I give up, is it flooding or compression?
 

Due to Sandy and the fuel shortages I have resorted to driving the Miata in this freakishly cold weather. Normally id have the car put away already, but I dont want to wait in a gas line just yet. During the summer the car starts like a champ. As the weather gets colder the car gets harder to start. The first start of the day has a really slow crank and then it catches, sputters, and dies. If I try to crank again immediately the engine will crank half a turn and then just stop like its trying to either A. Compress fluid or B. Compress air. I have my cranks numbers scaled very conservatively for temps lower than 60F and the same goes for the ASE. I tried to increase the ASE bins for temps lower than 60F but it doesnt seem to be helping. If I wait it out for like 2 minutes and try again it starts fine(assuming air bleeds out). This only happens during the winter months, NEVER during the spring/fall/summer months and no matter how much I mess with the ASE and Cranking BINS I cannot make it better. The battery is new but its small size may not be helping cranking in the cold, but after it has run even for 10 minutes the engine will crank hard and fast.

Normally I wouldnt care because I never drive the car where the weather is cold enough to cause this condition. But this has been a persistent issue as the temps got lower and I am honestly now starting to wonder wtf is going on and I cant fix it.

My biggest concern is, could it be flooding or could it be just the compression skyrocketing with the presence of a little fuel in the cylinders and what is the potential for damage to the engine besides burning out the starter?

How's your battery? This sounds like what my battery was doing on the stock ECU when it was on its last legs. Batteries are fickle beasts, I've seen them get flaky on both ends of the temperature spectrum.

Yeah, this was the failure mode of the Westco battery I had in my '92. In warm weather it started like a champ, but as soon as it cooled off (and we're talking in the 40s), suddenly it could barely turn the engine over in the morning.

I'm curious, this "new" battery of yours- what is it exactly?

Duralast Gold from Vatozone

370 CCA

If the car stands all night, the next morning it cranks like its half dead. Let the car stand 9 hours while im at work and it cranks fast and gets the engine started within a second or two of turning the key.

Based on your question I can already see I need a new battery. Luckily the car is going into winter storage in 2 weeks at most, so I doubt ill pickup a new battery accept maybe take this one back to vatozone and get it replaced under warranty.

Duralast suck. They are neither durable, nor do they last. I will never buy another one. The one I put in my wife's car died in less then 3 years, and the one in my 4 wheeler lasted a single season. They are cheap because they are junk.

Go with a Interstate. They have never let me down.

^^ Same. I replaced my Doesn'tLast 3 years in a row in my NA. I'm running a fat beetch Optima Red in my NB, narry a cranking issue to be had.

All this talk of cheap batteries made me go out and take a look at what I have in my '90:

https://www.miataturbo.net/attachmen...1&d=1352320463

https://www.miataturbo.net/attachmen...1&d=1352320463


I have no idea how old this battery is. It was in the car when I bought it 2.5 years ago, and it didn't look new then. Normally I'm pretty anаl about things like running flooded batteries in Miatas, but the rest of the car was in such piss-poor shape that I just said "fuck it" and fabricated a simple mount to hold it in place. (It was just sitting there loose when I got the car.)


Ironically, this is the cheaper of the two Duralast brands, with the lesser warranty (2 years.) Still cranking like a champ, though admittedly it doesn't often get much below 50° around here.

Duralast/Battery (51R-DL) | AutoZone.com

Is that a generic acid flodded wet cell battery? The Durrpalasts they were selling me had vent tubes and the part number was "MIATA" I'll see if I can find the receipt, but I think it was the Duralast Gold series.

That's the kicker. Somewhere just south of IIRC 45° is where things really taper off. In the winter, I notice that it's gets harder to start my Jeep the colder it gets. When temps dip into the negative double digits, it can really strain a battery.

The one in my car is a 51R-DL, which is not the specified fitment for the Miata (hence the custom hold-down bracket).

The one which they spec for the Miata does have vent tubes, but to the best pf my knowledge it is still a flooded battery rather than an AGM. (I'm not 100% certain of that, as I've never cut one open.)

Who knows? Perhaps Duralast IS private-labeling the Eastpenn-Deka AGM battery just like Westco. Lord knows, that battery was crap.


edit: Some googling is producing conflicting data on the subject. Apparently Johnson Controls manufactures most of the Duralast batteries, but I have come up with a few hits that suggest Deka has supplied Duralast at some points.

A detailed photo of the top of the battery would be useful in determening this. The Deka AGMs have a very distinctive upper cap.

Yeah, at one point, the Duralast Gold batteries were AGMs from Deka. Like I say, I had 3 of them :) Word around the campfire was that people kept blowing them up with standard chargers so they just replaced the inventory with lead/acid jobs, but at least they left the vent tubes. I was confused that you didn't have the tubes on yours.

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So what are my options besides a larger battery + custom bracket?

Does anyone make a decent battery that fits and wont crap out in the cold?

I have a brand new Westco battery (got it last winter), and it even seems to slow down in the cold. Cranking is much slower in the morning now that it has gotten cold. Hasn't died on me though. Sorry Sam, just more anecdotes about small batteries.

My Interstate is exactly the same size as stock. Has the vents, as well as new vent hoses included. I don't think it's AGM, but the caps (where you'd normally add water) are not removable. Cost me about 80 bucks at the local Interstate warehouse.