Have a 91 civic Si with a b16a swap in it. Car was not starting a few days ago, turned out to be fouled spark plugs (all of them). Replaced them and the car fired up and ran great for about 5 days. Now the car will not start again, plugs appear to have already been fouled out. I also am only getting 13-20 mpg. Here is my question

I know that this car has a bad o2 sensor (check engine light code points to it). Could a bad o2 sensor really be the cause of this poor gas mileage and how quickly my spark plugs are fouling? The plugs were coated with carbon, not oil. Engine does not leak or burn any at all.

What else could it be? Dizzy? Dizzy cap? PCV Valve? Fuel injectors? Fuel filter? Any help would be great appreciated, I am stump.ed

NOTE: Problems appeared to begin happening after I adjusted my FITV and cleaned my IACV. Could this be related at all? Came to this forum as a lot of you out there are much more experienced than me! Please help!

 

if you are obd0, there should be 2 oxygen sensors. you need to get the check engine light off before it will ever run correctly. i don't think your FITV or IACV would foul it so bad it won't start. sounds like there is another problem.

 

I agree. How do I know if i am ODB0? I swear my car only has 1 O2 sensor.. any help on locating them both would be nice.

I also agree that the FITV/IACV would not foul it that bad, but do you think the issue is related to the faulty o2 sensor(s) or that there is a deeper problem? I'm also going to replace my PCV Valve.

 

Also, could I have a bad fuel regulator? Also, it appears my fuel regulator has a dial to the left of it. Could this need to be adjusted? The guy who owned it for me was going to boost the car.

 

probably running too rich. there should be a psi gauge near the fuel regulator, i believe you want to be around 35psi. you need to look at the ecu and/or the distributor to see if it's obd0. post pics if possible. there would be 2 oxygen sensors right in front on the header near the head. if not, you may have an aftermarket header, or it's obd1. does the sensor have 1 wire or 4?

 

first you need to tell us what ecu you are running. help indentifying your ecu here
http://www.hondata.com/techecuid.html

secondly, you need to fix your o2 sensor problem. it is definitely the cause of your gas milage and spark plug issues. the sensor could be bad or it may not be wired properly to the ecu, etc.

are you sure? i can only find 1 o2 sensor for obd0 systems (in the exhaust manifold). and i know for sure obd1 only has one o2 sensor


sounds like an aftermarket regulator. you need to either swap back to an oem regulator or adjust the fuel pressure to the proper setting. pretty sure its 38psi w/ vacuum disconnected