I have a 89’ standard 240 and when i hit 3rd gear at almost exactly 5000 RPM the engine just bogs down…its like the feeling as if you were to shift from 3rd then to 5th. All power to the wheels is lost maybe my clutch is giving out and it just slips. It also does this in 4th and 5th but not in 1st and second. Im not sure of the RPM the enging bogs down at in 4th or 5th…im scared of blowing somthing. Im asuming its some kind of sensor thats messed. I also noticed that my spedo doesnt always work sometimes it jumps around or it will sit at around 220km/h or just not work at all. Maybe this could be the speed sensor which could also be the reason the engines cutting at 5000rpm…Id really appreciate help.
-Devin
pm me if u want to buy a speedo sensor
When my speed sensor and speedometer went, the engine wouldn’t do what you’re descrbing, but the speedo would. It could be one or the other, or both.
My engine would simply cut right out, but at random times, not a certain RPM. Your engine may be cutting out, then bump starting itself back up again… next time it bogs, push in the clutch (but keep the gas down so it’s at the same RPM) and see what it does. I did that and the engine shut off completely. Got a new speedo and sensor and it worked.
This is really annoying ive only ever once tryed to see how fast i can get the car up to…bad idea i spotted OPP at the side of the highway jumped on the brakes got from 180 to 110 in a second…got away…cop wasnt paying attention 
got lucky…now the other day i cant even get over 130 without the engine doing the same thing…its not the clutch cuz the RMP drops to sumwhat near idle…it sounds and feels horribly wrong when the engine does it. I tried pushing in the clutch asap when it bogs on me and its as if its like normal…i give it a lota gas let the clutch go accel back up to 130 same thing…every time. Only thing i have noticed is when i put in a mechanical oil pres gauge i noticed two wires just chilling there near the stock oil press wires…Wondering if these could be important? if so wtf are they for. if i had the money id have my SR…unfortunatly i hav to live with my KA…but i cant live with this problem. im deffinatly looking at replacing the speed sensor but its working when i have this problem…my sensor works when it wants to…Would a engine diagnostic tell me exactly whats causing the problem or any shops sumone can recomend who knows there 240s really well?
Thanks -Devin
Removed the 4th and 5th gear sensors…fixed my problem??? No idea how that worked but now in third i can get about 5000rpm and i have no problems in 4th or 5th either…Whack and i didnt replace my speed sensor as of yet. Once i get my new one in there ill wire a switch to it get rid of the 180 fuel cut off.