Engine bogs down

[onefast87]

I have a 91 se auto 4x4 and it randomly starts to bog down. When it does bog it takes much throttle for it to clear up. Feels low on power till 3000rpm, sometimes it drives normal and feels great.

Ive done plugs, maf,spark plug wires, fuel filter.

Ive checked the fuel pump and fuel pressure, leak down test, timing check, with no results. No ecu codes popping up.

With the key on and the throttle opened partially i can hear a buzzing sound from the transmission.

Short of trying another tps or ecu im not sure what else to look at.

Any help would be great

[Slartibartfast]

Interesting about the trans buzzing. I had the same issue on my '93 recently while I had it all to bits. The trans started buzzing whenever I turned the ignition on. Drove me nuts trying to find the issue until I found the battery was down to eight volts or something (I'd been running the fan, messing with the windows, and testing circuits with the engine off). I charged it back up and it went from buzzing if the key was on to only buzzing key on and throttle open a little like you've got. Full charge, no more buzz. I have no idea if this issue has anything to do with what you're dealing with, but it couldn't hurt to check the battery voltage and condition of the clamps/fuse links/etc.

 

You might also try wiggling wires/plugs under the hood to see if you can make it act up--or clear up if it is acting up. It could be a bad connection somewhere that can't decide if it wants to make good contact or not.

[onefast87]

Turns out its the 02 sensor thats causing my issue, when i drive with it unplugged it runs just fine, no issues, pisses me off because its a genuine nissan part thats only a year old

[Terranovation]

For me the buzzing noise was a wire rubbing and shorting out, I have glow plugs on mine since it's a diesel. The glow plug wire was rubbing against metal so electrical tape sorted that one out.