2001 Qx4 - Codes P0140,P1441,P0160,P1491

[flipdog0]

went down there and was going to attempt to drive the car around the block, but as i said the car wasnt holding an idle, I was able to push the gas and brake and flip the car into drive, but the RPMs were reving up into the 3's and I wasnt getting any movement both in drive and in reverse. any insight?

[Towncivilian]

Uhhhh... I really think you should be getting different codes if the engine can't hold idle. If the transmission isn't engaging gears either, there might be electrical problems or your PNP switch is failing. How does your transmission fluid look? It should be reddish, not brown or black.

Have you checked for obvious leaks around intake plumbing and vacuum hoses? Without a proper idle it'd be difficult to spray brake cleaner or starting fluid to help detect leaks.

Perhaps you should remove both the throttle body and idle air control valve and thoroughly clean them out. Use throttle body cleaner spray. This might help your idle situation if both are significantly clogged.

[flipdog0]

Well like I said, the codes I had were coming up before this newest set of issues arose, I was out of town for about 5 months while the car sat and the battery died thus potentially losing any new codes that should/could be showing.

I couldnt tell if the transmission was engaging or not but I was able to put the car in neutral (when the battery was dead) and push the car in order to change the oil. (using the lock overide)

I will check the transmission fluid.

Yesterday we checked for obvious leaks and couldnt detect any. We used another flammable lubricant but didnt have any brake cleaner i was able to hold the gas pedel down and keep it around 1000 rpm but we might try again with real brake cleaner.

[Towncivilian]

Try performing idle air volume learning. Steps are on page EC-57 of the factory service manual.

[flipdog0]

So in order to clean the MAF sensor all I need to do is unplug the sensor plug and then use the T20 torx bit to unscrew the casing. and spray with MAF cleaner?

[Towncivilian]

Correct. You will need a security Torx T20 bit if it has a raised portion in the middle of the screw head.

[flipdog0]

so i cleaned the MAF sensor (it looked brand new) and now I am showing the code P0100...

[Towncivilian]

Is the MAF harness securely connected and are the contacts free of corrosion? Did you let the cleaner sufficiently evaporate before reinstallation?

If you end up needing a new MAF it's inexpensive at $90 before shipping (compared to $442 for a new OEM Pathfinder MAF). You can use this Maxima MAF, many members have used it without issue here. I'm not sure why cleaning sometimes causes a code.

[flipdog0]

I cleared the code. i read where you need to clear it sometimes. Now the car isn't even turning over, i get no clicking nothing. I am pretty frustrated and running out of time to fix this thing. I scheduled a tow truck to come out here tomorrow at 8:30 am getting a tow to a mechanic who has been in business for 31 years in this town. 90$ diagnostics fee and 90$ per hour. I am afraid I am going to be seeing a fairly large bill, and I hate that considering the car is so old.

[flipdog0]

actually it clicks one time when I turn the key to the start position.

[Towncivilian]

Sorry that you're having so many issues, without seeing the vehicle in person it's difficult to troubleshoot problems. I hope your mechanic finds a solution. Remember that even a rather large bill is still ultimately cheaper than a new car payment in the long run. Let us know how things go!

[flipdog0]

Thanks for the words of encouragement and all of the help and information you have provided, I will keep you informed on what I hear back. The should be able to get to my vehicle on Wednesday.

[flipdog0]

So I got some bad news from the mechanic today.

*the car not wanting to start was indeed the starter going bad which I suspected
*the car not wanting to move when I put it into gear was the transmission, the mechanic is saying I need to rebuild the transmission which would run between 2-3k
*the engine idle issues and shaking the mechanic attributes to a head gasket problem. Without breaking into the engine it is not sure what the exact issue would be but he was thinking around $1800
*this is all before I fix the codes that were showing in relation to emissions as well as fix/replace the exhaust.
*not to mention cosmetically the rear bumper would need to be replaced if I were putting all this money into the car.


all this being said I feel like I would be putting too much money into a car that will still have nearly 180k miles on it.

should I try a second opinion?

I currently put the car up on craigslist for $1000 as is and explained the current issues.

what would you do?

[Towncivilian]

Don't opt for a transmission rebuild just yet. Have your mechanic do a pan drop & filter change and a full fluid exchange, and see if transmission problems persist.

I'd suggest getting a new starter, not a rebuild or remanufactured unit. Or have your original starter rebuilt. Aftermarket ones are crappy. You can get a new OEM one and put it in yourself, it's just held in by a couple bolts and it should not be difficult to replace if you're at all mechanically inclined. I think it's easy to access, at least it is on my 2WD. You might want to take a look yourself, it's on the driver's side.

Head gasket issues are uncommon on our engines. Has your engine ever overheated? Does it consume a lot of coolant?

[flipdog0]

Yea I am sure I could replace the starter myself. How much does the OEM starter run.

As far as the transmission issue, how much would the pan drop and filter change cost? The mechanic stated the transmission fluid wasn't showing on the dipstick at all (like it was out).

When I tried to put the car in gear everything seemed normal but then I gassed the car and it wouldn't move at all, forward or reverse.

As far as I know the engine has never overheated but again I was not driving the car when all these things happened, and all I really know is what my friend tells me. The mechanic says he sees antifreeze being burned and coming out of the tailpipe. which leads him to believe it is a head gasket issue.



Do you think that it is worth trying to fix all of these issues? I would like to keep the car ideally, but time is of the essence and I feel like with the mileage I could only get $4000 or so for the car after it was fixed. I would be willing to spend 2-3k if I knew it was going to be fixed after all that but if we are talking 5-7K I really think it is not worth it.

I could have the car towed to the infiniti dealership but that would be another $134 bucks + $129 diagnostic fee (not to mention the 101.50) I have already spent towing this thing around.

[Towncivilian]

A new OEM starter goes for $300 online - ouch. RockAuto sells remanufactured starters only, and I doubt any chain stores sell new ones. Maybe if you get a reman one from a reputable brand (Bosch, Beck/Arnley, etc) it might be fine, not sure. Have you checked both ends of the battery terminals for corrosion or damage, and had the battery tested to rule it out?

Did your mechanic check the transmission fluid with the engine idling, and after selecting every gear and returning to P? If not, he checked it incorrectly. I'm unsure of the approximate cost of a pan drop & filter change and fluid exchange, sorry. If you are up to it, you can do a pan drop & filter change and fluid exchange in your driveway. There is a DIY guide on the pan drop here, and fluid exchange steps are in the general information thread under the "Transmission & driveline" Q&A section.

I'd imagine the cost of headgasket replacement to be quite high as it's difficult to access and might require removal of the engine (at least the factory service manual recommends it).

I think you should ask around for an approximate cost of head gasket replacement and then weigh your options from there. You can likely DIY the starter & transmission service, so you'd just be paying for the head gasket work. Maybe get another opinion about the head gasket too, I still find it odd to hear of a head gasket issue with our vehicles, especially if you're pretty sure that it never overheated. Has it ever had a coolant service?

[flipdog0]

I am 99% sure that it is a starter I have been experiencing random issues with it for a couple of years now, and I replaced the battery with a brand new battery in the last week.

I do not know if he checked the fluid that way, seeing as how the car wont idle....it is possible that it wasn't checked like that.

He mentioned 1800 bucks at some point to repair or replace the head gasket and mentioned something about how the car is running on 5 cylinders. He was thinking the transmission was slipping and caused the car to overheat which blew the gasket, of course I don't know jack from james in this town so for all I know they could be dodging the work.

They did say they were not going to charge me for the diagnositic fee and are letting me keep the car there a couple of days until I figure something out.

[flipdog0]

but my friend was able to drive the car after the car started shaking and idling poorly, albeit not very well to the place that it was parked and had no trouble with the transmission or so he says. (before it sat for 6 months)

[Towncivilian]

If the trans was overheating, it would put itself into limp mode and you wouldn't be able to drive very nicely. It won't cause the car to overheat unless you drove like that for a very long time, and you'd know since you'd be stuck in second gear (if I recall correctly). You'd also have the "O/D OFF" light blinking 7 times at ignition on. Also, without the engine idling and the fluid checked properly, you can't be sure of the fluid level in the trans. The transmissions on our vehicle shouldn't overheat with normal driving (i.e. no towing, racing, etc) and a stock and functional cooling system.

If there was a misfire, the service engine soon light would be constantly blinking, and you'd feel and notice the rough idle/driving.

I really think you should see if all power valve screws are present. If one or more are missing, that would almost certainly be the cause of many of your driveability and idle issues. A compression test might be a good idea too.

Is/was steam ever coming out of your tail pipe while driving or idling? Do you recall ever needing to add or top off the coolant overflow reservoir? I'd suggest to look for bubbles in the coolant overflow reservoir (which indicate exhaust gases in the coolant), but you can't maintain idle to check that. Pull a spark plug and check if it looks way too clean (or just post a couple photos here), if it is that's indicative of coolant consumption and a bad head gasket is quite possible.

I think your mechanic is a moron. Ask him why he thinks your head gasket is bad other than idle issues.