mb76pl

hello all,
so, I'm struggling with this problem for a while now
the car is 2004 maxima, the symptom - power loss at very specific rpm range. Very reproducible - each time i put my foot down the gas pedal, car accelerates smoothly until it reaches 2500rpm, then it looses power (it's like I took my foot off the gas pedal half way) it accelerates poorly till ~3000rpm, then the power kicks in again and it accelerates correctly till red.
The car is stock, except for Fujita CAI. Fujita sits there for few years, problem started around half a year ago.
What I replaced so far:
- throttle body
- MAF sensor
- spark plugs

what I checked:
- vaccum's ok
- air filter clear
- engine ground connectors cleared
- injectors ok (according to consult)

no errors from ECU

how to diagnose this ? anyone please ?

dfj240

iTrader: (1)

Shot in the dark, but it's possible that it's your fuel pump. I had a similar issue with my 300zx TT many years ago, eventually changed the fuel pump and the issue was resolved. It would go to 3k Rpm and then bog down severely until about 3,300-3,500 and then go again with no problem. Definitely test the pump before buying a replacement and going through the trouble of pulling that assembly apart, but it could be that or the filter.

I'm not real confident in that, I have to admit, but my first item would be the MAFS, which you say you already replaced, so I wanted to point you in some direction based on a similar instance I encountered myself.

Did you replace the MAFS with an OEM unit or and aftermarket parts store one? The Maxima doesn't seem to respond well to, or appreciate the aftermarket pieces. It's possible the replacement MAFS could be a reject.

Just brainstorming to throw some ideas at you.

mb76pl

dfj240, thanx for ideas, especially for a tip on fuel pump.
I was taking it into consideration at some point, but I figured with clogged fuel filter the behavior should be power loss from some rpm up (since the fuel pump wouldn't be able to give enough pressure).
But since you had similar issue, I'll definitely go with fuel pump.

The MAF is original nissan part. I didn't notice any change in car's behavior after replacing it... I notices a slight improvement after replacing throttle body though, but nothing really close to what it should be.

GaMaxinKy

I have an 2006 and a similar issue, my car is going into safe mode, but it throws a code and the Slip light and Traction control lights are on when it happens, but you cant accelerate past a certain RPM. May not be the same issue, good luck...

kimbo

GaMaxinKy:
Your symptoms are like mine; i.e. no power above idle (engine speed would not go beyond idle speed) and the ABS and Traction control lights would go on. No engine malfunction light.

What did you do to fix?

angus1x

Been dealing with similar problem for the last 10-12 years after replacing my 1994/5 VG30DE SOHC V6 with same bought directly from Japan.
Was able to find one with only 13,000 miles.My old engine had over 200,000 miles and the timing chain had been sounding like a diesel running for around 100,000 miles before replacing the tensioners with no change it the sound.
Every thing pluged right up and engine started and seemed to be alright until driving it up to cruising speed and when driving at steady speed it begane to fail like turning off the key all the way down to just bearly running.If I give it gas it comes right back and runs fine,but if I hold steady throtle is just almost quits.Runs great if driving like race car,giving gas and letting off.
I've spent thousands of $ with Nisson repair ,local mechanics ,and had it in the local highschool vocational mechanics class for the last 5 years thinking they would have the lateist diognostic equiptment and could fix it.WONG.
There are at least 6-7 different mechanics that said they hadn't ever seen one they couldn't fix eating crow now.
Nisson said they couldn't do anymore till I bought new PCM but after trying 3-4 different ones with same problem they said they couldn't repair it and not to birng it back.All the local guys want to do is replace parts and sensors till they find the problem but never could,and each one you take it to wants to start over with there (new parts).
I have the car back in my garage now but still the same problem 10 years and several thousand dollars later.
SO I keep reading Nissan fourms and watching the 10 year old (NEW) tires dry-rot on my car.