ChromeSE5

iTrader: (3)

I get this weird hesitation around 2000 to 2500. When I put enough gas to bring the needle a little past half, the hesitation doesn't completely go away but it is a lot less noticeable. But when my gas needle reaches half way between 1/2 and 1/4, then the hesitation is pronounced. This happens when I lightly press the gass. Sometimes during hard acceleration, the car might bog, but that is very random. This is after I installed a UDP.
thanks

BewstAdd1ct

your symptoms seem to be pointing to the MAF, but the fact that it ONLY happens at certain fuel levels suggests otherwise.

have you run a fuel pressure test yet?

ChromeSE5

iTrader: (3)

no i havent. How do you do that? I wonder also if its my fuel filter clogging up or whatever. I am going to try the "seafoam" fix before buying anything else.

BewstAdd1ct

locate the schrader valve at the end of the fuel rail, connect a fuel pressure gauge. start car, check for fuel leaks, road test...


let us know what you find. you can probably rent a f/p gauge from pep boys or whatever.

waytoostock00

check ur gas cap and also ur purge control system(if maxima's have them) there might be a bad or clogged valve or hose and its causing a vacuum to form in the gas tank which might explain a hesitation that only occurs after u used a half tank. a vacuum forming would fight the fuel pump and cause a low fuel pressure problems or even premature fuel pump failure .maybe u could just unscrew the cap remove and then put it back at a half tank if the problem goes away replace ur gas cap because the valving that prevents the forming of vacuum is defective
just my .02 good luck
ps: it's probably not a clogged fuel filter if it happens only after a half tank is used

ChromeSE5

iTrader: (3)

well, it had nothing to do with my fuel system which is good. Actually, it was caused by a loose belt (guess I didnt tighten it all the way). It started squeeling about two days after I posted this and the hesitation got worse. My theory is that it would slip and when the belt "caught", the UDP would slow down cause of the "catching" of the belt. But anyways, it doesnt happen anymore so its all good.