Technical Topics specific to the Hatchback body - NOT where you post pics/build specs of your car.
By filipeg
#359174 Hello forum members :) I hope someone will take the time to read my problem and i hope you will understand my english.

I bought a 94 eg with d15z1 with 90 hp (i guess its VX in USA, i'm from Europe). The previous owner said that check engine light was on for a few months and i assumed the EGR was clogged and I liked the car since there arent many of vtec-e around here so i just bought it with the CEL on :P Since then, a year passed, i still havent fixed it.

It wasnt on all the time. If i started the car when cold, it would usually appear after first gear shift of before. But if it was at working temperature, and then turned the car off and on, cel was off for as long as I-read carefully now-kept accelerating. When i released the gas pedal (in whatever gear) and started decelerating the cel would come instantly on. The interesting thing is that if i accelerated with no cel on, and then put it in neutral before releasing the gas pedal, cel wouldnt come on. So, basically i could drive like that (turn off/on the car when at working temperature,and when driving put in neutral before releasing gas pedal) without cel on. Another interesting thing, when driving without cel on and holding it at 1500 rpm, it would (i dont know the appropriate word so i'll try to explain) act like i released and pushed the gas pedal and repeat that fast. But only at 1500 and if i would pushed the pedal harder, it would just accelerate further. But!! When the cel was ON, this wasnt happening. I could drive at 1500 without the mentioned "recoil". With or without cel, car runs rather fine, no issues at all (except the fact that when hot, sometimes i have to wait to turn the car, guess its main relay), mpg is fine (cca 6 L/100 km, dont know how many mpg that is, but i think its just fine since its mostly city driving and in "red zone rpm" on daily base). I passed the exhaust gasses check with no problem.

First I have read the cel code 48-lean air fuel. It was the only code blinking. The fuel pressure was 1.5 bar with throttle, so I replaced the fuel pressure regulator and the fuel pump. The pressure was then ok, but cel still on. I got my hands on another O2 sensor (worked without cel in "donor car"), but cel still on. Then another O2 sensor, again no change. TB and EGR were cleaned, IACV, MAP, temperature, everything replaced or cleaned. Tried another airbox, even with no airbox. Timing belt is installed properly. And after all of that, the 48 still shines on my dashboard. I dont know whats left to change or check other then trying ecu from another vx, but i guess it the ecu was wrong, the car would run good at all (but im not an expert).

To be honest, i stopped being worried about this and continue to work on car. Another interesting thing. I replaced my original 4-1 header with cat in it with 4-1 header without cat (from d14a3) and putted the whale penis intake and the car continue to act like before. A month ago, i installed 4-2-1 from D16A9 and now the cel is on all the time. But mpg and everything stayed the same, so fuck it.

If there is someone who has some advice, please share it. Like I said, it doesnt actually bother me anymore that much because i wasted to many time on fixing it already :P , but it would be nice to get rid of that issue.

Thanks in advance :)
User avatar
By TrailerTrash
#359175 bit of an odd issue id say

I found this
http://honda-tech.com/honda-civic-del-s ... e-2976740/
it might be helpful

from what im getting from a few threads i browsed through, it could be the o2 sensor or the heater for it.

good luck dude :thumb:
User avatar
By suspendedHatch
#359194 Check your fuel pressure and fuel pressure regulator. Replace your fuel filter if it hasn't been done. Have your injectors serviced. Confirm all the parts are correct on the car. The Z1 is peculiar with parts, and even the parts stores get it wrong. Wrong spark plugs, wrong O2 sensor, wrong distributor, wrong thermostat.
There are wideband O2 Z1's and non wideband. The O2 sensor has to match the ECU.
The distributor is the same as the D16Z6.
The spark plugs are a different heat range than all other Civics. The thermostat is a different temperature. Neither of these things will cause something as drastic as what you're going through, but should be checked after you've got your problem solved.
User avatar
By suspendedHatch
#359195 cca 6 L/100 km works out to 39mpg, assuming you're calculating it right. You use the odometer, not the fuel tank size.
39 is not good for a VX. You should be getting 45-48.
By filipeg
#359228 Thanks for advices!

Fuel pressure was ok after changing fuel pressure regulator. Fuel filter has been replaced when i bought a car, so that means 20 000 km ago. Spark plugs are correct, i got the "serial" number from Service manual when i replaced them. This O2 sensor thats currently in the car, was taken from another D15Z1 which was sold for parts because rust ate him.
Haven't checked the injectors and distributor!

Hmmm, if I got it right, 6 L/100 km is the same as 39 mpg for US, but for UK its 47 mpg O.o

The plan is to get multimeter and some friends to check O2 sensor by following the scheme in service manual.
By Kentexian
#6909147 Necromancing this thread!

@OP, did you ever get a resolution?

I have a stock VX that is throwing 48 intermittently. My mpg is in the 30s and the idle is STUPID low, like 100-200 RPM.

The feeling like Im about to stall at stop lights is the real annoyance. I too have tried just about everything I can think of except injectors, thats next on my list.