So I changed my spark plugs 2 days ago and I disconnected the throttle body sensor while doing the change (I plugged it back in after the process) and when I put the new spark plugs in (NGK spark plugs) I lost more than like 75% of my power. It felt very weak and it didn’t feel like the same car at all, I’ve tried searching it up but couldn’t find anything. When I put the NGK ones in I didn’t check the gap or torque them down. So I went and bought new spark plugs this time the recommended denso ones from the dealership instead of getting NGK’s again. I gapped them and torqued them down to the correct spec (18 foot pound ). I did the reset TPS process (The video tutorial said I need 12.9v in my battery when I did the TPS process but I only had 12.2v I didn’t want to go out and buy a new one so I still did the process). When I tested the car out it gained power and it wasn’t accelerating by itself anymore but I still lacked power I couldn’t spin any wheels ( I could usually spin wheels with just 65% throttle ). Can someone please help me out I’m really lost. Feel free to ask questions and I’ll respond.

 

Have you pulled codes yet?

 

Did you disconnect the battery long enough for the car to reset? If so, it may take awhile for the car to re-adapt to your driving style. Also, just to cover everything, I'd still do the re-set/re-learn procedures for the throttle bodies since you unplugged them. May do nothing but can't hurt to make sure that's not causing the issue.

 

Does it turn over well? Did you change your coils too?

 

No there is no check engine light and I do t really know what you mean by pull any codes.

 

It does turn over well but the first time when I put the NGK’s in, It turned on all the way at 5rpm then when back down. But after I out the Denso ones in and torqued them down it starts and idles perfect drives good too but just doesn’t have the power it used to have.

 

After everything else failed I saw a AutoZone posting saying disconnect your battery for 5 minutes but that did nothing then I saw another posting saying disconnect it over night and I’m about to connect it in an hour I’ve left it for about 12 hours. I’ll get a new battery if that doesn’t work and try the throttle reset.

 

A CEL may not be triggered, but codes may still be held in memory. Pulling codes means using the OBD2 port to connect a code reader and seeing if any non-critical codes come up.

 

double post https://www.myg37.com/forums/g37-sed...ark-plugs.html

 

Did you at least check if your throttle bodies butterfly valves have no carbon deposits?

 

My guess is that since you unplugged the throttle body sensor, it needs a re learn. I had this issue after cleaning my throttle bodies. Watch this tutorial, it will allow the throttle bodies to relearn.