2 weeks ago........car started hesitating really bad.

opti is new, waterpump is new, spark plugs are new, wires are in good condition (dont see any burns), engine has been running perfect for a year. intake and everything is clean, no carbon buildup.

replaced fuel filter, MAP sensor..........didnt help.

replaced O2 sensors. reset PCM (disconnect neg terminal for 30 mins). test drive car and it still hesitates for 10 mins, then all of a sudden everything is fine.

this is where it gets interesting.................

now all of a sudden the hesitation is back.............at first i figure it was just the O2's dieing again, since all the autoparts store had in stock was crappy Bosch.

so today i unplug the O2 sensors, and disconnect the battery for 30 mins.

ive been driving all day and it still hesitates horribly.

someone tell me what i did wrong.........shouldnt disconnecting the O2s make it run open loop?

i do not think this hesitation problem is caused by the opti or plug wires, because 2 weeks ago i the problem went away after replacing O2's.

 

ttt

 

Disconnecting the O2 sensors does indeed put your car in open loop. However, the PCM is written to create a small driveability issue when in "limp home" mode so that you will get the car fixed. If the hesitation is exactly the same, then you probably have a secondary ignition problem. How old are the wires? How long did the hesitation go away for when you changed the O2 sensors?

 

i posted a thread yesterday where people said it would put it into open loop, thats why i did it.


the hesitation is slightly improved after driving all day, but its still there..............just not as frequent.

i have new plug wires on order.

last time i changed the O2's, the problem went away for 2 weeks, ran perfect, now its started hesitating again.