KA24E problem with first gear

[phi_ho1]

My friend just got a 89 240sx and we are having some issue with the first gear. the car will go in first gear but after we REP it up to 3500 RPM the car start to shake. it feel like some shake u hard and let go and shake and let go again. the car also make a zzzuuu zuu zuu sound when that happen. could it be the MAF? Tranny? or sensors problems? if we put car in second gear and any other gears to run, it will not do that. if we shift before 3500 in first gear it will be find but it's hard to drive the car. if anyone know about this issue let me know.

[FRoSt415]

no shaking in any of the other gears? did u rev it higher then first gear? sounds like bad shifting skills, haha. is it bobbing? do you feel like your bull riding? it might be something with the fuel but you dont have the problem in any gear so im confused.:confused: take a video and see what else other ppl say

[phi_ho1]

shifting is no problem but the car worn't REV over 3500 RPM first gear. yeah driving the car is like riding a bull for sure in first gear.