Hello everyone. ok here is my problem. i have a 2000 maxima se. i have already replaced all six coils and spak plugs about 15k ago. i put a cat back exhaust on teh car and it gained very little power. i was having idle issues and it just ran horrible. i found the tsb on the MAFS. so i had the MAFS replaced and i also seafoamed the fuel system with it in the gas tank and cleaned the trottle plate and the car ran like a maxima should run and idle was beautiful. i was very pleased. so i thought hey why not and i got a high flow carsound/magnaflow converter and a y pipe for my baby. i put both on at the same time and WOW what a power loss. im talking 20-35hp power loss. not on teh dyno but i know my car and i know she is a PIG. it seems like anythign after 1/4 throttle it just makes noise and isnt makign any more power. i put about 2500 mile son the cat cause i heard your supposed to break it in and teh car still runs horrible. now the car has 108k miles on it but my 96 had 125 and i tell you would SMOKE this car hands down. i have read through here and havent found anyone with my problem. i even wen as far as taking apart the butterfly valves which are still in tact(no broken) like one of the threds said on here. someone please help, i want my maxima to be like a maxima not a single cam honda. write me back on here or email me at maximase96@aol.com please and put the email as power loss maxima. thanks guys its much appreciated

 

hmmm that sounds strange.. cause i know you lose some power in low end with y pipe..
but i gained a bit on high end..
is you VIAS ok?
honestly i dont know what would be wrong.. maybe possible leaks?
what brand do u have

 

hmm ok i got a cat back and was thinkin of installin a hi flow cat converter too...should i do this after what happened to you or do you think the powerloss is from ur y pipe??

 

I dont have a clue what its from. everyone i read says they got big gains from the y pipe. i just got power loss. myabe mine is just my car who knows. it feels like maybe not enough fuel????? when i turn the a/c on the throttle seems more punchy even though still after 1/4 or 1/3 throttle it isnt making any more power. is there a fuel filter on this car? i dont see one under the hood like in my 96. is it in tank? maybe i have a clogged filter and its causing low fuel pressure and giving me such a power loss? do i need to upgrade to a walbro fuel pump? all i have is cold air intake, y pipe, highflow cat and cat back exhaust system

 

Your fuel pump is in the gas tank, but I doubt that is the problem. All I have is a K&N panel filter and a stainless steel Budget y-pipe on my 95SE. I have experienced no power loss at the low end whatsoever and notice a considerable performance improvement above 4,000 rpms.

 

yeah i know the pump is in th tank, where is the filter?????? i have a power loss no matter what rpm from 1000 to 6500 is a power loss. its driving me bananas.

 

Put the stock Ypipe and cat on and see if that is your problem, sounds to me like your cat might be clogged- not too supprised as aftermarket cats don't do anything for our cars, and at the same time don't last at all.

 

yeah the car ran fine/strong with teh stockie y pipe and cat on i changed them out and it runs like a big ol piece of poooooppppppp. im going to put the stock cat on and see how that is. i dont think the AM cat is clogged it ran like **** the second i started it and drove. but ill try that and if not then im putting all the stock stuff back on. i cant take it being slow anymore. i want the v6 power not the 4 cylinder power i have now

 

No One has any insite on this????

 

I have magnaflow cat , dont feel any power loss. I had this cat on for 20k miles so far. Just eliminate the problem areas one by one. When you accelerate quickly is there hesitation ?

 

You have a strange case you had problems before the new exhaust. These problems dissapeared from what you write and then when you put on the new exhaust you lost the power. Are the symptoms after you installed the exhaust the same as you were having before? Is your car throwing out any codes? I would try resetting my ECU and all that fun stuff at technosquareinc.com If that doesn't work then you better find a good mechanix.

 

there are no trouble codes, no knock sensor codes, the problem started after i installed the y pipe and converter. it ran strong with just a cold air intake and cat back exhaust so i figured i would get a few more ponies out of it with the y pipe conveter combo and instead i lost ponies. it just doesnt make any sense to me. there isnt really hesitation under acceleration its just a dog, not making full power at all. when you mash the throttle the engine goes fine no skip or bog. just not full power. im lost with this one. no one will answer me about the fuel filter in this car. is it in the gas tank it self? cause i dont see one under the hood

 

I'd put the stock converter back on and see if that helps. You may have gotten a defective one with some sort of breakdown inside. That's the most likely cause and the easiest piece to swap. You wouldn't be the first to get a defective aftermarket cat.

 

I believe that the 02 sensor needs to be re-installed in the new Y-pipe. I wonder if that has something to do with your problem. But I would think that your car would be throwing a code out.

 

i replaced the oxygen sensors cause they were bad and giving me codes before i did anythign with the y pipe. at the time of y pipe replacment i replaced the oxygen sensors. im thinking maybe it is a defective cat converter. it seems to be the only logical explination. im going to try that this weekend and see what happens thanks guys

 

Let us know how it goes.

 

I have almost EXACTLY the same case, except that I haven't done anything to the MAF yet. I also installed a y-pipe (WSP) and high flow cat (magnaflow) and the car is just SLOW. A lot of low-end power loss and some high end loss.

Have you changed your cat to the stock one? Did it help? It's been a while since anyone posted here so you must have had enough time to do try things out

 

when i put my ypipe on it gained some low end torque. mine works awsome. and i just gutted my stock cat.

 

A perfect example of why you NEVER NEVER NEVER do more than one mod at the same time (at least not ones related to each other).....because if there's a problem, it makes it much harder to diagnose.....do one, test it out. Then do the next one, test it out, and so on....this is especially true for engine and suspension mods.....

 

good call, did he ever find the problem?


id put a fuel pressure gauge and vacuum gauge on it. i doubt its fuel pressure, tho, doenst sound like starvation...