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P2127,P2138,Poor Acceleration & Low Idle - 04 Spec V

40K views 29 replies 8 participants last post by  Se-R-Vspec 
#1 ·
Hello Everyone,

I've tried researching this and I could not find the issue that I am having to understand what I'm looking into. I searched google and mutliple forums but it was either finding nothing or forums with no results.

My car is throwing the P2127 & P2138 code and my car will barely accelerate and the rpms sit around 2 -3k rpms. It takes longer than normal to get to 20 mph. I believe it's in its "Safe Mode" or "Limp Mode". I tried recalibrating the Accelerator Pedal Position Sensor and doing the Idle Relearn plus clearing the codes.

As soon as I took the car for a drive and tested it from 1st to 2nd gear, the ECU through off the codes yet again and my car went into the "Safe Mode". I have a CAI and Headers with full exhausts but I haven't touched anything on the car since I installed the exhaust system last year. I don't feel any unusual leaks or knocking noises either.

It's funny because the car will be completely fine when the codes are not thrown but as soon as the ECU throws a code it loses power. Everytime I've tried clearing a code in the past it always comes back up with something else so I assumed it was because of the exhaust but I'm thinking it's the ECU...I've never disconnected the MAF and I've only hydrolocked my car once about a year ago. Does it seem to be an ECU defect or does it sound like the pedal is going bad and if so when can I find a replacement or assembly?

Thanks for any help on this.:confused::confused:
 
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#2 ·
IIRC, the throttle position sensor (TPS) is in the throttle body. Fairly common problem.

Everytime I've tried clearing a code in the past it always comes back up with something else
What other codes have you had in the past?
 
#6 ·
So I found a multimeter in my tool box and I checked the harness on the gas pedal. It's putting out 5.05V like the service manual says, but when I check they ECU side for the specific connectors for continuity the readings are at 0V. I checked on multiple dials and they all said 0V. It results to checking the harness for a short but if I can get readings on one end and not the other then atleast I don't think it's a short.

Also I checked my ECU and whoever the idiot at Nissan was the reflashed it a couple years back didn't plug in part of the harness all the way nor did they bolt down the bracket for it so it was loose on one end. I only have 66K mi on it so I think an ECU replacement on Nissan's behalf won't be so hard to ask.
 
#10 ·
I did the
Accelerator Pedal Position Relearn
Throttle Position Relearn (?)
and Idle Relearn in that order from the Service Manual on here. I'm trying to find it but I'm at work right now.

The recalibration is the Accelerator Pedal Position Relearn I was talking about which is turning the key on for 2 sec then off for 10 sec then on for 2 sec then off for 10 sec.
 
#11 ·
I think my car might be doing ok now. I was going to drive to Nissan to try and get the ECU replaced for starters but I think by replugging the ECU all the way in unlike what the techs at Nissan did as well as replug my accelerator pedal did the trick. It drove with no CEL codes today. But we shall see later on..if it goes to safe mode again then it's definitely the ECU..
 
#13 ·
Bad News, I got my car back and it's still giving me problems. I've lost $270 to Nissan's Stealership because they said the pedal was bad but it's still coming up with the P2138 and P2127 codes. I had taken it to them again and demanded a refund multiple times. They told me they would look into but I sent an email up to the Corporate consumer affairs to see what Corporate will offer to do now.

Just getting tired of this crap with the mistreatment at the Service Center. I didn't want to pay anymore than what I could afford so I picked up my car still dropping into limp mode. They said that the code coming up now is P0507. The code was cleared before I drove off but it went back into limp mode again.

I ordered a Reman. Throttle Body and looking for a new MAF in the mean time. I know I'm pissed at Nissan for selling me a car with multiple issues but I'm going to change my intake back to stock to see if that may help since I have a CAI. If it comes out to be a bad MAF because of my CAI then my apologies to Nissan but I've had the CAI since 2007. Cleaned the filter often and also have replaced it. Don't know why this is going on now.
 
#14 ·
P2127 Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage
P2138 Accelerator Pedal Position (APP) Sensor 1-2 Correlation

I read that you checked with a multimeter the ECU side for continuity with the wires coming from the pedal sensor and that it read 0V. I believe you should take a close look at the wiring for frayed or torn wires leading from the sensor to the ECU. Should everything be OK, then the problem's likely to be in the sensor itself, and in that case I think you may need to replace the pedal assembly....

As for the P0507 code, that's Idle RPM higher than expected. The idle relearn should be able to fix it....
 
#16 ·
^^^Perhaps they didn't program the ECU when they reflashed it.....mine did that when I first started it after I replaced my ECU due to killer foams, that was before I had a friend that worked at a dealer steal the Consult-II from his job for a couple of minutes to program the ECU. If you ever take it to the dealer again, request to be present when the tech plugs the Consult-II in your car and have him double-check every parameter....
 
#17 ·
I think I may take my car to autozone and have them do that with their system, they do that right?

I changed my intake to an SRI, took my throttle body off to look at it. It was really dirty so I wiped it down but I noticed when I wiped it down that it doesn't sit closed all the way. I'm hoping the new throttle body will correct that. My MAF didn't look dirty though.

My car idles at about 600 rpms now and it doesn't seem like it wants to stall..kinda scary idle though to me. I'll have to pull apart the dash this weekend and check the wires from the pedal to ecu though to make sure nothing is shorted too.

Getting somewhere atleast...
 
#18 ·
I believe they can check that. However, any adjustment has to be done with Consult-II unless otherwise specified by the FSM. Try with them first and see...

You haven't tried to do the idle relearn again, have you? That thing of the TB being partially open when off and the very low idle (our cars idle kinda low, but that's a little too low) makes me think the ECU doesn't recognize the proper positions for closed throttle and pedal released positions....
 
#21 ·
Ok so I don't think a wire is shorted. I didn't pull apart the dash but I had the battery disconnected for a whole day.

I reconnected it and when into Diagnostic I & II mode to clear the codes. But the code that came up was "0000". So I turned my car off then on to let everything turn on. Then started my car.

The car started and idled around 1000 to 1200 RPMs. I decided to take it around the block. I gave it a couple good revs between 2000 and 3500 rpms. I went to my next stop and then my car started idling at about 700-900 rpms.. after this stop i took it out of my housing area and gunned my car down a road redlining it. Then got to another stop. Now my car is idling at 600-700 rpms. I decided to turn around and start going back home and when I got to the next stop my car started idling between 400 -600 rpms.

Mind you, no knocking or anything in the engine and the Check Engine Light has not come on yet.

The light never came on the whole time I drove but when I got home my car was idling very low and it's abnormal to me to do that because I have a 4-1 header to a megan racing axle back set up which should have some idling sound to it. It sounded like my car wanted to bog out and I remember this has been happening everytime my car wants to go into a limp mode and barely accelerate,etc..

Am I defining a vacuum leak issue by chance?

NOTE- I did disconnect my MAF sensor while the car was on before I did this check and the car was stuttering really bad until I reconnected the MAF sensor it went back to "normal"
 
#22 ·
Check your vacuum hoses and see if there's a crack or tear that's causing a leak. It may be better to check with a mechanic's stethoscope.....
 
#23 ·
Thanks for the advice on this. My girlfriend's dad has a mechanic that does work for them really cheap so I'll see if I can get him to check the hoses. I just put in a new air filter and sprayed down my MAF with MAF cleaner too.


Just in case..this is a picture of my car when it warms up and idles..it doesn't hesitate but it sounds pretty low when sitting in one place

 
#26 ·
You know, it kinda looks like the way mine idles...I've seen my tach needle go there without any hesitation.....

Just watch it closely and get the vacuum hoses checked up anyway. If it remains stable and doesn't go into limp mode, you're good to go. Keep us posted!
 
#27 ·
So after I tried driving it again last weekend it went into limp mode again. I filed complaints about the service center and even went all the way up to Corporate about the car still not being fixed. I had to take it back to Nissan yesterday per Corporates request and apparently nothing is wrong with my car now. It idles around 600-700 but has not dropped into limp mode.

They tested it out the whole day and got no codes. Seriously WTF is going on..now nothing is wrong and I'm looking like an ***..but my parents are calling BS on the condition of my car as well as me..so if it dies on me again I'm going to take it somewhere else. Day 2 and nothing has happened to the car yet but I'm still monitoring it as I drive.

I'm saving up to either pay off this car or trade it off now..heh..Maybe I'll go for a WRX when I save up enough.
 
#28 ·
^^^ Hey, man, I'm gonna go out on a limb and say the throttle circuits on your ECU are on their way out. When she's in limp mode, try stomping the hell out of the gas pedal and see if that wakes her up. If not, try a restart and stomp it again. Do this maybe 3-5 times and see if it shakes the limp mode off.

Long story short, the spec stranded us in vegas throwing the same codes IIRC. Thought it was the TB, so i had a buddy drive us home (to cali) and back for my spare TB. Didn't do it. Out of sheer frustration (driving 8 hrs and still 500miles from home at 3am) I cursed and stomped the living sh*t out of the pedal. Viola, it would wake back up for a few miles, then I'd have to do a rolling restart THE WHOLE WAY HOME. Eventually it got worse and worse, to where I'd have to rolling restart a few times before she'd wake up.

Previously, the day before I had been hauling @$$ from Reno to LV, doing 120ish in 105' temps. I'm thinking that f*cked with the alty, which in turn fried whatever circuits on the ECU that controlled throttle. I changed the TB, MAF, and gas pedal, no dice. It wasn't until I sourced a junkyard ecu (5L non-nats btw) and bam, up and running again.

FWIW, I've been there, it sucks, and I feel your pain.
 
#29 ·
I'm glad I haven't been the only one going through this in a way. This BS all started with the Nissan Tech refusing to replace my ECU and they still have refused to do so. I can only think that it really could be my ECU because I know i don't have a short, or else nothing would work or something would have caught on fire by now. I have a new TB assembly at home and I was thinking about replacing the MAF but the MAF does not look damaged at all nor does the connection.

I just have to figure out what kind of ECU I have if I'm going to do this on my own without Nissan eventhough it's still covered under warranty til my 80,000th mile. I'm gonna keep this thread saved in my bookmarks because you guys have given me some good pointers on where this problem may exist.
 
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