one800bobby

Guys my 88si Rex is doing something different, my car is idling up, and down like crazy, but the funny thing is when I turn my A/C on it stops, but thesecond I turn it off the idle starts again what do I do and what do I look for..

5_LiTeR_EaTeR

okay whats goin on has little to do with the a/c. Alot of people come in the shop and say my a/c is bad because when ever I turn it off or on it makes the motor change conditions. What really is happening is something else is wrong in the system obviously because its surging. Well the a/c does is when you turn it on it engages the a/c clutch and pull some hp off the crank and smoothens it out a little bit. what I would check is 1 of 2 things. First its very possible it could be your o2 sensor. A bad o2 sensor will send the ecu a bad reference signal based on the burned fuel mixture in the exhaust. If the sensor is a little bit plugged or old then it will read either lean or rich CONSTANTLY and be sluggish. I said constantly because an o2 sensor is suppose to switch from rich lean rich lean rich lean and etc... and that means its trying to balance out the fuel mixture. When it o2 goes bad it becomes sluggish and will read either rich or lean for a period of time then switch over. When its good it will send back the reference signal back to the ecu and tell it to either enrichen or lean out the fuel mixture. If it not that than I would next check fuel pressure. A fluctuating fuel mixure would most definately make it surge but most likely its your fuel filter putting a restriction on fuel pressure. If either of those work then try back with us.

-Alex

one800bobby

AL, thanks for writting. well it's kinda dark outside and I can't work under the hood, but I'm gonna change the O2 sensor. Why cause I knw it's not the fuel filter cause it's just been recently replace about 2wks ago when I had the timing adjusted to the proper setting, but which O2 sensor do I change? just tell me where it's located. al thanks..

88crxSi

located on the exhaust header. Also, mine does the same thing. I notice it drops alot when I turn on headlights too...anybody on that? Electronic Load detection messed up?? or O2 ??

91rexBUG

u know...i had a motor that did that once...it kept surging from 1300rpms to 2200rpms consistantly....turned out to be a vaccum leak...strange things...i found mine by spraying starter fluid around all the vaccum lines and ---- like that...then it makes the engine rev up real fast and theres ur leak...but that was my problem....maybe ur's is different.