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. AFR’s 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 it’s 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? I’m baffled. This just started out of the blue and before I start tearing things apart I figured I would ask.

Sounds thermal. Do the logs show good voltage for a while before the voltage drops below 12?

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.

They don't test alternators at a sustained 180F ambient.

So I’ve been trying to figure this problem out. So far I’ve

checked battery
checked alternator
cleaned and checked all grounds
re gapped plugs to .25
checked all plugs and connections.

Car are always starts and warms up perfect. Three times now I’ve taken the car out and all is good until I really get into the boost then the car sputters farts backfires and the tach goes crazy than the car dies. Once I tow it home and let it sit overnight it will start and run fine again. I’m obviously dealing with a flooding issue. I pulled the plugs this time and they looked good but I could smell gas.

My question is can a tune screw up over time or once you have things pretty well dialed in can you forget about it other than fine tuning maybe depending on current weather conditions?

If it’s not tune related maybe it’s time for COPS?

any insight or advice would be appreciated.

It's all guessing until you share a log and tune.

yeah take a log of it running fine while warming up, then going into boost and acting crazy. Can't help till then.

Will do. Was just frustrated and looking for some instant gratification!!...... lol

So here is my current tune and a data log of it warming up. I shortened the data log to where is was nearly warm and stalled out since it was uneventful until then.
I just started and warmed the car up. Couple strange things happened.

First I've never seen it stay this rich during warm up. Usually its rich at first 12-13 during warmup but once its warmed up its pretty steady at 14.7-15.4. This time it stayed rich the whole time?

Second strange thing that happened is at nearly 180' the AFR gauge kicked E9 and the car died. It started right back up but died again a few minutes later and was a little difficult to get started again.

I realize i have some more tuning to do. the richer AFR's during warm up is something new but nothing has changed in my tune and its always performed great until now. i will get a datalog of what the car does when i get on boost and it stalls as soon as i can. Again any insight would be greatly appreciated.

First off, have you tried targeting 950rpm idle? If you're on anything other than super soft OE motor mounts, 950 is usually MUCH smoother than 850, just an FYI.

Your main sensors seem to be fine, which are coolant and MAP. I really don't like how your wideband keeps dying, and you're having a number of sync loss issues related to your CAS, I'd look into those two things first. I can't tell if the sync loss is because it stalled or it stalls because of the sync loss.

Im running stock motor mounts at the moment. It seems to idle nicely but I’ll play with it and see what 950 feels like. Thanks for the tip.

Ive always had problems with my stupid wideband. Honestly I’d like to get something better. Since new it takes forever to heat up and then randomly it will just loose sync than come back. I do know that when it died the other day while warming up my wideband flashed E9 than the car died. Other than inspecting the CAS plug and wires is there anything else I can do other than just replace the CAS?

Trying to figure out why my wideband dies out. It is powered and grounded through my Brain built ECU so not sure what to check for? All wires seem fine and not damaged.