Mechanics

LOSING ENGINE POWER

2003 Nissan Pathfinder

Car: 2003 Nissan Pathfinder SE 2WD, 108k miles, Auto

In the last month or so my car has had a problem starting normally. After turning the ignition and the engine starts I usually have to press the accelerator very briefly to keep the engine from stalling. I changed the fuel filter and it got a little better. Now it cold starts are ok and I have to press the accelerator (again, very briefly) sometimes to keep the engine going.

Today, while entering the highway and accelerating, the engine seemes to have partially lost power and I could go no faster than 60 mph. The RPMs dropped and stayed around 2000 and no weird sounds. Engine sounded normal, but pressing the accelerator did not make the engine go any faster. I pulled over and checked the engine. All fluids ok, no weird sounds. After this I started it back up and it seemed normal. Went on the highway, shifted smoothly and normally. I tried a " passing" acceleration and the same thing that happenned before happenned again. Engine power dropped and could not go much past 60 mph.

This sounds to me like a fuel supply problem - electrical or mecahnical.

Any ideas before I take my car in?

Thanks for any advice.
Avatar
D70nerd
August 1, 2007.



You need to rule out the exhaust system for restriction 1st then have a fuel pressure check

Test the coolant temperature sensor for your cold start problem.

Rasmataz
Aug 13, 2007.
I have the same two problems with my 2001 Pathfinder (105K) - cold start that clears up in about one minute, and power loss at highway speeds or going uphill. As you suggest, both feel like a fuel problem. I've been running high octane feul for years and have had no previous problems. Any luck discovering the cause(s)?

Thanks.

Tiny
Kevin Barry
Nov 26, 2007.
Sorry to hear you're having the issues I have been having.

The Nissan dealer I went to replaced a bank of fuel injectors and the "throttle body." Have not had the problem recur again. Something tells me that the fuel injectors did not need replacement tho because they replaced the injectors first, but the problem happened a few days later agian then they replaced the throttle body (has a computer black box attached to it) and the problem has not occurred again as I said above.

One more thing ... the bad throttle body seems to have caused the fuel mixture to be too rich and that damaged my "bank one" catalytic converter. The dealer wanted to charge me over $1000 to replace it but it can be bought for less than $100 and installed by a mechanic for about $100. beware. :-) Hopefully your cat converter is ok. http://www.autopartswarehouse.com

Good luck.

Tiny
D70nerd
Nov 26, 2007.