Acceleration lost/gain after turning head lights off

Velrod43 · 06-10-2021, 02:06 AM

2009 370z auto, 150k miles. Recently started losing acceleration and Rpm will not go over 1.5-2k. Only when I’m driving with lights on and doesn’t do it immediately, usually after about 30 min of driving. I believe it’s a drain somewhere but shows 14v on dash, and battery has 12.9v while off and 12.7 while running. Also, when I say loss of acceleration I mean 40 mph max flat surface and will newly come to a complete stop on a long hill. A few times It has picked up and drove normal for a few minutes before reverting back. Just wanted some input before I take it in. Besides that only other issue is minor condensation in tail light which I will replace (not sure if that will make a difference but have seen threads where some said changing that fixed electrical issues).

JARblue · 06-10-2021, 08:13 AM

Does sound a bit like a drain. But your best bet is to pull any DTCs and report back.

Velrod43 · 06-10-2021, 08:46 AM

So far no warning lights but will run a OBD just in case. Before I found out about it going back to normal with the lights, I cleaned MAF and Throttle Bottle extremely well.

JARblue · 06-10-2021, 08:58 AM

Quote:

Originally Posted by Velrod43

So far no warning lights but will run a OBD just in case.

There are lots of codes that will not illuminate any warning lights. Based on your symptoms there's almost a guarantee that you have at least one if not several codes triggered.

bcrider · 06-14-2021, 02:54 PM

check at the battery terminals with car running light off and then check again with lights on. If you have a huge voltage drop with lights on then you at least know its not the charging system and something with the lights. Aftermarket headlights?

06-10-2021, 02:06 AM	#1 (permalink)
Velrod43 Base Member Join Date: Jun 2021 Location: Tennessee Posts: 2 Drives: 09 370z Auto Touring Rep Power: 4	Acceleration lost/gain after turning head lights off 2009 370z auto, 150k miles. Recently started losing acceleration and Rpm will not go over 1.5-2k. Only when I’m driving with lights on and doesn’t do it immediately, usually after about 30 min of driving. I believe it’s a drain somewhere but shows 14v on dash, and battery has 12.9v while off and 12.7 while running. Also, when I say loss of acceleration I mean 40 mph max flat surface and will newly come to a complete stop on a long hill. A few times It has picked up and drove normal for a few minutes before reverting back. Just wanted some input before I take it in. Besides that only other issue is minor condensation in tail light which I will replace (not sure if that will make a difference but have seen threads where some said changing that fixed electrical issues).

06-10-2021, 08:13 AM	#2 (permalink)
JARblue A True Z Fanatic Join Date: Mar 2011 Location: Austin, TX Age: 43 Posts: 36,450 Drives: 11 Z34, 98 E36 M3 Rep Power: 2684440	Does sound a bit like a drain. But your best bet is to pull any DTCs and report back. __________________ 2011 370Z 6MT Sport Gun Metallic \| ARC \| CJM \| Ecutek \| FI \| Fujimura \| R2C \| SPL \| Stillen \| TWM \| Z1 \| ZSpeed \|

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06-10-2021, 08:46 AM	#3 (permalink)
Velrod43 Base Member Join Date: Jun 2021 Location: Tennessee Posts: 2 Drives: 09 370z Auto Touring Rep Power: 4	So far no warning lights but will run a OBD just in case. Before I found out about it going back to normal with the lights, I cleaned MAF and Throttle Bottle extremely well.

06-14-2021, 02:54 PM	#5 (permalink)
bcrider Base Member Join Date: Apr 2016 Location: North Ga Posts: 8 Drives: Tacoma Rep Power: 9	check at the battery terminals with car running light off and then check again with lights on. If you have a huge voltage drop with lights on then you at least know its not the charging system and something with the lights. Aftermarket headlights?