Hi I have a 1997 Honda Prelude SH MT and it hesitates after it warms up. When the engine is cold in the morning, it is very responsive to the throttle. A better way to describe the hesitation would probably be, when I press the pedal all the way to the floor when the engine is cold, it jumps right away. However, if the engine has already warmed up, the RPM's sort of bog. Here are the list of the things that I have inspected and replaced:

Replaced spark plugs with NGK Iridiums
Honda OEM Distributor Cap and Rotor
NGK Spark plug wires
Denso O2 Sensor (noticed a great increase in mileage after replacement, but still not reasonable)
OEM Honda Fuel Filter
OEM Honda PCV Valve
Cleaned EGR Ports and Valve
Measured voltage of TPS at WOT and closed and it is fine
K&N Air Filter

I'm thinking this could either be a clogged cat, dying fuel pump, or the knock sensor as somebody has told me. But I'm wondering, wouldn't all these three throw a code if they're faulty? Because I'm not getting any codes right now. Hope somebody can help me because this is driving me and my wallet crazy.

 

anyone?

 

i went thru the same, changed it all. keeped bogging, do a compression test and im sure you'll get an answer there. mine had low compression on one cylinder and bad piston rings.

 

Do a compression test, as well as a vacuum test, the vacuum test will show you if you have an exhaust restriction. Dont cut a vacuum line, but just add a T at the end, and use a separate piece of line to connect a vacuum gauge into an manifold vacuum line and have the car rev'd to and held at 2500 rpm for 1 minute with someone in the drivers seat. Watch the gauge, if it drops as the rpms are held, then the cat/ exhaust system is clogged. If it doesnt drop look else where. :D hopes that helps, had to do that in my 2 auto classes already lol. :D