JCH13 - Turbo Miata Rehab Thread

[JCH13]

Ah, I did not swap the CAS, I think I will swap the old one on then. I will have to get back out to my friend's garage to get the old CAS.

Might also be a fuel filter from what I've read, and the current fuel filter is in dire need of replacement, so I'm going to do that tonight.

 

[JCH13]

Replaced the CAS and fuel filter (fuel filter and bracket were insanely rusty, all of the line clamps broke and I replaced them). Big misfires are gone, but it still seems a little rough. I'm going to try swapping out the plug wires tomorrow.

 

[Black2na]

Try new plugs also

 

[PseudoSport]

Do the misfires show up in a data log? Are you getting any red lines in the middle of the log like MegaSquirt is loosing signal?

Since the engine was out you might want to check the ground connections near the back of the intake manifold. All the sensors and MegaSquirt are grounded at the same point.

Also what are you running for a plug gap? I use to run .025-.028 or else I would get spark blowout under boost.

 

[JCH13]

Haven't run a datalog, but I will tonight. The misfires/stumbles feel very slight and barely register on the tach. Before CAS/fuel filter they were quite obvious.

I will double-check the engine ground strap and the sensor ground, both were taken apart during the swap.

I am running relatively new plugs, less than 4k miles on them, gapped at the FM suggested 0.026in.

 

[JCH13]

Misfires are virtually non-existent after a slight tweak to the spark map. Cleaning the grounds and swapping ignition wires didn't do much.

Datalog shows no tach drop-out or anomalous sensor readings.

I guess plugs are the next thing to try.

 

[JCH13]

Per suggestion of another Miata owner I seafoamed it yesterday... holy mother of god there was a lot of smoke! Seems to have helped a bit, there were definite a shit-load of deposits in that engine... going to give it a second round today before the plugs and wires go in.

 

[JCH13]

With some old LC-1 parts from JLee I got my wide-band O2 sensor recalibrated and working again.

Also got my KnockSenseMS connected, sensor mounted (Flyin' Miata knock sensor mount), working, adjusted, and programmed on the MegaSquirt, really quite painless.

Woo! Fully instrumented for tuning! :awe:

 

[JCH13]

Sorry for the necrotic lack up updates ATG, I've been insanely busy between trips and buying a house.

I got a house in the town where I work that has a 23'x26' pain of main garage bays, a 14'x26' "paint booth" bay on the back, a side addition, and a shop on top. It is mostly insulated (needs a little work) and has a wood stove and an oil furnace (likely going to get rid of both and get a propane heater, but i digress...)

Installing some turn signal intakes on my Miata tonight, should help get more cold air to the turbo and generally keep under-hood temps down.

 

[yottabit]

Per an older post- I tried the electrolysis thing too but ultimately found beadblasting to be much more effective, what are your thoughts?

 

[JCH13]

Per an older post- I tried the electrolysis thing too but ultimately found beadblasting to be much more effective, what are your thoughts?

I had to leave the components submerged for a long while with some serious current going through it for it to work well. It was somewhat difficult to get a good electrical connection to the rusted parts, but it is key to do so.

I chose electrolysis because I could set it and leave it for a day or two, and I didn't have access to a blasting booth that would handle the sub-frame.

What sort of setup did you have going? What electrolyte did you use? How much current?

 

[JCH13]

Finally did a real tear-down on my exploded engine now that I've mostly settled into my garage. I was somewhat surprised at the results, but it makes sense for an overheated Miata engine. Piston number 4 was totally F'd in the A, err... F'd in the ring-lands. Parts of two ring-lands were broken off and one of the rings was cracked into a few pieces. Cylinder number 4 gets the hottest of all of the cylinders, especially when the engine overheats, because of the cooling system layout. Before I seriously race again I will have to setup a coolant bypass that will even out the cylinder cooling. With those ring lands busted I think there was a ton of blow-by that put fuel and moisture into the oil. All of the bearings I cracked apart were super scored. I have a feeling I would have spun a bearing soon.

Pictures!

 

[exdeath]

RIP :'(

 

[manimal]

Ya RIP man!


Your new garage and paint bay sound awesome! Show us some picts!!

 

[JCH13]

Ya RIP man!


Your new garage and paint bay sound awesome! Show us some picts!!

They're coming! I need get it presentable first though. I'm working out lighting and vacuuming up 25 years of over-spray and dust D: I have never used a shop vac on a wall or a ceiling before...

 

[manimal]

They're coming! I need get it presentable first though. I'm working out lighting and vacuuming up 25 years of over-spray and dust D: I have never used a shop vac on a wall or a ceiling before...

At least save us some before pictures!!

The employee bathroom at my shops door hadnt been opened in a long time when I moved in. I pointed the power scrubber at it with my eyes closed while crying...


well I may be exagerating but it was bad.....looked like someone did a upper deck when they left....

 

[JCH13]

Well, after months of focusing on house work and then the FIRST robotics competition I'm finally back at working on my Miata. At least a little bit.

Last night me and the new roommate about finished prepping the new-to-me subframe for painting with a combination of a needle descaler and cross-twisted wire wheel like this one:

I then replaced a sway bar stud that had snapped off during dis-assembly. The backing snapped off just using some vice-grips, which was nice. I then trimmed a bolt to the same length and braze-welded it in place. Definitely overkill, becauseracecar.

You can see the three little points where the stud was spot-welded in place. I think there's another, smaller, stud that I also have to repair, but couldn't find it.

Bolt-head braze-welded in place with high silicon bronze wire. Corrosion resistant, strong, and plays nice with semi-rusty steel.

I realize as I post this that I never updated a few other bits I've worked on, will update soon.

 

[JCH13]

Painted the rear subframe with rust bullet, trying to decide what color to paint it. Emergency orange maybe?

Got one of the front suspension corners taken apart, all of the rod end boots are totally shot. The rod ends themselves seem all salvageable. The grease is coming out really clean, doesn't look like any significant amount of dirt made it into the joint.

 

[phucheneh]

You talking about tie rods or balljoints?

No effing way I'd reuse those balljoints, or tierods that look like them. Even if the joint isn't really dry/contaminated, those things have got some miles. Greasing it and slipping a new boot on doesn't make it 'new' again.

edit- also, joining different materials with brass works fine, but the strength is not there. It's all filler material. If that bolt is bearing any kind of load, that weld will break.

 

[JCH13]

You talking about tie rods or balljoints?

No effing way I'd reuse those balljoints, or tierods that look like them. Even if the joint isn't really dry/contaminated, those things have got some miles. Greasing it and slipping a new boot on doesn't make it 'new' again.

edit- also, joining different materials with brass works fine, but the strength is not there. It's all filler material. If that bolt is bearing any kind of load, that weld will break.

Rod ends = ball joints, same thing, different name.

There is absolutely no play in the ball joints what-so-ever and they move quite freely. They're on a car that sees 5k miles/year and gets a complete suspension check at every auto-x. It may be a calculated risk, but it is one that I'm quite comfortable with. The ball joints looks particularly gross because they're still covered in sand, and the boot has cracked because the car has been lowered for the past six years.

Also, good thing I didn't use brass then, I used silicon bronze, if you were paying attention. The only force the weld needs to resist is the tightening torque of the rear sway bar stud, a whopping 14-21ft-lbs. The head of the bolt keeps it from pulling through the sub-frame as the sway bar bracket is tightened on.

Besides all that, completely annealed silicon bronze has about 1/2 the yield strength of mild steel. I've brazed-welded over 10x the surface area of the original spot welds. At the very least my braze-weld is about 5x as strong as the original welds.

 

[manimal]

I wouldnt worry about those welds braking at all. I am sure your rod ends are fine but they are so cheap and you have everything apart I always rationalize that taking it all apart again is worse than paying a few extra bucks though you take that stuff apart more than most people so that may be moot as well.

Orange would be awesome for the subframe.

 

[JCH13]

I hear ya manimal. The lower front ball joint isn't bad, $25. The steering tie-rod end is a little more painful at $60. The upper ball joint is part of the upper control arm, which run $100 used (if you can find them) or $280 new. I'd be looking at $730 to replace all of the front axle's rod ends, or $42 for new boots. $688 'pays' for a LOT of labor if I can postpone replacing them

The plan is to take everything completely apart and then clean and anti-seize all of the threads and shanks. That way if (or when) one finally starts to go it'll be a fast swap-out. All it takes is jacking up the car, popping a wheel off, and turning the steering wheel, and all three joints are easily accessible.

 

[manimal]

Doesnt advance auto have mr2 upper control arms for 70 bucks ish? You can stack the coupons if you do it online as well.

http://shop.advanceautoparts.com/we...works_15511130-p?searchTerm=upper+control+arm

Dorman is 171 there ouch.

 

[JCH13]

MR2 control arms would work great if I wasn't working on my Miata

I know, easy to get confused since I hang out with MR2 guys and race MR2s

This is the OE replacement. I would get this one instead and save $50.

 

[manimal]

MR2 control arms would work great if I wasn't working on my Miata

I know, easy to get confused since I hang out with MR2 guys and race MR2s

This is the OE replacement. I would get this one instead and save $50.

lol never mind! I am home with the flu and dayquil is a bitch