91' 240 w/ 97 DE motor hesitates extremely bad after warming up

[smokin240]

I posted this under the Nissan Mechanic section, but it seems that section is dead. I hope the mods don't mind I post it here as well:

It started doing this all of a sudden one day when I was sitting at a red light, revving the motor because it was long light, and was just being a moron. Anyway, I pulled into a gas station to ask for directions to where I was going when it started to lose power. At first, I thought it was my imagination, but then the idle dropped. I turned the car off, went inside, asked for directions, and came back out to go to where I was going and it was hesitating incredibly bad, and at one point actually died. So, it would do it so bad to a point where I could barely accelerate at all. The more gas I gave it, the worse it seemed. I had to give it about 1/7 gas and it would get up to speed faster than giving it more gas.

So I noticed the other day that it's not so bad when it's been sitting until about 1 minute later and the car is warmed up. I put the motor in myself and have had issue's like this before. Once was bad grounding, another bad plug wires, and last a dieing battery - all caused hesitation. It's almost like there's no backpressure, and it can't breath or something. Of course that's not it though. Anyone have any suggestions or idea's? Thanks.

Oh, another thing.... the TPS has been falling off alot lately. I have a feeling maybe that not being on tight may be causing issue's. But since then have secured it well and it still has the same problems.

[smokin240]

bump - I replaced the MAFS and TPS. After I put the new TPS its' symptoms eased off alot. I don't have such a hard time accelerating now, and I can drive it without having others honk at me for driving so slow haha. I can give it about 15% throttle before it bogs out badly... then it stops hesitating at higher rpm but is still slow. So any ideas now? Thanks.

[smokin240]

Maybe the ECU is having issue's? I don't smell gas when I drive it so I don't think it's a fuel problem.

[Sidewayzzz]

had damn near the same problem with my 240...unplug the o2 sensor...see if it still hesitates when it warms up...if the problem is gone, get a new o2...

Or you can use your ECM to troubleshoot the o2, put it in mode 2, while the key is in the ignition, then start the car .. if your CEL doesn't flash more than 5 times in 10 seconds you have a bad o2.

[smokin240]

Ok, I'll give that a shot when I get the chance. Another update, the car runs almost perfect when its cold. Once the engine warms up it gets worse and worse.