240sx help rpm issue

[Rydellwipf]

So here's my problem I bought this 240 89 chassis with a 91 ka swap the engine is a auto because of the tps sensor has two plugs and has a 5 spd swap so here's my problem I start the car and go to take off in gear it won't go past 4 grand on the tach but in neutral you can redline the engine I talked to the Nissan dealer near me he suggested I put an 5 spd ecu and install the harness for the transmission so any help would be greatly appreciated only code that my ecu is throwing is 34 and I replaced the knock sensor already but it still throws it

[centralcoaster33]

I've had this problem! You are geting the top speed limiter engine cut out. I think. You're 5th gear position switch has been swapped with your neutral position switch. So, in any gear outside of neutral, your car thinks it's in 5th gear and it only allows like 115-120MPH which is around 4K RPM I think. So, get under the car and swap those two plugs. They are the only two that are interchangable and the others are keyed differently if I remember correctly. Please post back when you solve the issue and let us know the sollution. Others who search and find it will appreciate the information. Good luck!

[centralcoaster33]

PS - check the continuity of the wires going to your Knock sensor. There are several plugs along the way, so several points of failure are possible. Trace it back to your ECU. If you put the new sensor in correctly (which is a PITA IMHO) then it is likely the wire. It looks like two wires, but it's really just a sheilded wire and the thing grounds to the block I think. Or, you just need to clear your codes since you just recently installed it.