Hey guys, new member here, great site! Need help diagnosing my 2001 Maxima SE 5 speed. It has been losing power lately, but idles perfect and runs excellent until you load it and try to spin up the rpm's. No codes in the ecm, no missfires, just hesitates real bad under acceleration. I also noticed it is pinging/ detonating badly, and the exhaust note sounds a little different to me. I am thinking the cats are clogging, but don't want to spend all that money unless I get some re-assurance from the pros! Is there any way to test this? I wish it would throw a code!!!

Thanks for any help or advice!!!

Randy

 

MAF.....

Can we get instabans for blatantly not searching?

 

I have been searching for hours, thats how I found this site! Haven't found these symptoms with a concrete fix yet. Thanks for all your help.

 

Well I would also say start by replacing the MAF as you have stated that the engine "hesitates real bad under acceleration" ( you will also note that the Maxima doesn't like the super hot temps. and will under perform just because its hot (you haven't mentioned your current outside temps.). The engine ping can be from a couple of things, most often bad fuel or low octane fuel, and can also be from the outside temps. thinning down your oil (have you checked the oil level lately?).

Just my 2 cents on some of the reasons you are finding your Max under performing.

 

If I may just chime in here, since I have been experiencing this issue since the day I got my Maxima...

...There is most certainly no guarantee that the MAFS is bad. There are other causes for bogging. It's entirely possible that it is, however, I bought brand new OEM MAFS, Coils.... etc. and so on with no luck. As it turns out, my pre-cats are clogged. Everyone pointed me straight to the MAFS, and coils, and I foolishly replaced them without testing the old parts. This is not, by any means, to say that it's not your MAFS, because it very well could be, but you need to do a good amount of testing before you start throwing money at it. I've thrown over $2,000 into just parts on my car trying to solve that issue with no luck. I'm just now to the point that I am in the process of getting what's needed to replace/gut my pre-cats.

My advice, TEST the MAFS, TEST the backpressure, and TEST everything before you replace.

Here's a link to my thread:
http://forums.maxima.org/5th-generat...l?ref=esp-link

Read through that. Mine is a 2002 with a 3.5, but it should still give you some good info and a good path to start on. Let me know if you have any questions, and, if you'd like, I'll let you know whether replacing my pre-cats solves the problem or not. Cheers.

-Nathan

 

Thanks guys, I agree, don't think it is the MAF, I checked the fuel trim with my scan tool, and it's right on the money. If the MAF was out of calibration bad enough to make the car run like it is running, the fuel trim would be way out. Did the voltage testing on the MAF, and it is in spec. I am getting a weird noise from the exhaust, it sounds different, I am pretty sure the pre cats are clogged. I am going to remove the upstream o2 sensors and do a back pressure test next. Thanks for the helpfull info. Glad I didn't listen and buy a MAF for nothing!

 

Let us know how the back pressure test goes...

-Nathan

 

Buying a MAF is never for nothing. ALL of them fail and it's ALWAYS the 1st thing to replace whenever symptoms of this sort appear. It's cheap and is the cause at least half the time.

There's a new thread every day and no one ever reads. Hell, people will replace the maf with a crappy one and complain that it wasn't the problem. That's why it's going to be suggested 1st by me or anyone else. If there's no code and no obvious sign of another failing part, then the maf is highly suspect. If it's eliminated, then you can safely move on. I'm sure I (and maybe others) sounds like ****s, but without such obvious things eliminated it's hard to diagnose anything.

You're right, the cats are very likely because they are absolutely worthless.

If you know others in your area with maxis you can swap parts to see if it solves your problem, so you don't have to buy the part (aka you can't complain about replacing parts ).

 

Where do you find these "cheap" high quality MAFS?

 

The point I'm trying to make is that there are ways to test whether the MAFS is good rather than just replacing it blindly when you could be replacing a perfectly good part.

It's just as easy to rule out a part by testing it as it is to replace it with a new one, and it's, obviously, less expensive.

I'm speaking from very recent experience here that it's highly likely that it's clogged cat/pre-cat(s). Mine is, and I spent a ton of money replacing stuff that didn't need to be replaced because I decided to just throw parts at it, instead of taking the time to test. I could've saved myself a couple thousand dollars if I had bothered to test stuff instead. The price I pay for laziness I guess.

-Nathan

 

How about point to something that actually inspires learning instead of the same old tired script?

Check the FSM, work through the diagnostic procedures to rule out components/systems until you have a short list. Then you may want to call around and get an idea how much shop labor would cost to come up with a diagnosis.

 

RR5 - Consider your sig copied... Oh, and good point, well made.

-Nathan

 

Bravo.

 

Not a problem at all! Better to give than receive

D&%# right!

 

I removed both upstream o2 sensors today and road tested. It's bad cats. It sounded like crap, but ran much better, plenty of power through the rpm range. Those pre cats look like they are tough to change, hope it goes well...lol.

 

I am having to order a new Y-pipe because my front pre-cat was too stubborn to come off with any shred of grace. Lol. The bolts at the top where it bolts to the manifold came off without much trouble at all. A little PB Blaster goes a long way. Good luck mate, hope it goes well.

-Nathan

 

very happy to see someone actually doing the proper testing and getting the results without just replacing stuff that is perfectlyfine

Well done randy, well done!