Yesterday I bought gas at the local Shell (93) and drove to my Daughters house in San Antonio (130miles). No problems at all. This morning my wife takes the car to the store and says it's running "funny". I drive it and sure enough, it's popping and missing at part throttle and at idle. What I'm thinking is there was water in the gas that settled out over night so I bought some "Heet" gas treatment and I'll drive it back Sunday, but what I want to know; do you think my diagnosis is correct? What else could cause this? Throttle position sensor?

Thanks for any and all help.

Tex

 

That's possible Tex, on the Hot Rod power tour this year they ran across several gas stations that sold watered down gas. You could be 200 miles down the road before you discover it then it's too late....sad.
Gary

 

I'm starting to think it's something else. It runs fine as long as there is a load on the engine, once you level off and cruise, it starts to missfire. It's not electrical, in that, it's not a "spark" problem. If it was a lack of spark, you would see a CEL from the Cat over heating. I don't know, I'm gonna reset the computer in the morning and drive it home, we'll see what happens.

 

Hope you made it home OK. I would think most things that could cause this symptom should set a code in the ECM. (MAF, TPS, crank/cam pos etc.) Have you checked for vacuume leaks? If you have a copy of the service manual there are some things you can check without Nissan's scan tool, like SRT(system ready test) status, this might tell you if the engine managment is so sick it can't set a code. Good luck, keep us posted.