Thanks for joining, TurboNA!

That's a simple fix; just drive it wide-open all the time! ;)

Location?
If you tell people where you are I am sure there is someone in your area that would be happy to help. I have no doubt that you and your buddy can figure it out, but 2 minutes with a Miata nut might give you all the information you need to better know where to look. What you have is very important. First step is to figure that out, then use the search feature on this sight to learn what others with the same setup do to make it work for them.
Also, you might want to look for another Miata for your daughter since you will surely fall in love with this one and want to keep it for yourself!

Post up some pics and cut/paste the list of mods. It's probably a Greddy turbo kit and very simple to maintain and even simpler to upgrade if you desire.

We can do our best to explain the Miata specific details that your GNX friend can't.

Also, fill in your profile with your location and we'll see if there's a local in your area in case you need something explained in person.

Truth. Happened to me.

Wasn't actually much of an issue with my daughter. She didn't really like the car because she could only carry one friend. Plus, manual transmission, manual crank windows, etc., etc. Not much of a girlie car, but a great man's car if you like to drive.

Dare I say it? Samnavy really needs another one.

Don't think I haven't already thought of that.


Canton, Ohio. If someone is local feel free to send me a PM and I'll give you my phone number. If I were to keep it, I'd honestly drop in an LS. If she ends up falling out of love with it, that's what will happen. I've had a Jeep CJ for over a decade and dropped an SBC 350 in that. I'm no stranger to fabbing or creative mods.

I will do that.

You know, one of the things I like about it is that she can only take one person with her. And being a manual, she can't text and shift. The only draw back is why in the heck aren't there any cup holders???

Drinking and driving is irresponsible. Also I find that the liquid has trouble staying in the cup anyway :skid:

There are a few turbo miata guys in the central ohio area. theres also an Ohio Miata Owners facebook group.

Thanks. Sent a request to join the group.

Finally getting around to posting this.

Megasquirt aftermarket ECU mspnp w/ vtps, IAT-sensor(Maf delete)
Innovative LC-1 wideband O2 sensor
hks t2 turbo manifold, ceramic coated Turbocharger
Cat back 2.5" full stainless exhaust
ACT Clutch
305cc supra fuel injectors
Walhboro 255lph high pressure fuel pump
Front mount intercooler

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ditch those gay wheels and taillights and it looks decent

also it looks familiar

did you buy it from possible MT member? (sorry if you already mentioned it, didn't read thread)

Looks good except for the injectors. Those are a VERY WEAK LINK in your system unless you're somehow running more fuel pressure.

Lemme splain. The 90-97 Miatas use a return-style fuel system. The stock fuel-pressure-regulator will only allow so much pressure to build up in the line and be available to the injectors no matter how big your pump is. A completely stock fuel system (plus bigger injectors) flows enough for well over 250whp and probably more like 300whp... the math has been done and done somewhere. So the Walbro is overkill if you're still on the stock fuel pressure regulator. And so if you're still running stock fuel pressure, then only stepping up to 305cc injectors isn't a big jump in fuel available over stock. Most guys around here shooting for 10psi or so start at 440cc injectors and many step up to 550's even for modest boost goals just to have some overhead. So how much are you running and what does the LC1 read when you romp on it?

Wow, that's almost identical to the 95 I just sold, but it was white. Had the same Wings West body kit, same spoiler, same white gauges.

Seriously, those wheels are probably costing you 30-40HP (depending upon gear) and are trashing your handling and braking. You could sell those to some poor, ignorant bastard, buy something decent and pocket the difference. Advertise them to anyone with an unusual love for the letter "Z."

I would not let my daughter drive on wheels like those. Stopping matters. Just sayin'.

BTW, I graduated from Norton HS (near Barberton) many decades ago. Know the area well.

All the mods were done by the PO (who had it advertised on this board). I've only had the car for a couple weeks. It's reading 12-14 at idle. Jumps to around 22, sometimes a little higher when I'm really into the gas at high revs, but I don't really do that since I don't want to abuse it. I just picture taking off and hearing the axle or drive shaft detonate.

I'm not really interested in HP. This is my kids car. I just want it to run reliably for her. The fact that it's turbo charged wasn't a plus for me. I was actually considering taking it back to stock since the PO gave me all the stock parts with it. When the tires go bald we'll talk about different wheels to keep the tire cost down. I've got the factory tires/rims with it.

I graduated from Jackson in 1984.

Really?? Anytime it's any leaner than 12:1 when you're in boost you need to immediately let off.

That's why I emphasized stopping. Handling and braking were my main concern, not the HP. The factory tires/rim would be much better than what you have.

Unless you're hitting a track or autocross, you'll be waiting a long time for a Miata to wear out its tires. They're really light. I usually end up swapping based upon age rather than wear. My dad worked for BFG. He gives me a hard time when tires get around 4 years old.

Looks like you're having a nice Spring up there. Big hail and tornadoes down here.

He might be getting a misfire and the WBO2 is picking up the excess oxygen.

If it's happening when he gots off the throttle, it's overrun cutoff (which is a good thing).

I was driving it around today and I was wrong about the high reading. It's doing that when I'm going fast and let off the gas. The engine compression slows it down and the gauge jumps to 21+. During acceleration it's rarely above 13. I haven't tried to punch it hard lately but it seems to actually drop to around 10-11 when I'm accelerating. I need to find some open road where I can push it and let you know what it's doing.

That's called "Overrun Cutoff." Basically, the ECU is cutting all fuel when it detects that you are coasting in gear. Good for fuel mileage and the engine in general.

I assume you have a PC for tuning? MS is pretty powerful.

Good to know. I've got a PC and a whole bunch of stuff but haven't taken it out of the box of "stuff" yet. Last night it got really hard to shift, like the clutch wasn't releasing all the way. It went away itself, but came back again before I got home. I'm guessing it's a hydro clutch.

Yes. The slave cylinder is the most common wear item, although it might also be the master. On the slave, you can squeeze the rubber rod cover to see if it's leaking. Leaks from the master will be harder to detect unless it's a large leak. It doesn't take much leakage to make the clutch disengagement soft, especially with a stiffer clutch like the ACT Stage 1 (excellent clutch, BTW). There is also a clutch adjustment at the pedal. Your car apparently hasn't been driven much, so you need to be watchful for problems related to dried-out seals.

Fortunately, the clutch master and slaves are dirt cheap and easy to replace. That's what you'll find about the Miata. In general, robust. When items go bad, they will be common wear items, will be inexpensive and easy to service. It out-Jeeps a Jeep.

I'm well past 200K in mine.

There is an OEM Field Service Manual in a sticky here (https://www.miataturbo.net/useful-sa...-manual-48633/). Recommend that you download it. It's an indexed PDF. Very useful.

pls post pic of amp / subwoofers in trunk...

:rofl:

If you're accelerating and its reading 13 its too lean. I'd say get to about 4k in 4th and lay into it. It should dip down lower (richer) at first then level out around 12-12.2. Then when you let off it will skyrocket which is whst you want to happen since the injectors shut off.

Ditto on the suggestions to ditch the wheels. Slap some 15s on there and a nice thick tire and it will handle and ride better.

https://www.miataturbo.net/attachmen...ine=1368907674


That's actually more like what its doing. Its pretty much right on 12 but does dip down when it's accelerating hard. As far as the wheels, they're on it for now. The kiddo likes them and it's her car. When she wears them out and has to replace them I'm sure the stock wheels will appeal to her.

Changing the oil soon. Do I need to do anything different since it's turbo charged? Does the turbo charger itself need any maintenance?

Oil changes are pretty much the same as non turbo. Turbo is maintenance free item till it blows up and stuff.

Turbo cars usually have a a lot more carbon deposits in the oil, so don't be too alarmed by how dark it may be. I know I was with my first turbocharged vehicle. Also, I'm not sure if it applies to all turbo motors, but with the subarus I've owned they tend to use a little more oil so you have to keep a good eye on the oil level between oil changes.

ROTELLA T6

still pretty cheap if you have an advanced auto near by... im new to using rotella, and im impressed... i know most of the time, its just in your head, but i SERIOUSLY noticed a difference for the better immediately with it

I'll have to keep it in mind for the next time. I just used a 10/30 full synthetic. I religiously change my oils and filters at 5K. It's the cheapest insurance you can buy for your vehicle. And I always use WIX filters.

The only thing a bit different with a turbo is the amount of heat the oil can see in the CHRA. Using synthetic (as you did) helps the oil resist coking in those passages.

+1 on the diesel oil. Miata is a flat tappet engine. It really likes the diesel formulation of anti-wear additives (which have disappeared in the latest gasoline oils).

An engine builder buddy just said the same thing today; since the EPA ordered a reduction in Phosphorus content in over the counter oils last year he's seen more wiped cams in a year than in his entire 25 years of engine building combined.

My G8 lost its cam. It's the roller-tappet L76 engine with the lifters that can shut off cylinders for mileage. GM replaced the cam and all lifters under warranty. Common problem (not just G8s, but Silverados, Escalades, etc.).

So, screw it. G8 gets Rotella now. I'll give up 1mpg to avoid putting water in the engine.

Damn... and G8's arent all that old... the mileage couldnt have been THAT high when it happened. lol
Was it confirmed that it was from the oil???

Nope. Service bulletin said the lifter design was defective -- although they used that same lifter on multiple product lines and multiple years. G8's are just the tip of the iceberg. When I took it to the dealer (who mainly does SUVs and pickups in my area), service manager recognized the symptoms instantly.

I was just tired of running an oil designed for the EPA rather than to minimize metal wear. GM still swears by that EPA rotgut (they kind of have to, CAFE standards and all).