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VVT swaped NA6 chassis with MS3 PNP. Has AE101 ITBs as well, but that shouldn't matter. I believe my issue is that the car is not registering any RPM, but I've looked all the places I know how to figure out why that might be. Here's what I've tried/tested:
1. Coils and injectors work with test mode. I both hear them and smell fuel when I pulled the spark plug.
2. The crank angle sensor is wired correctly and works. I tested the signal with an oscilloscope at the ECU connector and saw it changing when hand cranking the engine.
3. Same with the cam sensor. Scoped good waveforms when cranking at the ECU connector.
4. I've logged a crank attempt, but couldn't determine a cause from the log.
5. For good measure I replaced the crank sensor, cam sensor, and ign coils.
I've attached my .msq and log files here. Let me know if anyone has any advice or where I should start looking next. I'm guessing it's some setting off in the megasquirt since the wiring/electronics and hardware seem to check out.
I've done a bit more cranking, and a lot more verification of hardware, but have made no progress. Still not getting a sync while cranking, and not seeing anything that looks like a cam or crank input, and no RPM of course. I've hooked up the timing light during these crank attempts and am not seeing any output from the light, which I'm assuming is due to the no sync situation.
Any help would be appreciated. I've attached a log of a recent crank attempt.
As an update, I started fresh again with a base map from DIYautotune and am now getting sync. However the car still will not fire. I did test with some brake cleaner and got a puff from cylinder 1.
It looks like you're still on 4g63 spark mode. Sounds like you're using all NB sensors (which you should), so switch to Miata 99-05 and it should work better.
At the same time, set your trigger offset to 0, you no longer should have enough error to be able to do -16 like you could with a fully adjustable CAS. Also IIRC, the ignition input capture needs to be switched.
Thanks, I forgot to post the new tune, which is using those settings. This is the 4th time I tried to start fresh again...
Log attached as well of cranking with new tune. Seems like its just a tuning issue and me being a newb, but I'm not certain which settings to fiddle with. Apart from the obvious fuel mapping anything else I need to consider specifically for ITBs? IACV is not hooked up right now, but my right foot works for air.
Again, thanks for the help. The car has an appointment at the dyno 7/25, so it will get a proper tune eventually, but I'd like to get it working at least passably so that I can actually learn something.
Made a few changes and attached. You still had some weird **** in there. Do yourself a favor and replace the plugs. Sounds weird, but if you keep ******* with these plugs without it starting, it'll foul pretty easily until you have a base tune on it. If it doesn't fire on this tune with MINIMAL throttle (you were giving it a lot in the log), try switching ignition input capture mode and cycling the key a few times. If the engines ever been apart, it also helps to double check mechanical timing.
No luck. Log files attached of rising and falling edge capture. And yes lol that was definitely the caveman yell equivalent of throttle input. No sputters at all, just steady cranking. I did put a compression tester on cylinder 1 which read ~120, after verifying the timing at 10 degrees with a timing light, and checking the timing marks on the exhaust, intake, and crank at TDC (I have no upper timing cover so it's very easy and obvious). I also replaced the spark plugs, coils, and wires with brand new NGKs. I checked with an old spark plug using test mode and there was indeed a spark, with the plug on the wire out of the head.
The engine was running before my swap, and the only work done to it would be me changing the timing belt and head gasket while it was out of the car, no bottom end or head work. My last VVT swap I ended up timing the intake cam 180 deg from where it should be, such that the intake and exhaust valves were opening together for each cylinder, making no compression. That was a hard lesson to learn so I've checked that 10x over.
The ONLY hint I've found would be this random wire that would have gone to the back of the 1.6 head, but I have no clue what it would be for. It is zip tied to the clutch hard line and passes through the firewall near the driver's area. It doesn't seem like it should matter, but it is out of place.
Here are some oscilloscope captures of the injectors, if that helps at all. I did smell some fuel at the tailpipe after taking the cranking logs, and during test mode I shoved a towel in the intake runner and confirmed the injectors are outputting fuel.
Injector while cranking:
Single pulse from test mode:
Multiple pulses in test mode:
Last edited by rustyredna; 06-29-2022 at 10:48 AM.
You got me, if you've verified spark, fuel, timing, and correction, it should start. If it was sputtering at all, I'd say make sure your trigger wheel is installed correctly, but it's not doing that. The plugs were replaced when I told you to, or at the beginning of all this?
I've replaced the plugs now a total of 3 times on this engine, and I did replace when you prompted even though the previous set had less than 30s cranking time on them. Good thing I bought like 5 sets when I was ordering parts for this project, since they're cheap I had a feeling they would be good insurance. The ignition coils are also brand new.
If the timing was far off, then I wouldn't be seeing a compression of ~120, which I believe is fine on a cold engine? If I was injecting fuel as the exhaust valve was opening of course it would never start.
I really DON'T want to do this, but I do have the engine in the NB that I could put in for testing...
120 is extremely low for a VVT engine. I would expect 150+ from a cold engine, but it's difficult to compare compression testers. Maybe check the other 3?
Could be my harbor freight compression tester, but I will check the rest of the cylinders. However, that wouldn't be bad enough for the car to not start, it would just mean I'm due for a high comp bottom end over the winter.
Considering I put this in since my 1.6 read 110~120 that may not have been necessary...
But also this is how the top of the piston looked, so I'd believe it either way.
Ok, so I got it to make a couple of pops by putting about a teaspoon of fuel in each of the intake runners, but it did not catch. That would seem to indicate that it's not getting enough fuel, but I adjusted the cranking fuel values and it didn't seem to matter.
I've also attached a 5 second clip of it cranking, maybe the sound will provide some clues.
Car started for a moment when pouring another teaspoon of fuel directly into the spark plug holes, log attached.
My plan going forward will be to increase the fuel by 5% steps until something happens. When that gets old I'll either take the injectors from the NB and put them in this car, or I will put in the set of ID1000s that I have around.
I'm almost certain the problem is fueling related, and it seems to be injectors, since I have a brand new radium rail with a 1.6 regulator. Hopefully I'll be receiving in the mail today a fuel pressure gauge that I can use to confirm fueling is good. Worst case I bought from a friend a walbro 255, turbosmart FPR, and ID1000s that I was going to use on a future turbo build, but may need to go in here to rule out fueling (GM flex fuel sensor as well, but I hear there's nothing to be gained from E85 on a N/A stock head).
Well I'm a ******* moron. Fuel pressure gauge showed up and read 0 even while running the fuel pump in test mode. I didn't believe it at first, but there clearly was no pressure in the line when I squeezed it. Turns out my fuel feed and return lines were reversed... There must have been just enough leakage past the FPR to fool me. Corrected that and the engine runs, even though it does want to rev to about 4500 because my throttle cable is a little too short. Good thing I had set the rev limiter to about 2500 in case that happened (I think this is some of the "weird ****" you had corrected, but I put it in there for a safety measure knowing my throttle cable was suspect). Correcting that issue in the morning and I'll be able to actually tune this thing.
Thanks so much for all the help, I really appreciate it. Just need to get this thing road worthy, then off to the dyno 7/25 for a real tune.
06-23-2022, 04:37 PM
Crank, no start, no RPM ms3 VVT swap NA6 chassis
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