Car won't accelerate when D or R.

It was the alternator. I bought a new one for $99 on rockauto.com and paid someone $150 to install it.

already replaced alternator & battery. nothing else shows up on the mechanics diagnostics

This very thing happen to my 2002 Infiniti I35 as well. Only I was getting a battery symbol warning light on my dash. I knew it was most likely my alternator or my battery. When I got home I tested my battery. It was showing it was low. I put it on my charger over night. The next day it started and drove just fine. I now know my battery is working fine and there a good change my alternator is gone bad. It wasn't until I had to make a 20 minute trip on a rainy night I ran into the problem. I was trying to conserve as much battery juice as possible. I had to drive with my head lights on but I would only use my wipers once in a while and nothing else. About 15 minutes in to my trip I notice a lost of power in the engine. I made my way to the shoulder of the road. The car was still running but only at an idle. The car would not accelerate forward, Only move at an idle speed. I put the car in park and pressed the petal down. To my surprise the engine revved normal. But shift in any gear it would not rev-up. I thought my transmission was going out. Anyway, long story short. Had the car towed home and did some trouble searching. Found out the alternator has a direct link the the transmission. When their is a lost of battery power the transmission can no longer function properly. Again I charged the battery and everything work normally. A bad alternator was my problem (radiator has be be removed). Cost to me was 175.00 for a do-it-yourself job.

Had same problem. My problem was the plastic tap that's on your break pedal behind the break light switch was broken (keeping the brake lights on, that's how I've noticed). So the ECU read I was breaking while driving, making it go into safe mode and not go faster than 20 mph

My car did the whole idle thing but has plenty of battery gas and new starter help guys.

My car is having a similar problem. It will not accelerate in drive or in reverse. Then the battery died on me. I jumped it and it started up but the same problem persisted. It would not accelerate in drive or in reverse but would rev as expected in park and in neutral. Could this be the alternator or what could this be? Please help!?

The battery keeps dying and it will not accelerate in drive or in reverse. Wtf could this be?

The same thing is happening with my 2014 q50. I just brought a new battery and the car won't accelerate.

My 2015 q60 is doing that same thing. Did you get an anwser?

I have 06 g35 coupe put new alternator and battery not even month ago and now I started smell like a burnt wire or burnt plastic when I was driving I couldn’t accelerate had to pull over it only wanted to accelerate on park or n I kept it on for five minutes finally kicked in made it home seen there was smoke near alternator I think went bad going get it checked out hopefully that’s my problem my email tattoorus94@yahoo if anyone can help and let me know if this happen to u

My G 35 will not accelerate it will only idle.

Lol everyone has the same problem. Don't buy this car.

Mine starts out okay, then won't accelerate past 5MPH

Did anyone find out how to fix the problem