I recently swapped a 96 motor in my car, a 1990 240sx, car is running rich like hell , it also have a lumpy idle.
I checked for code and get a long beep and 2 short so I assumed that would be code 12 for the maf, I replaced the maf from a 92 to a 91 unit, still having the same problem, I also change the ecm from a 92 to a 91 unit, same issue.
The idle only change when I unplug the maf, I can even move the maf out of the intake path and the car still idle the same, I unplugged 3 out of 4 plug wires and the car still idle rich. The distributor has been replaced with a 91 unit and crank set to tdc before install.
I went as far as replacing the entire wiring harness, still having the same issue.
The motor is from 96, I replaced the lower intake with a 91 unit, and I soldered the underdash harness as per the faqs and matching all colors. Car is still running pig right, I purchased new park plug yesterday and they are all black.
What could be causing this problem?
A could of more thing that I may try before running out of ideas, replace the entire fuel rail system to eliminate the fact that I may have bad injectors of a faulty fuel regulator,
Trying to use a 96 240sx maf sensor on the car.
The car drives but carries out black smoke and backfires a lots.
Any suggestion is welcome at this point.
bad o2 sensor?
I drove my ka sohc with no o2 sensor for 2 month and it never ran that rich , I am not sure if that will cause the maf to not have any reading .
I will replace it anyway and see what happen .
#1. vaccum leak
and a question for ya , did u take off the egr shit ?
and seal the outlet in the manifold? very important…
I blocked it with a home made block of plate . I am pretty sure this does not leak , I will however run a pressure test on the intake manifold just in case .
Few are the things I have not tried yet , Can a bad TPS cause the problem , assuming that it’s not senting the signal to the ECM ???
make sure the dizzy is in correct
change that water temp sensor to the s13 one i gave you
then let us know whats happening
I pulled out the valve cover yesterday and set the dizzy to piston 1 . I even opened and close the intake valves before setting to tdc just to make sure I was in the right compression stroke .
It lines up perfect with piston 1 .
Today I am regrounding the entire engine , I am off the create my own kit , if it fails that I will replace the fuel system , that include fuel rail and injectors . I am guessing that some injector may be suck open or maybe some debrit got in the fuel rail plugging the regulator .
Wish me luck.
I replaced the fuel rail assembly and have new injectors in , the car has a good trottle response , buggs a bit between 1000 and 2500 but pulls great to redline . Still getting occasional black smoke from the tail pipe but no as much as I used 2 , also not getting as much backfire when I drive .
I am gonna try to reground my MAF to the car itself and see what happens .
any mopre sujection ?
Update
Got it running after replacing pretty much every sensor in the motor , Now motor has a loud ticking noise when reving passing 2000 rpm , car dies after 30 sec , ticking get louder and louder when trying to rev , all that occur during the 1st test drive after fixig the richness problem . :roll:
Could be the timing chain , tensioner , guide or valves kissing each other.
All that before even reacing 120 km from purchase . I guess the motor is now crap.