Issues after a hard night.
 

Quick story:

Bought turbo miata off a guy. Car has always had battery problems, had a tiny battery before. This lead to coil dying, I suspect the alternator isn't the best either, car is always running out of juice.

So after a couple months of downtime, I replaced the coil, put in a new wideband 02 (old one was gone, car was running on narrowband), and some pads. Car ran great, but even with a JDM stock battery, I notice car is always running out of power ( I end up charging it every other night, and it seems to not help too much). I suspect the extensive alarm system and HID headlights do nothing to help here.

I finally take the car out for some hard running with a friends fast honda. Before, I had never stayed on boost for longer than 20 seconds and a couple of gears. This is a good 10 minutes of intermittant thrashing the car, still nothing even close to a track day. I notice car is loosing power. Temp and oil pressure have not budget, cooling on this car is sufficient. I step on it, hoping its just a hiccup, car wont rev past 4k rpm (this is where the turbo fully spools). Gauge showing me lean or just going blank. I pull over, perpexled, off boost car is fine. I let it sit for 5 minutes. Turn it off. Let it sit for a bit, turn it on and it runs fine on boost again. Within a couple of pulls the symptoms start coming back. I watch boost, its slightly erratic or falling short. I go home, its fine, but these symptoms seem to come back without too much hard running and I did not have this problem before.

My question: Unless you know exactly what this is (Erghm....Scott?), could it be, between those damn bright headlights and lighting all that fuel is draining battery faster than the alternator can replace, causing the car not to light all the fuel after staying on boost for a while. This would explain why it shows up as lean when the symptoms start showing up. So far I have seen these symptoms only during night, but I do very little driving during the day, and it seemed fine in the day...I think.

It seems all my problems with the car have been battery/charge related, as such Im hoping so is this. It definately does not seem mechanical. Maybe with the constant low power this coil is going too, or something about the spark plugs... I will take a look tommorow, input and help would be appreciated.

P.S: Garett custom setup, intercooled, emu for management.

Thx in advance guys.

^ Whats that?

He means you have a vac leak.

Sounds like a vacuumn leak possibly associated with your low power issues.

When I changed out the stock headlights and put in the Hellas, I noticed that they DID draw a lot more AND a couple times I found I had to charge my battery after some all night driving trips, slow crank at startup. The WESTCO battery does have a lot to be desired in supporting our cars beyond the stock configuration.

I took my alternator to an alternator shop and had them beef it up, make it more heavy duty in its output. I also took the time to improve the grounding system, that can have an affect on drain as well. I have never had another problem since and am still running the WESTCO battery.

Anytime you increase the electrical demands over stock, you have to consider also increasing the supply. Installing a larger battery with a deeper reserve will only act as a bandaid. Once the battery is in service a while, it will also tend to have issues because the demand is still greater than it's input - output from the alternator.

Offhand, I do not know/remember what the output of our alternators is, but when you do the math on the draw/operating side, it may well be that your ignition, lights, etc all but zero out the output of the alternator and it's ability to support running drawdown demand and charging simultaneously.

I believe you can get a heavy duty alternator to replace the stock one now. It was not an avaiable option back in the mid-90's when I was dealing with it. You may end up going to an alternator shop and having them build yours up for you like I had mine done. I actually had them build a second alternator and have it in the garage just in case mine dies at some future point, spare is good when it comes to alternators and such.

Damn it. I had a feeling someone would say a leak. I guess I'll try to hunt it down. Any tips on where to start and best way to go about it?

93inNM, thx for the advice, I was going to see If I could find a higher output alternator somewhere in the mazda family, but I guess getting it beefed up is another option.

Get an optima red top while you're at it -they last 4ever (cranked 200+ times on one when the car was dead over a period of a week).

why the hell would you buy a JDM battery? it's the same thing as a USDM battery but with an additional rice tax.

Lol I was thinking the same.

I didnt. I have a stock JDM miata, swapped it over. Anyways, problem is still there. Im loosing about 3psi. I have checked and tightened all the visible hoses. Tried spraying break cleaner. I have tried changing the blow off valve. Its still happening. And as for the wont rev past 4000rpm, that came back on a long drive, if that makes sense. On the highway, after about 100km, wouldnt rev past 4000rpm, and gauges were fading. Once I got back to town in stop go traffic it was fine. However the loss of boost is my immediate concern, I have a feeling the other problem is my weaksauce alternator.

Any ideas? Obviously its happening under boost, so I think something is coming loose while boosting? This would make the vacuum leak hard to detect with the engine not running or even idling. Im so sick of this crap :vash:. Scott I CANT FIND IT!!! How about you fly over here and fix everything for me. I will buy you a beer, and give you some used HP pads. Maybe even a used clutch :bowrofl:

Hook up a fuel pressure test guage and check that out. Make sure you pressure is correct. Then route the guage out the back of the hood and leave it on the windshield and go flog your car. See if fuel pressure is falling when the problem occurs.

You could also easily hook up a vacuum gauge and use it to check for leaks. Also can be routed through the back of the hood and even into the car without too much trouble.

What does a tiny battery have to do with ignition coils failing?

What makes you think the car is running low on voltage?

"The car is running down on power"? You mean no HP or no voltage?


My friend, I suggest you take the vehicle to a competent technician.

Diagnosing an issue like this is pointless.


Tony

Fuel pressure is fine, I have a permanent gauge in the engine bay.

I replaced the coil because one side of it was dead, it wasnt sparking 2 cylinders. Forget my battery issues, I can sort that. Its the boost thing thats bothering me.

And you watch that gauge when your driving the car under load how???

Just because you have static fuel pressure doesn't mean you have fuel pressure when the car is in boost.