Hi,
I have a 2002 Pathfinder SE with around 40K. When its in drive (or Rev) the veh skips every 5 or 6 sec; Like I'm missing a firing on a Cyl. This only happend when the truck in in drive (any gear) or rev and at a standstill.
I took it to the Dealer (thinking it was a tranny problem) and they said that it was a MAF sensor problem ($800!!!). Well, I won't let them rip me off because, the MAF, while $$, it pretty easy to do myself.
My ? is, has anyone seen this problem?? and did a MAF fix it???
My thinking is that if I has a bad/Faulty MAF the skipping would happen all the time.... and not JUST while the truck is in drive.
check your connector to the MAF 1st. are you getting a CEL/SES at all? you can go to Autozone and they can read codes for you which will lead you in the right direction. you might want to look and see if that is covered under emissions warranty. that way its free. with low mileage like that call Nissan Customer Service (if its not covered) they may allow it. it never hurts to ask.
__________________
Dave
96 4WD XE Reg. Cab ka24e
Calmini 3" SL, Steering, Lock-rite rear, LSD front
I pulled the connector off of the sensor and there was no corrosion, it that is what you are thinking.
<are you getting a CEL/SES at all> I'm assuming you mean error codes. No, the ECU is not displaying any error code (check engine light is off). The dealer said that they did a rolling test (??) and the error only showed up then. Which doesn't jive with what I'm seeing (the "bad idle" happens every 5 to 10 sec while in a gear and at a standstill).
I have the "magic" sequence that turns on the OBDII diags (blinks the engine light w/ the error code). I'll try that and see if it spits out any code.
I dread calling Nissan CS. the muffler rotted out at about 35K and they wouldn't cover that.. after several hrs on the phone in the span of a few weeks.. But you are right it doesn't hurt to ask---well it hurts a little ...
do you think a bad---or going bad ...MAF sensor would display this kind of behavior??
I'm not sure if that is your problem or not, I was going off what I thought off. I would think the MAF would set a code though, I think you said it happens while idling, try disconnecting it and see if it changes, my initial thought without going to the dealer would have been the TPS or IAC. and yes the CEL/SES (check engine light/service engine soon) for codes. I would still take it to Autozone because the ECM can store codes (unless the dealer cleared them out). but if you start disconnecting sensor one at a time (I've heard some people do this) if the CEL comes on the sensor is good. I don't know if you disconnect the start engine the shut off and reconnect or do it all while the engine is running. I don't know how wise that is to do but some sensors allow this I guess. if you have a sequence to clear the codes each time it may be worth a try.
__________________
Dave
96 4WD XE Reg. Cab ka24e
Calmini 3" SL, Steering, Lock-rite rear, LSD front
that's a good idea...I'll try to disconnect the MAFS and see if the problem doen't get any worse. If it doesn't than that will tell me that the sensor is cooked. The only weird thing is that the engine runs rough only when the truck is in a gear. If it is a sensor then maybe the change in something (vacuum???) is causing the sensor to feed poor data to the ECU, making the engine misfire...
that's my WAG...
If there is a error code in the ECU, then turning on the OBII diags; the check engine light should blink out the code.
I found a way ( on the web) to do this... I'll post it later. But you do something like: turn on and off the key 3 times at the third time push the gas petal down 5 times and on the 5th time the check engine light will blink out an error code.
If the MAF code is still in the ECU it should show up....
you can do a search on here for a thread about codes and OBDII. Yes, if codes are in the ECU they will show up. the vacuum is a possible add-on to the problem, it certainly would hurt it to check them out.
__________________
Dave
96 4WD XE Reg. Cab ka24e
Calmini 3" SL, Steering, Lock-rite rear, LSD front
Since you didn't have a CEL, I'd be surprised if it was the MAF. Also, your symptom doesn't sound like a MAF, more like a bad spark plug or wire. If you just did a tune-up, make certain you got the plug wires in the correct order; switching two wires can produce the symptoms you described. Maybe a weak coil, but again the ECU should detect that and light the CEL.
__________________
Life is too short to take it too seriously
I haven't done a tune-up. The fact that in Park the engine runs smoothly would tell me that it's something else.
This weekend I'll go down the road of looking for codes in the ECU disconnecting the MAFS to see what happens.
Thanks for the replys to my post!!! I'll send out an update this weekend......
Regarding the Mass Air Flow Sensor, yes they are fery expensive. I had one go out on a different make auto. $500 or so new from the dealer. $74 at a wrecking yard! It was a very easy part to replace. Also, at 40Kmiles, is there any warranty still available?
Here's the post for turning on OBDII diage Nissan calles it Diagnostic Test Mode
Without Scan Tool
On Board Diagnostic System Function
The on board diagnostic system has the two functions.
MIL Flashing without DTC
If the ECM is in Diagnostic Test Mode II MIL may flash when engine is running. In this case check ECM diagnostic test mode. How to Switch Diagnostic Test Mode.
How to switch the diagnostic test (function) modes and details of the above functions are described later. How to Switch Diagnostic Test Mode.
The following emission-related diagnostic information is cleared when the ECM memory is erased.
1. Diagnostic trouble codes
2. 1st trip diagnostic trouble codes
3. Freeze frame data
4. 1st trip freeze frame data
5. System readiness test (SRT) codes
6. Test values
7. Others
How to Switch Diagnostic Test Mode
NOTE:
* It is better to count the time accurately with a clock.
* It is impossible to switch the diagnostic mode when an accelerator pedal position sensor circuit has a malfunction.
* Always ECM returns to Diagnostic Test Mode I after ignition switch is turned "OFF".
How to Set Diagnostic Test Mode II (Self-diagnostic Results)
1. Confirm that accelerator pedal is fully released turn ignition switch "ON" and wait 3 seconds .
2. Repeat the following procedure quickly five times within 5 seconds .
1. Fully depress the accelerator pedal.
2. Fully release the accelerator pedal.
3. Wait 7 seconds fully depress the accelerator pedal and keep it for approx. 10 seconds until the MIL starts blinking.
4. Fully release the accelerator pedal. ECM has entered to Diagnostic Test Mode II (Self-diagnostic results).
How to Set Diagnostic Test Mode II (Heated Oxygen Sensor 1 Monitor)
1. Set the ECM in Diagnostic Test Mode II (Self-diagnostic results). Refer to How to Set Diagnostic Test Mode II (Self-diagnostic Results).
2. Start Engine. ECM has entered to Diagnostic Test Mode II (Heated oxygen sensor 1 monitor). ECM will start heated oxygen sensor 1 monitoring from the bank 1 sensor.
How to Set Diagnostic Switch Monitored Sensor from Bank 1 to Bank 2 or Vice versa
1. Fully depress the accelerator pedal quickly and then release it immediately.
2. Make sure that monitoring sensor has changed by MIL blinking as follows.
How to Erase Diagnostic Test Mode II (Self-diagnostic Results)
1. Set ECM in Diagnostic Test Mode II (Self-diagnostic results). Refer to How to Set Diagnostic Test Mode II (Self-diagnostic Results).
2. Fully depress the accelerator pedal and keep it for more than 10 seconds . The emission-related diagnostic information has been erased from the backup memory in the ECM.
3. Fully release the accelerator pedal and confirm the DTC 0000 is displayed.
Diagnostic Test Mode I - Bulb Check
In this mode the MIL on the instrument panel should stay ON. If it remains OFF check the bulb. Refer to "WARNING LAMPS".
Diagnostic Test Mode I - Malfunction Warning
Diagnostic Test Mode II - Self-Diagnostic Results
In this mode the DTC and 1st trip DTC are indicated by the number of blinks of the MIL as shown above. The DTC and 1st trip DTC are displayed at the same time. If the MIL does not illuminate in diagnostic test mode I (Malfunction warning) all displayed items are 1st trip DTCs. If only one code is displayed when the MIL illuminates in diagnostic test mode II (SELF-DIAGNOSTIC RESULTS) it is a DTC; if two or more codes are displayed they may be either DTCs or 1st trip DTCs. DTC No. is same as that of 1st trip DTC. These unidentified codes can be identified by using the CONSULT-II or GST A DTC will be used as an example for how to read a code.
A particular trouble code can be identified by the number of four-digit numeral flashes. The "zero" is indicated by the number of ten flashes. The length of time the 1,000th-digit numeral flashes on and off is 1.2 seconds consisting of an ON (0.6 - second) - OFF (0.6 - second) cycle.
The 100th-digit numeral and lower digit numerals consist of a 0.3 - second ON and 0.3 - second OFF cycle. A change from one digit numeral to another occurs at an interval of 1.0 - second OFF. In other words, the later numeral appears on the display 1.3 seconds after the former numeral has disappeared.
A change from one trouble code to another occurs at an interval of 1.8 - second OFF.
In this way, all the detected malfunctions are classified by their DTC numbers. The DTC "0000" refers to no malfunction. (See "TROUBLE DIAGNOSIS - INDEX".)
Diagnostic Test Mode II - Heated Oxygen Sensor 1 Monitor
In this mode, the MIL displays the condition of the fuel mixture (lean or rich) which is monitored by the heated oxygen sensor 1.
To check the heated oxygen sensor 1 function, start engine in the Diagnostic Test Mode II and warm it up until engine coolant temperature indicator points to the middle of the gauge.
Next run engine at about 2,000 rpm for about 2 minutes under no-load conditions. Then make sure that the MIL comes ON more than 5 times within 10 seconds with engine running at 2,000 rpm under no-load.
... 
Linear Mode
