hehe well my civic isnt dying but its not exactly where anybody would want it to be.

Car stats:
1998 Honda Civic EX Automatic
D15B engine
Y8 atx tranny
Y8 ecu, wiring harness, intake manifold, and exhaust manifold.

Its throwin 6 codes at me.
P1256 - Manufacturer Contrl Fuel Air Metering
P1399 - Manufacturer Contrl Ignition System or Misfire
P0300 - Random/Multiple Misfire
P0301 - Random/Multiple Misfire Cyl 1
P0302 - Random/Multiple Misfire Cyl 2
P0135 - O2 Sensor Heater Circuitry Malfunction

Any ideas?

Some one told em that its either a vacuum leak or the O2 sensor took a dump. I dont think its a vacuum leak because Cyl 1 and 2 are the only cylinders to consistantly misfire.

To add to the twist, the engine will not start to misfire until after the car has warmed up (i.e. 10 - 20 mins of driving). If i start it up from a text book defined cold start, the engine will run fine. No problems.. then about 10 to 20 mins into the drive, the misfiring will start. It'll get to the point to where it'll misfire all the way up to around 4,000 rpms on the car's stock tach (havent check the VAFC since i hid it from view).

Thinking it would be the O2 sensor only, I'd floor it to force the ecu to switch from the O2 sensor to the MAP sensor and it would still misfire all the way up to 4,000 rpms.. the peak of the where it will misfire to is actually random but since i travel on the highway most of the time is it stuttering to 4,000 rpms..

Any ideas? Any help is welcome. Thanks guys!

 

Do you think your CEL codes and problems may be related to possible ECU/wire harness incompatibilities of the D15B engine swap into a 98 Civic?

Check your fuel pressure, as such misfiring problems can be caused by a clogged fuel filter or bad fuel pump. Also check components of the distributor (cap, rotor, coil) and the plug wires.

 

P1399 - Manufacturer Contrl Ignition System or Misfire
P0300 - Random/Multiple Misfire
P0301 - Random/Multiple Misfire Cyl 1
P0302 - Random/Multiple Misfire Cyl 2

Plugs, wires, cap, rotor should take care of those. Go OEM, don't buy generic crap.

 

Probably your # 1 & 2 spark plugs are bad / incorrect heat range.

 

Yeah do what mxs said first, and see if the problem is still there. Also reset the ECU and see which codes reoccur.

 

thanks for the advice regarding my ignition components guys. i had a tech from a honda/acura dealership tell me that P0135 meant the O2 sensor took a dump. I thinka combination of abadO2 sensor and badspark plug wires is causing all this. The spark plugsare OEM spec I havent messed around with them yet(I think they are NGK I'd have to check). I pulled them out the other day to check for any oil on them or if there was any damage done to them and all four seemed brand freakin new right out of the box!I really appreciate the advice tho thanks!!

RonJ, I dont think its the wiring harness incompatabilities. Aside from the intake manifold, the D15B sitting in my car needed NO wiring harness modification what so ever. It used the same sensors from the D16Y8. What made the swap feasable was using the old manifolds (i.e. exhaust and intake). I've been running that D15B for about 10,000 mi strong. I also do not think its a fuel problem because it happens regimentally. The engine's backfire is very predictable.

Thanks for the advice tho I will keep it in mind! Thanks guys! Any more help is appreciated

 

I don't think that an intermittent problem rules out issues with the fuel system, or even the ignition system. Furthermore, the O2 sensor problem may contribute to backfiring. In this regard, you definitely should solve the O2 sensor problem as it will substantially reduce gas mileage ($) and may damage your catalytic converter.

 

I've put that O2 sensor up there on the top of my To-Do list as faras all this goes. No point in blowin unnecessary cash on s/p wires, cap & rotor, when it can be used for that O2 sensor.