help!my fuel consumption going craziieeeee!

[myupgrade]

hi guys,

I own a Honda Civic EK which previous owner had installed a turbo on it. The piping was set at 2.5 inch (normal for a turbocharged engine) and I was not realized (silly me) on the diameter.

I normalized my civic (uninstall the turbo - only B16a) and have it tuned to get more milage. However, I completely forgotten about the piping size until I went for a regular check.

Quickly, i changed the piping to 2.3inch, but surprisingly, my fuel consumption went crazy..even for half tank, I've a\only managed to get less 200km without activating even 1 v-tec!

does the mapping of the ECU corelate with piping diameter adjustments to create such problem?if yes, why?

please help

myupgrade

 

[shiroitenshi]

the engine makes adjustments based on the o2 sensor (other than IAT and MAP), I don't think they ever took pipe sizing into account.

Usually fuel consumption goes to hell when you have a compression loss, due to valve sealing, piston ring etc.

Check you compression numbers, and if it's normal, then only suspect the fuel mapping. or it could also be that your 02 sensor decides to crap out at the exact moment you changed the piping.. hard to say.

Most of the time, the tune will run true, it's the external factors that are a variable.

And closed loop part throttle systems rely heavily on the o2 sensor, so any problems there will result in poor mileage, leaking valves and pistons rings may play havoc with the readings the o2 sensor is getting, and it will adjust fuelling along.

Since it's a turbo, it's also possible that the previous owner has the the ECU chipped to run open loop, in which case that may also be a possible cause.

 

[myupgrade]

hm..
i'm not sure..in this case, i'm using mapping-ignoring O2 sensor (open loop)-i've problems with O2 sensor..

and i dont think i have problems with seals since recent block change..

 

[shiroitenshi]

I thought so.
if you run open loop, then that's your problem. 02 sensors are good for FC and emissions, but little else. if fc is a concern, get a 2nd hand o2 off the junkyards and go back to close loop.

02 doesn't ignore ECU maps. What it does it make sure there are no changes made to injector duration no matter what other sensors like IAT are getting.

So there's no 'fuel trim' that happens after the initial map from the ECU.

Intake pressures at part throttle change when you change piping, and without 02 sensor to correct it, your MAP pressure will be different, and the ECU will read off a different part of the map based on the MAP. I tested this by tapping MAP sensor and IAT signals to my datalogger, and using math formula to calculate volume.

No choice but to retune, bro, unless you go back to close loop, which is the best for fuel savings. of you could swap back the pipe. bigger pipes don't really affect flow much when they're connected to the stock header.

 

[myupgrade]

hm..another question to ask..

I've retained the "tabung", n only changed the diameter of the piping..is the huge "tabung tengah" (mine turbo-sized) also played part in the problem?

 

[shiroitenshi]

hm..another question to ask..

I've retained the "tabung", n only changed the diameter of the piping..is the huge "tabung tengah" (mine turbo-sized) also played part in the problem?

The ECU won't know what exhaust you use.. what it knows is what vaccuum pressure it will see at part throttle.. and if you want FC, put back the o2 sensor.

But sometimes, if FC really bad, it points to other problems (compression loss/valve leak) other than the tuning.. so it pays to check.

Tabung tengah, I dunno. never rojak exhaust parts before. usually just use the complete set.

 

[evoX2]

how do i know if my current chipped ecu is running close or open loop?

 

[shiroitenshi]

how do i know if my current chipped ecu is running close or open loop?

tap a voltage meter to D14. stoich is 0.5V. You need a fairly expensive multimeter or a voltage meter to see the voltage cycling. Most normal meters are too slow to detect the voltage cycling. Some people built circuits to detect it but it's not so easy to do, unless you have background in electronics.

 

[J101]

since it was a turbocharged car before, why not check :

1. the injectors? prolly its running some 400cc or god knows what size

2. open up the ecu and prolly it has been chipped

3. if your o2 sensor is having problem, the check light is on but then again since its chipped thats why theres no error code

4. prolly some supra twin turbo fuel pump inside your tank

 

[shiroitenshi]

since it was a turbocharged car before, why not check :

1. the injectors? prolly its running some 400cc or god knows what size

2. open up the ecu and prolly it has been chipped

3. if your o2 sensor is having problem, the check light is on but then again since its chipped thats why theres no error code

4. prolly some supra twin turbo fuel pump inside your tank

Yeah, forgot the injectors & fuel pump.. but since he said it was retuned already, should be ok... lucas disc type injectors has faster response time, so shouldn't be so bad. If he's using H22A, shouldn't be that big of a difference.

Higher rated fuel pumps can run on stock engines, just need to compensate at the fuel regulator.

This is a first time I've heard of people detuning their ride, lol..

 

[fobs]

This is a first time I've heard of people detuning their ride, lol..

haha! thatz a good one,...
i'm also particular abt my fc,...

bro threadstarter,
can u accurately measure ur FC??? so that we, if not i will tell u whther itz really crazy or not. If u are getting 16-18sen/km based on current fuel price of rm1.92/litre, u're still ok,...

do u know how to measure ur fc accurately? the fuel gauge from F to middle is NOT equals to half tank, for ur info,...

fill fulltank,... reset trip to zero,...
run till almost E
fill up fulltank again,...

amount of money divide by km = FC which is sen/km

 

[eg9_05]

this is crazy men....my car eat me 0.25sen/km.......
i pump rm60 fulltank every time n it can run approx 230-240km untill the fueltank light on.
isit normal fc on my eg9 wit h22a????

 

[fobs]

this is crazy men....my car eat me 0.25sen/km.......
i pump rm60 fulltank every time n it can run approx 230-240km untill the fueltank light on.
isit normal fc on my eg9 wit h22a????

as we've discussed in myhavoc abt fc and i can average out how a h22a accord consume petrol,...

abt 23sen/km normal driving
abt 30sen or more for vtec all da time driving,...

fuyooooooo bro,... eg9 with h22a!!! can fly mangggggg!!!

 

[myupgrade]

hm..

possible 20-21cent/km (daily driving-no open v-tec)..too much laa...should be around 15-16cent/km..

 

[fobs]

hm..

possible 20-21cent/km (daily driving-no open v-tec)..too much laa...should be around 15-16cent/km..

yup ideally 16/17 sen,... ur b16a auto? i had an sr4 previously, engine was out of tune, 20sen++ also,... 1.6 manual,...

sold already.