Recently I've been having a problem with the engine where when I hit the gas the engine will rev to a certain point, drop down about 500-1000 RPMs and then steadily rise like normal. It also seems like my throttle response isn't quite what it was before. About two weeks ago I installed the crawford plenum, and it was working fine, great gains int he butt dyno; until recently that is. However in the directions it claims that a way to tell if there's a leak is if the RPMs aren't steady. So basically I have to see what I can figure out later after work.. but until then, has anyone else had this problem? Also, does anyone know of any other possible causes that could be related? Hopefully it's nothing serious...

 

how is the engine at idle? A lot of intake leaks will make your idle unsteady.

 

it's not perfectly steady at idle, but it's not as bad as the problem I described above, it was like that at idle before the manifold though.

 

i had a similar problem, where i would rev up to 3,500-4,000 and it'll lag for a bit, then if i persist with my foot on the throttle, it'll go back up. It almost felt like a clutch-slip, so i took it to Nissan, and concluded that it was an ECU problem. They swapped my ECU for a new one, under warranty although my car has 65k miles on it. good luck.

 

I had this problem ... it was clutch slip. Once I replaced my clutch and flywheel it became normal again.

 

could be clutch slipping and not able to grab?

Opps, sorry, didn't see the reply above.

 

Yeah I'm pretty sure that's what it is after checking it out, my clutch lost the little life it had left after the 4 hours of traffic on the garden state parkway. I'm ordering the JWT clutch / flywheel package this afternoon.