mmm i just swaped my non rev motor for the REV UP motor and now my idle when i start up jumps by its self to 2k and then goes down between 1k and 1200 when i get on it car feels like theres something holding it back but i get the same thing, power while crusing it stutters i can get off the gas and the idle will stay there at rpm's

 

Thanks for quick reply. I'll pull some plugs and read them. I just find it hard to believe that plugs can take a dive that quick unless they crack. The only thing I changed was fuel. It ran strong when I parked it.Now in one start up it acts up. Every time I kill it and start it while it's screwing up, problem goes away.

 

OK changed plugs the originals were worn and looked bad. Gap checked .056!
Still have stumbling problem. Everything looked great. I have not checked coils. My instinct tells me bad gas. How can something run good-go bad-then good again. When water gets in fuel it floats around in a bubble. Maybe thats the issue. This car under the hood and every where else looks and feels untouched. I just broke a cherry by changing plugs. Just to let you know I'm not exactly a novice. I have a '92 camaro I've built ground up for road racing with 485 hp and 500 ftlb torque. I'm thinking keep it simple stupid. FYI 63000 miles on G35.

 

your code points to multi cylinder misfire. I still think it is ignition related. If you are convinced of bad gas run it out and refill with premium and dump a bottle of octane boost in for good measure.

Also when you do that disconnect the neg battery cable and let it sit for a couple hours. it will clear the code and reset the ecu. after I replaced my gasket and had the battery disconnected while I did it it ran a little rough after everything was back together. I initially thought I hadn't fixed it but then it occured to me that the ecu had to relearn. After about 25 miles everything smoothed out and the idle is low and steady.

 

Old thread, I know.

What was the final outcome?

 

Thought I'm not FI, I'm having the same issue today. Feels like water in the gas and it was really sputtering and shaking at low RPM. It died at a few stoplights but I tried to keep the revs above 1200, which seemed to help. I got a bottle of Heet and filled the tank (I was at a 1/2 tank) with BP Premium since that was the closest station. It seemed to help a little bit after getting on the highway except when I really got on the gas, it sputtered and took a few seconds to give me some power. As soon as I got off the hwy, died and took me a few minutes to restart.

Just dropped it at my local Nissan indy shop and the guy said water in the gas is highly unlikely and uncommon, so we'll see what they come back with.

 

Well, my guy just called and said it is throwing P0340 , P0345, and one other code (edit: P0335, crankshaft), which are the cam position sensors. $500 later, I should be back in business.

Edit: Also one of my coils are weak, so getting that replaced while they are digging around.