Evo 9 low miles. full bolt on.

Car was not doing this ever. Only changes were, it was at the shop getting a tune, replaced injectors and installed a boost gauge. Also BOV was crushed.

About 150 miles after the tune I randomly died coming up to a stop sign and i thought to mysel wtf?
It kept happening. Especially with the AC on. In stop and go traffic where I would accel and quickly dump gear when people would break infront of me. 3 point turns, etc.

I brought it back to the shop and they spent the day before and all day with me trying to figure it out. Everytime the car did this, the voltage would drop significantly. Old battery down to the 11s and new battery to low 12s.
Checked for vaccum leaks.
Fixed boost leaks.
Tried different BOVs.
Put in new battery
Messed with the tune for hours.

The only thing that got it to not die was going from a tephrav7 table to a regular evo 9 table. This helped to not die. But it would still dip and voltage would drop but it could save itself at least. But it was dropping still beyond 700-800rpm, especially with the AC on. I'f im sitting idle and turn on the AC (no lights, no headlights, no breaklight) my voltage commonly drops to under 12.5 and the car shakes, sometimes almost dies. Even with a brand new 700ccamp battery.

I havent stalled yet since we changed tables on the tune, but with the AC on I still believe something is wrong. AC always made the car run worse, and had bigger dip/rising when coming to stops and just sitting idle, but it never dipped as low as it does now, or has a hard time getting back up like it does now. Where should I look next in terms of culprit?

I had the alternator checked twice and they said it was fine. Car volts is about 13.6-14.1 in new battery while driving. When car is off its about 12.2 when I first put in keys and about 12.5 when I'm ready to turn the key.

The only electrical change was adding the boost gauge, I'm going to disconnect it and see if for whatever reason that had an effect. If its not that, should I be looking at the AC system itself?

Even once I'm already driving with the AC on, if I stop at 10 redlights, at atleast 1 of them, the voltage and RPM will drop again to 12.5 or under. It had died previously 1 or 2 times simply from this, but since the table change and new battery it has not happened but still comes close sometimes.

My gut tells me something electrical is going on and the AC is just a ton of extra stress so it brings out the problem more. IDK why the Evo 9 table vs Tephrav7 table would have any impact on that, I don't know enough to understand.

 

sounds like parasitic drain. No new battery should have a resting voltage of 12.2v

 

I have similar issues with the ac on. Hoping a tune will resolve it.

 

I disconnected the boost controller both the reader and the gauge itself (EBG)
Didn't seem to do much.

Maybe ill go somewhere to get a drain test done.

Any other input?

Basically every time I brake hard from 40mph or less I can get the volts to drop at least 3 points. Is that normal? I guess I've never ever paid attention to voltage before now so I have no idea what's normal.
If I brake hard with AC on I can get it to drop into the 12s once and a while. But definitely not every time.

 

Does the voltage go down when the rpms are lower than your set idle?

It sounds like you need your idle tables tuned. If your tuner can't tune it maybe I can help. PM me and I'll get you situated. If we figure it out then I'll update the thread.

 

Also check for a loose ground connection in your engine bay.

 

PureDrive, I'll PM you but I don't have my cable at the moment, should get it back next week and I can send you the tables, but I know he messed with the idle tables for a while and nothing was helping. It would make the idle higher but wasn't stopping the dip and dying in those particular situations very much.

Only 1 person noted, is it agreement that my new battery shouldn't have a resting voltage of 12.2? What should it be at?

 

12.2 Volts on a 12 volt battery with the engine off sounds right. While it's running it should be around 13-14 volts. If the rpm's get real low, around 500ish, the the volts may drop.

 

Puredrive, That's correct.

About the RPM drop, should the volts only drop ONCE the rpms go low? Because from what I can tell its happening at the same time or maybe even the volts are dropping first. Because there are a few normal dips where it goes to 700 but the volts don't drop at all and the car doesn't shudder.

The times it does shudder and/or die the volts drop just as fast or maybe even premature to the RPMS dropping.

 

If you have not already, try adjusting the idle screw in the throttle body. I have an Evo IX SE that was having the same type of issue, and it was because the idle screw wasn't properly adjusted after I installed my WORKS wider-bore throttle body. It's definitely worth checking. Also, if you are venting your blow off valve to the atmosphere, it can cause some stumbling issues at idle due to the design and sensitivity of the Evo's Mass Air Flow Sensor. You may be able to adjust the tune to compensate for that to some degree though. Feel free to PM me if you have any questions. It is works great. If not, good luck with your further diagnosis.