Hello everyone, I'm new to the site and I could really use some help. I have a 1994 Nissan XE V6 4x4 5speed with about 160k. So, here's the problem; the truck just seems like it doesn't have any power. It's not skipping or sputtering, but running smoothly, just bogging down. It acts as if it isn't getting fuel IMO. It isn't as noticeable in 1st or 2nd(unless I'm towing something) and will rev through them rather easily. In 3rd it isn't as bad, but 4th and 5th gear bogs down considerably and my top speed is around 60mph. If I'm towing by boat, it bogs down in every gear and my top speed is 45 and you can forget pulling it up a boat ramp . I've replaced the fuel pump and fuel filter. I've also made sure there were no blockages in the fuel line from the filter back to pump, along with running enough fuel system cleaner and seafoam through it to burn down a small city(not at the same time mind you). The MAF, O2, TPS, and crank angle sensors all seem to be working according to the computer(modes 1,2,4,and 5)and the only code I can pull off the computer in mode 3 is egr function which turned out to be a small vacuum leak. I have also pulled off the MAF and cleaned it using the instructions posted on this site. The truck doesn't smoke, and when I pulled the spark plugs they looked like the truck has been running lean. The timing is dead on, and all regular maintenance has been done in the 6 years that I've had it. It has been doing this for a few weeks and I am officially stuck . Any help would be greatly appreciated!!!

clogged honeycomb in cat converters.

welcome to the board

ever changed the O-sensors? swap those out, as well.

cat has been gutted, and no the O sensor hasn't been changed, but according to the computer it is working properly. Would just the O sensor be this detrimental to the performance of the truck. In 4th gear with the pedal to the floor it takes a mile to get from 40 to 50mph. Am I wrong to think its a fuel problem? Faulty ground perhaps(but it doesn't skip, just bogs down)? Bad fuel injectors?

I had a vehicle that I couldnt get any power out of, in my case it was a plugged cat.. but you say yours is gutted, sounds like something plugged...
you dont have any air (intake) restrictions do you?

quote:

Originally posted by Nutsmakr:
cat has been gutted, and no the O sensor hasn't been changed, but according to the computer it is working properly. Would just the O sensor be this detrimental to the performance of the truck. In 4th gear with the pedal to the floor it takes a mile to get from 40 to 50mph. Am I wrong to think its a fuel problem? Faulty ground perhaps(but it doesn't skip, just bogs down)? Bad fuel injectors?

I just ran into a problem similar to this one. It ended up being water in my gas tank. We were thinking that it was due to condensation. I've only driven my truck 3-4 times in the past year or two, and have always left it w/ about a 1/4 tank or LESS of gas in the tank. So, my mechanic drained my tank, threw in a bottle of dry gas, filled it up w/ new gas, and badda-bing....runs just like it did 2 or 3 years ago (which is good and Strong) Hope this helps! Later...

^^The cat was the first thing I thought of so yeah, its gutted. I think I am gonna unhook the exhaust after the manifold and see if that changes anything.

^When we dropped the fuel tank to replace the pump it only had about a gallon or so in it but I'll check it out.

I unplugged my TPS sensor and started the truck and I got no change at all and it didn't throw a code. Could this mean that it is bad?

I keep running this stuff back over in my head and I keep coming up with the same stuff(keeping in mind the stuff I've already done) - MAF(computer says is working properly, O2(computer says working properly),TPS(explained above), or the computer itself

and thats a pretty expensive list...

**UPDATE** - I took out the sparkplugs again and wow, the truck is definitely running lean. It's got to be a fuel problem. Also I unplugged the tps completely and it threw the appropriate code, but there was no change in the truck at all. Suspect? So the only thing I have left is that somehow all 6 of my injectors are clogged up and I need new ones which cost $texas