having some driveability issues

[4gotn1]

ok heres the problem, i have a 1990 240, and my car has a major loss of power when the throttle is anything past 1/4 open. but anything under 1/4 open and all the power is there. itis very diffucult to drive like this. it idles great. and revs all the way to redline at 7. no it is not stock, i have a good amount done to it, including ecu tuning. but i know its not the ecu. because it ran just fine in my buddys 89. anyone have any suggestions.

[s13sr20chris]

if your car has mods we really need to know more. is it rich or lean? how do the plugs look? etc. i would also do the basics like check ign timing and fuel pressure.

[s13sr20chris]

http://www.nicoclub.com/zerothread?id=81587

[4gotn1]

well the plugs are brand new, they are beru silverstones, not ngk's. the wires are magnecore and also new, as well as a distrubitor cap and rotor. and it did not have this problem before. do you want me to list everything done to it because i can? it seems to be running lean, and i cleaned the mafs and it helped a little, but then it started acting up again. i do have an a/f gauge and it read constantly lean, not to sure how accurate the gauge is tho. my fuel pressure is set to 34psi at idle. and timing is set to stock. here is just what is done to the engine only obx header custom intake kyo exhaust 2.5 in test pipe port matched intake and exhaust magnecore wires beru silverstone plugsmsd blaster 2 coil asp underdrive pulley removed emissions (completely) obx adj fuel pressure regulator high flow fuel filter walboro 255lph 16in electric fan conversion removed secondary butterfly valves nismo motor mounts nismo transmission mount new distributor cap and rotor myth concepts chipped ecu myth concepts ground kit i have a lot more done to the car but i dont think there relavant to what could be causing the problem

[s13sr20chris]

what is your maf voltage at idle and while messing up? also tps voltage would be good.

[4gotn1]

ok i will tonight after workis there any easy way to test it without having to disconect the maf? and when it messes up the car is moving, it wont do it when sitting still. its only when driving the car does it seem to loose all power after 1/4 throttle.

[s13sr20chris]

yeah, you can take sewing needles and stick them in between the wire insulation and the rubber boot in the connector. slide it in till it stops then you clip a multimeter test probe on the end. run the probe wires inside the car and watch the meter while you drive. i do that all the time for intermitant problems.

[mygodrulz]

You might also check the TPS for a proper voltage sweep. Do this with the engine shut off. You could be having problems with the TPS going OL somewhere in the sweep.