Vehicle doesn't accelerate. Low on power

Tiny
SERRANASJ
  • MEMBER
  • 2004 INFINITI G35
  • 3.5L
  • 6 CYL
  • RWD
  • AUTOMATIC
  • 81,000 MILES
My Infiniti is having an accelerating issue that I cant find out what the issue is. About a month ago I notice that when I started the car when it was cold it would start fine but the RPM would only go up to 700 when its suppose to go up to about 1300 and when it warmed up it would stay at around 600 but if you shut it off and then started back up it would not stay running unless you hit the gas a little and then let go of it slowly, it would stay running. A few days ago go I notice that you would step on the gas pedal and it would not accelerate the way it should. I figure that the issue was the throttle body, I replace it and know it starts up fine all the time at its normal RPM but it still has the problem of not accelerating. In park I floor the accelerator and the rpms go up slowly like the throttle body is not opening fast like it should when you drive it takes time to accelerate and it changes gears at 2500-3000 rpm with the accelerator pedal to the floor. There is no misfire or lack of power other then the throttle body not opening. I also replaced the sensor on the gas pedal. There is times when I do start it and it revs up great like it should you put it in gear and it responses like it should with just a small tap to the accelerator. But just after a few second its goes back doing the same thing. My VDC and slip lights are solid but they have been before this issue. I have also tried to reprogram and reset the throttle but it seems that I cant get it to work. Please help me with this issue
Wednesday, July 16th, 2014 AT 8:26 PM

21 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
There are no trouble codes associated with this issue? To be honest, the stability control system can cause the engine to power down because it feels a tire is spinning, a brake is locked. However, and this may sound crazy, but I have seen the steering angle sensor cause this issue. Has that been checked? One last thought, low brake fluid can cause these lights to come on too. Have you checked that?
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Wednesday, July 16th, 2014 AT 8:44 PM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
The two codes that come up are p2136 and p2128. The brake fluid is fine. These lights are on all the time is not when I drive the car. I can leave the car siting for a few minutes and then start it back up. It will rev perfectly but after a few revs it just kind of locks itself and does not want to rev like it should, instead it does it very slowly with the pedal floored. This is performed in park position.
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Thursday, July 17th, 2014 AT 2:25 PM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
P2138
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Thursday, July 17th, 2014 AT 6:34 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Are you sure it isn't a P2138? I have nothing for a 2038. From what I know and from what I have read via manuals, the AAP sensor, which you said was replaced, is where the problem is coming from. The switch may not be bad, but there is either an open in the wiring or a bad connection. When this code is set, the ECM regulates the speed of the opening of the throttle. That is why it is so slow to respond. It's doing what it is designed to do. The engine is in a fail safe mode. As a result, acceleration is slow.

The APP that you replaced is actually 2 sensors. What I need you to do is start by checking the connection on the APP to make sure nothing is damaged or out of place.

If all looks good, start with sensor one. Unplug the connector at the APP and check voltage between terminal 6 and ground. (Do not use the ECM ground). Voltage should be around 5v.

If that is not good, check wiring harness for shorts or open circuits between ECM and APP.

If good, check sensor 2 the same way but via terminal 4. Voltage should also be around 5v.

NOTE: Before disconnecting the APP, turn the key off. Once disconnected, turn the key to run position with engine off to make checks.

Let me know what you find so I know which direction to go next. Also, there is a body ground on the upper part of the steering column. Make sure it is good.
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Thursday, July 17th, 2014 AT 6:48 PM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
I just checked for the plugs and wires and they seem fine. I also checked the voltage. In the TB Im getting 3.37V in one and 5.4 on the other. One in the top line of plug and one in the bottom. High voltage is at the top line.(Where the remove push clip is). I also checked the voltage at the pedal sensor and Im getting 5.3V. Let me know if you need me to specify a little more and thanks for your help.
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Friday, July 18th, 2014 AT 10:14 AM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
I also did notice that for some strange reason when I plug the OBD2 Scanner with the ignition ON the fans will kick in at high speed and the SES light goes out when the scanner is still reading. If the motor is running the RPM gauge will drop to zero and the the fans will also kick in at high speed. The fans wont stop until I unplug the obd2 and turn the ignition to the off position. I believe this is not normal but might be related to the issue Im having in someway.
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Friday, July 18th, 2014 AT 10:34 AM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
I also have notice that when I start the car it revs fine a few times but after after a few tries it jut wont rev. When that happens if I try to floor the gas pedal and then tap the brake its like it just cuts it out and wont accelerate even though is doing very slowly and only up to like 2500 RPM the brake cuts out the acceleration.
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Friday, July 18th, 2014 AT 1:14 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,114 POSTS
Next, I need you to check two grounds. See attached image.
Image (Click to make bigger)
Thumb
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Saturday, July 19th, 2014 AT 5:44 PM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
They are both fine
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Wednesday, July 23rd, 2014 AT 5:31 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Next we need to check the harness for a short to power or a short to ground between the following terminals:

ECM terminal 91 and APP sensor terminal 4

ECM terminal 47 and electronic throttle control actuator terminal #1

If these check out, the next thing that needs checked is the TPS.

To do this, reconnect all wiring. Turn the key on and place the trans selector in D. Check voltage between the ECM terminals 50 and 69 (TP sensor 1 and 2) and ground. You should see the following readings:

Terminal 50 = Throttle fully released should be more than 0.36v
Throttle fully depressed should be less than 4.75v

Terminal 69 = Throttle fully released should be less than 4.75v
Throttle fully depressed should be more than 0.36v

If this doesn't work, try the relearn for the TP sensor, Do the following and then retry.

Make sure the throttle is fully released.
Turn the key on and then off and wait at least 10 seconds.

NOTE: Make sure the throttle valve moves during this 10 seconds by listening and confirming an operating sound.

Let me know what you find. There are still many more checks to go through. The ones we still need to cover will be based on what you find with these. I have attached a schematic of the APP wiring system to help guide you.
Image (Click to make bigger)
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Wednesday, July 23rd, 2014 AT 7:17 PM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
I replaced my ecu because I notice that one of the chips inside was fried up. That was the reason why my fans where kinking on, every time I connected the OBD2 reader. There was a good possibility that my accelerating issue was also a bad ECU. I bought one installed it and reprogram it. But still same accelerating issue. The problem with the fans kinking on every time I connected the OBD2 and rmp gauge dropping completely got fixed. I just want to know what made the ecu get fried like it did. I believe that it must be more like a specific part thats causing this issue not a bad wire because I've check every wiring and they are all fine. I have the interior completely striped out and. If you have any thoughts what could it be to go after let me know. Also another issue thats been persisting lately is brakes are looking up completely all 4. Not allowing me to move the car. Replaced brake master cylinder and abs pump but still the same. They get replaced when I loose up the brake lines in the master cylinder. Im getting extremely frustrated with this vehicle and I need help.
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Friday, August 15th, 2014 AT 10:57 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi:

As far as the burnt up component, anything could have caused that. There could have been an internal short in the unit itself.

The brakes are a new issue. Have you done anything with the calipers recently? You have a new master cylinder, correct? And if I understand, the brakes release when you open the brake hose at the MC?
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Friday, August 15th, 2014 AT 7:46 PM
Tiny
SERRANASJ
  • MEMBER
  • 9 POSTS
I have not touched the calipers and yes when I loose booth of the brake hose in the MC they release you can hear them and fluid releases with pressure. I would like to solve the issue with the acceleration first and then move on to the brakes. This issue just happened out of no where. I thought maybe the abs pump which also consist of the vdc could have been bad and locking up the brakes causing the it to go in a limp mode. But still nothing.
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Saturday, August 16th, 2014 AT 10:53 AM
Tiny
DATA11ROB
  • MEMBER
  • 3 POSTS
Hi did any one fix the acceleration problem having the same issue change the ecm the throttle body and the accelerator pedal with the sensors and still do not want to accelerate
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Friday, February 8th, 2019 AT 7:46 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,627 POSTS
Hello,

Let pick this back up to see what's going on to me it sounds like you have a clogged catalytic converter lets confirm the issue by following this guide.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

This guide can help as well

https://www.2carpros.com/articles/engine-has-low-power-output

Please run down these guides and report back.

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Monday, February 11th, 2019 AT 10:29 AM
Tiny
DATA11ROB
  • MEMBER
  • 3 POSTS
The problem is more like the car goes into limp mode when you just start it it accelerate good one time then after that it wont accelerate fast. The car this chat had the same symptoms but it seems that no one posted the solution to the problem
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Tuesday, February 12th, 2019 AT 6:22 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 51,627 POSTS
Lets run the codes to see what comes up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run down this guide and report back.
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Thursday, February 28th, 2019 AT 12:09 PM
Tiny
DATA11ROB
  • MEMBER
  • 3 POSTS
Hi jen, thanks for your help we found the problem it was the app after all after checking every system on the car and replacing computer and intelligent power supplie which it was rusted the aftermarket app was not giving the right signal we change the pedal 3 time and then decided to use the infinity pedal $160 and it worked perfectly car has a separate issue with the abs and trac control
Do not use after market app sensor
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Sunday, March 3rd, 2019 AT 5:08 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Welcome back:

I'm glad you got it taken care of. We purchase aftermarket parts thinking they are designed to work properly and this is the result.

Take care,
Joe
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Sunday, March 3rd, 2019 AT 6:44 PM
Tiny
DATA11ROB
  • MEMBER
  • 3 POSTS
Thanks Joe.
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Monday, March 4th, 2019 AT 5:14 AM

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