My 2004 maxima has a problem with throttle response. We have replaced the throttle body four times, first three by mechanic with remanufacured, last time by me with new Hitachi. It always seems good for a little while, then reverts to same problems. Often, it runs normally, then out of the blue, it goes bad. It may give almost no response, where rpms never go above about 2500, even with pedal to floor. I can persist, and get it up to about 30 mph with VERY slow acceleration, shifting up when I get to a downhill segment, but it is very little power, just a little more than idle. It has a third mode, where it will rev up to about 4500 in first, then less as I shift up (it is a manual, m6). In this mode, I can get it up to about 45 or 50 mph, but ir takes about a mile. When in "normal" mode, it runs as ever, good power and throttle response. But, in the "no power" (a little more than idle) and "low power" modes, there is little response if I pump/flutter the pedal, though it does a lot more with the pedal on the floor than with less pedal. Obviously, it is dangerous in traffic if it is normal and then drops into one of the other modes.
The last time my mechanic had it he checked all the wires (some of which he had previously replaced), and he went through all of the Nissan-specified diagnostic protocols. Finally coming back to the throttle body. It was after this that I bought a new Hitachi online.
I also had it at the dealer, who I hold in fairly low regard. They said, "no problem, we'll just reprogram it." They "fixed it," I paid $150, got it back, same problem as ever. When I went back, they said, "it is your non-oem throttle body." (This was after second reman installed by mechanic.)
Obviously, I'm stumped and frustrated. Any ideas/tips would be much appreciated. THANKS.

 

Did you do the relearn procedure for the new throttle body? Have you cleaned your MAF and Temp sensors? Do you have any codes? If so can you post them? If you have a SES or check engine light and can drive it, can you go to an Autozone or Oriley auto and have them pull the codes for you? If so post them.

 

Could be a couple of problems, I would do these 3 things and the problem should be fixed:

1: when the Maf is bad it usually limits revs to 2500-3000rpm, i would try cleaning it but be VERY careful cleaning the maf to no damage it.

2: Replace your knock sensor and harness, aswell as clean and add grounds. My friends 350Z had a problem similar to this it turned out to be his knock sensor harness and very bad grounds. We cleaned up all his grounds add one to his TB as well as engine block replaced the knock sensor and harness and the difference was almost unbelievable.

3. Nissan does not automatically relearn the throttle position so you have to do that as well when replacing the throttle body, people who are unfamiliar with nissan will not know that and could end up costing you a lot of money.

And Hitachi makes Nissan's OEM throttle body:



Whoever told you otherwise obviously does not know what they are talking about or are trying to get out of the fact they messed up.(my car is swapped so this why the TB looks funky) I've caught my dealer being lazy before and had them refund my money. Put they are slick and will think up any explanation just to prove you wrong. Threaten to take the problem up to Nissan USA and things should be settled.

 

I will get to the parts store and get the cel codes; thanks pimp.
crusher, I didn't get the Hitachi until after it had been to the dealer, but I will try your other suggestions

 

Sorry for the slow reply....I took it to O'reilly on Sunday, but the check engine light had gone away, and it was in "normal" mode. So, I started driving it every day, and it didn't act up until Thursday. It went into "no power" mode and cel came on. Code was P2135, having to do with voltage A and B. I've been wondering if the problem could be in the pedal. I found "Maxima Lever Complete-Accelerator, W/Drum," part #18002-4Z80 0 listed along with a nut for tightening it down. It appears to be the pedal along with an electronic module attached. It is under $50.