Bought car less then a year and half ago from second owner. The kid pretty much destroyed a show car in it's time so trying to make a decent running vehicle again.

My car is running extremely rich and getting about 340km/Tank which is horrible but considering was getting 200km/Tank when I got it, it's a good start.

The CEL was on when I purchased and code was coming back EGR valve and once replaced the light went off.

Was wondering if the ECU may be to blame for this? I've been told my ECU is rare and hard to find and haven't been able to locate one so if could be possible cause may try to get a chipped ECU that will work.

Would like to try and get mileage close to what it should be anyways as cost effective as possible.



1992 Honda Civic Hatchback VX
Motor: D15Z1 1.5L VTEC-E
ECU: P07
ECU Board: 02D01560-1500 H8Y-D



Parts Replaced and Mods Before Purchasing:
5 Wire Wide-band O2 Sensor (New within 6 months)
Distributor Cap (New within 6 months)
Catalytic Convertor Removed and Straight Piped from Down Pipe to Muffler
Performance Muffler
Cold Air Intake
Front Upper Strut Bar


Parts Replaced and Mods after Purchasing:
Main Relay to Fuel Pump (Used 3 Months Ago)
Spark Plugs (Replaced 3 Times Since Purchasing, Completely Burnt and Charred White)
Wires (Replaced 3 Months Ago)
Fuel Filter (Replaced 3 Months Ago)
Oil Filter (Oil Change 1 Month Ago w/ Lucas Oil Stabilizer Added)
EGR Valve and Gasket (Used 1 Month Ago was tripping CEL, not after replaced)
PCV Valve (Replaced 2 Months Ago)
Gas Cap (Replaced 1 Month Ago)
2g Positive Battery Cable Replaced
4g Negative Battery Cable Replaced
Energizer Battery Replaced
Valve Cover Gasket
Multi Grounding Cables
Voltage Monitoring Gauge
Vacuum Pressure Gauge
Instrument Cluster w/Tach
Short Throw Shifter
Front Shocks and Springs
Rear Struts and Springs



General Information
- Not leaking any fluids at all.
- Head gasket isn't blown
- No bubbles or shavings in the oil
- Need to add quart of oil maybe once a month
- Strong exhaust smell
- When engine cold exhaust smokes white, lessens as engine warms
- No misses or sputters when car is idling
- Idles high around 1000rpm
- Car sputters/hesitates at low rpm's occasionally between 1500-2400rpm, when sputters the cruise control light (don't have cruise control) in dash flickers in sync with the sputters, then drives smooth as can be when at higher rpm's.
- I can feel the VTEC engage after sputter around 2400-2500rpm's, but can't feel the second switchover at the higher rpm's, not sure if it's opening the rest of the valves or where such a small motor it's not noticeable.
- Don't seem to be any vacuum leaks and PSI gauge shows pressure changing as the throttle is pressed and released.



Any input on to what route I should take, or possible ways to determine exactly the issue would be appreciated. Far from mechanic, but know basics and electronics wiring. Have a couple backyard mechanic friends, but all seem stumped at this point.

 

Ill tell you right now I used to have thismotor and the gas mileage was never good we Maybe had the same problem but idk

 

Really? I guess when these motors are running properly they can get up to 850km/40L tank of fuel was told by the local Civic repair shop here but the next stuff to replace is starting to get very costly if can't pin point things.

Custom ECU website mentioned that possibly the wide band O2 sensor these use mixed with having the catalytic converter removed could be reason, but with the sensor pre-cat in the headers in my head there's no way that should cause it, but I'm far from mechanic, and if was me wouldn't have done a ricer thing like just piping it, would done full exhaust, but want to get car fully sound before dump money in to a hamster powered gas guzzler lol

 

I would check your ECT sensor, bad ECT sensor sensor symptoms, poor fuel mileage and running rich, especially if engine seems to run better when cold, [first started up] then once warmed up. 94

 

Changed ECT, looked like it was from 1992 :-P Gained a bit of mileage, but nothing considerable, maybe 20-30km. Is there any other sensors or cheap replacements that may have any effect at all on this?

 

I have the 94 of this car and its all bone stock at 127k miles with a lil bit of rust in the usual honda spots. that sputtering at low rpms im having the same issue. its a tube underneath the intake manifold that needs replaced. its used during lean burn mode at low rpms and it tends to be one of the first to dry rot. im in the us and i get rediculous milage with this car like 40-50mpg. i filled the tank and drove for almost 100 miles and the needle barely moved i dont think its even hit 3/4s full yet. im really really curious how the cold air intake and exhaust work did for ya. thats what iv been curious about doing. the cold air intake im curious about if you can hear the vtec better with it. i used to have a 2000 accord with a 3.0L vtec and when i put on a short ram when vtec kicked in it got really nice and loud and kicked nicely. for the exhaust im not sure what to do with it yet. to either put on a catback system or just an apexi n1 4" muffler on the end. just want to enjoy the vtec, enjoy the gas milage, and give it that ricey sound as well. that strong exhaust smell if you find out about that please repost. my 89 crx dx i recently sold had that issue i had no idea what was causing it.mine idles like that as well. my guess was gunna say what about the IAC valve? also i didnt know there was a second switch over.all i read was that vtec kicks in early cuz its vtec-e for economy to achieve better fuel efficiency and that its not the same as actual vtec, although when driving it damn near feels like it. sorry for all the miles per gallon such idk how to convert or anything just saying from my perspective.

 

i hear the only the denso oem 02 will work my new less than a year old 02 is shot and am getting crappy milage as well. No check engine light? take out 02 look and see if cat is plugged as well.

 

try replacing the TPS sensor, if it isn't working the ecu will run on a default mode and the motor will run rich. usually there's a check engine light though, but you never know.