1990 nissan d21 4 cyl, no power at top end

[np0110]

This maybe long, I have replaced timing chain,TBS,Fuel filter,ETC, fuel injectors, fuel regulator, plugs,wires,dizzy cap,o2 sensor. triple checked timing,that is dead on. no codes on ecu (55), compression is #1 160, #2 160, #3 160,#4 152. got good spark to all plugs, does not smoke, starts and ides fine, with no misses. I dont have any power at top end or on hills. seems to get worse as it warms up. truck has 140k miles. Have smell of unburnt fuel.. fuel pressure is good as well..Any Ideas,, I am at my wits end trying to firgure this critter out.

[r34 gtr]

You could take it to a chassis dyno and use their wide band O2 sensor to see what is going on. It will probably cost you about $50, but it would really be worth it.

Then again, you could just own a Nissan truck. My frontier doesn't exactly fly up hills with its 142hp KA24DE.

[seang]

How is the fuel sending unit doing?

[np0110]

fuel sending unit? i have checked fuel pressure and it is ok,,

when in 5th gear, I step on gas, it just makes noise but rpms drop and starts to shutter..wierd

[seang]

The reason I mentioned the sending unit is that you can have pressure and still have a seeping return line. You said you smelled gas. Beats me, it was just something to look at.

Is the catalytic converter getting plugged up? I know sometimes when they get bad they will run alright when it is cool, but will act up upon getting hot.

[np0110]

I think that was my next move, I was gonna pull 02 sensor when it happens to see if cat is clogged. or is better to just drop cat and drive it to see if it improves. will check out fuel return. that could also be a sourse of my issue. i didnt mention, I am in alaska, when i say warm temp outside was around 5 degrees when it happened..but still could be cat

[np0110]

Its not the CAT or sending unit..pulled the cat and no change..any other ideas?

[Saudade]

Is it only in 5th? How does it run in the lower gears? Does it sound like it's just straining or is it cutting out?

[np0110]

I notice the lack of power in 4th and 5th. 1st and 2nd good pwr. poor fuel mileage as well..feels like its straining,,i pulled air cleaner off the other day. to see if it was starving for air,,no change..

[D21 owner's Dad]

Have you found an answer for this problem? Looks like I'm facing something similar.