Gee Emm

Sorry to hear about this. Any mechanical noises apparent?

Maybe pull the plugs and stick a camera in there? If it is smoking, oil or coolant is getting into the chambers, may be something as 'simple' as HG. Hopefully not a major drama anyway, whatever is the problem - fingers crossed for you.

Tchaps

Well that sucks pretty hard.

I'm no expert at reading plugs but to me two of those plugs look hot and / or lean. I would get the injectors tested / cleaned.

I thought Miatas ran heat range 6 plugs as stock - and really for FI you should be running 7 for your hp.

As others have said compression test and leak down test is your friend.

Also check over any vacuum lines and connections thoroughly - could be as simple as a vac line coming off and throwing the fuelling way out, massive over-fuelling could also cause smoke. If the ECU is just happily sitting at 100KPa it will overfuel in vacuum, underfuel in boost.

rwyatt365

That sucks *****, big time!

As has been suggested, a compressions test at least will help in the diagnostic process - a leakdown test even more so. Were you hearing any "expensive noises" when you attempted the restart? Depending on the size and density of that cloud of smoke, my first guess would be that you lost a ring land due to potential detonation brought on by an over-lean condition. Hopefully, it's something simpler, and less expensive.

Cincykemo

Thanks for all the replies, really.

A couple of people have asked about mechanical or "expensive" noises. I heard no metallic type noises coming from the engine.

A quick trip to Horrible Frieght and I have a couple of diagnostic tools.

Cincykemo

I had the belt tensioned on the exhaust side. When I pulled the valve cover it was still in time.

After I verified timing I pulled the plugs.

These are brand new plugs I put in yesterday, the same as the ones I pulled out. #4 Is the top and in order from there. #2 Was wet with gas.

Then I went about performing the leak down test. #1 And #4 were at about 8% leak down with #3 being at 25%. #2 However was a different story.
It was faint but I could hear the compression coming out of the dipstick tube. I'm guessing this is a ringland failure?

I took my borescope and started looking at each piston.

Certainly not the best picture on it but 1,3 and 4 all looked about like this (above.)

And #2 looked like this (above.)

From my very limited knowledge I'm assuming #2 had a lean event caused possibly by a bad injector. Last night when I made the short pull that ended this motor I was looking at my AFR's and they were in the high 10's, low 11's. When I drove the car earlier in the day I took a log of driving around and I got on the highway and did a couple of small pulls and sent this to my tuner. He looked at the log and confirmed that everything looked as it should have. So again this would lead me to think it was a bad injector.

Well, ****. I really just wanted to enjoy this car for a little bit before winter. I'm pretty disappointed atm, I put a lot of blood and sweet into this car over the past 2 months. It beat me up at every turn, literally, my balancer came off and cracked my forehead wide open. I tried to do everything right but in the end I think this cheap set of injectors got me. Did someone say forged rods?

Tchaps

I think that is probably oil and not gas on plug 2.

It might not be rings - you could have burned a valve, but either way that engine is hurt, coming out and there's repairs to be made.

Its hard to see on potato vision (no offence), you might get the head off and find nothing up with the pistons, but I would still strip it all down.

I have personal experience of pistons looking like absolute murder on a camera, then when the head comes off it turns out to be a bit of soot. In my case I'd cracked the skirts which was only apparent when I got the pistons out the bores. Don't assume anything if you are going to reuse this motor, check it all out.

Do yourself a favour and get a different crank in there without a worn keyway to save yourself the bother of breaking another key in short order when you get it all back together. Sort yourself some decent injectors and go through and check all wiring and injector outputs on the ECU before you fry the rebuild.

Sorry to see you having so many issues. I know the feeling of being kicked in the nuts repeatedly by your car and its not a fun time. Hope the rebuild goes smoothly.

Cincykemo

It definitely smelled like gas.

Tchaps

Is it still wet now or has it dried?

Gas will evaporate, oil won't

Cincykemo

Does anyone agree with what I think happened? Different opinions? Can you check for a faulty injector with a multimeter?

EO2K

iTrader: (37)

If you think the injectors are questionable, either replace them with known good ones (Injector Dynamics or FlowForce immediately spring to mind) or send the ones you've got out for cleaning/flow testing/verification. I've used WitchHunter Performance (witchhunter.com) in the past for these services. Listed turn around times have always been accurate, and $23 per injector isn't a bad deal. ~$100 investment in actually finding the problem is cheaper than another engine.

If you decide to buy new injectors, do some reading and ask around before you buy. There are still a lot of vendors out there selling marginal to straight up trash compared to other options.

Kinda. Set your multi-meter to ohms and check between the two pins. There should be a published rating for your injectors somewhere, but you'll know pretty quickly if one is bad due to the radically different readings.

I went and CTRL+F'd both pages of your thread and couldn't figure out what injectors you are running. Care to enlighten us?

EO2K

iTrader: (37)

I should clarify... this will tell you if one of the driver coils inside the injectors are bad, it won't tell you if the injector is partially clogged or if the spray pattern is fuckered. There are DIY ways to check these things, and I know on the Megasquirt there is even an injector test mode. It requires some creative plumbing and can get messy, but it might be useful.

Cincykemo

[QUOTE=EO2K;1610904I went and CTRL+F'd both pages of your thread and couldn't figure out what injectors you are running. Care to enlighten us?[/QUOTE]

They are Siemens Deka injectors, probably one of the worst parts I have on the car. They were a last minute switch out when I was getting dyno tuned out of town last summer on my old setup. The tuner had them lying around, they had been flow tested, they fit and I needed a new injector besides what I had come to the dyno with that day.

Cincykemo

Welp
The shop I had do my last 2 dyno tunes is doing the disassembly and the rebuild. I'd love to do it myself but apartment living isn't conducive to pulling engines.

I went and looked at the disassembled engine today. #2 Piston was cracked, all had signs of detonation and there were chucks of metal at the oil pickup. The cylinder walls looked good and the bearing were a little worn but not terrible.


The flywheel wasn't great either. Can you have this style flywheel resurfaced? The shop wasn't sure.

Originally I was gonna do forged rods, forged pistons, have the head checked/hot tanked and OEM everything else. That option is starting to look a little pricey with the extra machine work for the forged components.

Now I'm thinking a full oem rebuild and putting my money into my fuel system.

Tchaps

Are there any signs of something else causing the problem like the rings butting etc?

I think if I was trying to keep things on a budget, particularly if you have to pay someone to do it, I would look at getting another stock second hand engine, or even just a new second hand short block if you can find one. How much are they where you live?

If I was feeling a little more flush I would open it up and stick some forged rods in it.

Can always keep this old engine to build up if that takes your fancy.

If you had signs of detonation on all pistons what does your spark map look like? What AFRs were you running under boost?

Cincykemo

New Plan:
-Got a BP4W Block (good keyway)
-Supertech Pistons 83.5mm 8.9:1
-Manley Rods
-Manley Rings
-ARP Main and Head Hardeware
-Boundary Oil Pump Shimmed to 66psi
-Full OEM Mazda Gaskets
-Refreshed BP05 Head (orginal)
-Flow Force 640cc Injctrs (e85 compatible)
-Radium Fuel Rail
-Radium Rail Stock Fuel Line/FPR Adapter Kit
-Analog Fuel Pressure Guage (On Rail Mount)
-New OEM FPR
-E85 Rated Fuel Soft Lines
-Already Have A Flex Fuel Sensor

The goal is a detonation resistant short block good for the low 300's (down the road.) Unfortunately the people building the short block are not Miata guys. Their specialty is the 4g63 platform and they do all machining in house. I'm hoping because the 4g63 is a cast block, crank driven oil pump and was designed in the same era as the BP their machining processes will be successful on my platform. Still trying to figure out what piston to wall clearance, ring gaps and what the break in procedure should be.

As always suggestions and links to helpful posts are always appreciated.

Cincykemo

The tune on it when it blew minus 1 session of doing some auto tune.

Tchaps

Certainly that spark map is safe in boost, aslong as ecu and actual engine timing are synced, I would think there is some power to be found in that.

Advance around 100kPa is particularly tame - normally target 28deg here from about 3500rpm up - will help the car feel more lively during small pokes say adjusting speed on the motorway.

Also there is no such thing as a detonation proof shortblock - i've personally cracked forged pistons in my engine from a massive det event caused by a dodgy vacuum hose.

I'd be tempted to leave off the fuel rail stuff and instead invest in an ATI damper. I've personally broken a stock damper off the front of the engine on track with a dual tb supercharged setup. This was on a healthy crank, properly torqued bolt etc. I never managed to fully remove the charger stall on gear changes, 3 years of redline shifting eventually wore the keyway, cracked the key, unwound the crank bolt and let the pulley reek havok at 7krpm. New crank, oil pump, water pump etc - was not fun. The stock pulley only mounts on the very end of the crank, it has very little support. The ATI specifically has the pulleys as one assembly with the cambelt drive gear, so they are supported by the full nose of the crank - not just the very end.

FWIW I went for 3.5thou p2w clearances

Cincykemo

I said det resistant not proof.

Yeah the ATI damper is definitely a consideration. With a specialty crank pulley needed its an additional $600. If I go that route I'll probably downsize from my 140mm to a 130mm crank pulley. Overspinning my blower is always on my mind.😬

Tchaps

You say tomAto I say tomato

FYI the ATI is 138mm diameter already - the front pulley section is larger than the stock pulley. If you need a big boy 160mm 8 rib ATI overlay you know who to ask

Cincykemo

All the things!



Ended up with an ATI damper as well. I'm definitely not impressed with the quality control in this ATI damper. As you can see in the picture the indent for TDC isnt sitting in between the teeth of the timing gear but off to one side. It's only cosmetic as it appears the broach for the keyway is lined up correctly but for $500 that's stupid.


I had Tom at FFS order a custom 130mm pulley to run off this ATI damper. My current pulley setup is 140/62.5 and at redline I'm overspinning the blower by a good amount. I can't change my nose pulley but with this 130/62.5 combo it puts the blower rpm right at 15k @7200. Whatever power I loose in boost I'm hoping to make up for in timing with e85.

Got my cylinder head back from the machine shop. They decked it .006 in, did a valve job and replaced all seals with Mazda oem ones. Now I'm waiting on the shop building the motor to get bearings ordered. Looks like mains are hard to come by but I have everything else.