Welcome to Miata Turbo Forum - Turbo Kitten is watching you test compression.
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Haven't debugged this yet, but the car is parked down at the park 'n ride lot down the street from my work. It'll be towed home if it doesn't start tonight.
Timeline:
a week or so ago, the car died randomly while driving slowly (25 mph, light throttle) and I was able to coast to the curb and restart it. It restarted with a backfire and I went on my way. the logs show nothing other than RPM going to zero.
Over the last few days, I've felt the "hiccup" during cruise. The car would buck for an instant--likely dying and restarting over the course of a split second on the fwy. it did this a few times on the way to work. only under light throttle. flooring it seemed ok.
then I pull off the freeway today and am waiting in the left turn lane to turn onto the street my office is on... the car feels a little boggy through the turn and dies dead in the far crosswalk. Tried a half dozen times to restart with various states of pedal (none, some, flood-clear) and nothin.
some dude in a bad tie helped me push it to a lot. It's humid today so he's a badass.
Checked a few things on the adaptronic--nothing appears odd. loaded a fresh map: no change. I have sync and whatnot.
I did notice that the injector current stays at zero during cranking in the F11 data screen, but the voltages are reasonable. I popped the hood and nothing looked odd. wiggled some sensor connections and no change.
...
Obviously when I get the bitch home I'll check for fuel and spark but I'm open to other ideas. I suspect it's a broken connection somewhere that finally came completely apart.
...
PS All people who mod cars should have AAA Plus. Having a car towed up to 100 miles for whatver they charge is a bargain. Especially if you use it annually.
Check the crank and cam sensor signals and sync status.
Knock on aluminum, the miata has never died on me (except when it threw a rod after I over revved it).
The (unhacked) BMW, OTOH ...
+1 on having AAA. I have had it 2 years and used it once on the Miata and once on the BMW for a failed water pump. Hope you get the problem sorted out. I had a MAP sensor connector flake on me about a year ago and caused a similar problem.
+1 on the AAA coverage. I bought it for me and my wife for the reasons stated.
Crank angle sensor would be my guess too. Even though mine is 'working' I suspect it might be on the path to failure since it has the screwed-up trailing edge problem.
My guess is Crank Angle sensor. My Miata did the same thing not too long ago.
if it were, it wouldn't register any RPM in the logs.
the first time it died a few days ago, I happened to be logging. Note that the LC1 doesn't output useable data when it's too lean, rich, or battery voltage is low. You can see in the graph just to the left of the marker where rpm drops and MAP goes to atmospheric. You can see me crank it once and it almost starts and then the second time it catches and runs.
For some reason in this log batt voltage drops to zero (!?) for a split second and it backfired as it started probably due to some random enrichment kicking in. MVSS (veh speed) goes to infinity briefly also.
Second set of graphs is today. basically me cranking a few times and nothing happening. note battery voltage is low-ish but not zero!
my guess is more likely cam sensor. mine's a little hacked up from being broken and repaired and I have a spare so it's an easy one to test.
See the thin area between the connector and body? snapped off. so I carved out the contacts and wired it back together. been fine for yeeeears which is why I never put in the spare.
y8s,
Are you running closed or open loop for fuel?
Also the LC1 will read AFR from 8 to 18, ( the engine wont run outside this range) when it reads 20 it’s warming up or in a fault mode (have a look in the LC1’s manual).
I had a faulty OEM O2 sensor which caused no end of intermittent faults, I unplugged both O2 sensors and ran open loop with the fuel this helped isolate the problem for me.
I only have the CAS (NA8A)on mine so I can’t comment on the other sensor.
Hope this helps (I was able to try another ecu in my car and the fault remained), I am sure the problem in not the ecu.
Ted
I'm running autotune (closed loop + corrections to fuel map).
It may be the adaptronic excluding <9 and >22 AFR from the LC1 serial connection.
In either case, the Adaptronic uses a fixed fuel pulse for cranking. I suspect it should at least *try* to turn over even if TPS, MAP, and O2 feedback are not available. Hell, it should do more than it does if I lose cam sync.
I have also lots of start problems with my shitty custom harness. With rich numbers in the cranking table, the car starts when it want to. I tried lot of numbers in the cranking table and different cranking advance timing. Nothing work fine.
Also have lots of hiccups...
y8s, the only thing we have in common is we used BAT85 diodes and we have the same '01 car.
I noticed a curious fact. If I clear the Pcodes the idle goes high until the pcodes come back (1-2 seconds)
Maybe the problem is related with the sharing of the CKP or CAS signals.
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2001 NB, T04B-H3/T3 stage III, Adaptronic.
Balls alive! Car soon back on the way to work.
