My engine light keeps comin on. ecu shows code 1, changed o2 sensor and nothing. reset it and nothing. the light comes on usually in 4th or 5th gear after driving a bit on the highway. So, I turn the car off(while in motion)and turn it back on like five seconds later and the light is off. when the light is on it hesitates a bit like a bad fuel pump but only under 2500rpms, above that its fine but gets awful gas milage. when i restart the car it runs fine and sometimes the light doesnt even come back on. really dont know what the problem is so if anyone could give me an idea i would be very greatful

 

The ECU isn't seeing any activity from the 02 sensor. Shutting down the engine and restarting resets the system for a while. Check your wiring from the sensor to the ECU for continuity. Make sure the sensor itself is working, too.

 

Sounds like cheap gas syndrome.

 

I dont think its the sensor, been replaced less than 6 months ago. Ill check the wiring, but you think a fuel treatment might help a bit. heard something about a ground on the thermostat maybe a problem... enlighten me

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by xisda1 &raquo;</TD></TR><TR><TD CLASS="quote"> heard something about a ground on the thermostat maybe a problem... enlighten me</TD></TR></TABLE>
unless you ever took off the engine harness it should still be hooked up it will run like crap if that ground isnt grounded. its on the thermostat just folow the lower radiator hose to the motor and youll see it.

 

redo all of your grounds, see if it helps, it did in my case

 

as a matter of fact i had to rewire the whole thing (dpfi to mpfi). Does the ground wire come out of the wiring harness or does it just connect directly from the thermostat to the frame

 

harness

 

check the ground around the wire my buddy had the smae prob and the ground wire that wraps around the actual o2 wire just one little strand was touching and made it not orkne more.

 

i had a perfect idling and running b16 then I installed a p30 IM. threw code 1 while cruising in 5th.
tried 3 different o2 sensors. still got code 1. then the car sat for 7 months with 3/4 tank of 93. still throwing code 1 with old gas. after i finished the tank, i picked up some seafoam and ran 1/2 of it through the brake booster port, 1/4 in the oil and 1/4 in the gas. haven't thrown a code 1 since. hth.

 

thanx folks Ill let ya's know whats happens