I hope someone can help. We have a 2003 G35 sedan that has an aftermarket sound system and when the bass is loud as it get the trans starts to shift very hard. I've heard this was an issue with the 03's. Has anyone found the fix for this?

 

There are some funny problems out there aren't there?

Do you have a cap for the sub amp? Strange things can happen when there is a big sudden power draw. Also, this might be one of those few times when a grounding kit could be usefull.

Hope this helps.

 

I've done the grounding with 4 ga. to the block, intake maniflod, inner fender, ecm,tcm, and transmission. car has a yellow top up front and for testing we added a second yellow top in the trunk. I even took 3 4ga. wires from the amps directly to the batterys negitive post. no luck

 

You need a power capacitor. How much power are you pushing between your amps? You are getting a high current draw which causes irregularities.

Up to 1000-1500 I would use a 1 Farad capacitor.

2000-2500 I would use a 2 Farad

Depending on the power of the amplifiers, you might consider upgrading the power lead.

I would also upgrade the battery grounding cable from the battery to the chassis.

 

I'm not familiar with the Infiniti 5AT, but other manufacturers use some form of resistor to soften the shift signal to the valve body, If your power cables to the amp are running too close to the resistor or even the TCU, you could be getting interference though the cables shielding.

I'm shooting in the dark though. Try changing the routing of your power wires to the amps.

HTH

Willey, you're a smart dude.

 

Upgrading the negative terminal to chassis ground would probably be the most help. A capacitor in this situation is most likely a bandaid, not a fix. If adding a second battery did not help, I would say with 99.9% confidence a capacitor would not either.

What sort of system are you running? I run a Zapco AG360 and AG750 with just a diehard platinum (Odyssey) up front and have no issues with hard shifts on the stock alternator.

 

Do not get a cap

Your electrical will need to charge the cap as well as power everything else.

Have you checked your grounds on the trans it self?

 

try grounding the transmission. I had the same problem, but it somehow fixed itself..