honda_fun

The car & motor is a 2001 Acura Integra with a B18B. Has 170,000km on it.

Recently the timing belt came off. It was replaced and a new water pump went in. The motor ran like new for roughly 4,000km. Lately my check engine comes on every 100km and my OBDII reader gives me codes 170 & 172 (Fuel Trim Malfunction and System Too Rich). There is no difference in the drivability, but a muffled noise has started to develop in the engine. The noise is proportional to the amount of throttle I'm using, not the RPM of the motor. When I clear the OBD codes, the check engine light stays off for a week before coming back on, but the soft knocking noise always stays.

I'm not sure if the muffled noise (which sounds like puttering or soft knocking) is related to the OBD codes ... So I may have 1 problem or 2. But I don't know where to go from here! Any insight or previous experience would be great. I have searched the forum and may be led to think it's the O2 sensor?

AWD Terror

Try to describe the noise a little better. A knocking sound can be cause under heavy loads by crappy gas among other things.

Try and run some good fuel injector cleaner through the system. Could end up being a cheap fix.

honda_fun

Thanks for the reply, I'm on my way out the door to try some cleaner.

The soft knocking sound is a puttering that starts when I push the throttle down at more than 50%. It sounds like something rotating. The sound is linked to the throttle, not the RPM of the motor. So if I am cruising at 3,000rpm with my foot off the gas I won't hear it. When I press the gas pedal down quickly the knocking begins even if the RPM is slow to rise. Because the sound is linked to the throttle I have reason to believe the low knocking noise is linked to my OBD codes 170 & 172 being thrown.

honda_fun

Have tried some fuel injection cleaner with no results. I might have had too much fuel in the tank which diluted the cleaner. So I'd like to burn off alot of fuel, and then try the cleaner again when with less than 1/4 fuel.

kronikSLOW

are your valves properly seating, or a lil bent by like a degree or 2.

honda_fun

When the timing belt went, I heard from many people that I may have bent valves. It makes entire sense now. The knocking noise and the fuel OBD codes could both be the result of bent valves.

Time to do some research on how to check the valves and fix the problem!

2001B18C1GS-R

any updates on this what solved the [problem