96 240sx with 95 ka equals car being a dick

[largetacticaldrift]

Okay, let me begin by saying I have searched and searched and not found an issue quite like this one. So here is some back story, my friend asked me to help him swap out his blown motor for another ka. I was supplied two cars, a 96 se 5 speed and a 95 automatic. I pulled both motors and swapped over everything from the 96 motor to the 95 motor and dropped it in to the 96. So we have a 1996 240sx with a 95 motor in it. Cool. The motor fired right up after everything was reinstalled and drove fairly well with exception of some fierce hesitation between 1k and 3k. So far the only codes i've pulled are for barometric pressure sensor, egr and knock. Not so big a deal considering the car ran perfect with those same codes just a few weeks prior. I've timed the motor, set the tps to the correct voltage range, inspected all injectors and they all function correctly, no vacuum leaks, no ground issues, no hard codes, O2 sensor seems straight, swapped maf out for a known good and it has harness continuity. New plugs, new cap and rotor, compression test revealed 120 psi on all cylinders, low yes but consistent. I have religiously gone through the FSM and done everything that is recommended. I still can't solve this bogging issue. I hooked up my timing light to each plug wire and watched the light strobe in cadence with the spark plugs firing but when I goosed the throttle each cylinder lost spark during the cars bogging. I doubt i'm washing out my spark since it has a walbro 255 and a 300zx ff with a factory fpr. I'm kind of at a loss right now. So i'm going to post a video of what the car is doing and hope that you guys can give me some feedback. The motor is a 100 percent bone stock 95 ka. Heres a link to the video 96 240sx bogging, hesitation, loss of power, bucking - YouTube (http://youtu.be/ssAME9ZGnV8) If i just ease into the throttle it works fine, but if I put the pedal to the floor it starts with this crap.

[drftngs14]

I had the same problem with my 96 years ago, ended up being the distributor. It got so bad it'd do it under normal throttle and bogged everytime

Edit: Also was getting no codes at the time either

[OnTheChip]

If you're getting knock sensor code, the timing is being retarded 6º all the time. Try advancing the distributor 6º and see if that helps.

Dave

[bad dog]

or you could cut the wires between the knock sensor and ecm , put a 560,000 ohm resistor between the 2 wires going to the ecm , the ecm will think the knock sensor is good . the chip is correct in that the ecm will keep retarding the timing if the knock sensor is bad , at the same time the ecm may decrease the injectors duty cycle to reduce gas because of the retarded timing .

[largetacticaldrift]

Awesome, thank you fellas. I'll try tricking the ecu with the resistor and i'll swap out for a known good Distributor. I'll let you guys know.

[largetacticaldrift]

Oh and in reference to the distributor being bad, I have a 93 that I rock as my daily and it sat in the corner of my shop for over a year because everything passed inspection but I was still losing spark. Turns out that the reman dizzy I bought from the parts house was no good. I went to the local Nissan dealership to use their consult reader and I discovered a service bulletin that said not to use remanufactured distributors for a certain year range of vehicle. I forget what specific brand it referenced but it stated that the units were not built to spec and would inevitably fail. The problem they discovered was that the parts would ohm out correctly and pass bench testing but were in fact putting out incorrect voltage. So I bought a used dizzy and bam I was back in business. Just thought that i'd share that.

[Juantwo3]

my car has a knock sensor code and it doesnt bog.

[largetacticaldrift]

Okay everybody, I had a friend ship me a 1996 240sx distributor and as soon as I timed the car, BAM. Everything was fixed. The car runs perfect, zero bogging, idle is perfect. I hope the thread helps somebody in the future and I really appreciate everyones input and the suggestions you guys had. Like I stated before, the remanufactured CAS/Dizzys that they sell at the parts house are failure prone. This is the second one that has acted up on me and didn't throw any codes. Hope this helped, hope you guys have a great day.

[SD_Kouki]

I love happy endings :hyper: