Rough Idle---Help

[FknBuZZard]

Ok, so I installed new timing belt and pullys, and a new injector. the car wants to idle between 500-1200 rpms, It backfires (the exhaust is off.....Previous owner...) Seems like from 1000-2500rpms is rough when driving, but 3000 and over it runs like a bat out of hell. Ive been tinkering with the idle control box on the side on the intake, but now it idles at 1200rpms, if i adjust to go lower the rougher it gets when idleling. I also unplugged the o2 sensor right behind the motor. didnt make any difference, nor did it set off a check engine light. I put 3 gallons on racing fuel in to today hoping maybe an injector was clogged or something. still no difference. and kinda scared to do a compression check cause if a cylinder is F'd thats really going to put me in a bog, Any suggestions? maybe starting with the cheapest fist, being that im a cheap a**. Thanks Everyone for your Help!

[FknBuZZard]

Ok so I did a compression test. Compression is between 168-175.

[Ace2cool]

Compression is great then.

Hm, might be a vacuum leak. Possibly a faulty IACV.

Have you tried to check the O2 sensors using mode II on the ECU?

Have you set/checked your timing? 3000rpm is where the VTC solenoids advance the timing, so if there is a timing issue, that's where it would "clear up."

[FknBuZZard]

Not sure how to check 02 sensors using mode II? Yeah i forgot to check the timing after i had replaced the belt.... but i did align all cam gears and everything else where it needed to be. Ill try the timing and see, thanks

[FknBuZZard]

Ok so I have good vaccum, I ran mode 2 to check the left and right o2sensors, the right is fine, the left is saying its lean. so i ohm out both sensors and got 6.2 for both.. where do i go from here? replance the left o2 sensor? also the car will idle fine when cold, just when it warms up is when it starts acting up. only code i got form ecu was 55

[nissanfreak12]

Before you do anything, or even put money toward the car, set your timing like mentioned by Ace. You want to use a timing light and set it to 15btdc. Then you want to may sure your TPS(that little black box you have been playing with) is properly set. If the idle is bouncing like your saying, more than likely you have a vacuum leak. Easiest way is getting carb cleaner and spraying over all vacuum lines and intake tubes.

How did you check your vacuum to know you have good vacuum?

[FknBuZZard]

Ok guys, I figured it out, the damn gasket for the phlenum wass all tore up.. i sprayed starting fluid around the gasket area and got a rev of the motor.. so i pullled off the phlenum and got all that straighted out, its idleing alot better now, but still alittle jumpy, I used a vaccum gauge on the cross member thing thats on top of the phlenum, read somting like 15.... On the Left side. I also found a hose on the left side bottom of Phlenum not connected. So now im going to TRY and get it back on, U cant see metal tubing where it hooks up. So its going to be a challenge to get my dic skinners on it. Yeah Timing was dead on 15