My Qx4 Wont Follow Simple Diagnostics.

[CanuckQx4]

Im freaking stumped with this car!! I am having trouble following the seemingly simplest diagnostics and procedures from the FSM for this thing.

First heres the problem. If I were to start it, sometimes it will crank for an extra second or two and then kick over, sometimes it goes right away but not usually. BUT it will ALWAYS/EVERYTIME stall out instantly if you dont give it a little gas for 2-3 seconds to keep the rpms up. Then I can let off the gas and it will idle on its own, but LOW. 500-600rpm at best.

Runs perfect on the open road, only problem is startup.

I figure it all started once I messed around with cleaning the MAF, adding a cold air intake, changing spark plugs and trying some "diagnostics"

Right now Im starting on the simple procedures. I was trying to do all 3 of the procedures in this helpful thread.
how-to-ecu-relearning-procedures-t445702.html

ACCELERATOR PEDAL RELEASED POSITION LEARNING
THROTTLE VALVE CLOSED POSITION LEARNING
IDLE AIR VOLUME LEARNING

I dont think any of the three are taking. Theres no indicator for the released pedal position test, on the throttle valve position test I dont hear ANYTHING in my engine when the car turns off, what are you supposed to be listening to?? Is the throttle valve another name for throttle body?? And the Idle Air Volume test definitely isnt working, I dont even know if Im doing the correct test for my year ( 2001.5 ) but I have been trying to do the one in the link, and my CEL never starts blinking, and my idle doesnt change. So it isnt working

So what do you guys think I should try??

Ive seen another version of the idle air volume test, which just involves key on and off a few times and disconnecting the brown plug on the throttle body, but that one didnt work either, my car stalled out when I reconnected the plug. Ive got 3 manuals and dont even know if Im using the right one.

I wouldnt mind some clarification on this either, when it says key "OFF" do they mean just clicked all the way back counterclockwise? Completely out of ignition? One click back from "ON" position? Was a little unclear on that.

I'll leave it at that for now, this is getting long!! Hope I can get some much needed help getting this biatch to start like it should!!

Thanks guys!!

[Towncivilian]

All of the learn procedures in that thread are applicable to 2003-2004 R50s only. I think our 2001 R50s only need idle air volume relearn, and for that you should follow the FSM's procedure. Key "off" should be all the way counterclockwise, in the "lock" position I'd assume. See page EC-58.

Does priming the fuel pump several times by flipping the key to ON then OFF before cranking help your startup issue? Also see if cleaning your battery terminals & connectors help any.

[CanuckQx4]

I only have a 2001 qx4 manual, and 2003. I dont see 2001.5 But why would the test not take for me??

I do prime the pump everytime usually before starting it, doesnt seem to help, but Ive never done it more then once before turning it over.

I did replace the battery with a new optima 2 months ago, terminals clean and tight, voltage is 12.8

Im more worried Im not doing the right tests.

All I wanna hear when I turn the key is the darn car jump to 1500 rpm like it should, not 400 then stall lol

[Towncivilian]

2001.5's idle air relearn procedure is identical. I dunno if the 01.5 QX4 had its own FSM, but the Pathfinder 01.5 surely does.

Fuel filter recently changed? And do try priming the pump several times and let us know if it helps.

[CanuckQx4]

Ya Im confused why the test isnt taking myself.

Do you have any knowledge on the throttle valve location and test?? It doesnt mention in the idle relearn procedure that if the throttle valve isnt working the idle relearn wont take. And I defintetely dont hear anything when I do the throttle valve test....

Fuel filter was changed 2 weeks ago when I started caring about this problem when I started seeing a new girl who is a bit of a priss haha

I'll try the priming in multiples on my way to work, lunch and back tomorrow and see what happens

[Towncivilian]

I dunno, never had to do any of these tests yet. I'm unsure of any of the specifics.

This is kind of a shot in the dark but maybe leave your negative battery terminal disconnected for a while to reset the ECU? Maybe try cleaning the throttle body too (make sure to use throttle body cleaner and nothing else).

[Pathy415]

I dunno, never had to do any of these tests yet. I'm unsure of any of the specifics.

This is kind of a shot in the dark but maybe leave your negative battery terminal disconnected for a while to reset the ECU? Maybe try cleaning the throttle body too (make sure to use throttle body cleaner and nothing else).

I was just going to mention this, but yeah, try cleaning the throttle body

[CanuckQx4]

The throttle body is squueky clean.

All I really want to know is how to perform these 3 tests I was trying in the first post.

I think the idle air relearn test is the key to getting it to idle, but I need to figure out the throttle valve test first

[ARKQX33V6]

Canuck, does your model year book mention start procedure that includes a throttle input of 1/3 way down or does your vehicle before this event always start with no input of the throttle?

If your throttle input is squeaky clean it is possible that the throttle plate is in the closed position. Your action in giving it throttle causes the throttle plate to open. Check your at off, throttle plate for a slight open state, you may need to adjust it. Or get used to putting your foot into the gas pedal.

I read that you battery voltage is at 12.8 VDC. That is very close to minimum of 12.6 VDC. These cars never see float voltage because the ECU, radio and alarm systems have a current draw. You should have a battery charger on hand, if automatic at 2 A trickle the battery should charge for some time and raise the voltage closer to 13.

A full charge will go as high as 15 V, but letting it sit and de-stratify the voltage will settle near 13 V, then drive as usual and when you park, test the battery voltage, closer to 13 would be better, 12.8-13.1.

The battery terminals, the ground cable the + cable need to be shiny clean, no crud, no oxidation and a float charge especially in the Summer heat.

If you try these things let us know. By the way 8-10 year battery life should be expected if well maintained.

[CanuckQx4]

The car used to start with no throttle input, would jump up to 1500rpm and work its way down in a few seconds to 750.

The throttle body is fully closed when my foot is off the gas definetely, isnt it supposed to be??

Im pretty sure 12.8 is damn good battery voltage, Ive seen cars rest in the 11's. Im no expert I guess, but it seems on the high end of most resting voltages, and my car runs 14.5 while running

Im VERY interested in succuessfully performing the idle relearn test and getting some info on the throttle "valve" and what it is and why I cant hear it when I preform that test....

[CanuckQx4]

made it to page 2 pretty quick bump!!

[CanuckQx4]

[ARKQX33V6]

Canuck
voltage is on the threshold, would like to see 13 v. Try charging the battery and float charging to top it off. Throttle position at on, idle at temp depends on what Nissan has in that model...either a slight open throttle or the use of an Idle Air controller. Any way you look at it the air must be there.

Go thru your exact model book and read the cold start procedure and look for what takes place, also look into the idle screw setting if the car has one.

From the history of cold starts you have a similar system to the 1997 QX4 but I do not know your car specifics.

Have you tried resetting the ECU, then doing a cold start, let it idle with no input from you.

[CanuckQx4]

Wish I could find a FSM for a 2001.5 Qx4

I may reset the ECU today and see what happens

[asnorton44]

Wish I could find a FSM for a 2001.5 Qx4

I may reset the ECU today and see what happens

Try this link:
http://x.infinitihelp.com/forum/local_l ... &catid=288

[CanuckQx4]

I signed up for that forum but it has a little lock picture on that download I think, says access denied

Id really love to get the right manual downloaded so I can do some reading, appreciate the link hope we can get it to work!!!