After spending months re-tuning my car to the n-th degree after a rebuild I finally thought I have reached "Tuning Nirvana" (cue awe-inspiring music and a burst of tuning enlightenment), when I ran into a new problem. Last week while driving into work and sitting at a stoplight at idle, the car glitched. There was a slight click from an unknown relay under the dash and the whole electrical system seemed to shut off for a millisecond. Before and after that, everything was fine. Then yesterday, again at idle, it did that same thing...twice.

My first thought was, "the cam sensor is loose and causing the ECU to lose RPM sync". But I checked it and it was tight as a...well, it was tight. I also checked the connectors to the MS as well as a cursory check under the dash.. Everything was as tight as it has always been.

So I drove the car in today and, again while at idle, the glitch returned. Only this time the car shut down! Of course it immediately restarted but I know that this will not be a self-healing problem. One thing I noted, If I hold the "idle" above 1500 RPM, the car won't glitch, but a normal idle (around 950 RPM) provides the right "environment" for the glitch to appear and even then it seems to be random and intermittent.

I've included a copy of my tune and a snippet of the log when the car died. I'll be going to get a new CAS and CPS today - just in case. But I'm wondering if there is a tune issue that I'm overlooking

 

Thinking about it...perhaps it is a connection to the coils?

Just thinking out loud...

 

You do get up to 4 lost sync counts in that log, reason 31, which is a cam code as far as I can tell from a quick google search. I'd start by looking there. It's not always a loose connection, try replacing the sensor. The click under the dash is just the FP relay shutting off.

 

You da MAN!

I've got some spare cam sensors laying around, I'll swap this one out and see what transpires.

 

Well, my spare is doing the same thing. Time to go to the stealership and get an OEM CAS. They quoted me $287!

While searching the Google-verse. I heard that the Spec Miata dudes use a Mitsubishi CAS. Does anyone have a part number?

 

Just DIY one. The pickup is available from Haltech, probably cheaper elsewhere. One of the locals overcame a longstanding intermittent problem this way, it also allows replacement of the dodgy connector. If interested I can probably find his write-up, LMK.

 

I'm IN! My whole car is a DIY kludge, so why not one more!

Edit:
Doing some searching, I found this about using the Haltech "Red" sensor In there, it mentioned that the weak point was not the stock CAS, but rather the connector. SO...I'm wondering if I zip-tie the connector and secure the wires better, will that make a difference (before spending $90 on the Haltech)?

 

You've got a couple of spare sensors, so try this: take small needle nose pliers and give each of the pins a small twist. I do this on Snap-On 14v tools that stop working randomly. It's fixed them every time. Why not try it on a cam sensor?

Ballenger also sells a potted sensor with a 3 pin DTM connector that should work much better, getting rid of both the cam sensor and harness side connector:

https://www.bmotorsports.com/shop/pr...RoCguoQAvD_BwE

 

Yes, that is what I was searching for, on the local forum. Can't find that on Haltech's site, but it is probably a generic item if you want to go down that path.

However, Ballenger has you covered ...

Curly beat me to it!

 

Just as a "Day-1" fix, I secured the wires leading to the CAS connector and got no errors on the drive in to work this morning (where previously I got 4 on Monday morning, and1 Monday evening).
I'll give this a try tonight and see what happens tomorrow..
Here's my game-plan;

1. Try Curly's "pin twist" and see if that solves the problem. (Would dielectric grease help?)
2. Build a bracket (ala the way those guys on the Binky YouTube channel but not as elaborate) to support the wire run. If the errors go away then, fine, or...
3. Shell out the Big Bucks for the Ballenger solution and use the bracket to support the wires. Again, if that solves the problem then cool, otherwise...
4. Go Full Monty and do the Haltech solution.

Comments? Questions? Other recommendations?

 

Dielectric grease will not help and will likely hurt. Once you've figured out the problem and are sure that you have a reliable connection there, you could apply some to keep corrosion away (if you have lots of water/salt/snow around). Dielectric grease doesn't help conduct electricity, it merely protects the metal contacts from corrosion.

Here's the Mitsubishi CAS from Treasure Coast. I didn't even know this was a thing. https://treasurecoastmiata.com/i-225...10-18-221.html

Note that Curly and Gee Emm link to two different pages on Ballenger: one is for all the CAS options, one is to the specific Spec Miata DTM-connector solution. The more general link shows a non-stock sensor with a different connector, for $75. That's certainly an option, and you can get the connector as either uncrimped terminals or a pigtail.

IMHO, a bracket supporting the wires isn't a bad idea, but it's not a solution. If the wiring bundle is sensitive to movement, the wires inside are bad and need to be replaced.

To me, the "full monty" solution isn't haltech, but to replace the CAS wires all the way back to the ECU. But I don't think we're there yet...

 

Beerbaron

• Check on the dielectric grease. I have hood vents and the right side are pretty much right above the CAS, so water intrusion is a concern. The car is garaged, but I do DD it and park in the parking structure at work on rainy days so direct "drippage" has not been a problem.
• I saw that Treasure Coast sensor and might just buy from them, but a Mitsu part number wouldn't hurt (if I have to source it elsewhere).
• I'll have to work out the bracket. It won't be pretty (but not much else on the car is) however "function over form" is my motto.
• I thought that Curly and Gee-Em were looking t the same sensor! $75 for the non-racer version is a bit more wallet-friendly. And I like the way the connector points along the front of the engine instead of poking out like the stock one does.
• Last night I had a nightmare about replacing the wires all the way back to the ECU. 25 year-old wires probably need a refresh. But I'll save that for the next time I blow up an engine and have to re-think the engine bay.

 

So...I'm looking at the last thing that thebeerbaron said, about re-wiring back to the ECU and I started looking back through old datalogs because I don't recall EVER having problems with the CAS...ever. What I saw was that I wasn't having these problems until around May 8th. Then I started asking myself, "What was I doing around May 8th?"

Then I realized that I was chasing a pesky oil leak from a crack in the valve cover at that time and I was taking it on an off repeatedly. I wasn't disconnecting the connector on the CAS before removing it, I was just removing the sensor with it still connected and laying the whole thing over the coolant hose. Is it possible that by doing that probably 3 or 4 times fatigued one or more of the 25 year-old pins/wires enough to cause an intermittent connection?

Since I'm no good at de-pinning connectors (I have the tool, but I can NEVER get the damn thing to work), I'll just order a pigtail from Ballenger and cut off the old connector. I'll put that into my task list as number 0.

 

Just for the hell of it, double check your battery connections

 

A worthwhile tip, but I went down that rabbit hole about 2 months ago trying to track down a nagging condition where the car would only start with a jump box. Battery terminals are snug and secure and I even put in a shiny new ground strap to boot.

'Preciate the input.

 

Absolutely possible.

If it was my car, I’d remove the covering on the CAS branch of the harness, from the connector back past the place where it was getting flexed, hopefully back to where it branches off the rest of the harness. I’d carefully inspect the wires for exposed areas of copper, corrosion, or any place where the wire looks pinched, or is particularly stiff. I’d also look at the back of the connector, where the wires enter the terminal seals.

This is a good catch, nice diagnostic work!

 

Thanks.

The new pigtail is on the way and inspection will commence this weekend.. Stay tuned!

 

Revisited my link - my post above reopened old wounds involving failed sensors ...

Does anyone - looking at you Curly, but anyone - know if the Ballenger CAS sensor is this mythical Mitsubishi one, if it is, or is some sort of clone, what is the relevant part number/car model it comes from? It appears the same sensor is used in all four of Ballenger's kits, and I assume that the sensor end of the lead uses standard heatshrink that can be removed without destroying the plug/wiring inside.

I am happy to replace the CAS with a non-standard installation, but not unless I know where to source a replacement if needed, quickly and fairly cheaply. Waiting on one to come from Murica is not on.

Thanks for tolerating this small thread drift!

 

Hear, hear! Drift on Gee-Em.

I'll replace the pigtail, but if the Mitsubishi CAS is better, I'm all for it.

 

From what I can suss out, there’s a cam sensor manufactured by Mitsubishi that is a direct replacement for the Mazda part which is made by … whomever. I found something on Amazon that looks like a Miata sensor, but I have no way of knowing if it’s right or not. It’s made by Mitsubishi for their Outlander. Part number 1865A069.

Then there’s a sensor sold by Ballenger that has a different connector on it. They say “This is a Miata CAM sensor with a different plug. A newer generation, more robust sensor with a more reliable connector is used for improved durability & performance.” I’m digging, but I don’t think I really have enough info to figure out what car it comes from.