I have quite a few problems. First of all, I'm 2000 miles over an oil change, Let's just put that on the table. My problems include:

*rev limiting at 4200 RPM, with MAP unhooked reached 6200rpm but had definite knocks in the pistons (REAL bad timing)
*idle shakes like you've never seen before. I mean I'm talkin about like the vibrating beds at the motels that shake vibrate.
*I have been gettting EGR CEL engine codes but they've gone away after some re-routing

Help me with my celica. I know for a fact that all four mounts need to be replaced (162,000m) that would probably eliminate the shaking. I did also notice that my #1 fuel injector seemed to fit very "loosely". Could a faulty injector be the problem? Help me out 6gC Buds

Also, unplugged the O2 Sensor with no noticable difference.

Without the MAP sensor, you will be running either too rich too lean. Your ECU can never tell. It also controls your ideling. Hook it back up! ASAP!

Mounts don't need replace unless they are torn, damaged or broken. Do not fix wat is not broken.

i'm no expert but i'd check the timing belt, it might've skipped and needs to be replaced, also double check the timing on the distributor.
If i were you i'd park ur celica before you cause some more serious damage

maybe, I dont know, change the oil while you're at it..

Check sparks, plugs, wires, cap, rotor...

ok guys... I changed the oil, changed the transaxle fluid, changed the spark plugs, changed the plug wires, and gutted my catalytic converter. Still no change. I tried hooking it up to a 2 bar map sensor off of a all trac and it ran fine but still would not rev above 4100 rpm. Now this brings me to the conclusion that it must be fuel delivery system related.
I checked my injectors one by one and the first injector felt a bit loose like the O ring might be weared so i ordered a new O ring set. Another thing I'm going to go ahead and change is the fuel filter and pcv valve. I know that my PCV valve has 162000 miles on it so I'm going to try all of these things and if I have no avail then I am sorry but I would be forced to sell off the celica and leave the 6GC club which I don't wanna do. Does all this **** I'm doing sound like im on the right track or am I pouring money down the drain?

wow thanks for all that useful information!

when and how did this 1st start. you said the motor knocks?

your oil was very old, but how what the oil level at that time?

have you checked the ecu for codes?

well #1 you SHOULD NOT be driving or reving your motor with the map sensor disconnected.
#2
sounds to me like a bad ignitor connecton.

I agree, having ur revs limited is not fuel delivery problem, thats an ignition problem.

Right now I have unhooked the exhaust directly from the bottom of the catalytic converter just for the sound.... kinda like open header sort of thing. What happened is one day my engine was running fine and then the next day I am experiencing a high Idle ~1200 rpm and the fact that it won't rev past 4100rpm. I replaced a rear motor mount which made me happy but I'm not so sure that I want to put more money in this celica... 6gc guys: does this sound fixable? what should i check (using a multimeter)? Thanks in advance!

give us some details about your car, it helps a bit.

check your codes...if its the ignitor it will thow a code. could also be an old cap and rotor.

when was the last time if at all the timing belt was replaced?...if it has never been replaced it might be worn down and messed up. it is also good if u dont know when it was replaced if at all to go ahead and do that anyways just for regular maitenence

The timing belt cover has been warped and the gasket between the timing cover and the engine. there could be some dust/dirt build-up... but I dont think it's that. I think it's electrical. I took off my distributor cap and saw a small amount of carbon scoring around the inside of the cap. where should i go from here? I know there has to be a good amount of certified mechanics on this forum so please help me out! thanks

like art said, id start with a new cap and rotor, cheap enough.

sounds like that migh be your problem ...get a new cap and rotor and report back