planetpapi
Posts: 9
Joined: Wed Oct 08, 2014 9:00 am
Delivery Date: 21 Jun 2014
Leaf Number: 340768

Re: Sudden loss of acceleration while driving.

Fri Jan 23, 2015 12:40 pm

I just got my LEAF back from dealer nearly 2 weeks later. It appears the "Master Wiring Harness" or "Main Engine Room Harness" was faulty. The codes I have are P2138 and P2127. The dealer admitted they have never seen a LEAF so taken apart before. That includes, say, EVERYTHING. The Front bumper, Side panels, Front seats, Inverter, Electric motor, AC lines, Brake lines, ABS control unit, PDM, Both front tires, Center console, Glove box, Steering control assembly, both A-pillars, Instrument panel, Accelerator pedal and Brake pedal assembly... you name it. The technician spent 25 hours! The total car at Nissan assembly takes 22 hours to build new, I was told.

The part cost was about $1500. The car was hardly 8 months old and this is the second time the problem occurred. I was in touch with Nissan customer support and told them this will be a LEMON if it happens one more time. Basically I now drive it with fear. Austin, TX is a hill country and if I lose power while going up hill, that would be something to talk about. Nissan should recall this vehicle asap.

rogersleaf
Posts: 290
Joined: Sun May 18, 2014 7:50 pm
Delivery Date: 22 Mar 2019
Leaf Number: 307726
Location: Kent, Ohio

Re: Loss of acceleration

Fri Jan 23, 2015 10:33 pm

Wow, I'm hopeful for a less invasive solution.

I experienced a 2nd occurrence about a week ago. Once again had stopped for a traffic light. The car went weak on initial acceleration for roughly 4-5 seconds, there were no alarms or indicator lights, and the problem cleared on it's own. The roads & weather were the same, clear and cold. Leaf Spy is not showing codes that would likely be related. The only other abnormal condition spotted with Leaf Spy was the TPMS sensor positions were not reset after having the tires rotated.

A few days later I stopped at the dealer and discussed the problem with one of their service managers, who discussed it with their LEAF technician. Their hunch (and only a speculative hunch at this time) is this is related to a safety interlock that disables the accelerator when the brakes are applied (brakes in this case can also be regeneration). Basically if the computer thinks the car is braking/regenerating it won't accelerate correctly.

They indicated if I left them the car this could get very invasive and not find the problem. So, I agreed with the service dept to keep the car for now and experiment to see if I can find a trigger. In my case the LEAF is not being driven much now due to the cold weather range so it's not as critical for an immediate fix.

Another speculation I had was the possibility the key fob had lost communication with the car. Thus far, think I can rule out the key fob theory. Was able to start the car and put into gear. Then, hung the fob on a bush next to the driveway and was able to drive around the block without the fob without any problems.
2014 SV - Brilliant Silver - returned 1/2017 at end of lease.
2019 SL - White - w/Tech Package

robot256
Posts: 21
Joined: Wed Nov 13, 2013 2:47 pm
Delivery Date: 02 Mar 2013

Re: Loss of acceleration

Tue Feb 17, 2015 8:53 pm

Hey guys, chiming in here with a third account of this problem!

I took home my 2015 Leaf SV mid-December here in Maryland. Drove it 300 miles without issue, if I recall correctly. Then I went out of town for the holidays. Came back and I occasionally experience loss of acceleration like you guys are saying, except mine has always been restored within seconds of it occurring. It only happens after sitting at a stop sign or stop light for more than 30 seconds. It actually happens in two distinct failure modes:

(1) Move my foot from brake to throttle, and there is no power at all for between 1/4 and 2 seconds, then it is restored. This symptom seems to happen more often when it is below 25 degrees out, and it has been sitting cold for a while. No alarms or lights come on.

(2) Move my foot from brake to throttle, and there is a burst of power, then it drops out and limps along at about 3kw motor power (and also limits regen to this amount, if I lift my foot). After 3-12 seconds, full power returns, but I think the duration is getting longer. I used to think tapping the brake pedal and going back to the throttle reset it, but I'm not sure that helps anymore. Now it stays in "evil turtle" mode across the whole intersection, and I have to put on my flashers so people don't rear-end me. This symptom normally happens after it has been driven for about 20 minutes already, and has happened even at 40 degrees (the hottest it's been here all winter). No alarms or lights come on, but you can see the limited power output on the energy gauge.

I took it to my dealer on January 29 (the #1 Leaf dealer on the East Coast, so they of all people should know what they're doing). They did not see any error codes in the computer, but agreed this sounded like a serious problem. They kept it for a five days, but were not able to duplicate the problem in the ~10 minute test drives they took every morning (trying to get the first symptom after a long cold soak). I came and did a test drive with the service manager (but without the tech in the car) and he saw it happen, so he agreed to keep the car. Two days later, they still had not replicated it with the tech in the car, and told me they couldn't replace any parts under warranty without the data and to come back when it got worse.

They apparently had run it by the Nissan service rep, who had the same hunch--that it was related to the rear brake sensor (???) which would disable the throttle if moisture was trapped in it. This might explain the first symptom but not really the second.

Since then, it has happened 9 times, and happens 3 or 4 times during the course of an entire 80-mile discharge.

I just ordered a Freematics OBD-II Logger in the hopes of capturing all the Car-CAN messages, to see if anything shows up about the throttle position sensor or brake sensors or whatever. Here's hoping something useful shows up. At this rate, though, I should be able to take it to them in a week or two with instructions to drive it for a whole battery and they'll be guaranteed to see it.

Tom AB3LN

planetpapi
Posts: 9
Joined: Wed Oct 08, 2014 9:00 am
Delivery Date: 21 Jun 2014
Leaf Number: 340768

Re: Loss of acceleration

Wed Feb 18, 2015 10:39 am

If it's hard to replicate the problem with Nissan tech, I would invest in a dash cam ( in addition to the logger) that records and loops videos. It would just be another tool to back your story for whatever technical/legal reasons. In the event of rear end driving a faulty car, it (evidence) would come in handy. I bought one from review site wirecutter.com for under $50 I think. Just a suggestion.

rogersleaf
Posts: 290
Joined: Sun May 18, 2014 7:50 pm
Delivery Date: 22 Mar 2019
Leaf Number: 307726
Location: Kent, Ohio

Re: Loss of acceleration

Sat Feb 21, 2015 7:05 am

robot256,
Your failure scenario #1 is identical to my observations, and "evil turtle" did not light any Turtle-mode indicator on the dashboard.

Their theory that it's related to a brake sensor makes perfect sense (actually any sensor or leaky connector causing an intermittent short or open). My own hunch is a harness connector/sensor that is not completely sealed to water (salt brine in my case in NE Ohio) and would expect to find this quicker with a visual inspection (connector full of green fuzz or salt residue). But, in this age of scan tools, most want to scan for a malfunctioning sensor that might not produce any error codes. The service mgr that I discussed my case also hinted they know of similar acceleration quirks on other Nissan vehicles with CVT transmissions.

Please post back if they find a fix.
2014 SV - Brilliant Silver - returned 1/2017 at end of lease.
2019 SL - White - w/Tech Package

robot256
Posts: 21
Joined: Wed Nov 13, 2013 2:47 pm
Delivery Date: 02 Mar 2013

Re: Loss of acceleration

Tue Feb 24, 2015 9:48 am

Here's an update:

I spent some time browsing the troubleshooting forum and noticed that a wide variety of symptoms were associated with low/underperforming 12V batteries. Since that's a really easy thing to test, I hooked up a volt meter to the 12V outlet while driving. On my previous (2013) Leaf, the DC/DC output would go up to 14.6 volts initially, charging the 12V battery, but would normally drop to the 13.1V float setting soon after power-on. I was expecting something similar.

In my new car, however, this never happened. I drove for 15 minutes, with it stuck at 14.6V. Figuring the 12V battery must be low, I left the car parked in Ready mode for 3 hours and it stayed at 14.6V the whole time. Then I hooked up my Battery Minder for 4 hours (hooking the negative cable to the inverter chassis as usual), and when I returned it claimed to have fully charged the battery. Since then, almost a week and 200 miles have passed with no issue. This supports the hypothesis that the throttle glitch is caused by a low 12V battery, though a week of data is not conclusive (previous "good" spells have been almost as long).

But it does not resolve the question, why was the 12V battery low? Was it simply that I left it parked (and probably not plugged in) for two weeks in December, immediately after delivery? Or is there a systemic issue with the battery or the charger? If the throttle problem returns after a week or a month, and goes away after another session with the Battery Minder, then I will have sometime concrete for the mechanic to look at. If it doesn't return, then I guess that's it.

When my Freematics OBD-II logger arrives, I will set it to log the TPS, brake sensors, and 12V bus voltage. Even if it doesn't catch an issue with the throttle, it will make monitoring the 12V bus easier.

User avatar
turbo2ltr
Posts: 1376
Joined: Fri Jul 30, 2010 11:13 pm
Delivery Date: 04 Feb 2011
Leaf Number: 185
Location: Phoenix, AZ

Re: Loss of acceleration

Sun Mar 01, 2015 7:06 am

I've felt something similar but only when I accidentally don't move my foot over enough to the throttle and the brake is not fully released before the throttle is pressed.

As an experiment, stopped, hold the brake with your LEFT foot just light enough to not move, then press the throttle slightly just before releasing the brake. See if the behavior is similar to what you are experiencing.

Have you gotten new shoes lately? :)
Silver SL-e
Ford F450 Crew Cab Hybrid Conversion

rogersleaf
Posts: 290
Joined: Sun May 18, 2014 7:50 pm
Delivery Date: 22 Mar 2019
Leaf Number: 307726
Location: Kent, Ohio

Re: Loss of acceleration

Mon Mar 02, 2015 6:00 pm

turbo2ltr wrote:I've felt something similar but only when I accidentally don't move my foot over enough to the throttle and the brake is not fully released before the throttle is pressed.

As an experiment, stopped, hold the brake with your LEFT foot just light enough to not move, then press the throttle slightly just before releasing the brake. See if the behavior is similar to what you are experiencing.

Have you gotten new shoes lately? :)
This was the first suggestion from my dealer. Safety interlocks built into newer cars prevent 2-foot driving by disabling the accelerator when the brake is applied. The safety works fine on my car (have tested this technique). This is not the same observation. With the interlock activated, my observation was the accelerator is either completely dead or completely alive (no 5 mph limp).

I had my LEAF out on Saturday, it happened again. The recovery time was long enough to pump the accelerator several times before the system starting working correctly. The only thing to add from this incident is that I shifted into B mode while stopped at the light. Once again, the conditions were the same...sunny, cold (15F) & dry, roads were clear, no dashboard indicators of a problem. I had charged the car to 100% in the morning and ran a solid 40 miles of errands prior to the incident.
2014 SV - Brilliant Silver - returned 1/2017 at end of lease.
2019 SL - White - w/Tech Package

rogersleaf
Posts: 290
Joined: Sun May 18, 2014 7:50 pm
Delivery Date: 22 Mar 2019
Leaf Number: 307726
Location: Kent, Ohio

Re: Loss of acceleration

Sun May 03, 2015 3:19 pm

Just an update...Car had it's annual battery check along with some other basic maintenance. The belief is the loss of acceleration was related to the ABS control, which is also related to grabby brakes. They tested & changed out the ABS module as defective and updated software. Time will tell if this fixed it for good.
2014 SV - Brilliant Silver - returned 1/2017 at end of lease.
2019 SL - White - w/Tech Package

Leafy42
Posts: 1
Joined: Sun Jan 24, 2016 10:23 pm
Delivery Date: 09 Jan 2015
Leaf Number: 314674

Re: Loss of acceleration

Sun Jan 24, 2016 10:29 pm

This happened to me last Thursday (1/21/16). Entering freeway, got up to 40 mph, then no acceleration. Very scary. No accident. Thank God. Pulled over and restarted car then worked fine (so far). 2015 Leaf.

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