Guys need your thoughts on this problem got a 99 civic si running hondata s100 just standard bolt on right now. I have a check engine light on engine is running rough and bogging down. It has a o2 sensor code for the sensor 1. I swapped out the obd1 ecu and plugged in the stock ecu for codes of course the second o2 is showing up. But i bought an oem brand new o2 from honda for the downpipe and it's still showing up with that front o2 code and running rough intermittely any ideas?

 

i have the same problem...i just clear the codes everyday B4 i drive..gone through 2 O2 now...

 

Well i've got another o2 sensor coming from honda thinking i got a bad one. I've already tried to clear the code when i do it boggs down then throws the code again, so i hope this fixes it. It won't run right too even get out of my driveway.

 

I installed the new o2 sensor on friday bogged a little bit right at the start up. Then idle decent for about 15 mins. It was steady smoking the whole time not white it was grey coming out. After idling for a while it bogged down like it was going to cut off but didnt then idle jumped up not high but a little then straightend back out. It continued to bogg and smoke for at least 45 mins. I have replaced the o2 sensor, plugs,fuel filter. I have replaced the iac valve last year. There was a wire that had popped out of my conversion harness but fixed that too at a lost any ideas?

 

maybe your headgasket, somehow your spark plugs are getting fouled? have you been losing coolant? check our oil too a bad oxygen sensor will not cause your car to lose power or smoke, i ran without both my oxygen sensors and it never smoked, hope you resolve your problem

 

i have'nt checked the oil level yet. I did do a compression check got 180/190 across 1,2,3 but 4 is 155 the motor has 40k miles on it don't drive it much. the 4 plug smells like gas. Replaced the front o2 sensor that's all the scanner was showing that was bad. My buddie told me to check the map sensor. When i run it smokes constantly and had some rusty looking water underneath. I changed the coolant timing belt and pump 2 years ago.

 

I checked the oil level yesterday everything there is good. No coolant found in the oil. Checked the coolant level was ok. I swapped the map sensors from the oem si throttle body and started it up. Didn't change much bogged when first started then cleared up for about 5 mins then started idling like a v8. Buddie told me too check the coolant temp sensor? any more ideas guys?

 

Take it to a mechanic for a diagnostic? Seems like you've already thrown a lot of money and time at the problem.

 

I actually haven't spent any money on it at all just checking everything on it going over the basics. Got to get a new conversion harness that's a must. Can't get my car out of my driveway right now.