Engine Jerks When Letting off Accelerator

Tiny
CLOROX.BLEACH
  • MEMBER
  • 2002 NISSAN ALTIMA
  • 195,000 MILES
I am having quite a few problems with my Altima. I think I will start from the beginning. The problems starting happening when the car was hard to start. It wouldn't crank unless you was pumping the gas pedal. The SES light was on. At that time, it was pulling the codes for the crankshaft positioning sensor, O2 Sensors, engine too lean, and speed sensors. I had all of them replaced. A few days later my SES light came back on. Around this same time, I begin getting a******** sensation when I'm driving and let off the gas pedal. I took the car to AutoZone and they scanned the codes again and now its pulling the codes P1574 Speed Sensor, P0128 Temp Sensor, and P0171 Engine to lean bank 1. I would like to know hwat could be causing the******** sensation that I am having, and what are the conquences of driving a car that has a lean running engine. Also, I forgot to mention, when I press the gas while the car is idling, it feels like something other than smoke is being pushed out the tailpipe. When I look behind the car, there is a black liquid coming out of the tailpipe. It is cold these days so I dont run the AC so im sure it cant be water. PLease help me with this issue. Thanks.
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Monday, November 7th, 2011 AT 3:45 AM

13 Replies

Tiny
ASEMASTER6371
  • EXPERT
First of all, what are the odds that all those sensors failed at the same time? Nill. Codes never identify bad parts, just failed systems.

The crank sensor is a common failure and there is a tsb on it from nissan. There is an updated flash as well for this issue which would solve most of your problems.
The 171 code is not an o2 sensor, it most likely is a vacuum leak somewhere and can be verified by a smoke test on the intake system.

I would have a shop check this for you as throwing parts at it has not fixed your car. The repairs will probably be narrowed around 1 system.

Roy
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Monday, November 7th, 2011 AT 4:02 AM
Tiny
CLOROX.BLEACH
  • MEMBER
Ok thanks. But what could result in driving the car while it stating that it is in a lean running situation? The shop and everything that I need to fix the problem, as well as the Nissan dealership, is in the next city over about a good 35 miles away. I don't want to put further harm on the engine if any from driving it lean.
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Monday, November 7th, 2011 AT 4:07 AM
Tiny
KHLOW2008
  • EXPERT
After replacement of the sensors, were the trouble codes erased?

Lean running conditions for one bank cna mean a skipped cam timing or clogged fuel rail, vacuum lekages and many more.

Clear the codes and run engine before rechecking the codes again and see which comes up first.
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Monday, November 7th, 2011 AT 7:39 AM
Tiny
CLOROX.BLEACH
  • MEMBER
I have erased the trouble codes several times after the sensor replacement. But when I turn my car on and let it idle, the SES light comes back on giving me the codes for a speed sensor (which was replaced) and a temp sensor ( this code is new). Then after a few hours of driving the car, the engine too lean bank 1 code shows up again.
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Monday, November 7th, 2011 AT 1:25 PM
Tiny
KHLOW2008
  • EXPERT
What were the EXACT trouble codes retrieved?

Have a compression test performed to see if they are within specs.
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Monday, November 7th, 2011 AT 4:53 PM
Tiny
CLOROX.BLEACH
  • MEMBER
P1574, P0128, P0171 are the trouble codes. Also, just starting today, when the car was idling, the rpms got down to about 500 then eventually acted like it wanted to shut off, but didnt. When I shifted to reverse with my foot on the brake, the rpms got even lower to about 250ish and the engine started knocking but didn't cut off, but the car drives normal except for the******** I get when I let off the gas pedal.
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Monday, November 7th, 2011 AT 5:01 PM
Tiny
KHLOW2008
  • EXPERT
Let start with the P1574 and P0128 since they are the ones that came on first.

DTC P1574: ASCD VEHICLE SPEED SENSOR

Description

ECM receives vehicle speed signals via 2 different lines, and detects vehicle speed for ASCD control. Vehicle speed signals are input from instrument cluster and Transmission Control Module (TCM) separately. Signal from TCM is via CAN communication line.

Possible Causes

Malfunction is detected when ECM detects a difference in values between the 2 vehicle speed signals. Possible causes are:

CAN communication line open or shorted.

Instrument cluster circuit open or shorted.

Defective instrument cluster.

Defective vehicle speed sensor.

Defective TCM.

Defective ECM.

DTC Confirmation Test

Start engine. Ensure TCS is turned off. Select DATA MONITOR mode with scan tool. Drive vehicle at more than 25 MPH. If 1st trip DTC is detected, go to DIAGNOSTIC PROCEDURE. If 1st trip DTC is not detected, system is okay at this time.

Diagnostic Procedure

1. Check for A/T system DTCs. If problem is found, diagnose A/T system. If problem is not found, go to next step.

2. Check VSS, VSS circuit and instrument cluster. Repair as necessary.

DTC P0128: THERMOSTAT FUNCTION

Possible Causes

Malfunction is detected when engine coolant temperature has not risen enough to open thermostat even though engine has run long enough. Possible causes are:

Thermostat stuck open.

Leakage from sealing portion of thermostat.

Defective ECT sensor.

DTC Confirmation Test

1. Replace thermostat with an OEM replacement. Turn ignition on. Select COOLAN TEMP/S in DATA MONITOR mode with scan tool. If COOLAN
TEMP/S is less than 140 F (60 C), go to next step. If COOLAN TEMP/S is not less than 140 F (60 C), allow engine to cool.

2. Drive vehicle at a speed of 50-75 MPH for 10 consecutive minutes. If 1st trip DTC is detected, go to DIAGNOSTIC PROCEDURE. If 1st trip DTC is not detected, system is okay at this time.

Diagnostic Procedure

Remove ECT sensor, and place in heated water. Measure resistance between sensor terminals, with water at specified temperatures.
See ENGINE COOLANT TEMPERATURE SENSOR RESISTANCE table. If resistance is as specified, test is omplete.
If resistance is not as specified, replace ECT sensor.
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Monday, November 7th, 2011 AT 5:17 PM
Tiny
CLOROX.BLEACH
  • MEMBER
I just had the speed sensor replaced a week ago. The thermostat code is a new one though. The main thing I am concerned about is all the problems and symptoms that my car is experiencing and the lean running condition it is in. I'm pretty sure a speed sensor nor a thermostat would make my car behave in such a way.
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Monday, November 7th, 2011 AT 8:10 PM
Tiny
KHLOW2008
  • EXPERT
Please take not that the speed sensor code does not necessarily mean a bad speed sensor. It could be the wirings and other components as stated in the diagnostic information.

The ECT can cause lean running conditions if it is telling the engine conflicting information as compared with others.

Lean running running conditions can be due to vacuum leakages, slipped cam-timng etc. Have you checked those yet?
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Tuesday, November 8th, 2011 AT 2:12 PM
Tiny
CLOROX.BLEACH
  • MEMBER
I haven't been able to have them checked at this moment for other reasons, but I really need to use my car so I need to know what problems could occur when driving my car when it's running lean. I was told by two technicians that it wouldn't affect anything major, but I have read online that driving lean will melt the internal engine components. I don't know which to go buy. What's your opinion on that?
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Tuesday, November 8th, 2011 AT 2:51 PM
Tiny
KHLOW2008
  • EXPERT
When the CEL comes on, the lean running condition would be compensated by the ECM so there is actually no real harm to the engine.
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Tuesday, November 8th, 2011 AT 3:32 PM
Tiny
CLOROX.BLEACH
  • MEMBER
Even with all the******** and rough idling its doing? It drive's fine, just that it idling rough and the******** I get when I let of the gas pedal.
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Tuesday, November 8th, 2011 AT 3:36 PM
Tiny
KHLOW2008
  • EXPERT
If you haqve not cleaned the throttle body and IAC, get them cleaned and retest. Sometime poor idling would cause a lean condition.
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Tuesday, November 8th, 2011 AT 3:53 PM

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