Loss of power when below 3000 revs

[99pathy]

I drive a 99 pathfinder 3.3 le. It's got 247xxx kms. I'm due for an oil change and I'm going to do plugs fuel and air filter as well. I have what I believe to be an exhaust leak from the engine bay ( sounds like a ticking noise but very loud) I also have removed the muffler as it rusted away from the tailpipe, and a hole in the first larger muffler (technical term I think is reciprocator?)

When I'm accelerating at anything under 3100 rpm my truck is very sluggish almost feels like a hesitation. Like she wants to accelerate but something is holding it back every second.( feels like I'm changing throttle position slightly over and over again) then once I get past 3000 revs I suddenly have power and start to pull away. Anyone have any ideas. Engine code says knock sensor but its 200$ sensor an I don't wantto throw down the money on a 200$ sensor if it's not going to fix the problem. Any ideas?

P.s idle is much smoother then under acceleration under 3000 rpm

P.s.s hesitation doesn't seem to exist in park or neutral. And havent gone fast enough in reverse to see if problem exists

Also any ideas on efficient ways to fix my exhaust leaks would be really appreciated.

Thanks,
John

[ARKQX33V6]

O2 Sensor(s)
Lack of fuel, filters
Advance mechanism
Plugs fouled, too wide a gap
Valves set too tight
Injectors bad ECU
Blocked Recirculator of exhaust gases, EGR
Using high test fuel and excess carbon
Timing is off
Carboned up throttle plate area

Just a few things to check with 1000-3000 bad performance, cost to check and repair is minimal, but if you need parts
O2 sensors, plugs etc
costs will rise

[99pathy]

Thank you I'll have to get it checked out. Hopefully she Just needs a good 250000km tune up

[Joe99qx4]

I have a 99 qx4 with the 3.3L in it and since I've owned it, ( 3 years now) it has always done what you described. i thought this was a built in feature; that when you hit a certain RPM, it would open a valve or somehow change the cam ratio..(like the v tech engine on Honda's) that would increase power. Are you saying that I should have the power all the time? Thats would be GREAT news if that is true.

When I'm getting on the interstate, I get a instant boost of power then I hit the 3000 -3100 rpms.

[MCNPathfinder]

I've had the same issue with my 3.5. I had the dealer check it out when they had it for the last oil change, they said that it could be a combination of things such as the fuel filter, air filter, etc. I told them I did all that stuff already, they said the spark plugs would be their next guess. Mine has ~114,000 on it and the spark plugs have never been changed apparently. I plan on doing them this weekend, we'll see what happens.

[Joe99qx4]

i've changed plugs, fuel filters and it has not helped. I wouldn;t say that I lost any power below 3000 rpm's, I just get a sudden kick when it hits the 3000 mark. I think it's something that is designed to do this, I just don;t know how it does it..maybe it advances the timing or something like that...

[SOUTHSHOREQX4]

I had the same problem....I had a exhaust leak and thought that was it. I took it to the stealership and they said that some coupling for the clutch fan or adapter on the cooling fan went bad. Had it changed for free cause i had a extended warranty, but he then told me even though i had a warranty them exhaust is only covered to 80k miles...even though i explained to him when i paid $3000 for the warranty the service manager told me its "bumper to bumper"...he said its not included and quoted me $2900 for muffler and tailpipe.....WTF!!! Went to my local Meineke and had a magnaflow put in with dual Stainless tips for 250. Anyways try that part on the fan...my acceleration improved instantly.

[ARKQX33V6]

RPM should be constant flow up as throttle opens no 3000RPM boost unless super charged or exhaust gas boosted.
Check your exhaust gas system, recirculated exhaust look for blockages.
A slow heated O2 sensor(s) will cause this also.
Verify input conduits and fuel.
Check valve timing and ensure advance is working