General Miata Chat A place to talk about anything Miata

Strange charging issues!! Need Advice

 
Old 04-15-2019, 10:30 PM
  #1  
Junior Member
Thread Starter
 
Paulryan's Avatar
 
Join Date: Jun 2016
Location: Wichita Kansas
Posts: 93
Total Cats: 27
Default Strange charging issues!! Need Advice

Took my car out of hibernation a few weeks ago and have a strange issue going on. Car starts and idles great. AFRís are perfect. Go out driving and everything is fine. Nothing in my tune has changed since the fall. (Brain built MS3 base map with mild auto tuning). Once the car is warm and I go into boost a few times the car will stumble, my tach starts jumping all over the place and it starts bogging sputtering backfiring and tries to die. I can get it to kick in and out of running somewhat normal by oscillating the gas pedal. Had my wife tow me home one time and was able to limp it home the other. I did have TS running this last time and saw the battery voltage drop and continue to drop as I limped my way home all the way down to 11 before it died as I coasted into the garage.

Took the battery in to be tested and itís good. Took my alternator in and it tested good as well. Checked my grounds and they are good. Has anyone heard anything like this before? Iím baffled. This just started out of the blue and before I start tearing things apart I figured I would ask.
Paulryan is offline  
Old 04-15-2019, 11:10 PM
  #2  
Tweaking Enginerd
iTrader: (2)
 
Join Date: Mar 2013
Location: Boulder, CO
Posts: 1,006
Total Cats: 120
Default

Sounds thermal. Do the logs show good voltage for a while before the voltage drops below 12?
Ted75zcar is offline  
Old 04-15-2019, 11:35 PM
  #3  
Junior Member
Thread Starter
 
Paulryan's Avatar
 
Join Date: Jun 2016
Location: Wichita Kansas
Posts: 93
Total Cats: 27
Default

That’s my next step. I wasn’t data logging last time just had TS up so I could watch batt voltage. Really thought my alt would test bad. My thought was it wasn’t charging and once the voltage started to drop to a certain level things go haywire but since my alternator tested good guess that theory is blown.
Paulryan is offline  
Old 04-15-2019, 11:50 PM
  #4  
Tweaking Enginerd
iTrader: (2)
 
Join Date: Mar 2013
Location: Boulder, CO
Posts: 1,006
Total Cats: 120
Default

They don't test alternators at a sustained 180F ambient.
Ted75zcar is offline  
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
capitalcrew
Miata parts for sale/trade
3
04-19-2019 10:16 AM
Jarrell Williams
MEGAsquirt
6
04-17-2019 02:03 PM
ATX.
Engine Performance
2
04-15-2019 05:19 PM
Patrick Andreae
General Miata Chat
4
04-14-2019 05:59 AM
pdexta
MEGAsquirt
6
04-11-2019 07:47 PM


Thread Tools
Search this Thread
Quick Reply: Strange charging issues!! Need Advice


Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.