sc400 won't rev past 4000 rpm

[soneencris]

I have a 92 Sc400 that will not exceed 4000rpms in any gear and neutral. I have changed the ECU, checked fuel, changed one ignition coil, changed AFM, and o2 sensors. I have searched and found some with similar problems, but none with solutions. I also checked the EC1 plug and thats good. If anyone could point me in the right direction it would be greatly appreciated. I do not have a CEL, and it has the W58 conversion. The problem was there before the swap, but I thought it could be transmission related. SO I did the swap anyway.


Thanks,
Chaco

 

[samsdad]

Check that the oil level sensor for the Hydro-fan is plugged in. It's on the radiator by the airbox then clear the codes (it will have code 56 in it)

 

[spf_lexus]

Check to see if your fuel regulator has not failed. If it has, it would not supply fuel at high rpm. Check your base fuel pressure also, base should be 40-45psi at idle.

Can you add some details of whats happening at 4k? Sounds, smells, feel?

 

[soneencris]

Check to see if your fuel regulator has not failed. If it has, it would not supply fuel at high rpm. Check your base fuel pressure also, base should be 40-45psi at idle.

Can you add some details of whats happening at 4k? Sounds, smells, feel?

The car just tops out, and won't go any higher. In neutral it seems like it is floating the valves, but not so much when driving. I can get to about 3800-4000rpm before it feel like I am about to break something. Every now and again I get a rough start and rough idle, but it is not that often. Besides that you would never think anything was wrong. How do I check the fuel pressure? Does bridging fb and B+ do anything, because I did do that, but the probblem persists.

 

[cuzzo]

air filter restriction and spark plugs replacement.

 

[spf_lexus]

You would be better off taking the regulator off and testing the diaphram with a vacuum tester.