Engine just died in traffic
 

Gents,

I could use some help.

The car has been running great, but I was having issues with Shadow Dash cutting out. I was taking a log on SD after making some Android settings changes, and generally enjoying the ride home. I was in after work traffic a couple of blocks from my house and it just died. I believe that happened at the 1363 sec mark on the zipped log. I'm no expert, but I assume there's no "logging" going on (in Shadow Dash) when the engine isn't running. So, at 1363 secs, (I assume) I've restarted the car, and the Bosch O2 sensor is going through its warmup. Whatever is wrong must have happened before then. A few minutes before I had pulled through First, Second and a little bit of Third to see if Shadow Dash was still cutting out. Then I sat at a light for a little while.

She did not restart right away. I cranked it over for several seconds while coasting down the street, but had to pull over and let traffic by. None of that is reflected in the zipped log. Today is one of the hottest days we've had so far this year.

The other log was taken a few minutes after getting home. I shut her off in the driveway and got out of my suit and tie. When I restarted her, she would idle at 14.1 plus or minus a bit, but then run up to the mid-high 15s for a few seconds. Back to 14.1 or so, then back in the 15s. It's something she does not normally do, so (I assume) it's related.

Any help would be greatly appreciated.

Any time an NB shuts down in hot weather, the first step is to replace the CAS.

Need composite log from when it wont start/dies.

Probably CMP (CAS)

When that happened to me on the highway I had an exposed wire touching my valve cover and the main fuse got burnt.

You're talking the Camshaft Position Sensor on the front of the cam cover?

Last time I had a CPS failure, I had a loss of sync and that was the reason given. The unit in there now is an Intermotor brand from CarQuest. CQ had one. The local Mazda dealer said it would be a few days. I got the CQ part and have several hard track days on it, but I'll bet it's not six months old. I'll order the Mazda part.

There's no loss of sync shown in the log. Is that a telltale sign?

Quick update: I've started the car six times in very warm ambient temps without issue. She started normally and ran smoothly. I have not, however, taken her out and gotten her good and hot since I'm concerned about getting stranded. I ordered the OEM replacement CPS and will take her out when it arrives.

Could it be anything else?

Thanks,

In my experience, highly unlikely. I have seen new CAS sensors fail almost immediately, I have seen new ones last forever. Buy two, put one in your glovebox along with a 10mm box wrench.

Yep this has been what I have seen. No rhyme or reason when they die, or randomly don't work when hot. OEM or non-oem same issues. I keep a spare hanging around just like I do in my 7.3L diesel truck.

I have 3 questionable ones at best. Aint seen a good one.

It happened again with a replacement CPS
 

Gents,

I bought this Genuine OEM Mazda 1999-2005 Miata Camshaft Position Sensor ZJ10-18-221 Free Ship | eBay since it seemed like no part was actually recommended. I was driving today in average August heat--CLT was about 196, MAT 113. Suddenly the engine died. The log shows it at about 740 seconds. AFR went to 22.4 and the battery light came on. No loss of sync. Did I purchase a bad part?

Thanks,

send that to DIY. Your log is missing about 100s of data after that event.

Check your battery terminals

for extra info for the future check this out

Cam Sensor Issues / Fix - Spec Miata Rules & Competition - Mazda Racers

http://cdn.growassets.net/user_files...pdf?1438809477

spec miata folks have issues as well with the 99-00 cas and have been granted this mod as a repair for the problem

Does it make a difference that this was logged with Shadow Dash?

Also, when it died, there were no other cars around. I tried popping the clutch a couple of times, but no luck. I had enough momentum to make it onto a side street. I pulled over, did the WTF dance, and recycled the key. She started normally and Shadow Dash continued logging. I assume no logging while the engine wasn't running.

Fixed that for you. Anyone who has ever owned a CRX or Civic Si of the same vintage, Ford Probe, Mazda MX-6, etc. can tell you how crappy the Mitsubishi sensors can be (READ: Ignitor units, CAS, etc.).

That was an interesting read. If true, and suspect it is, I have two good spare CPS. I'm trying the zip tie method right now.

The sensor I purchased in Post #10 has failed four times now. It is being returned. I found the receipt for the Intermotor part I purchased from Advance Auto back in April 2016. I still had the box. It has a "Limited Lifetime" warranty. She exchanged it free of charge, and it is still under warranty if the new part fails. I have that one installed right now. No issues on the drive today.

I purchased and soldered in this:

https://www.bmotorsports.com/shop/pr...oducts_id/2257

It provides a noticeably tighter fit than the original plug.

I've had no issues since installing the new Intermotor sensor or the new plug, but the ambient temp has been significantly lower than when I started having problems.

DAMMIT DAMMIT DAMMIT
 

Gents,

It happened again on a cool, rainy, Summer morning despite a new cam position sensor and new pigtail. CLT was about 187. MAT 101 or so. The car was not hot. It just died. Battery light came on, and the AFR on the MTX-L read 22.4.

I actually had the laptop logging. At the very end of the log Battery Voltage drops to 9.6. I don't know if whatever happened also caused the battery voltage to drop, or if the drop caused the issue, or if it is just an artifact of the engine quitting. I pulled onto the shoulder and coasted to a stop. I set up the laptop to do a composite log, but when I recycled the key, she started normally.

Any words of wisdom would be greatly appreciated.

Thanks,

9.6v would probably make the ecu quit.

Did something short out somewhere?