I need help, this has been an on going project for the last 2 months. Just trying to get this car running properly. OK, I went to the mechanic on Friday and we took off the TPS and cleaned it and plugged it back in. The car ran perfect for the rest of the day. Better than its ever drove for me. The next day I had all the spark plugs changed and the car started acting up again. So I pulled the Tps sensor once again and all problems went away. Even the hard shifting from 1st to 2nd that I have been experiencing for 2 months now. Monday moring the car is acting up again. So I replace the Tps sensor and it runs better but not perfect like before. The car will just rev up on it's own. I'll just be driving down the street and the RPMS will jump up to 4000 or 5000 and the car will try to take off. Today when trying to get on the highway it jumped back and forth constantly for like 8 seconds. And died on me twice while driving down the road. Then I filled up the tank, since it was a 1/4, now all of a sudden it running strong again. WTF!!!! Whats going on. Has anyone had similar problems or know what this can be. On Friday I finally got a glimpse of how good the car can run, but now its back to just ****ing me off.

 

Come on guys, I'm dieing here. Nobody even has an idea what might be causing this? Well, does anyone know where I can get a diagnostic test ran? I tried Autozone but they said the computers would go back that far to a 94. I would rather not go to the dealership.

 

My VE's died on my twice lately when accelerating, but both times it was low on gas, so my diagnosis for mine was it was getting down to the gas mixed with the crappy stuff at the bottom of the tank (stuff that gets stirred up when a gas station refills it's tanks). Fill it back up, and the stuff is all settled to the bottom again. Not sure if that's really what happens, but it seems to be what's up for me.

 

First of all the TPS must be adjusted so that the closed throttle position switch is on when your foot is off the gas. This is why you were shifting hard, the closed throttle position switch was not off when your foot was off the gas, it is also why it was idling a lot higher than normal. What you can do is rotate the TPS clockwise a little until the idle drops down to normal.



Secondly you car is dying but only when low on gas? That sounds like the filter on the fuel pump is getting clogged, so when you fill the car with gas there will enough fresh gas in there for the 'sock' to unplug itself and provide enough gas for the car to run. Also it is know that the relay for the fuel pump can go bad (its located in the truck), its cheap to replace. It wouldnt be such a bad idea to just replace the fuel pump, right now in the 'group deals' forum there is a deal for the Walbro fuel pump with the installation kit and filter for under $100. I just recently got it and plan to intall it soon. It does not come with the large o-ring for sealing the access panel, I reccomend you get a new one also.

 

Thanks guy's I see if this works. I can definitely use all the help I can get. Oh, so you think that the reason why my car was reving back and forth while driving was the throttle position close switch or do you think that that is another problem. It's been driving pretty good today, still hard shifting though. And when I get on it, like the on ramp to the highway the car acts possesed, hesitates and starts reving up and down.

 

You're not the first Max with that problem, mine does that, as do many others. General consensus limits it to the Mass Air Flow Sensor, or the wiring harness for that sensor. Check the harness first, as the sensor itself (new) is like 600 bucks, or something outrageous like that. It's also been fixed with the O2 sensor, ignition coils, and a number of other things, but if your problem is like mine, and it sounds like it is, it's only doing it when the car's drawing a lot of air, and the sensor (or the harness) sends an incorrect message to the ECU, sending it into "limp-home" mode.

 

http://www.autozone.com/servlet/UiBr...ction=loadPage

Would this be a good deal. Man I was hoping it wouldn't be that. But I guess its better than bad ignition coils. I really need to reset my ecu and clean the sensors. To reset the ECU I just have to unplug the battery right?

 

You should do the TPS adjustment before spending any money. I mis-spoke in my previous post, it should have been rotate the TPS clockwise (after lossening the two 7mm bolts).

 

Yeah, try the TPS adjustment first, but just be prepared in case it continues to do the limp-home mode thing (check the harness first if the TPS adjustment doesn't work).

 

I'm not sure but I think the check engine light would come on if the car were in 'limp' mode, and I think it is supposed to limit either the speed of the car or not allow the car to go into fourth gear.

I can also suggest to check the connectors on the Mass air flow sensor, they are known to go lame. You can clean them and also pinch down the connector on the female side so that they grab better.

 

Where is this TPS located? I wanna try it on my max tooo.

 

I think this is all my fault to begin with. When I went to autozone to pick up my throttle position replacement, they guy behind the counter sold me some de-electric stuff that is suppose to help keep the connections clean. I think you usually use them on spark plugs. He told me it would be a good idea. So when I installed the TPS I put some on the connectors and also unplugged the MAFS and put some on those connectors. Well, today after my morning class I drove over to my MOM's house ( so I could use her garage and get out of the snow) and clean the connectors really good, I think I got way too much of that crap in the plugs. I got alot of it out with a toothpick and a paper towel. The car is driving 75% better, its not shifing as hard, but it still ocassionally trips out. I didn't have time to adjust the TPS so I'll get to that later on. Does anyone know if that de-electric stuff can cause these problems or am I just really confused.

 

Yes it can, the dielectric grease is meant to insulate the connector electrically, thats why its used on the spark plug boots. It can be used in light amounts to prevent air from getting at a connector and causing it to oxidize.


The TPS is located on the throttle body (right hand side).

 

Check out Craig's (MAX of da month) web page, it has a good shot of the TPS on "adjusting the timing" or something like that.

 

hey thanks !

 

What exactly is 'limp' mode? can you describe it? And yesterday when I was driving home a stopped at a stop light, when I step on the gas to go the car shut off, I starte it back up and the check engine light started blinking on in off. If I pressed the brake it would go off, but whenever I touched the gas it would start blinking. What's up??? And if I'm going to reset my ecu, I just need to unplug the battery right? How long should I leave it unplugged??

 

Overnight.
The nissan tech here said to disconnect both terminals, connect them together and then connect the whole mess to ground.

 

i did a search on the org. and the threads say 4 things

1) overnight
2) 10-15mins
3) 24hrs
4) there is a thing under the passenger side that you can turn and it'd reset the ECU

anyway so is overnight 8 hrs? I think I did it for 6 hrs and it didn't work (but I only did the -ive terminal)

 

From what I've seen/read on the org, plus what I know about batt stuff, you'd disconnect the positive overnight to reset the ECU (you'd take off the positive anyway, no matter how long it's supposed to be).

 

Engine won't go beyond 2500 RPM without shutting down and turning back on below 2500 thus the bucking. If accelerated normally (slow) it will shift below 2500 about 2000 and go through all 4 gears still allowing you to drive 60MPH in overdrive but never crossing the 2500RPM barrier. Its a map built into the ECU.

 

Ok guys,
How can I know for sure its my MAFS acting up on me? I don't want to replace that bad boy unless I have to, for what I understand it can run up to $400. Does anyone have any ideas or know where I can pick up one for cheaper. 94 VE

 

If you have friends with Maxima's, see if they'll switch you MAFS's for testing purposes, sometimes junkyard MAFS's work too. The plugs are usually troublesome (corrosion and whatnot) so you might try cleaning both ends of that too before you buy a new MAFS.

 

I personally have spent over 1200 dollars chasing this problem, and if you search you will find no definative answer. There are a number of inexpensive things that can be done before you go chasing parts. Some people have fixed thier problems with adjustments some have replaced many parts like myself and intermiitently still have the problem. I know a friend who gave up and sold his car. The mechanic that bought it still has not been able to fix it. Adjust the tps as mentioned. If your car starts to buck loses power then gets power back when the rpms go under 2500 you can be sure its you maf. If it is bad it will send the computer a code. Most likely its harness has a problem and it is still good. Disconnect it ans clean both ends with electronic parts cleaner take the female side and slightly bend the connections to assure a tight grip. You should also clean as many electrical conections as possible on the car as many people have been able to clear up the problem or at least get the computer to compensate for it by cleaning or replacing other parts of the system.
A new MAF can be bought from courtesy for 360 with 12 month warrenty. I bought a rebuilt unit from autozone rebuilt by cardone who offers a 12month 18k mile warranty. My first replacement was defective as are many rebuilts but finally threw a code and they replaced it. I now have the problem only when cold about once a week 1 or 2 bucks and its gone. I'm certain in my case its the harness and am trying to figure out how to replace it or circumvent it with new connections.

Good luck

 

Ok, I adjusted the TPS and the car is shifting a lot better, but still losing bucking. I guess you would call it a buck. When I'm driving down the street just minding my buisness the RPMS start going crazy. I'll be siting at about 2000rmps and it will jump to 3000 back and forth a couple times. It even does it when I'm on the Highway doing 60 or 65 the Rpms will go crazy where ever there at. Could this be something else? I've cleaned the connectors really good, but no improvement. What type of electrical cleaner are you talking about? I don't have the money to start dropping like crazy to fix this. I just bought a 2003 Trailblazer last Tuesday and have to tag it.

 

It doesn't work that way on a FI system. The fuel pump is a: always circulating the fuel from the pump back to the tank via the pressure regulator and b: drawing from the bottom of the tank... so everything is pretty much kept stirred up... until you shut off. This also means that the fuel is run through the filter many times per tank.

On carburetted cars, it was a one way feed, and water in the gas was on the bottom until it got used and the better gas floating on top of the water got down to the bottom.

 

If your RPMS fluctuate over 2500 RPMs, then I would say it isn't your MAFS. If your MAFS is bad, you won't be able to go over 2500 RPMs. My Max is doing the same things as yours, and for me it was one bad ignition coil. Like the earlier post said, find a friend willing to let you swap out parts for a day or two. Or buy new parts and pay the restocking fee, if you can take them back if they don't stop the bucking or shutting off.

 

Alright here's some new info, today when driving home I heard some weird noise coming form the back of the car. Like a rattaling or nocking when I experienced power loss. Does this sound like it might be an exaust leak?

 

Sorry to keep bugging you guys, but does this sound like it could be an exaust leak or a bad cat. How can I find out if has a leak or not?

 

Use a rag, put your hand over the tip of the muffler for about 5 secs with the engine running and listen for hissing. If it builds up pressure and the engine starts to die... no leaks. A little hiss... small leak. A loud hiss or rumble... big leak.

Also, any muffler shop should give a free inspection and tell you if you have a leak.

Don't make things more difficult than they need to be.

 

Thanks, I'll check it out.

 

Ok, I put a towel over the exaust and no change at all. I left it there for about 20 seconds and my Max just kept on running strong. But I couldn't hear any hissing. I guess I'll take it to a muffler shop as soon as possible. Thanks

 

Ok, the Max is in the shop and they called me and told me that they think its the knock sensor. They hooked a computer up to the ECU when they test drove it, or something. But they need to test the knock sensor its self to see if its dead. They also said labor alone to replace it runs around $500. Does this sound right with the problems I've been experiencing? The muffler shop said I don't have an exaust leak.

 

You probably DO have a bad knock sensor (or bad sub-harness, or corroded connection, or all of the above) but it is probably NOT your problem. Tell them thanks and decline the repair... for now. It's not fatal.

How come YOU didn't know the sensor was bad???? YOU could have gotten the same code from the ECU yourself.

However, the KS is costing you power and economy, and could be contributing to/masking/exacerbating other problem(s). My KS is bad too, but I'm not gonna worry about it just now... the parts that need to be removed to get to it are some of the same that need to be removed to get to other things too... like VTCs and injectors, etc. I'm gonna wait and see what else I need to do and then do it all at once. You can wait too.

So.... for now, YOU go to a Radio Shack (at the mall, maybe) or similar and ask them for a packet of 470K Ohm resistors. They are like 99 cents plus tax (you can swing it I'm sure). You will use one of these to circumvent the KS, and have 4 left over. Let us know when you have them in your hand.

BTW, you'll need to start using premium gas now if you aren't (you aren't using regular are you?)... 91 octane or better. 89 might be ok, but the manual calls for 91 for the VE (I think), and with no KS, you'll need to be safe. Top off the tank on your way to Radio Shack.

 

I knew the ECU was sending the Knock sensor code, thats why I was trying to reset the ECU. But I don't know wether it would make my car act insane. I thought it just lessened your Hp. Yea, I plan on waiting, I saw a write up somewhere on the org, were someone changed the knock sensor without dismantaling the engine. I think I'll try to find that.

 

The KS shouldn't be making your car act insane, but it is killing power. 99% sure you can't get to the KS without pulling the intake and "stuff". See this thread: http://forums.maxima.org/showthread....readid=189127.

99 cents is less than $300+/- in parts at this point, plus the labor is either yours or it's extra $... well, you know that already.

Do this today and feel the difference!

 

BTW, resetting the ECU doesn't make the problem go away or change performance... it doesn't do anything but clear the codes that are stored. If the problem is still there, the code(s) comes back as soon as you turn on the key or start the engine.

Did you get any other codes that you didn't tell us about?

 

No thats the only code stored. I didn't think that would cause the problems I'm experiencing, so I'm still at a loss. Someone in a previous thread was saying that it could be my cruise control malfunctioning, I don't see how and I never use it. But I tried to engage it yesterday and its not working anymore. (It worked in Dec. when I bought the car, before the car went mental on me.) So, I guess I'll check it out too. But I really don't know how the cruise control would affect it, expecially went its not suppose to be engaged. Also, since I bought the car I've never put anything less that 93 octane in it, but the guy before probably ran 87 octane for years. Thats why I was going to try to reset the ECU, I was praying that the change in gas would make a difference.