My '05 G35 Coupe only has 35k miles on it. I acquired it from my mom who passed. She kept it in the garage and rarely drove it, it only had 22k when I got it. So I got misfire codes and replaced spark plugs and coil packs. Figured if one was being done might as well do all. Started and ran great for few miles. Then it sat again for couple days. Mind you it was driven daily from the time I got it Dec. 2018 until Covid. Now it has sat for 2 months with working at home. So I get in for a spin bc it is so fun to drive. I get a block down the road and suddenly between 1000-2000 and 2000-3000 RPM hard shift and feels like bottom going to fall out so I carefully turned around and went back to the driveway. Is there something possibly in the engine area that could be loose from when I did coil packs and spark plugs? bc this never happened before and it has such low miles. I'm puzzled and don't think a new tranny is needed so early in mileage. I am waiting for a new better code reader to come in today so I can hopefully pick up what it could be. My other reader isn't picking anything up but its really an old nothing reader. Any thoughts? If it is going to throw temper tantrums now and not be reliable I may get rid of it and I was really enjoying no payments and having such a cool car with such low miles.

So issue hard shift between 1k-2k and 2k-3k rpm, started right after plugs and coil packs were replaced.

Any input would be GREATLY appreciated.

 

Step 1, pull and inspect the plugs. You might have bent a pin on the harness, might not have torqued the plugs down properly, might have a defective plug that grenaded.

Step 2, put all the old coil packs on and only replace JUST THE ONE that went bad. Here's the thing about troubleshooting, you always run the risk of buying defective parts, if the part you used wasn't an OEM Genuine Nissan Parts then you run an even higher chance of defective parts because for the most part generics just aren't as good. You don't know that one of these 6 new coil packs wasn't bad? If you replaced JUST THE ONE that was throwing a code then you don't have to worry about the other 5 that are working properly.

Coil packs aren't exactly a wearable item, sometimes they fail but more often than not they will outlast the entire car, it's a waste of money and makes troubleshooting more difficult because now you have 6 potentially bad coil packs, use the 5 that you know worked. I've never understood why people replace all their coil packs in one swoop, unnecessary waste of money.

Your issues definitely sound like engine misfire problems and not transmission problems, make sure your new OBD2 scanner uses protocol ISO 9141-2, that's what these vehicles use.

 

Also clean up all the grounds, battery negative and the other side of the cable, primary engine jumper from the right side of the timing chain cover to below the coolant reservoir, two wires bolted to the top of the timing chain cover.

Mileage has little to do with corrosion and these computers are pretty notorious about misbehaving with dirty grounds. Wire brush the lug, the mating face, the bolt threads, apply a very thing layer of electrical anti-oxidation grease, bolt everything back together.

 

So the plugs and coil packs can cause the hard shift?
Yes the reader uses ISO 9141-2 protocol but showed no codes.
I used torque wrench according to spec. and NGK Iridium plugs that are to spec with my g35.
Took it for a spin and it acted fine again for the 4 miles I drove in all speeds.
Think she is throwing temper tantrums off and on bc not getting the daily long drive lol

 

Also cleric let me know if I'm wrong but I've heard from many people that you must use oem coil packs when replacing a failed coil pack or issues will occur like what is being stated.

 

I typically don't begrudge aftermarket coil packs as long as they came from a reputable manufacturer, bosch, delco, hitachi, etc.

 

My brother in law had come over and looked at all my work and was very surprised at my good work. He did clean the nasty throttle body. Then took it for a ride to make it do all I said it was transmission wise. It did the crazy hard shifting and some other weird things. He said it could be that it just needs to relearn and to drive it a few days. Well it kind of freaks me out driving it like that so I Finally just took it to a shop so they can run more test than my OBDII since no codes were kicking back. They too were impressed at the plug, coil pack, etc work I had already done. They said everything looks and sounds great and through the all the manufacture tests they could do only one thing flagged and that was it is stuck in manual mode. But even when I drove it in manual mode it did that stuff so we shall see. It was near closing time and they are closed Sunday. So it sits in their garage so they can do more tests Monday, all the time they have spent testing has been free thank goodness. They so far think they just need to get it unstuck from manual mode and reteach it for me, even though it will adapt to me when I drive it. I never realized these were so temper mental lol Just want here back on the rode so I can get out of this house and go for a fun drive. Glad it isn't anything major at 36K miles. I really don't want a car payment and when I get tinted windows, new radio installed, do regular maintenance and small things like that this will last me a long time from what I can tell from your paosts and MOTORDYNE guy on youtube.

 

Any time you clean the throttle body you need to perform the idle air recalibration. If the throttle body is ever unplugged you also need to perform the throttle closed position recalibration.

Section EC - Engine Controls, at the front under "basic service procedures".

https://www.nicoclub.com/infiniti-service-manuals

 

Yes it threw a P0507 code right after that was done so we went to the service manual on it. Thank you for sharing the service manual. It is bookmarked now and some sections downloaded.