Brief synopsis. During an autocross the car suddenly died. The OBD code was 0339 or CAS failure or intermittent connection.
It would occasionally hit when turning it over like a distributor 180 degrees out of phase. Which meant it was getting some fuel and some spark.
I replaced the CAS, man that was hard to find, and it still doesn't run. Now we're not getting the every so often out of phase hit, but that be because it's cold and hasn't been started for over a week.
Any ideas of where to go next. Reader still has the CAS code in it and IIRC we won't get a new code till it's run a little so we can't tell if something else is wrong?
Apparently we have no spark. I tried both #1 & #2 plugs with long screw in it and then holding almost on the engine and no sparks.
Both coil packs are new, maybe 1,000 miles on them. Typically if a coil pack went out the engine would run, but very poorly as it would be running on only 2 cylinders.
Because of the suddenness of the car quitting it says to me some sort of blown electronics or a connector coming loose. Of course the car hitting occassionally before kinda blows that theory.
So where else should we be looking?
Now we've pulled both coil packs and reconnected them as well as disconnecting and reconnecting ever connector that appears to go to anything engine related still no avail.
We haven't checked every fuse, but we've checked all those that appear to be engine control related.
And of course nothing shows on the OBD reader
I just realized that CAS could apply to CRANK angle sensor or CAM angle sensor.
We replaced the CRANK angle and now because it appears that if the CAM angle is out it might affect spark we are about to try to find one of those too.
We can't get one till 2:00 CST
Grasping at straws here!
We just found the wire off the oil pressure sensor had been knocked off. He had the oil changed just before the autocross.
If that showed no oil pressure would that shut everything else down?
That's reason #486,000,000,000,000,000 and 1 that you should always change your own oil
Nope, that didn't work either so now I guess we have lunch and hope the CAM angel sensor comes in a little early.
In reply to carguy123:
Nothing useful to reply, but good luck!
If the computer doesn't know where the engine is, it won't fire the coils.
Are the camshafts actually turning?
Is the gap set correctly on the new sensor?
The car is a '99.
For some reason the forum either didn't like my phone or else my phone didn't like the area we were in because a post was lost.
OReilly's ordered the wrong part so after waiting we then had to drive 40 more minutes over to a store that had the part and 40 minutes back. It still has no spark and yes the camshaft is turning.
We're bumfuzzled. It quit working abruptly after working flawlessly all morning. It was at full throttle when it stopped AND we were getting some spark &/or fuel because it would kind of hit occasionally. It just felt like a distributor installed backwards.
Now we don't get any spark and we have replaced both the CAS & the Camshaft sensor as well as replacing the VICs solenoid, which was broken and therefore we had a vacuum leak, and fixing a broken wire on the oil pressure sensor.
We've set the CAS tight & loose. The instructions I found said .029-.059 and almost everyone said to use a credit card to set it. We've tried at least 10 different settings and still nothing.
We are not getting any codes on the OBD reader at all.
It happened so quickly it's got to be a broken wire, fuse we haven't found, blown ecu or something that is a go/no go system, but I'm stumped.
It does appear we are getting gas as the gas smell is strong on this one when the plugs are pulled, but they were not wet. Of course we haven't been turning it over long periods of time.
The NB1 cam sensor has a reputation for failing when it gets hot. The crank sensor seems to be more resilient, but I keep a couple in my spares box as well just in case. The right diagnostic tool for this is an oscilloscope, probing the wires going into the ECU to look at the cam & crank signal patterns. If those aren't correct then the ECU isn't going to fire either the coils or the injectors.
The NB1 coil packs also have a reputation for failing, but I agree it would be unusual for both to fail at the same instant.
I don't think the ECU can even seen the oil pressure sender signal, certainly I've never heard of it affecting how the engine runs.
Check the grounds near the throttle body -- that's where all of the electronics are grounded and if that bolts comes loose the car can do some very strange things. If it's not that and you've replaced the cam & crank sensors, then all I can think of is a chafed wire in the harness somewhere.
If the OBD reader you're using has worked with this car in the past then I'd start my troubleshooting with trying to determine why it's not working now.
APEowner wrote:
If the OBD reader you're using has worked with this car in the past then I'd start my troubleshooting with trying to determine why it's not working now.
It's my understanding that the car doesn't throw codes until it restarts and runs a short while, no?
Back at it again. Since we couldn't fix the engine we decided to throw on a Wilwood big brake kit I had laying around and some Racing Beat sway bars. Makes sense right?
I have supreme confidence we will get it running eventually so when we do now it will turn and stop better. Sometimes you've just got to clear your head.
What is that little gizmo called that turns everything off in a crash and where is it located?
In case you hadn't noticed I'm grasping at straws here.
All fuses and relays appear to be good. The grounds are good. The CAS and camshaft sensor are good. All vacuum lines & solenoids are good.
It stopped in mid stride at full throttle and now we get no spark, but we think we are getting fuel (or at least we have a fuel smell when we pull the plugs and they were moist. We haven't pulled an injector, but that's not far down our list to do.
Give me something!!!
There is no crash sensor on the Miata.
I'd confirm that the main relay is actually turning on. Check that you have switched 12v with the ignition on the white/red wire on the MAF. The same wire is found at the cam and crank sensors, but a main relay failure would kill them all.
I've got 9 volts at the MAF, should I have 12?
Should be close to whatever your battery voltage is. This is the white/red wire, right?
I'll check the battery voltage to be sure.
If battery is as low as 9v that would probably explain why the code reader is no longer reading either.
It'd be a longshot, but it's possible that's your whole issue.
No, the battery has been on a charger before but has been off all day today as we've cranked & cranked so it's a temp condition.
The code reader works, but there's nothing to read - or so I'm told. Apparently once you fix the code the car has to run again before it will show other codes.
There's nothing to read as in "it's not responding" or "there are no codes"?
I don't know the Miata's electronics specifically, but a lot of computers will go into failsafe shut-down mode when voltage gets much below 10v.
It's not normally below 12V, that just happened because of all the cranking so that's not the problem.
There are no codes to read until the engine cranks again, or so I'm told. We read the code that was there when the engine went down which was the Crank Angle Sensor, but that didn't fix it. We still have no spark.
We are throwing in the towel and are taking the car to the junkyard tomorrow and selling it for scrap
