01 Altima RPMs fluctuate when slowing w/ clutch depressed

DARNDT21A

MEMBER
2001 ALL OTHER MAKES ALL OTHER MODELS

When slowing, only with the clutch depressed, the RPM on my Altima fluctuates between 1300 and 1900 RPMs until I come to a complete stop when ithe RPMs drop to a constant 1000 RPM. I hooked my EZLINK Scanner to it and got the following in monitor mode:

Test 02 Fuel System 1
Toggles back and forth between closed loop and open loop
Test 10 Ignition Timing
Above 20 mph toggles back and forth between -4 deg and +20 deg
Test 12 Air Flow Rate
Air flow rate fluctuates from.67 to.91
Test 13 Throttle Position
Throttle position stays at 0%
Test 14 Oxygen Sensor 1
Fluctuates from.010 to.050
Test 16 Oxygen Sensor 2
Fluctuates from.010 to.040
Note that the throttle position stays at 0% which is consistent with visual and throttle blade does not move.
It did have a trouble code of P0304, #4 Cylinder Misfire and I replaced the plugs and wires. The code has come back so I will replace the rotor cap next. I wouldn't think this problem is related. The RPM fluctuation started a month ago and the Service Engine Light came on the first time just 2 days ago.

Does anyone have any hints of what to look for?
Thanks, Dan

4 Replies

DARNDT21A

MEMBER
4 POSTS

1) Nissan Altima, 2001, 135K miles, 2.4L engine
2) Replacing the distributor cap and rotor eliminated the problem of the P0304 code.
3) The problem with the idle fluctuating from 1300 to 1900 RPM every few seconds doesn't seem to occur when the car is first started and the choke/fast idle is engaged.
4) I made a donation as suggested.

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Sunday, February 4th, 2007 AT 1:10 PM

RASMATAZ

MECHANIC
75,992 POSTS

Your O2 sensor shold be flip flopping at.45-.65

Look at the STFT and LTFT trimmings where they at.

You have a lean mixture-try a vacuum leak, EGR stuck open, low fuel pressure=clogged injector, pressure regulator&pump.

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Sunday, February 4th, 2007 AT 3:24 PM

DARNDT21A

MEMBER
4 POSTS

Using my friends scanner I've been able to eliminate the oxygen sensor as the cause of the RPM fluctuation. It also allows me to turn off the injectors. When I turned off the #1 injector it ran rough and the RPMs still fluctuated between 1300-1900. When I turned off the #4 injector it ran rough and the RPMs stopped fluctuating.
Do you think the injector is bad/leaking or do you think it might be something else causing the injector to misbehave?
Thanks in advance for the assist. Dan

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Monday, February 19th, 2007 AT 5:01 PM

DARNDT21A