NB MX-5 Hey, it's Minnie!

Got home from my trip about a week ago. Did the drive in one shot, took about 18 ½ hours (lost probably an hour due to construction and accidents along the way). I did some more research before I left and found some of the problems I was having could be down to a faulty IAT sensor. I read if there was no sensor plugged in, the Megasquirt would use a default temperature of 80 degrees. Figured it couldn’t hurt so that is what I did. Seemed to run better on the way home, except for some issues with idle speed at odd times.

Now that I was paying attention, I saw a direct correlation between outside air temperature and the amount of heat coming up from the transmission tunnel. There was a decent amount of variation during my trip. Once home I ordered a DEI heat shield to install to hopefully fix that problem.

After recuperating and washing her dirty butt, the first thing I did was install the new IAT sensor. Before I did that I took resistance readings of the old and new ones for comparison. What I found was the old sensor showed a measured resistance, while the new one was infinity. That was definitely one problem.

Before I could go any further, the county finally got around to fixing the sidewalk that goes through our driveway so I had to park her out of the garage. That threw my schedule off for a few days. I did snap a nice shot of her in the neighbor’s drive:

Doing some more research I found there have been instances of grounding problems with the coolant sensor with coolant reroutes. Since I was still having the occasional problem with the cooling fan not coming on I decided to remove that possibility from the mix. After measuring the diameter of the factory coolant sensor I stopped in Ace and picked up these:


A little work with cutters/crimpers and I ended up with this:


Finally got back into the garage today so I installed the factory coolant sensor with the ground wire like so:


I have a copper washer to seal the sensor, the ground lug goes on top of that. The other end of the ground wire runs to the engine lifting fitting at the rear of the engine. The ring terminal is a bit bigger than it needs to be for that bolt, I will probably change it out at some point.
I see I forgot to go over what I did with the throttle cable. As mentioned I moved it around a little, but it was still having a high idle after driven a bit and things were hot. I popped the hood after a drive and checked, the cable was tight and holding the throttle off the stop. I loosened the cable a bit and fixed that. I will say that apparently Mazda’s idea of 3mm slack and mine differ greatly.

Today after helping my oldest change his oil (I supervised and gave him grief after he missed the drain pan for the umpteenth time) I ran to Ace and got some more appropriately sized ring terminals so I could redo the one end of the coolant sensor ground wire. Measured the bolt threads and ended up with 3/8” being the size:


I got the bigger terminal off with no problem, went to put on the smaller one and the fun began. Went through four trying to get them to grab the wire good enough but they kept coming off. Cheap StaKons was the reason, and trying to work in a confined space. Finally got one on, then managed to drop the bolt as I was putting that in. Searched and searched with no luck, finally found it lying on top of the starter. Got that fished out and went to put it in only to have that ring terminal come off. Grrr. After some more gnashing of teeth I got that all done, so now I feel better about it.

Hoisted her up in the air and went underneath to figure out how I was going to install the heat shield on the exhaust. Found out I should have bought a two foot piece instead of the three foot one. I marked it and then cut it down:


Not quite cricket but should do for me. I’ll keep an eye on it to make sure it doesn’t start unraveling. Put the hose clamps in and then placed it where I wanted it. I couldn’t place it directly on top of the exhaust due to the location of the O2 sensor but I have it over the section that is closest to the transmission tunnel side. That ended up like so:


Time will tell how well that works.

I gave the youngest grandkid his first ride in her, put him in the passenger seat while I was jockeying her around to her place in the garage. He thought that was pretty neat. Of course I had to give him a shot in the hot seat:

Have just taken a short drive (plus the temps here have dropped) so can’t say yet how the exhaust shielding is working. Nothing fell off at least!

I ordered one of the Flyin’ Miata shifter insulation kits. Should have bought one during MATG and saved shipping, but oh well. That arrived today so I pulled the center console to install it. My old insulation had seen better days:


There are no instructions for the kit. The only real question I had was which side to install up? There are four pieces, two with large openings and angles on two sides (for the bottom), and two donuts which lay on top. After looking at the cabin insulation kits FM sells that are the same DEI material, I decided that the white side would be installed down. Slipped the first two pieces on:


You can put the angled sides however you want, I decided to have them facing to the rear.

The two top pieces were next:


I finished up by putting the stock foam cylinder back in the center.

While I had the console out I did some cleaning and decided to see if I could figure out where I went wrong when I install the new lid a while back. The spring wasn’t functioning correctly and the lid wouldn’t hit the detent that keeps it open. The shop manual was no help so I removed the small metal plate at the back of the hinge area. There is a small plastic piece with two hooks on it, one of the metal piece’s screws go through this piece. I had a look at that and figured that maybe one end of the spring was to go under the hook piece. Reworked that and voila! The problem is when you remove that metal piece and there is tension on the spring, the spring pops out before you have time to see where it went. In any event my lid now jumps a bit from the spring pressure when unlatching it, and it locks open as it should. No pictures because I didn’t have enough hands.
You have been very busy Mike! I do hope that you finally solved that cooling issue that you have been having.

Better hide those keys from the youngest too! He looks quite happy behind the wheel. :D
I’ve been doing some research and thinking about my AFR issues. I finally decided to just swap back to the Innovate MTX-L wideband I was using to see if that fixed things. Did that over the past two days (I was pacing myself 😉). Got everything connected, calibrated and fired her up. Started right up and did not see any of the same weirdness with the AFRs bouncing around that I was with the AEM unit. Too her out for a short drive after also swapping to my silver wheels with S-Drives (temps have been lower here and figured I’d go ahead and do that. I don’t mind sliding around but the police don’t seem to like it when your tail is hanging out around a corner). Things seem to be back to normal with none of the problems I was having with idle etc once warm. I’ll be going out for some tuning once I get some other jobs done.

I did notice a slight coolant leak coming from somewhere underneath on the driver’s side. Couldn’t see it with a cursory look so will have to drop the undertray.
Coolant leak didn’t show up again for a bit so I thought it had maybe migrated from when I did something with the temperature sensor. Of course then it did show up again. Haven’t felt like pursuing that since I’m headed back to work soon.

I did pick up a slightly used Boundary Engineering Stage 1 oil pump, just have to figure out when I will install it. I also just bought a set of extended risers from DCBE Tech for my JDM Mazdaspeed rear spoiler. They will move the spoiler up and back by an inch. Unfortunately those won’t arrive before I leave, so everyone will have to wait until spring for me to install and take pictures of same.