Car doesnt accelerate as fast anymore
 

Im in this weird situation, my z which has now 64k miles. Has its check engine light on, last time this happened i changed air filter and it went away, this time i took it to a local shop, thry tried changing like 3 things, air filter, intake and battery. But didnt go away,

I also want to say i wanted to trade it in to get e92 m3, so they told me they will reset and i can trade in, but im not trying to do that. I took it to a diffrent shop and they said its giving engine codes. I told them i want a solution that can fix it not just hit or miss tries here and there. Then they say the code is for maybe spark plugs, maybe coil(not suspension), maybe 02 sensor, 'since its an engine code they dont know which item to fix exactly.

I personally never really changed anything, besides doing oil changes. I dont know mabey there is some fluids i shouldve changed after 50k miles.

Lastly, one thig that happens to the car maybe once a week is that im even though im using paddles it doesnt accelerate, i fully step on the pedal but it will gradully increase speed and dont go over 3000 rpm, almost like im just rolling in nuetral at a really high speed when im changing gears, turn the car off for 3 hours and its back to normal. So i dont know if something realted to this causing the check engine light.

What i want to do is actually go to reputabile shop in the ny/nj area, and trying to avoid going to nissan dealership, which they were telling me that they wanna charge $250 just to diagnose, im like yea ok.

I am pretty sure there are code readers out there that pinpoint exactly what the problem is... For all you know it could just be that the mass airflow sensors just need cleaning. You should maybe find a more competent shop and tech.

I remember seeing BrosFourSpeed on YouTube check a code on the fly and found it was his HFC and was able to clear the code too. Sounds like they want your money.

I hate to recommend this, but take it to a Nissan dealer. Many independent shops do not pay for the subscriptions (or in some cases they are not available) to look up all the diagnostic codes. If you want to spend the money, you can get the code yourself. There are cables and software where you can read them with a laptop and there are bluetooth adapters and software for smartphones/tablets where you can read them. If you do that and post on this site, you may be able to get someone to tell you exactly what it means.

The symptoms you describe could plausibly be caused by a bad O2 or MAF sensor. A cheap thing to try would be cleaning the MAF.

Good luck. That must be frustrating as all get out.

Agree with cleaning maf’s, as AIT is built into one of them & will pull timing if if it reads temperature above max.

As per NISMO IX, you need to find out which DTC(s) has been thrown. You can get ODB readers for as little as $20 or most auto parts stores will loan/rent you one. Google any DTCs.

After 64K miles, your MAFs could use a good cleaning. See comments by radix023 and jchammond above. At least one DIY on this site. Very easy job - takes about 15 minutes for a novice to do.

Thanks guys, appreciate the help.

I checked on youtube and some guy had the same symptoms and he cleaned the mass air flow sensor and throttle bodies, and there was a huge diffrence in the way the car responded.

Please do not ever say a code reader will pinpoint exactly what is wrong. All a scan tool will do is give you the issue the pcm is seeing and what area the problem is in. This is where knowledge and diagnotstic techniques kick in to do testing and troubleshoot the sensor, wiring, signal etc. This is what separates a true tech from the parts changers. From his story it sounds like he has already been hit by the parts changers and this second shop sounds like they are ready to start throwing more parts.

Op it's time to find yourself a reputable shop that will actually do diagnostics, and don't expect it to be free or you can bet you've just found yourself another parts cannon shop.

Some CRC MAF cleaner, and maybe some throttle body cleaning is in order. Make sure to disconnect the neg term on the battery first. Even if you don't disconnect the plug from the MAF or the throttle body, still recommend going through the ECU reset procedure and make your ecu relearn a bit.

Accelerator Pedal Released Position Learning
DESCRIPTION
Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.

OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON and wait at least 2 seconds.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON and wait at least 2 seconds.
5. Turn ignition switch OFF and wait at least 10 seconds.

Throttle Valve Closed Position Learning
DESCRIPTION
Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected.

OPERATION PROCEDURE
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.


Idle Air Volume Learning
DESCRIPTION
Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific range. It must be performed under any of the following conditions:

Each time electric throttle control actuator or ECM is replaced.

Idle speed or ignition timing is out of specification.
PREPARATION
Before performing Idle Air Volume Learning, make sure that all of the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are missed for even a moment.

Battery voltage: More than 12.9V (At idle)

Engine coolant temperature: 70 - 100°C (158 - 212°F)

Park/neutral position (PNP) switch: ON

Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger)
On vehicles equipped with daytime light systems, if the parking brake is applied before the engine is started, the headlamp will not be illuminated.

Steering wheel: Neutral (Straight-ahead position)

Vehicle speed: Stopped

Transmission: Warmed-up
For A/T models with CONSULT-II, drive vehicle until “ATF TEMP SE 1” in “DATA MONITOR” mode of “A/T” system indicates less than 0.9V.
For A/T models without CONSULT-II and M/T models, drive vehicle for 10 minutes.


OPERATION PROCEDURE

With CONSULT-II
1. Perform EC-42, "Accelerator Pedal Released Position Learning" .
2. Perform EC-42, "Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.
5. Select “IDLE AIR VOL LEARN” in “WORK SUPPORT” mode.
6. Touch “START” and wait 20 seconds.
7. Make sure that “CMPLT” is displayed on CONSULT-II screen. If
“CMPLT” is not displayed, Idle Air Volume Learning will not be
carried out successfully. In this case, find the cause of the incident
by referring to the DIAGNOSIS PROCEDURE below.
8. Rev up the engine two or three times and make sure that idle
speed and ignition timing are within the specifications.

Without CONSULT-II
NOTE:

It is better to count the time accurately with a clock.

It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a malfunction.
1. Perform EC-42, "Accelerator Pedal Released Position Learning" .
2. Perform EC-42, "Throttle Valve Closed Position Learning" .
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.
5. Turn ignition switch OFF and wait at least 10 seconds.
6. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
7. Repeat the following procedure quickly five times within 5 seconds.
a. Fully depress the accelerator pedal.
b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications.
13. If idle speed and ignition timing are not within the specification, Idle Air Volume Learning will not be carried out successfully. In this case, find the cause of the incident by referring to the DIAGNOSTIC PROCEDURE below.

"...what area the problem is in," is what I meant. "...don't not..." Is a double negative btw. Thanks for the correction...

Well apple helps me make all kinds of mistakes and proof reading on a 5c is a bit of a challenge.

Take it to an AutoZone, ask for a code read (it's free). Post codes here. Pretty sure it's gonna be P0101 and/or P010B, and the likes. I had the same issue, same symptoms, turn off the car, turn back on, and bam, power was back. Cleaned my MAF sensors 4 times, then cleaned my throttle bodies, boom, no more limp mode, and no codes either.

I used CRC’s mass air flow sensor cleaner (about 10$ a can)
1 can will do; spray them down very good & let completely dry before re-installation,
I wouldn’t use anything harsher on them/?as this stuff is really mild & designed for it... may take a couple good douchings of each one & be sure you’re spraying the filament/wire good.
Good practice to perform on regular basis.
Good Luck & have codes read & recorded before disconnecting batttery & clearing them off.

LOL, We have always called them Easter Eggers. They keep looking for the easter egg.

So i took it to a shop to do the cleaning, but light came back on after 100 miles. got fed up took it to nissan and they said well diagnose it and all we need to do is reset ecu , i told them idk how you gonna do it just fix it, i feel like a N54 driver now, so they did their thing and light came after 800 miles. went back and they said we can change throttle bodies for 1600, im like im out.
back to the Z forum

Don't throw money and parts at it. Get the codes read. Autozone does it for free, as has been mentioned.

nissan read the codes,
even they said its like 3-4 of them
mass air flow
throttle bodies
some minor ones from engine.

they said if you want all the code areas changed, its gonna be 4-5k. im like that is a set of new pss, nice rims, and other upgrades.
i kind of just want to change whats causing the light to come on, not spend a fortune on things that are not eveb going to get the light off

If you will pull the codes yourself and post them here, odds are that someone will be able to help.

I don't know why this is bringing back memories but, I had an 06 Sentra Spec-V that threw a code at 20k miles and went into limp mode. Dealer said it was the throttle position sensor or something along those lines. They replaced under warranty and all was good until 600-700 miles later when it happened again. My remedy, I went to the store and bought some purple power, and used that with a good power wash under the hood in the engine bay. Reset the battery and never had another "Service Engine Soon" light again, and trade it in with 93k miles on it.

Not recommending you do this, it is what worked for me on a different Nissan model.

You can buy a reader off Amazon for pretty cheap. Get the codes and post them here, I am pretty sure someone can help you.

clean your mass airflow sensors and your throttle bodies...there is a tutorial on youtube, it happened to me and my car flies now better than I can think off, time-consuming but easy to do :driving:

The OP doesn't sound like he knows much about working on a car. Probably telling him to clean MAFS is a bad idea. Best thing for you to do OP is to call a mobile mechanic and make sure he's got good reviews on Google at least. Make sure to call him while the check engine light is on not after you or anyone else has reset the ecu. Ask him for the specific codes after he diagnoses your car .We cannot stress that enough.

Cleaning the TBs and MAFs is not difficult. A local forum member might be able to help the OP :twocents:

:iagree:

Even a rank novice mechanic should be able to clean the MAFs -two easy-to-get-to small screws per MAF, remove MAF, spray with cleaner, let dry, replace. Takes about as much expertise and time as checking/topping tire pressures. More than one DIY on this site. The hardest part is getting the wiring out of the retainers to get enough slack and even that's not difficult.

I also heard if you dont wot your car will slowly detune itself to drive like a granny.

Warm up the liquids and parts and do a few wot launches ;)

Get the codes read at AutoZone for FREE and Post them here for FREE advice dude. Don't throw 4-5k at a stealership!

Advance Auto read my codes and for sure it was the MAF's/ cleaning the throttle bodies, and I did the research and there is a youtube video that covers both, I have a broken pinkie and a broken thumb, lost one of the screws somewhere in the engine abyss but found them I the Ace hardware store no problem, if I can do it with 8 fingers anyone can do it https://www.youtube.com/watch?v=85-y-QlU_-0&t=626s

Ok so I am assuming OP is going into Limp Mode. It was happening to me after I installed the Long Tube Intakes. Small particles or things like bugs can get into your Mass Air Flow Sensors and damage the small filaments inside the air flow sensors. It is recommended that you clean both sensors really good and re-install. Cleaning the throttle bodies is also a great idea. I personally had the same issue as OP and did this and the issue went away. I agree with everyone else commenting the same suggestion.

https://ibb.co/c2LLFo

The link has the photo of the codes.

So after this i bought 2 mass air flow sensors from someone on ebay from a crashed Z.
i deleted the check engine and it came back after 150 miles.
do i need to reset the ECU entirely?

Whether you reset the battery or reset codes with a reader, if there is a problem, it will still trip the code.

Ok so now you actually have codes to work off of. P0171 and p0174 so both banks are lean not just one. So things that are shared would be something to start looking at. What is fuel pressure and volumn values? Any vacuum leaks? PVC check valves. You have basically eliminated the MAFs (it's unlikely you got two more bad MAFs). So look for reasons why the car would be lean (unmetered air or can't deliver fuel demands) that would effect both banks, exhaust leaks before cats could be a cause but again the odds of having two is less common than something both banks share same for AF sensors. Now you actually need diagnostics.

So rechecked, and the code now is
P2099
Feel like selling the car now, who knows what mew code will come up if i fix this.

Looks like fuel and air issues to me. I have a cheapo 15$ reader and I can watch the voltages on all the sensors. Had it for a while now and works pretty good. Plug it in and rev the engine a couple of times. You should see stuff voltages changing. The internet can explain each item if you search on it.
Software icon says "OBDwiz". Just plug the adapter from the car's OBDII port to my laptop USB. Helped me isolate my check engine on my Tacoma to the O2 sensor. Fixed on first part replaced. :happydance:
Checked a code on my Z the other day. Cyl 4 misfire. Reset and it's been good. Think that one was a bad tank of gas.

Honestly these are very reliable cars and fuel trim codes shouldnt be hard for a competent tech to diagnose. If you don’t have vehicle knowledge then it is time to stay clear of the autozones, free scan diag shops etc. all they will be doing is getting the code and throwing parts at it, which you have already done yourself. Time to take it to a real shop, maybe one that is gold shield certified for emissions repairs (not sure if that applies in your area) as these are the shops that have to actually fix cars once all the parts changers are done and throw their hands up.

Good luck, as I said it shouldn’t be hard for a competent tech to diagnose fuel trim issues but sadly those are getting harder and harder to find as the industry keeps pushing them out. Once you find one keep him, possibly even his personal number if he isnt the shop owner, in case he quits. All the shops and dealers seem to forget it’s the techs that make the shop/dealer not the other way around and they only recognize it after people start quitting and their reviews tank.

My guess would be intermittent vacuum leak. You've got codes upstream and downstream of the engine all related to fuel/air mixture. Check for a loose or cut hose around the intakes. I think it's unlikely the gaskets are leaking unless you've had the manifolds off or have overheated the engine. If you run rich you can burn out the cats. Then you'll really loose power as the air won't flow through them any more. If all else fails, may want to consider a compression check on each cylinder to make sure it's not something really bad.