Hello all,

i have a 2012 maxima

takeda cold air intake, full borla exhaust, y-pipe, stillen underdrive pulley, uprev tune, thermal spacers for manifold and throttle body, etc......

problem is that it is random. at times during acceleration, mostly hard acceleration all of a sudden the car loses power. its like a governor of some sort kicks in as soon as you take your foot off the pedal and back on again the car goes again.

it will basically take off like a bat out of hell and rev up then all of a sudden its like someone shuts the fuel off. engine doesn't die it just holds speed that it is at. take foot off pedal and back on and it goes again. this did this before the uprev tune also.

any ideas on what it could be? I know when i did the spacers there was a sheet to reset the throttle. i don't remember if it did it before this or after. whatever it is it has to be some sort of electrical issue or sensor causing it.
thanks in advance.

 

Well you didn't put all of this stuff on at once so think back to the last thing installed before the first time the throttle acted up. Your problem should lay there.

 

i believe it started about 2 months ago. it was after everything was done with the exception of the uprev tune. it has been fine for a year with all the mods and just started doing it.

 

If the problem started after the uprev tune then I would verify this by uninstalling this feature and putting your cars computer back to factory specs if you can, then see if the problem persists. I'm not sure exactly what's involved with an uprev tune or if it can be reversed, but it is a starting point since all the other build addon's did not contribute to the acceleration problem.

 

no it did it before the uprev tune also. i had all mods done about a year ago and it started 2 months ago. i just got the uprev tune 2 weeks ago and it continues to do it even after that.

 

anyone???

 

What did the dealership say, assuming you had them take a look...?? Also as someone else recommended, sounds like it starts/ends with the tune.

 

did not go to the dealership. also it can't be the tune as it did it before the tune and still does it after.

 

Maybe your engine is 'choking' somehow or perhaps you are running the tranny too hot and it's governing itself to prevent further damage.....my only thoughts here. Hope it's helpful.

 

it actually seems to do it when it is cold. tranny temp is usually around 260 according to bully dog obd sensor.

 

260 seems pretty hot to me. I don't know about the cvt but ordinary auto trans typically are happy in the normal operating range of the motor 180-220 260 is def on the higher end. You may wanna check condition of the fluid and or consult a trans guy.

 

Great point, keep in mind that the CVT is known to run hot.

I have an OBD scanner and will check my tranny temp

 

ive seen my tranny get up to 300 or even 310 and it never goes into protect mode. these cvt trannys run hotter than conventional transmissions. it also doesn't seem to do it when the car is warmed up. also doesn't seem like a tranny issue. almost like something is cutting the fuel off. then as soon as you let off of pedal and get back on it everything kicks back in. wondering if i have a crack or small hole in intake somewhere and when motor flexes on hard acceleration it moves it enough to make a leak somehow.

 

well it is narrowed down to when the car is cold. basically if i try to go full throttle before the car is fully warmed up i can get it to do it. once its warm it will never do it. don't think it is the tranny either. seems like it is some sort of sensor or something just cutting fuel for some reason. no dtc codes are in computer and cel never comes on. if im doing 30 and punch it it takes off like an animal and then out of nowhere it will just cut out as if i lifted my foot off of the pedal completely. it will only do it at full throttle also. weirdest thing i have ever seen. i can't be the only one who has seen this before.

 

Try to find someone to put it on a scan tool and drive it and see if the timing gets backed out or if the knock sensor is telling the computer to pull timing. I know my scan tool shows me those parameters. I have seen people with older nissans have similar issues due to cold air intakes. The cold air intake created noise in the intake which pissed off the computer and it pulled timing. May not be the situation but if you've got your original air box it might be worth it to throw it in.

 

i put my bully dog on it yesterday just to monitor it while i drove. started the car and started driving. immediately i noticed that when i tried to go WOT it would rev up to about 5000rpm and then it cut out. when it cut out i instantly look at the bully dog screen and the throttle gauge on there dropped to 16%. it isn't throwing any codes either. but everytime i got it to do it the throttle dropped to 16%.
i did notice one other thing. before i got the uprev tune i removed the bully dog program from the car. after the uprev was installed i still use the bully dog to just monitor stuff on the car. i went into the bully dog settings and noticed that the timing was set to +2. i wonder if after the uprev was installed and just by turning on the bully dog it advanced the timing another 2 degrees because thats what was previously set in it? I adjusted the bully dog timing back down to 0 and it hasn't done it since. i know when they did the uprev tune they hard coded the timing in the ecu when it was tuned. after removing the bully dog program i never adjusted the bully dog tuner back to a 0 timing setting. so im wondering if this was the issue.

 

well it did it again, so my last theory of the bully dog messing with the timing went out the window. can the knock sensor be disconnected somehow just to test or is that not a wise idea? where is the knock sensor located?

 

Just an fyi the knock sensors are under the intake manifold. Its a long process to access them. If your going to attempt this make sure you have a valid reason to tare into this project as its time consuming. As I said earlier see if you can get the car to a tech that can check the car on the road while its happening if its not leaving any trouble codes behind. What are you using to check you codes? The bully dog?

 

yes, i am using the bully dog to check codes and also saw with that when the problem happens the throttle goes from 99% to 16%. after releasing pedal and pressing it again throttle goes back up to 99%

 

I would scope the throttle body or throttle position sensor. If your foot is down obviously % should still be high. Are the tires slipping at all? Any vsc lights when that happens?

 

No lights and have tried wwith traction off and same r
esults

 

Will research if I can tomorrow and get back to you

 

Thanks so much. I really appreciate it.

 

That sounds like my old Mazda I had...it was fuel filter that was clogged. It gave the exact same symtoms as you have described.

 

i guess i could pull fuel pump and check filter. wonder if it can be accessed through the trunk?

 

no you access it under the rear seat. before you do that get someone to take a fuel pressure reading. don't go to that trouble before you get a fuel pressure reading. You can have issues pulling that pump assembly out. Ive seen screws break, seals pinch, evap lines crack and then youll be chasing your tail. I don't want to discourage you but be smart and make sure you have a reason to pull the pump. Get a pressure reading if that's what you think it may be. I haven't had much time to look further into your issue. It is difficult at best to diag a problem that isn't in front of you. Feel free to shoot any ideas past me. I will provide any tech info that I can. Good luck. Let me know how many psi of pressure with key on and when cranking and once running. TTYL

 

Could it be the engine detuning itself either due to overheating or possibly slipping?

 

for reference i have all these same bolt-ons essentially and same tune; i do not experience this issue. i have however run into limping my trans which keeps me from going past 4k rpms. ive never experienced this issue here so i dont think it is related to heat

 

Seems like another 5+ hp with this cold/dense air now in the 40ish range here in WA.

 

I don't think it's limping. It pulls like crazy past 4k. It's almost like something is cutting fuel. This is diving be crazy. Also noticed that if I monitor my maf on bully dog it's up around 155 g/s at full throttle at low speed. As speed increases it drops to around 130. Could it be starving for air which cuts fuel? Thanks for all the replies guys. I appreciate it

 

sounds like to me your car cutting back to protect itself from something. mine did this too when i ran it at the 1/4 mile track. after the 1/8 mile my car did what yours did...but when mine did it it did it right when the low fuel light came on (yes i ran it with low fuel to save weight lol). so i think if something is out of place it cuts back to protect itself but prolly does not throw a code because theres no errors..its a protection feature..thats my guess. but when u were talking about your trans temps...thats really hot for a trans..so thats prolly whats throwing your car into some protect mode during a hard run. ya it might of not of done it before because maybe it has to happen a couple of times before it triggers the protect mode. but anyways..i left the track and filled the tank to half way and came back and ran again and it didnt happen again. so i think when i was low enough to trigger the light it prolly threw it into protect mode for the reason of so i dont run out of gas during a hard run which would not be good for the fuel pump. when your trans temps were hitting past 260 was your trans starting to whine? if so i would change the cvt fluid and install large trans cooler since the oem one is too small. the oem cooler seems just good enough for normal driving on flat roads but once you start doing hard runs or driving on roads going up hill or long trips on a hot day..the oem cooler does not cut it.

 

Found out trans temp is normal. It doesn't register right on the bully dog. Brought it to dealer and they said trans was fine and fluid looked brand new. I'm leaning towards the program. Up rev is looking into it.

 

well i guess that leaves what happened to me a mystery since im 100 percent stock lol

 

my problem went away but thats because i did it with a gas light on and im pretty sure it was because the gas was so low it pushed it away from the pump. I dunno why u pushed your car when it has not warmed up yet..thats prolly why yours was doing that(car going into safe mode from wot when cold maybe?)...does it do it when its warmed up fully? also have you figured out your issue yet?

 

well it definetely seems to do it more during the first 15 min of driving. although it has on occasion done it after that, not nearly as much though. It's definetely not the program in the car either. We went back to stock and it still did it.
so all in all i have no idea why it does it.

 

also I forgot to ask...when yours did it did the rpm drop or did the rpm stay in place? when mine did it it was sitting at 6k then all of a sudden the power is gone but the rpms were staying at 6k...kinda like the car was still in gear and coasting but with no fuel..which is in my case.prolly was lol

 

I dont know if anyone is still facing this, but I was. It happened more frequently when it was wet. I could be flooring it, and it literally felt like the fuel just got cut. It turns out that it was the VCD, Nissan's traction control. You can look that up for the details, but after a lot of frustration, it turns out that my brake fluid was a little low. After topping it off, no more problems. If anyone is having this, just check out your brake fluid. It could be a simple $3 fix...

 

I don't know if anyone is reading this or not anymore but this is a sure sign of a MAF sensor going on you. Once you said that it did it more when it was wet that set if off for me. Your MAF sensor is capping out or topping out. This happens quite often with stock vehicles with MAF sensors that are modified. Which is why they have MAF Calibration units that can modify fuel maps to adjust to your modifications.

This MAF problem isn't really a problem your sensor simply has exceeded its CFM range. Your ECM/ECU is unable to modify this either so a custom map won't help. So a good example of this is a home digital weight scale that maxes out at 200lbs. Once you max the scale out it just blinks 000. If you don't know how much you weigh then you don't think you need to drop any weight.

When your MAF maxes out it does something like a 000. Your car ECM sees 000 so it cuts power pack to a factory designated RPM/Throttle. No error will register because the MAF is still reading a voltage, it has just reached 5 volts which is the top end.

So now your probably asking yourself "why would a factory MAF do this?" Isn't it made for the cars engine size? The answer is simple not all sensors are created equal and not all engines are either. Also, if your cars engine breaths better or has modifications to open up the flow of the engine it will max out a MAF sensor. Toyotas are notorious for this as Toyotas MAFs sensors are windowed 10HP above factory. Having a simple exhaust on a Toyota will max their MAF's right out. Thus they have http://urdusa.com/p1260198051/URD-MA...duct_info.html

This is why many who boost their vehicles will try to delete their MAF and convert to a MAP sensor with a piggy back or full standalone system. Finding a MAF for your car with an extended range proves to be difficult because its based on your intake pipe size. However, a MAP is not based off of intake size or airflow its based off of atmospheric pressure and if you run out of sensor you can just buy the next size up.

So how do you fix this problem? Many times your MAF may be dirty, this can be cleaned with a can of MAF cleaner from AutoZone or electronic component cleaner bought from Walmart. Look up some youtube on the specifics of cleaning your MAF. Maybe when I get some time I will do a write up of our Nissans MAF and how it works with specific realtime MAF readings and show you what happens when you MAX it.

Until that article I wish you good luck and a pat on the back telling you take this pill and you'll feel better in the morning.

 

thanks for the reply.
i already changed out the maf sensor. so i know it is not faulty. it might be reaching the limit though.
are the maf sensors for the 350 the same where i can pick one of those up and see if that makes a difference?

 

The sensors are the same unfortunately. You could tap into it with a calibrator and see if you can alter the map. The MAF sensor on the 09-14 nissan are all the same from the versa up to the 370z. Now I do know that the MAFs are the same but the intake diameters of the vehicles are not. So the programming or line resistance on the 370z is made to skew the voltage appropriately for the added CFM (air). In most cases changing out a MAF even if the plug fits makes your ECM freak out. The resistance in the MAFs are usually different and also again made for different diameters.

Your problems do sound like your Maxing your MAF out. There is a positive on this though, you have a really good engine. I experienced this with my two track cars both Scions. When I built the engines and drove them without a standalone ECM I would Max my MAFs out. The compression was lowered but the high flow head and lighter cranking assembly would still produce more power than my stock engine hands down. Same deal as yours I'd back off the peddle and it would return to normal then when it rained it would do it more. Once I plugged in the Standalone after break in I could see exactly what was happening on my datalogs. MAF maxed out. I skewed it as much as I could by reprogramming my ECMs intake size parameters but that soon topped out too. In the end I changed my MAF to a GM Style which has more than enough for my needs. I also had to change the MAF style on my ECM for it to work. I'll have to see If I can take some pics so that everyone can see what I'm talking about.

I will check to see if our MAFs can be skewed for extra flow. They usually max out at around 120% load. Nissan doesn't give much wiggle room on Hard programmed ECM ranges. You may need to upgrade pipe size and see if UPrev can modify a MAF like this one http://uprev.com/secure/accessories/uprev-maf-gt.html

I know the custom MAFs are pricey but perhaps you don't even need one. See if UPrev can skew it in their programming. I can check into MAF Calibration and see if its possible to do a physical skew. Sooner or later I'm going to have to do it as well. Apparently many experience the same problems under hard acceleration or with light Mods like an intake.