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Floating Doc (Forum Supporter)
Floating Doc (Forum Supporter) UltimaDork
11/26/22 7:00 p.m.

I love a happy ending. 
 

As to your experience with your DMV, I have found that it is the same here. The people who work at the tax collector's office (where we register our cars and get plates, not sure how it works in other states) are really nice and determined to help. It's nice to see that's not an anomaly. 

WonkoTheSane
WonkoTheSane UltraDork
11/26/22 8:17 p.m.

Our DMV has been great here in CT as well.  They've always been clear and helpful when I've needed them. 

Glad to see this car is continuing along.

AnthonyGS (Forum Supporter)
AnthonyGS (Forum Supporter) UberDork
11/26/22 10:02 p.m.

Moving to a smaller town in MS has totally changed my view of DMV from Dallas.  

Keith Tanner
Keith Tanner MegaDork
11/28/22 5:33 p.m.

Plates! It's done! 338 is fully legal in the US!

I walked into the DMV with my notification of title and my Hagerty insurance card and walked out with a set of brand new plates. Finally, 338 can get on the road again.

Get ready for some more updates. First, clean it up and go for a triumphant drive.

Keith Tanner
Keith Tanner MegaDork
11/29/22 5:48 p.m.

Sigh. Snow.

I should mention that my title arrived in the mail yesterday, and I also got a call from one of the people at the county to let me know the state had approved the car and a title would be on the way. Amazing. Less than a week from paperwork to plates and title in hand - with a holiday weekend in the middle - and a followup call from a person to keep me in the loop. I hope Flyin' Miata is as friendly and efficient as our local DMV.

AnthonyGS (Forum Supporter)
AnthonyGS (Forum Supporter) UberDork
11/29/22 7:49 p.m.

FM is pretty friendly and efficient in my experience over the years.  Congrats on seeing this through!  I look forward to updates.

RedGT
RedGT Dork
11/30/22 4:23 p.m.
Keith Tanner said:

Also - during the down time, I pulled the injectors and sent them off to RC Engineering for cleaning. The car is much happier now. 

Did this address the high warm idle too or did that turn out to be something else?

Keith Tanner
Keith Tanner MegaDork
11/30/22 5:52 p.m.
RedGT said:
Keith Tanner said:

Also - during the down time, I pulled the injectors and sent them off to RC Engineering for cleaning. The car is much happier now. 

Did this address the high warm idle too or did that turn out to be something else?

That was the idle air valve that's only on 1.6 Miatas, a bit of an odd device that acts as an air leak based on coolant temp. I had a failed one. The one I replaced it with seems a little sluggish, but I'm going to get some drive cycles into it.

Faithful readers may remember I had a small coolant leak after my timing belt change. I decided to pressurize the system so I could spot it. I don't have a proper tester, so I built one out of brass fittings and an air hose. This actually went inline on the air valve.

Found the leak, reseated some hoses and replaced the tired spring clamps with worm gear clamps - not my first choice, but the OE stuff wasn't sealing any more. Aired up the tires, refilled the coolant and generally did some basic preflight work.

Keith Tanner
Keith Tanner MegaDork
11/30/22 6:00 p.m.

Drive time! I realized that it's been almost exactly 30 years since I bought my first Miata, a red Canadian 1990 just like this one. I think it might have been January 3, 1993. The difference is that something's wrong with the rear view mirror on this one, it shows some old guy with grey hair instead of the kid in his early 20s.

Anyhow. First stop was the u-scrub-it car wash to get rid of what accumulated during storage.

Better.

The car feels quite happy to be out of the garage. Great brake pedal feel, that wonderful Miata steering (that seems to be better on Canadian 1990s, weirdly) and the growly little exhaust that Mazda designed. Nice smooth power delivery from a happy engine and of course the snicky little gearshift. What it's missing is torque. I have become lazy, and found myself coming off corners in 4th at 2000 rpm. You can't do that with a 1.6 NA at 5000', you need to come off in 2nd and let the engine sing. Too much time in cars with V8s and electric engines and automatics and direct injection 2.0s with decent grunt. This car will be good for me :)

These two are together again. 338 was a support vehicle (of sorts) for the Targa efforts, in 2008 at least. They've never shared a garage because they lived 2000 miles apart. They have led very different lives both before and since that time, but they're going to stay together forever now. 

Now, if you'll excuse me, I'm going to go drive the red car again.

Keith Tanner
Keith Tanner MegaDork
11/30/22 10:59 p.m.

Interesting. 

I had the car out tonight - trip to the gym, then a few hours hanging with nephews, then drive home in the dark. And the high idle returned with a vengeance. What was different? Ambient temperature.

The idle air valve thing is triggered by coolant temp. As the coolant gets warmer, it gradually closes a piston that allows air to bypass the throttle body. Hey, EFI wasn't super-advanced in 1989. And when I got home, I popped the hood and found that the coolant lines to the air valve were cold. It wasn't getting any flow at all, so it stayed wide open in fast idle mode. Why was ambient temp a factor? Because I think heatsoak from the engine bay was playing a role, and allowing it to heat up enough to mostly close. But with the sub-freezing temps, the engine bay didn't get warm.

The coolant flow comes out of the intake manifold, through the idle speed control valve, into the air valve and then out to the thermostat housing. As far as I can tell, all of those hoses are cold which tells me that the coolant isn't coming out of the intake manifold fitting. That's where I'll start my investigation then, start disconnecting hoses and chasing flow. I'm gonna make such a mess. I always do with coolant.

Why does it seem to rise as the engine temp increases? Not sure, but I know I have a specific problem so I'll deal with that first. The IAC is also not seeing the coolant temp it's expecting, maybe it's something the ECU is doing as the sensor in the back of the head starts seeing legit temperatures. I see a lot of people block off this air valve because, well, because a lot of people have a low regard for factory engineers. I'm gonna make it work.

Keith Tanner
Keith Tanner MegaDork
11/30/22 11:43 p.m.

Well, I was right. I made a mess. I have coolant in my ear.

I pulled off the first hose coming out of the intake manifold (I don't know why the 1.6 Miata intake manifold has coolant in it, it just does) and the coolant in the idle speed control valve was brown and crusty. I fired up the engine and no coolant came out of the disconnected hose. I put some air pressure into the idle speed control valve, nothing happened. I decided to put some pressure into the hose going back into the intake manifold - backwards from normal flow - and all of a sudden got a lot of hydraulic noises. And a moment later, the radiator cap released and dumped a bunch of coolant into the overflow. So hey, we have pressure in the system! This is good.

I pulled the air fitting out of the hose and discovered that the radiator cap had stopped releasing pressure at 15 psi, like it was supposed to. Thus the system was still holding 15 psi of pressure. I got an immediate and enthusiastic bath of not fresh (but cold) coolant. Now my lips tasted bad and my ear was wet. But I know I have flow through the hose! After wiping everything down and spitting a lot, I cranked up the engine again with the hose still disconnected. Uh, yeah. We have flow.

I did notice something interesting in my previous testing of the air valve and air pressure. When I disconnected the system, I got a squirt of water out of the line that led to the rest of the system - but not from the air valve itself. I didn't think anything of it at the time but now I realize it meant there wasn't any flow through that valve. Huh.

So yay. I may have found the problem, some sort of blockage in that coolant line. Hopefully I disintegrated it and didn't just blow it somewhere else, but I may have to pull the intake manifold at some point in the near future to make sure. Given the flow, it'll probably end up in the same place if it clogs again.

We'll have to wait for another test drive to see how it does, then I'll probably have to readjust the idle speed because it's been compensating for this all along and it's acting like the idle speed screw is a little too closed.

Progress!

Professor_Brap (Forum Supporter)
Professor_Brap (Forum Supporter) UberDork
12/1/22 7:36 a.m.

My 90 NA has the exact same coolant issue and fixed almost identical. My issues never came back. 

Slippery
Slippery PowerDork
12/1/22 9:44 a.m.

Just saw this thread for the first time. It was a very good read! The older I get, the more I want cars to stay closer to factory specs. 

dyintorace
dyintorace PowerDork
12/1/22 10:23 a.m.

Brief thread diversion - was there an addition of a Carrera cabriolet to your fleet that I missed? 

Mr_Asa
Mr_Asa UltimaDork
12/1/22 10:30 a.m.

In reply to Keith Tanner :

When I was researching LS throttle bodies, I came across the factoid that early models had coolant pumped through them in an effort to prevent frosting at lower temps.  I would bet something similar was planned for with these.

Keith Tanner
Keith Tanner MegaDork
12/1/22 10:58 a.m.

Interesting. I'll see if there's anything in the factory manual about that.

Had another new failure last night I haven't had before, one of the headlights refused to go all the way up. It would only go halfway, then it decided it didn't really want to go all the way down either. They'd been working fine, I'd tested them before leaving the shop. I popped out the fuse and manually raised it, which is exactly why there is a manual adjuster :) When I got home, I dropped it down manually and it seemed to work properly. I noticed that it was fairly high effort to lift, so I'm wondering if it was another temperature related problem. I'll play with it some more.

Keith Tanner
Keith Tanner MegaDork
12/1/22 11:03 a.m.
dyintorace said:

Brief thread diversion - was there an addition of a Carrera cabriolet to your fleet that I missed? 

I was wondering if anyone would pick up on that :) No, I'm just housing it for a month as a favor for a family member. He keeps trying to get me to work on it but I will not be tasked. I'd rather work on a 33 year old Miata, it's more interesting than doing the legwork to outsource cracked leather repair on someone else's mid life crisis car. I did work on it long enough to get the frunk opened so I could get it on a charger, but that's so I don't end up with a dead Porsche in my way. 

Keith Tanner
Keith Tanner MegaDork
12/1/22 3:15 p.m.

Took 338 out for a run at lunch to see if the high idle problem had been fixed. The coolant lines in question were still cold when I got back. Idle had gone up to 2000 and worked down to about 1100, which I think was heat soak from the engine bay as it didn't start to drop until after the coolant was at full temp and it was coming down really slowly.

The correct solution here is to pull the intake manifold and clean out the lines at the source. That's not really all that much work, I'll put that on the list to do shortly.

Keith Tanner
Keith Tanner MegaDork
12/3/22 12:31 a.m.

Well, that was worthwhile. Pulled the intake manifold off and was able to blow air through the passage quite freely. Hmm. So then I tried to blow air through the idle air control valve coolant lines, which is what that passage was connected to. And...nothin'.

I grabbed a spare off the shelf and blew through it, it was free as a bird as I'd expected. So I pulled the IAC off the bottom of the throttle body and, yeah. There's your problem. There are supposed to be two holes there.

Weirdly, these two go into a dead end in the throttle body. I'm really not sure why it was built that way, but whatever.

Can I explain why I was able to blow air around the way I did yesterday? Not really. I'm puzzled about that, unless I somehow managed to move this clot to the IAC from elsewhere - the IAC and the intake manifold are both aluminum, so this must have come from further upstream. Maybe I did knock it loose yesterday and caused this clog. Dunno.

This was very clearly a problem with the flow to the air valve, though. I swapped in the IAC in the bag marked "1.6 GOOD" on the assumption that it is, in fact, GOOD. Reassembly tomorrow and then we'll see if I finally have this licked. And I'll keep an eye on the condition of the nice fresh coolant to see if it starts showing signs of contaminants.

dyintorace
dyintorace PowerDork
12/3/22 8:04 a.m.

I would imagine working on the Carrera would be very different! :D

 

Keith Tanner
Keith Tanner MegaDork
12/3/22 6:56 p.m.

Car reassembled. Just for fun, I put the original air valve back on as part of this. Immediate 2000 rpm idle. I swapped in the replacement one I had been running and voila, a totally normal Miata idle. Took it out for a drive and as the air valve closed off (as it should) the idle got pretty low. That was expected since I'd been messing with adjustments. Got it fully warm, popped in the appropriate Special Service Tool (paperclip) and set the idle. And there we go, happy car. I wish I'd figured this out years ago, Dad had to deal with it for a while.

Looks like the car had several problems. The air valve was definitely not working properly and yet the IAC was plugged up. I reamed out the IAC passages on the part I removed, that was not a mobile clog. Were they related? I can't see how, but I also don't know how one could have caused the other. Whatever, it's good now! Not having that big air leak has improved the throttle behavior as well, engine braking was a little muted :)

I also spent some time polishing the rear window. At some point in the past couple of years, I must have left it outside with the hardtop on and the rear window not inside the window protector. It's burned along the top. Canadian Miatas have very long-lived tops, this one is at least from the 90s. I tried to minimize the damage with some Novus plastic polish and made some headway, but did not completely cure it. There's a crack in the top above the driver's door as well, so either I live with the burnt window and come up with a patch for the top, or I just bung a new top on there. The latter would be the nicest choice but the top overall looks quite good. I haven't done a top replacement since 2002 :) I don't think any of my other Miatas actually have soft tops.

The other problem is that it only has an AM/FM/tape deck for a stereo - and I have very few cassette tapes and broadcast radio sucks. I've got a tape-to-1/8" adapter but the manufacturer of my cellphone has too much #courage to install a headphone jack and my iPod was hiding somehwere. Years ago, I modified my stock radio to take an aux input. Maybe I'll dust off those plans again and hide a bluetooth receiver behind the dash where it can't be seen.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
12/3/22 9:36 p.m.

TIL this sticker is rare nowadays

Keith Tanner
Keith Tanner MegaDork
12/3/22 10:50 p.m.

It's basically the sign of a 30 year old car that still has the original paint on the bumper :) I think it was only used from 1990-92 and the replacements have been NLA for some time.

Scopecreep
Scopecreep New Reader
12/4/22 12:45 a.m.

There is a vendor (Spinnywhoosh) makes replacements - I got one for my 92 SBY (although I don't think it will last 30 years).

https://spinnywhoosh.com/products/mazda-outline-decal?variant=39756227596

 

 

Keith Tanner
Keith Tanner MegaDork
12/4/22 12:49 a.m.

Yeah, and I can make my own too because I have a vinyl cutter. That's what I have on two of my three 1.6 cars - the other has the original bumper cover paint. But IIRC the originals weren't vinyl, they were printed. I'll double-check tomorrow to be sure. 

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