InTheZoneAC

iTrader: (11)

So my sister is learning to drive and I found this 98 civic lx auto for $2000. I knew about some issues that were easy fixes that I took care of already like a common crack in the header/02 sensor area.

Literally a day after I get it I get a CEL for P0170 Bank 1 Too Rich. Well I do the usual tune up after getting a used car such as:
-changing/gapping spark plugs
-new plug wires
-new air filter
-change engine oil(pennzoil ultra 5w-30)
-new oil filter
-new transmission oil(amsoil ATF)
-new coolant
-new thermostat
-new fuel filter
-new gas cap

Every day it's 50/50 with the car starting fine and others being hesitation while starting up like it's bogging or simply just won't start.

And when the car does start it runs like a champ, perfect idle, smooth shifting. But the hard part is always the starting, wheter after a cold start sitting overnight or a warm start after coming back from being in a store. Sometimes it starts perfectly, others not so much.

When it doesn't start I check for spark by pulling each plug wire and testing each one with a new spare spark plug. Sometimes there's spark, sometimes there isn't.

So when I check the plugs after a no start they have excess fuel and that would explain why I get a code for running rich and would also explain why it won't start, too much fuel to ignite.

-I know the main relay isn't bad because it gets fuel.

-I have bought a new distributor because the old one had a stripped bolt that holds the cap to the casing and would have a gap. New distributor has an air tight seal where the cap sits along with a new coil pack and ICM(which was also tested good at a local autozone).

-I also replaced the ignition switch in case it was intermittent.

-All fuses check good, fuel pump primes like normal when you turn it on.

-I have also replaced the fuel regulator and all injectors.

Only thing I have not messed with is the ECU itself. I'm not understanding how a good gas gap, fuel pump, main relay, injectors, fuel pressure regulator, distributor, plugs and wires can still cause the car to run rich.

I also replaced the primary O2 sensor when I replaced the broken header/catalytic converter because I had a CEL for that as well, but not anymore.

I have not touched the secondary O2 sensor that sits AFTER the converter as I don't think there's a problem with that or how it's even related to spark plugs not igniting upon start up.

If this car ever gets running like normal it will last forever with all the new parts I've bought for it.

Please help, I was hopeful all the previous stuff I've done would've fixed it and I'm tired of dealing with this cars start up issues. Remember, sometimes it doesn't get spark on a good new plug and that excess fuel will build up on the plugs that are installed.

I'm thinking the ECU could be bad, but wouldn't something go completely bad instead of being intermittent if it was related to the ECU?

I thought it would be easy getting this car running for her, as she's going to need it for school soon, but it's being a real PIA.

Former User

Any other codes?

If you reset the ECU, does P0172 return?

Have you measured the fuel pressure and tested the FPR?

Have you checked the valve clearances?

InTheZoneAC

iTrader: (11)

no other codes but bank 1 too rich/fuel trim

I have not checked the valve clearance. Timing belt was replaced by previous owner a couple years ago, which was probably < 25,000 miles, assuming everything related is good, but I guess I can check.

As for the code, it doesn't always come on. Yesterday I drove it around 25 miles, no CEL. This afternoon I start it, warms up, p0172 comes on.

I have not measured the fuel pressure or tested the FPR. I know there's a vacuum line to the FPR, but don't know what I need to do to test it.

Former User

InTheZoneAC

iTrader: (11)

thanks for the replies. I will check the pressure. I don't think the FPR is faulty as it is brand new from Honda.