Engine Rebuild Diagnostic Help
 

Hello All,

Relevant Details : 2000 NB, BP4W, Eagle rods + FM pistons, ACL Race Bearings (rod and main)
Boundary oil pump, ARP mains + heads, Reused the stock oil warmer/cooler
Engine was running when pulled, although very varnished inside. Bored to 84mm

I recently finished up my first engine build. I reinstalled the engine, seated the rings and did about 25 miles of driving around (55 MPH roads, lots of accel/decel), and not much idling.
I went out to run the car around some more, but my idle had been hunting and lean so I wanted to dial that in before. While I was sitting there trying to get the idle dialed in I started hearing a ticking/clacking noise.

Pulled into the garage, drained the oil (for the second time so far, first time after seating the rings). There was some metal grit in the oil both times I drained it. I cut the second oil filter open and did not see any large chunks.
My magnetic drain plug came out with some black material on it which was super fine.

The noise sounds like it is coming from the top end to me. I did lap the valves and reshimmed them when rebuilding the engine and was able to get all the lashes within OE spec.
I will be getting a mechanics stethoscope tomorrow to pinpoint where the noise is coming from.

At this point, I expect to pull the motor, but want to do my due diligence to avoid that if possible.

Things that I think are clues at this point are...

1. The limited idling I've done with the car was very hunty. I was able to get it to idle smoothly, but the idle AFRs had to be around 12.0. If I leaned it out much more than that it would start oscillating. I'm curious if that could be caused by a leaky intake valve? With a very lightly tuned VE map my AFRs while driving look within a few tenths of my targets.
   1. Full disclosure, I did change out my injectors from stock to FF640s when reinstalling the engine, but did update my tune to reflect that.
2. I do not hear the clicking noise when driving the car. I can rev smoothly through the rev range up to around 5500 and do not hear any noise. I hear it if I rev the car while stationary, and the sound is tied to RPM.
3. It did look like some of the metal in the oil was golden and non-magnetic, which leads me to think it's a bearing failure of some sort, or possibly wrist pin bushings. I did have to have my wrist pin bushings on my rods honed.
4. I went to ARP Main Studs when rebuilding. Machine shop checked and said a line (align?) bore was not necessary. When I plastigauged my mains, as best as I can tell, the measurements were at the tightest end of OEM spec, if not tighter. I opted to switch to ACL's HX line of bearings, which got all the clearances to 0.002, if not very slightly looser
5. When I went to do the first start I had an incorrect trigger angle setup in my tune after swapping to the FM 36-2. I was using 80 degrees (Hydra setting), however it should have been closer to 210 (speeduino). I cranked the engine for quite a while before figuring this out thinking it was an incorrect air/fuel mix. My oil pressure gauge is connected to a switched power, so I wasn't able to look at it while cranking, but I was seeing oil pressure (sometimes as much as 20 PSI) when I stopped cranking. Once I updated the setting the engine fired immediately
6. Oil pressure has seemed reasonable to me throughout my measly 26 miles of driving.

My plan is to check valve lashes tomorrow, along with pinpointing where the noise is coming from (top or bottom). I would be happy to find out this is just an issue with the valve shims, but I'm not expecting that to be the case.
Like I said, I am prepared to pull the engine, but figured I'd throw this up as a Hail Mary. Any thoughts or feedback is welcomed.

When I read posts like this, it's pretty much always to late. If you visually see glitter in your oil, this thing has to be pulled and inspected further.

Arp mains do not just tighten the clearance overall, they push the bore out of round, so there can be a pretty drastic difference depending on where you take your measurements. Better having a little bit of a loose engine than tight.

I'm interested in what happened here, seems like you did your homework. I feel sorry for you, this sucks big time, hope I'm wrong

Right, I was thinking about that as well with the ARP mains. It seems like they would be more likely to turn the bore into clamshell shape than a () shape. My thinking there is that maybe the horizontal bore was very loose, although I'm not sure that would cause a failure unless it was very far out.

Thanks for commiserating, I figure that's part of the reason I posted here. I'm certainly not the most precise/---- person on here, but I did try to do my research and build things to a level of quality that I was comfortable with. Thankfully I've been able to borrow any/all specialty tools from friends so I could try to do everything properly.

Ironically I was commenting on another thread about how much metal was normal for a new engine's oil, which was making me feel better. Oh well, we'll see what the diagnosis is after looking at it tomorrow. On the upside, if (when) the engine comes back out there are some smaller things I can tidy up while its out.

Anecdotal evidence here. Not an expert compared to the others here by any means.

When I built my motor the first time, I got the block line bored with the OEM main bolts, but ended up building it with ARP mains. My motor ended up spinning a rod bearing at 2,700 miles (seemingly from oil starvation) and I had to rebuild it. With a reman'd crank and .010" over bearings, my main clearances this time around were still within spec. 3,200 miles and four track days in and everything's still good so far. My buddy did the same thing with his built VVT/EFR6758 motor and it's been pushing 350-400whp for 20k miles without a problem yet. While it's worked for the two of us, I definitely don't think it's the way it should be done. We're both probably just lucky. As DV said, the bore deforms in more ways than you'd think.

On a lighter note, my buddy that I mentioned above had an issue with a ticking noise that occurred only at idle right after building his VVT motor. It ended up being the woodruff key. He replaced the key and crank bolt and it never came back. Given the golden oil hue, though, this may not be your concern.

I appreciate the input Z. The oil didn't look great, but with assembly lube and everything else circulating I'm not sure exactly what it should look like.
The engine bay is relatively full (AC, PS, turbo bits, etc...) but the noise sounded like it was coming from the engine itself.

The few miles I have put on it felt great, if anything it's more motivation for me to fix the issue and get it back on the road.

Well I'm glad it's felt great so far at least. I feel you, after running a freshly built engine (especially one you put together with your own hands), it's hard to wanna go back to anything else. I remember starting my built motor for the first time and thinking: "Wtf, this thing is so smooth now" lol.

Stethoscope-ing the motor while the noise is present will definitely be the next necessary diagnostic step. Just for sh*ts and giggles, though, do you have a photo or video of the recent oil you drained? And a video of the noise occurring? Oil qualities aren't going to tell you as much at this point as they would later on, but between that and a video of the noise, the others on here may be able to guide you a little bit.

What oil are you running? Another anecdotal piece, I'm running Rotella T4 in my engine and basically any metal dust in the oil turns it gold. Currently running OEM bearings and in all my early oil changes after rebuilding my engine, the metallic sheen was gold, or a slightly lighter shade of brown. Used blue assembly goo and my first oil change came out super dark.

I'm planning to grab some video of the engine sound tomorrow. I figure there isn't much use running the engine more than needed right now, so I'll do that when I have the stethoscope in hand (and after I take a break from thinking about it for an evening).

I'm also running Rotella T4 (the conventional version, not the synthetic blend). First start was using Lucas break in oil. SAE 30 and while the garage was warmer than ambient, it's also pretty cold here (just a bit above freezing) right now. I was curious if that could cause issues but I didn't find much definitive information about it. I figured if it was a big deal I would have found more info saying, "DON'T DO THIS!". That's another reason I'm hesitant to call out the color of the particulate, because the oil is certainly contributing to the color.

I wouldn't be surprised if a tiny bit of the crud is from the subframe, as I was wiping that down to avoid getting some of the spilled oil from the filter onto the floor. I am operating under the assumption that the vast majority of the particulate (and all the metal) is from the engine.
https://cimg7.ibsrv.net/gimg/www.mia...1a1c7bbc72.jpg
Oil drain pan after the majority of the oil was dumped off. 13mm spanner for reference


The photo below is the oil that I dumped out of the filter after cutting it open. I'll look closer at the filter tomorrow and get some photos of that as well. Lot's of dark particulate, but surprisingly little glitter.
https://cimg0.ibsrv.net/gimg/www.mia...c839b8a54e.jpg
Oil left in the filter once it was cut open.

When replacing main bolts with studs the cap can shift across the parting line. This is caused by the elimination of the eccentric action of the bolts as they are tightened. The process to re-align them would be align honing and very rarely would it require boring & honing. Usually boring is only required when installing different caps. Measurement at the parting line is important when installing studs. Vertical oil clearance is still paramount.

Valve lapping was a possibility and somewhat common for shade tree mech’s before the seats were hardened. This would be before unleaded gas, today it should not be used to recondition the sealing surfaces. It is sometimes used lightly for inspecting the valve to seat location.

There should be no metal to metal contact of the wet components in an engine. It’s not ideal to have metal particles in an engine after the first few oil changes. There are reasons for some to show up on a new build but if it’s a long term issue something will eventually fail. It will either be the components that are causing the particulates or from the effect of them on other components.

Engines that have complex wet cam drive systems as in chains and tensioners etc, are very prone to have metal particle contamination early in life. This is one of the benefits of a belt drive system. It is always best to pull an engine and disassemble it early when there are issues to avoid catastrophic failure. Parts for these engines are getting more difficult to find.

I appreciate the feedback Leo. When checking the oil clearance I did check it vertically.

If lapping valves is no longer relevant, I assume a machine shop would recondition the seats to the valves?

I've only changed my oil twice so far, but again, I'm trying to be realistic. In my mind, the likelihood that the engine is coming back out is very high. Hopefully it will be with minimal damage to the crank.

The valve seats are cut or ground. The valves need to be ground. If they are new valves they can be checked with a runout checker. I recommend grinding new valves. Valve’s that are out will eventually break from cycling.

Went out and fired up the car with a couple buddies. I believe the rich idle is coming from an issue with the FM 36-2 wheel and my fueling setup (running sequential, although it's unclear if Speeduino has the proper cam profile to support this).

We didn't end up concluding anything. The noise wasn't as apparent, if present at all. I did capture some video, checked valve lash, cam timing and ECU trigger angle. I looked more closely at the second filter and there were no large chunks of metal, just a few tiny specs throughout the filter.
The car idled decently, still super rich (think 12.0 AFR, Edit, checked my log and it was closer to 13.5 after warming up).
Tunerstudio is deleting my logs for some reason. I took two, but only one of them saved, and of course its the less useful one.

https://cimg6.ibsrv.net/gimg/www.mia...ac145cfe1e.jpg
This was about as bad as the filter got. No large chunks of metal, a few pinhead sized specs. Plenty of black crud
https://cimg7.ibsrv.net/gimg/www.mia...67c9d83c51.jpg
https://cimg9.ibsrv.net/gimg/www.mia...b4023cdc91.jpg
Warm measurements of the lash


Here are the video's. It seems like the noise is more noticeable in the cabin, although I didn't notice it as much today, if at all. My friend who owns a BP Escort thought there was a sound similar to lifter tick (solid lifters, not the case, but gives an idea of the sound).
Also, the car isn't quite fully warmed up when I'm in the cabin. The oil pressure is sitting around 35 when warm with a Boundary stage 3 pump and oil squirters deleted on fresh T4 15-40 conventional.

There wasn't any obvious noise, IE we weren't able to come to a conclusion. At one point when warming up I revved the car and there was a tiny bit of chatter as the revs were dropping.
At this point I'm thinking I'll sort out the tune and see if I notice anything concerning. Thoughts?

I can’t view the video, but is the noise the same frequency as a lifter tick would be? Bottom end issue would tick twice as fast as a valvetrain issue since the crank spins twice for every cam rotation.

Some of your cam lobes don’t look like they’re in great shape…

I wasn't able to replicate the sound yesterday. I thought I heard it very briefly but it was not obvious or apparent.

I'm also learning that my trigger setup was incorrect, so I've likely been running half sync. I'm planning on correcting that in my tune today. I haven't found any large chunks or shavings in the oil filter. I think I'm going to drive it and monitor for any sounds.
I don't want to lose more sleep over this, so I'm hoping to come to a definitive answer soon, however that ends up happening.

Yeah, I probably should have spent more time cleaning the cams, I figured any place that made contact would stay clean. The journals on the cams were all clean. For context this is what the head looked like when I pulled it.
https://cimg0.ibsrv.net/gimg/www.mia...da21deb31a.jpg
https://cimg7.ibsrv.net/gimg/www.mia...910491b81e.jpg

I took the car back out and put ~45 miles on it, taking it from 25 up to ~70. The noise I've been hearing was present once the car was fully up to temp and the oil pressure dropped to what I assume is it's normal range. This is my first time having an actual oil pressure gauge and I'm very glad I installed it at this point.

I just dropped the oil and cut the filter, fully prepared to confirm a kill on the engine. I would say the oil looked similar, if not a bit better than the last change.
The filter medium was similar to the last one as well, if not a bit cleaner. No large metal chunks or shavings, just a few tiny metallic specs.

I'm realizing that with the flourescent light and the oil, these photos don't really communicate much, but for those interested

https://cimg9.ibsrv.net/gimg/www.mia...d08bb3514c.jpg
https://cimg3.ibsrv.net/gimg/www.mia...98cc0f2bbc.jpg

I've linked a video of the noise from the cabin of the car here. It's somewhat hard to hear, but I've found that the cabin seems to filter out a lot of the other engine noises.
https://photos.app.goo.gl/CfaVQWEeiR3GdJFH8

The noise is pretty apparent when I stop at a stop sign, but is harder to hear when I pull into the garage and idle there for a minute. I'm not sure if that's a clue, but it seems to be the case to me.
It is definitely tied to RPM. I'm starting to wonder if it could be an accessory pulley or my crank pulley. I'm also guessing that this noise has been there the whole time, although the first time I took the car out it was idling terribly and I was rolling through stop signs, so it's possible I didn't notice it.

I haven't been able to pinpoint the noise with the stethoscope, like I said it's harder to reproduce in the garage.

If anyone has ideas of things to check, or recognizes that noise please chime in. I'll probably start looking into it again tomorrow after work to see what I can find.

When my car had oil starvation and developed a rod knock, I still drove it home and that is why the crank needs to be turned. The place to look is in the oil filler cap with a good flashlight. Pictures don't show up very well, but if you have a bearing problem. There will be copper glitter in the oil filler hole, shit tons, in every pocket, the tops of the cam bearing cap bolts, the Allen key holes on top of the studs, every little pocket in the head. It will be obvious, not some little glitter that isn't copper colored from breaking in the fresh hone on your cylinder walls.
At least, that's been my experience.

Also, the sound was only during the transition from coast to power. Drive, zooooooom, knock knock knock, coast... Knock knock knock zooooooom, knock knock knock coast. Like that.

I don't have much to add, but on the coattails of sonofthehill's post, my rod knock noise didn't show up at all during idle, and would only show up above 2k rpm, regardless of load. This was after fully spinning a bearing though.

How many miles do you have in total on the thing now? My engine seemed to be shedding metal at a similar rate to yours. That's not to say mine couldn't blow on the way to work tomorrow.

Edit: I take back that last part. Don't wanna jinx myself.

My car has a bunch of 11.5 second 1/4 miles on it since I changed the bearings and crank, after the first oil starvation problem. Which I imagine is due to inadequate cleaning of the block after machining. My car rips and could actually do much quicker if I actually have a crap.

What no fucking cats for me bro?
Like I gave a fuck anyway! LOL

I'm only at 70 miles, and 45 of those were on the filter I posted above. I'm starting to think I'm being overly paranoid. To be fair, there's another thread on here with a similar story from a friend of mine, and he just got a new crank in the mail.
I drained the oil today and didn't have any to fill it back up, because I expected to find large chunks in the filter. When I saw that wasn't the case I went back to the drawing board.

I can't run the car any more until tomorrow because I don't have oil to fill it back up, but I'm starting to think the sound is my injectors. I swapped to some FF640's that were used for a while in my roommates car.
I've got a couple tuning issues right now (Speeduino doesn't seem to support the 36-2 wheel with the Miata cam trigger), so although my car's running, my idle is super rich right now and a bit lopey.
I've found some anecdotal evidence on here and other places where people describe something similar to me, especially that the sound is easier to here in the cabin. Found some video's as well that sound pretty close.
My roommate who sold me the injectors also had top end noise, but assumed it was due to an adjustable cam gear that failed and caused piston to valve contact (high compression motor, I promise we're somewhat competent with cars). I'm starting to suspect it was the injectors, at least partially.

Son, when I first heard the noise I thought it might have been improper valve lash so I took the valve cover off. Lash was in spec or within a thousandth and I did not see any metal.

Z, I actually had rod knock in my subaru about a year ago and I remember recognizing it immediately the first time I started the car. This sound wasn't definitive for me, so maybe that's a good sign.

Once my oil shows up tomorrow I'll fire the car up and see what the injectors sound like with the stethoscope. Apparently it isn't uncommon for these to be pretty loud as they age based on some forum posts.
If I confirm it I'll try to get some more focused video of the noise.

You must have enough to make this post. Most don't ask and most don't give for help. I guess it is just the way it is. Here is one for sticking up for yourself.

Got my oil today and took the car out at lunch. Ticking noise was present. Pulled into the garage after driving around a bit.

I'm pretty confident at this point that the ticking noise is just loud injectors. The stethoscope around various points on the fuel rail (what I could access) was certainly noisy and clicky.
I also remember thinking that was where it sounded like the noise was coming from when I first looked around.

It sounds like this isn't uncommon for EV14 injectors. I'm coming from stock injectors so I guess my ears aren't used to hearing loud injectors.
I'm going to monitor the sound and fuel system as I continue to break the engine in. I assume it could have something to do with something else in my fuel system, as the rest is stock aside from the fuel pump.

For clarity, I'm running FlowForce 640 CC Injectors. These were used by my roommate for a while in his car but never saw boost. The noise might have been present previously in his car, but it was never attributed to the injectors if it was.

The best part is that the next couple days are going to be pretty warm here, so it's a perfect time to go cruise and get some miles on the thing!

Was this directed at me or SimBa? :rofl: Have a cat anyway for being a go-getter.

Keep us posted on the noise and your engine break in process. I don't remember my FF640s ever making an audible noise inside my cabin, but I also got them new and only ran them for a year and change. They did make an audible clicking noise if you put your ear in their general vicinity with the car running though.

Enjoy the car the next couple days!

Thanks, I plan to! Took it out last night and got the mileage up to 110. Went to the parts store and dropped off all of the oil I've been going through. One of the employees who "doesn't like cars" and "is a truck guy" said he would like cars if they were all painted like mine. I laughed.

Got into some boost and higher into the revs. The car still seems happy, although it clicks like a train on the tracks at idle. I'm not sure why it's so apparent in the cabin compared to the rest of the noise the car makes.
I was finding some slight hesitation when getting higher in the revs, but I looked at the logs and my TPS appears to be a bit noisier than before, and it's been triggering acceleration enrichment pretty frequently even when holding the pedal steady. I was seeing my AFR's spike rich while cruising, so that should fix it.
Idle is still hunting around a few hundred RPM and the AFR is inconsistent. I'm on open loop, but my IAC and Fuel values are stable in that region (IE, all the same value) and it's still oscillating a lot. I'm not sure if that's the injectors or something else. I've got my idle advance setup again, so maybe that'll stabalize things a bit.

I'll put more miles on it today. Might run around and return some of the specialty tools I borrowed from friends; mics, T gauges, ring filer.
I'll probably drop the oil again around 300 miles or so and see how it looks, but I'm feeling pretty confident about everything now.

Directed at??? :rofl: Holy smoke, 500 cats, hopefully animal control doesn't get wind of this.

You guys should know by now that I am usually talking out my arse. I am so full of shit that I need to vent some now and again so I don't exceed burst pressure. But seriously, don't forget to peek in the oil filler hole for glitter. Annnnd... Don't take me too seriously.

Hahaha, no I figured it was facetious. The arse-talking is greatly appreciated :) I just wasn’t sure if you wanted props from me or Sim.

Leo brings up a good point, though. Many posts with good advice go un-catted. Real shame.

Car is still running OK. I've got an ignition or fueling problem somewhere I'm pretty sure. The car hesitates around 4K RPM like a very soft ignition rev limiter. I'm assuming the same issue is causing me to have to idle super rich.
I've got some injector cleaner to run through on the next tank. If that helps I'll probably pull and clean the injectors.

Outside of that I've got about 200 miles on the car now. I'm planning to drop the oil around 300 and turn up the boost when I resolve the misfiring.

Got a log of the misfire occurring? Is it under heavy load or just anytime you get around 4K?

Certain kinds of injector cleaner work really well, just make sure you run the recommended ratio. Pretty sure I killed an OEM fuel pressure regulator on my car by putting a bottle of the stuff in on a near-empty tank lol. I’m sure you don’t need to be told, but I like sharing that story/info lol.

Logfile is attached. The misfiring can be seen around 626 S. It's a longer log, I took it on my way to the store.

You can also see the rich idle. It's pretty smooth right now, just running open loop + ignition correction. If I pull some fuel to get above ~12 AFR then it oscillates wildly and spikes to very lean. Not like a rough idle, but like a misfire.
It seems to be running better when it's cold.

I ran this same ignition setup with no problems before I pulled the engine, and had run ~10 PSI on a few pull (ran out of injector). I did put new plugs in (BKR7E) when the engine went in. I gapped them down to 0.030 last night but it doesn't seem to have made any effect. Running 3.5 MS of dwell, which is what I was running before.

I might steal the wires off my roommates NA tomorrow and see if that helps at all.

I plotted the RPM/S below so you can see where it's stumbling a bit easier. The worst dips are actually going negative. I realize a screenshot like this isn't too helpful, but figured I'd throw it up.
https://cimg0.ibsrv.net/gimg/www.mia...90fe280b75.png
Notice that RPM/S is going negative

Looks like you’re at 88kpa when it occurred in that snapshot. Does the misfire occur under load only or will it show up anytime the engine’s at around 4K rpm. Ignition misfires are usually exacerbated with more load.

If rpm/s is what I think it is (a measure of crankshaft acceleration/deceleration), then those dips in the graph when the engine is under load will correspond with any misfire. We’ve got a similar function with our Ford scan tools that uses CKP sensor acceleration along with cam position sensor info to identify what cylinder is misfiring in real time, and reflect it in a similar type of graph as shown in your log. From what I’ve seen, though, I don’t think there’s a similar way to see this in TS.

I believe your understanding of RPM/S is correct. I just graphed it here because it makes the changes in RPM easier to see than looking directly at the RPM graph.

I cleaned up the ground under the intake where the ignition coils ground and reseated the plug wires to the coil packs. It seems like that helped a bit, but it could just as easily be in my head. It was still misfiring. I'll swap my roommates plug wires in this afternoon and go again.

It seems to misfire under light or heavy load. I haven't been putting my foot into it too much though because I figure it's probably not the best idea to flog it when it's running weird and only 200 miles into the new engine.

Tried my roommates plug wires, no change.

Your roommate got the same ignition coils? Maybe give those a go as well.

Not a bad thought. I think they're compatible (1.8NA vs NB1), although I'm not sure how much my roommate wants me to disassemble his car. I'll think about that though. If it is ignition related I'm not sure what else it would be unless I got bad plugs somehow (ordered through Amazon, so it's possible)

I fixed the misfiring this weekend. I'm going to do my best to explain it here although I'm still trying to figure out exactly what was going on. TLDR Fueling issue related to my trigger setup on Speeduino

Speeduino does have support for a missing tooth trigger wheel (36-1, 36-2, etc...). However there is currently no support for the Miata's cam trigger. In theory this means you need to run semi-sequential fuel, however I had my car setup with a different trigger pattern and the car seemed to be running fine. I tried a few other settings including semi-sequential and a different cam pattern, but the car didn't want to run. I DID have the car fire up, but it was dying as cranking enrichment tapered off. I believe I could have changed my fuel table and corrected this, but at the time it didn't seem like an improvement over what I had.

I found some custom firmware that was released a few months back with support for the Miata cam profile. I compiled and installed that yesterday. I had a similar experience where the car was dying after cranking. Convinced I now had a valid trigger setup, I started adding fuel. I had to nearly double my idle fuel and retune my entire VE table, adding ~15-30 points across the map. Maybe more in some places.

With that change I'm now able to rev the car happily into the 5K range, although I'm waiting to put a few more miles on the engine before I want to get to redline.

I believe that the cam signal is never referenced once the car is running, so I'm not sure that the cam profile actually fixed the issue. Like I said, I think one of the other configurations I used would have worked as well if I retuned my fuel table. I was not seeing sync loss before, I was hitting my AFR targets, and I was setup to run sequential fuel.

My idle is still unhappy above ~12 AFR, but with some new confidence in my trigger pattern I'm going to see if I can correct that via tuning. I also added some fuel injector cleaner to my last tank of gas, so I'm going to see if that does anything.

Cat given for the in-depth follow up. Glad you're (hopefully) past it and ready to continue breaking in the new motor!

I was gonna say this deserves a post in the Speeduino section but it looks like you already beat me to it haha. Hopefully this helps someone out in the future!

How many miles on the motor now?

I'm hoping it helps someone. I still want to try to figure out what was really going on.

Changed the oil again this weekend at ~250 miles and it looked the best of the changes so far. Didn't cut open the oil filter.

I'm probably around 300 miles now. I haven't been babying the thing, but still don't want to go all out on it. I'm running ~5 PSI but haven't been flooring it. I realize that there's not really anything to break in at this point (rings are seated by now), but I still want to let everything settle a bit before ripping on it.

Having said that, I took the car out to the nearest fun road before I fixed the stumbling. No laptop, so I was able to carry a bit of speed into the corners. Feels good to be back in the car.

Heck yeah dude, you're getting there. I remember taking it real easy on my engine until ~580 miles the first time around, then adding 9psi around that time, then stepping it up to 17psi at 900ish miles.

Second time around, I was at full boost by about 300 miles lol. The first time breaking in your in built engine is probably the scariest, but after reading about guys driving up and down the street and then breaking their engine in by doing dyno pulls (one of my buddies included), I figure we're probably erring on the side of caution haha. I'm more cautious about ramping up RPM over time during the break in than I am with load now.

Good thing you can drive it properly again. Being able to use the car for its intended purpose gives you motivation to keep on trucking through the technical issues haha.

I think this thread has been successfully derailed, but I'm going to keep going with it.

Took the car out to figure out my idle today. Still couldn't get it to idle any leaner than ~12 AFR and realized I was running at half sync. Thought that was a code issue but eventually realized I forgot to plug in my cam sensor when I was troubleshooting yesterday. So I drove it on batch injection yesterday and a bit today, just happy that I could rev it out and that the idle was smooth enough.

Well, when I realized the cam sensor was unplugged, I plugged it back in and went back out. Immediately my car was smoother on light throttle cruise (prior it was super jerky). I was able to lean my idle out a bit, at least into the 13's, and could likely go further but I'm going to do that another day.

I think the voltage correction chart that I got from flow force was also a bit aggressive. I smoothed out the part of the chart around 14.0, so now I'm getting similar correction from ~13.7V-14.3V. Pretty sure some of my electrical accessories (fans mainly) were kicking on, causing a voltage droop and causing my injectors to swing ~5%. I think that was the main cause of the wild oscillations I was getting.

I'll do more in the next couple days to make sure things are working in a few different environments, but I'm starting to get very confident in the car overall. ~400 miles in and just got the boost turned up to ~10 PSI. This things gonna be quick.

Apparently there is a bug in the Speeduino FW I was using which caused a variable to overflow at 914 RPM and would cause the injector PW to drop to almost zero, which is what I was seeing in my datalogs. I thought it was a hardware issue, but the PW value in MLV is what the ECU is commanding. I thought maybe it was being thrown off by a mechanical issue with the injectors. There is a fix in the latest master firmware (not an official release yet).

I corrected that and now can idle smoothly at 850 RPM, ~14.7 AFR. Just crossed over 600 miles with the engine.

Last oil change was conventional at 500. Planning to swap over to synthetic at 1000 miles and then change again when the engine reaches 3k miles.

You sir, have more standalone troubleshooting skills than most anyone asking questions on here. Have a cat for figuring out the issue and following up. Keep us posted on how the motor's doing!

Thanks, I appreciate it!

I can't really take too much credit though. Someone else had already caught the bug and made the fix. I just found out about it and copied the changes over to the other firmware.