hi, I have a 98 civic ex coupe d16y8 5spds with 167,000km, aem cai, catback exhast. my engine threw a CEL today with fuel running too rich. Anyone know what could be wrong? Could my EACV (electronic air control valve) cause to throw a cel? Honda said it might be the fuel pressure regulator, but other mechanics said it would be something else, most likely not the regulator. Any idea? Please help.

Also my rpm had been weird lately, everytime i go into neutral, the rpm would drop to like 800rpm, then jumps back up to around 1150rpm then would go back down to around 800rpm.
Is this normal or is there something wrong with it.

I had replaced the following part,

Primary / secondary O2 Sensors
Map sensor
TW sensor
Resonator
Alternator
Spark plugs and wires

Thanks you!!

 

it seems more likely to me to be electronic. but then again you got a lot of NEW electronics so thats a tough one.....

 

most likely a rich condition would have something to do with your Fuel system. I would check your fuel pressure regulator, injectors (could be leaking) and your EVAP purge controll solenoid, (stuck open or leaking).

 

how do i check these stuff?

thx

 

i actually found out that the CEL comes on when the weather is hot, i can actually tell when the CEL will come on now, whenever the weather is hot and when i put the gear to neutral, the rpm drops then it will jump back up about 500 to 1000 more rpm. Any idea guys, thanks for the help.

thx

 

What code is it?

 

i don't remember, but its the code that said "Fuel metering too rich or lean" so i went to honda and check from the honda systems, it said "Fuel metering too rich"

thx

 

Next time your CEL is on, do this.
http://www.c-speedracing.com/faq/06.php

 

I don't know how to attach the scanned page but heres what needs to be done. The helms manual states if there is a DTC of p0172 (45) system too rich. Here are the propable causes.
fuel pressure clogged, stuck open
fuel return line clogged
fuel injector leaking
gasoline doesn't meet owners manual, (specified octane reading)
primary o2 sensor
MAP sensor
EGR
EVAP purge control solenoid valve leaking
Valve clearance.

Heres the procedure to check:
-Cheak fuel pressure. (you'll need access to some type of fuel pressure check gauges if not, you'll need to go to a shop.)
-if pressure is within specs D16y8 (38-46 psi with vacuum hose disconnected)
check primary o2 sensor.
-if not within specs-pressure too high-check fuel pressure regulator and return line. high pressure will cause rich conditions.
This is as far as you are capable of doing. the next steps will require you to have a scan tool.

I would recommend having the dealer diagnose the problem. They will hook up the scan tool and drive it in the condition that throws the MIL and take a snapshot at all the sensors. Thats the quick and easy way to look at all the sensors and figure out what is happening when the MIL comes on. The other route is you could go changine parts unless you have access to a scan tool.

I would assume the o2 sensor is dirty and not reading the oxygen level correctly.

 

I just replaced both my O2 sensors less than a year ago. Could they be broken already?

also, could the EACV or can be called (IACV) be causing the problem?

i will check out the pressure tonite.

thanks you.