Nissan XTerra - loss of acceleration and AC issues

[Zulfikhar Naiyar]

Hello Xterra experts,

 

I’m experiencing few issues with my 2014 X in recent rides. Wanted to share and hopefully find a solution if others have faced it in the past. 
The issue started with AC completely stopped cooling or even blowing hot air in the middle of the desert. Though there are no issues with the AC whatsoever while driving on-road or the initial off-road track. After about an hour or so of our desert drives, the AC stops functioning and just blows hot air. I thought this was due to the hot weather, but faced the same on a night drive when the temperatures were quite pleasant. That ruled out the hot summer to be a cause for it. 
My second guess was engine overheating. The coolant levels are fine and I’ve been checking the temperatures. The max it reaches in demanding patches of the drive during the day is about 96-97 degrees and quickly comes back to 91-92 while on a more relaxed time. So the fans seem to be working fine as well as coolant. 

After coming out of the desert, turning off the vehicle, ABS kill switch, 4H, etc. and the AC is perfectly fine all the way till back home. 
 

The above issue is still not fixed but I do manage to roll down the windows and have an occasional sandbath in our drives😎. 
 

While the above is still something of a personal endurance test😅, the other issue I’m facing is loss of acceleration or lag in power on even moderate climbs. 

This was a major issue exposed in my last FB+ drive with @Varun Mehndiratta .. I couldn’t effectively do most of the climbs which otherwise were pretty easy to capture previously. There’s a serious lag in acceleration and building up momentum. I’ve since had my vehicle checked by experts(garage) and still the issue isn’t resolved. They’re not able to figure out what’s the issue as every component seems to be working fine(individually). 
 

Just to add to that the mech’s advised there’s backfiring happening and this would be due to air to fuel ratio imbalance. Tbh, I didn’t understand that part but experienced it and whenever this backfire was replicated, the AC cut-off scenario would appear. Restarting the vehicle would solve the AC issue temporarily. 

I’ve got a cold air intake which currently is being replaced by stock air filter, to test if it solves the problem. I’d got the spark plugs changed and injectors cleaned recently. Which is the only internal recent change I could think of after which I’m observing these issues. Or the most recent is that I got a steam wash done at a new place, which I assume they’ve watered under the hood possibly causing any underlying electricals to act funny at times🤔. 
 

The diagnosis is still underway, so posting it here for any helpful feedback. 
 

Thanks in advance!

[Cha]

The AC sounds like AC fan failure(not the clutch fan), you have running air flow driving highway but not much in desert, and AC condenser doesnt work properly as no running air to cool it down. 

Acceleration issue can be the heated up fuel. I face the same in later part of higher level drives where I accelerate a lot. Once a senior offroader advised me that it can be the heated up and less condensed fuel affecting the engine performance. When more fuel gets pumped to the front due to frequent acceleration but partial unused fuel gets sent back to fuel tank and this unused parts become warm in the movement, and gradually heats up the rest of fuel in the tank. I noticed a lot of fuel vapor came out when I refuel on the way home from those drives, which evidences that the fuel was hot.  this should not be an issue for dual tank cars, for example most of Toyotas🙃

[Frederic]

Indeed strange. Your backfiring comment seems to me the most important point and indeed could be the culprit as to why the ECU would decide to limit the power and disable the AC compressor.

Backfiring or misfiring can have several reasons, from a clogged catalytic converter to defective oxygen fuel ratio sensors and many other causes. But in those scenarios you would probably have a check engine light and a fault code.. Is this happening ?

Make sure to double check if your check engine light is still working: when you turn the ignition (don’t crank) all your lights appear on the dashboard and the check engine light should appear as well. The reason I’m mentioning this is because I purchased an Xterra earlier this year that had no check engine light but after removing the dash we noticed previous owner had it removed ! We only came to know from connecting the OBD reader and seeing there were oxygen sensor error codes P1286. Car was slightly misfiring as well. Recently replaced both upstream oxygen sensors and running fine now. 

[Zulfikhar Naiyar]

Thank you for your replies @Cha, @Frederic .

I’ll do check the check engine light but it was working a while ago. And there are no error codes. That’s the mystery 🤔

[Krishna R]

Hello @Zulfikhar Naiyar

The AC blowing hot air should be mainly due to engine overheating. The X's ac compressor turns off after a certain temp is reached. 

How are you checking the engine temp. Manual or digital?

Did you do any tune after putting the Air Intake? Check the air:fuel ratio. IMHO, a cold air intake helps the engine breathe better and should actually improve the performance not reduce it. Which brand is your air intake AND mainly, i remember you had a snorkel, did you remove it or are you running snorkel + cold air intake setup? 

During summer, even during the night, the outside temp is high and the engine breathes hot humid air, so we should expect a loss of power depending on the car, but not substantial.

If the engine is overheating, there are multiple things to check. Coolant level check barely scratches the surface. 

I had issues with overheating for the last 2 months and took some measures to reduce it. Lets have a chat during our drive tomorrow and see if that solves the issue.

 

[GauravSoni]

Hi @Zulfikhar Naiyar,. A faulty thermal sensor could also send incorrect readings to dashboard making you believe that car is not that hot! … you have classic signs of engine overheating… loss of AC, loss of power… which returns to normal during On road drive… 

get following checked

1. radiator cap

2. thermostat

3. water pump

4. cleanup/ flushing radiator..

 

[Thomas Varghese]

On 8/3/2023 at 8:18 PM, Zulfikhar Naiyar said:

Hello Xterra experts,

 

I’m experiencing few issues with my 2014 X in recent rides. Wanted to share and hopefully find a solution if others have faced it in the past. 
The issue started with AC completely stopped cooling or even blowing hot air in the middle of the desert. Though there are no issues with the AC whatsoever while driving on-road or the initial off-road track. After about an hour or so of our desert drives, the AC stops functioning and just blows hot air. I thought this was due to the hot weather, but faced the same on a night drive when the temperatures were quite pleasant. That ruled out the hot summer to be a cause for it. 
My second guess was engine overheating. The coolant levels are fine and I’ve been checking the temperatures. The max it reaches in demanding patches of the drive during the day is about 96-97 degrees and quickly comes back to 91-92 while on a more relaxed time. So the fans seem to be working fine as well as coolant. 

After coming out of the desert, turning off the vehicle, ABS kill switch, 4H, etc. and the AC is perfectly fine all the way till back home. 
 

The above issue is still not fixed but I do manage to roll down the windows and have an occasional sandbath in our drives😎. 
 

While the above is still something of a personal endurance test😅, the other issue I’m facing is loss of acceleration or lag in power on even moderate climbs. 

This was a major issue exposed in my last FB+ drive with @Varun Mehndiratta .. I couldn’t effectively do most of the climbs which otherwise were pretty easy to capture previously. There’s a serious lag in acceleration and building up momentum. I’ve since had my vehicle checked by experts(garage) and still the issue isn’t resolved. They’re not able to figure out what’s the issue as every component seems to be working fine(individually). 
 

Just to add to that the mech’s advised there’s backfiring happening and this would be due to air to fuel ratio imbalance. Tbh, I didn’t understand that part but experienced it and whenever this backfire was replicated, the AC cut-off scenario would appear. Restarting the vehicle would solve the AC issue temporarily. 

I’ve got a cold air intake which currently is being replaced by stock air filter, to test if it solves the problem. I’d got the spark plugs changed and injectors cleaned recently. Which is the only internal recent change I could think of after which I’m observing these issues. Or the most recent is that I got a steam wash done at a new place, which I assume they’ve watered under the hood possibly causing any underlying electricals to act funny at times🤔. 
 

The diagnosis is still underway, so posting it here for any helpful feedback. 
 

Thanks in advance!

I understood the problem of ur car. Went through this couple of years ago. Call me if u want to solve the AC & loss of power plus the misfiring. By the way its nothing major work. Loss of power is because ur throttle body sensor has become faulty and the throttle body has to be replaced. This has  to do with your AC issues as I also have experienced the same. The backfiring happens when ur spark plugs don't match with original specifications or ur knock sensor is failing. My phone no is in my profile and u can call me anytime. The misfiring incidents started happening after u changed ur spark plugs. Try to remember.  

[Looper]

@Thomas Varghese good to see you buddy lurking around and dropping by to help.
 

BTW zulfikar wouldn’t be able to see your number as it is not public information otherwise bots will scrape that info in no time. 

[Zulfikhar Naiyar]

Thank you @Krishna R, @GauravSoni @Thomas Varghese and @Looper ..

just to update, really appreciate @Thomas Varghese getting in touch and guiding me through this. The spark plugs were indeed different ones! Not the ones for the Xterra. Got them replaced under @Thomas Varghese’s supervision 😅.. could feel an instant difference in terms of linear acceleration and smoothness..

Ready to roll and test it out tomorrow night with @Frederic 😎

[Thomas Varghese]

I understood the problem as soon as I read your post. Gone through this myself. 3 months I was offroading in the club with the same problem wondering what happened to my car. I am really angry for garages doing this deliberately to make us spend more money culminating in replacing a busted engine. We pay the bills given to us by them promptly. The mechanic keep charging us for replacing the knock sensor, the cam shaft sensors, the crank shaft sensor finally replacing the throttle body. When we reach this stage the engine head gaskets will be already busted. No codes will appear for the spark plug, instead all other codes will appear. We will never doubt a spark plug mismatch as we trusted the mechanic to have put the right ones for which we paid. The moment you realize u have been cheated u will feel so angry with the garage for making us fool. All this happens because the garages know the owner of the car lacks technical knowledge. They think its very smart to fool us like this. The clue to your problem was in your write up itself at the last paragraph. Instantly I knew what was the problem. When you don't put the manufacturer specified spark plugs with a different one having a different heat range the ignition starts to behave strange when the engine gets hot. I know the sequence of repairs the garage will suggest to get rid of the issue. You already replaced the knock sensor. Next they will say crank shaft & cam sensor. 

Anyways it your good luck I noticed the write up and reached out to you immediately. 

Enjoy your drive today and post the results. If at all any further damage has happened it will be the throttle body sensor as you may have used the throttle too much and probably heated up the motor rendering it weak. I hope you didn't reach to that stage as this spark plug change happened recently. In my case I had to replace the throttle body as I ran the car like this for 3 months and pushed the throttle excessively while offroading. Even if the throttle body motor has become weak don't worry. U get a used throttle body for 150 AED.