1997 Nissan Pathfinder Loss of Power

[hakanerdogan]

Hi Everyone.

At the recent days I'm having some issues about lack of power. Engine starts great, runs smooth and perfect, when you sit on throttle revs and accelerates brutal.



But....

While cruising at between 1500-2000 rpm (where you drive it most) when you increase the throttle, especially uphill, it hesitates to rev up, it actually revs up but without shuddering a giant powerful hand gently tries to pull the car back and releases... That's what you feel. No shudder, no feel like misfire, if you sit as a passenger in the car you may won't feel it If I don't tell you it's that light but kills the fun, no more enjoying the ride...

What I did;

-brand new distributor
-new spark plugs
-new plug cables (OEM, Yazaki)
-new water pump and belts
-new radiator
-new whole exhaust system
-changed every fluid of the drivetrain (front-rear diff, ATF main and the secondary transmission)
-and so many other minor parts like thermostat etc...

But I didn't change any sensors like MAF, Oxygen sensor which are suspicious to me, also the fuel pump. But it runs good in my opinion so I can ignore the fuel pump maybe, well I don't know and it makes me crazy. Here how it moves, which is OK to me.

https://www.youtube.com/watch?v=U1CqzEbeiAk


Car is not displaying any codes.

Any ideas you have?

Thanks.

[Kev90]

I am no expert on the VG33 motor but to me it sounds like an intermediate misfire. My v6 mustang felt exactly the same way and it was the coil pack. It started out like you have described and then the coil pack died 100% and it ran terrible and I finally got a check engine light. I know on Fords the engine must fault out a literal million times before the check engine light comes on while a Chevrolet's check engine light will come on all the time, I am not familiar enough with how many times it must occur with a Nissan to get a check engine light. First thing I would look at is the ignition coil failing or the power resistors. I found a website that has some good articles for diagnosing the issue, hope it helps!

http://easyautodiagnostics.com/nissan/3 ... articles-1

[hakanerdogan]

I am no expert on the VG33 motor but to me it sounds like an intermediate misfire. My v6 mustang felt exactly the same way and it was the coil pack. It started out like you have described and then the coil pack died 100% and it ran terrible and I finally got a check engine light. I know on Fords the engine must fault out a literal million times before the check engine light comes on while a Chevrolet's check engine light will come on all the time, I am not familiar enough with how many times it must occur with a Nissan to get a check engine light. First thing I would look at is the ignition coil failing or the power resistors. I found a website that has some good articles for diagnosing the issue, hope it helps!

http://easyautodiagnostics.com/nissan/3 ... articles-1

Thanks for the quick reply!

I will do the MAF test as the link tells.

But I do not think it's a firing problem because I have a brand new ignition distributor, spark plugs and wires. We don't have ignition coils like 3.5 Pathfinders, but maybe I am wrong and missing a point but distributor is the heart of firing and also a camshaft position sensor itself, in addition distributor cap's&rotor position is the timing, very old school but simple. All in all, If I fail to dedect the problem I'll probably change the MAF and O2 sensors, if that's no cure then the fuel pump but going to cost a lot...

Thanks again.

[Kev90]

FYI: On other vehicles with distributors there is one ignition coil with a wire to the center of the distributor cap and the distributor distributes the spark to each spark plug. Don't know it this is how the vg33 engine does it or if the coil is built into the distributor somehow.

Good luck!!

[hakanerdogan]

FYI: On other vehicles with distributors there is one ignition coil with a wire to the center of the distributor cap and the distributor distributes the spark to each spark plug. Don't know it this is how the vg33 engine does it or if the coil is built into the distributor somehow.

Good luck!!

I will check that. And try to record a video of the situation.

Thanks a lot.

[muketan]

Bir sürü nedeni olabilir, ama 1. sırada MAF sensörü gibi geliyor. Kontak sprey ile temizlemek çözüm olabilir.

[hakanerdogan]

Here I recorded a video how it hesitates at steady throttle, may gives you some ideas. Any comments, especially who experienced similar problems, welcomed.

https://www.youtube.com/watch?v=UaS-Ew0KuWc

Check engine light came after I disconnected the MAF plug while it's running in order to test the engine reaction, don't mind it. (Yes engine gone crazy when I disconnected the plug)

Thanks.

[hakanerdogan]

Well, it's been over a month and I found the problem.

Yesterday I fitted a LPG kit to the truck and wooaw, It's rumbling, running like a champ, silk smooth... Not displaying any error codes.

So the problem is not the sensors or firing elements. Maybe fuel pump or petrol injectors were the problem.

Just wanted to share.