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Fuel consumption - S2000
meewisse - 15/11/14 at 02:15 PM

Hello Locostbuilders,

We do have a problem with fuel consumption in our seven with S2000 engine. Except fuel consumption we have also the problem that it is not any more road approved by the MOT (APK in the Netherlands). They are saying that your lambda should be 1 and CO should be 0.35. Idle and on 2500 rpm.

Our mileage is 14 mpg or 6 km/l. Our seven is a VM77 around 600 kg. Engine: Stock S2000 engine with custom wiring loom and ECU from KMS Motormanagement. Tuning was be done with a lambda of below 1.00. We drive it with lambda control turned off.

Results from the Exhaust test (idle):
CO: 6.8%
HC: 225 ppm
CO2: 5.3%
O2L 6.2%
Lambda 1.06

What did we have already tested:
Compression OK
Injection OK
Valve timing OK


Any suggestions what we can test more?

Thanks!

Ivan - 15/11/14 at 03:48 PM

I am no expert but all your readings including your fuel consumption seem to indicate that your mixture is way off.

Have a look here:

www.autoshop101.com/forms/h56.pdf

or google "High CO2 reading at idle" or similar.

[Edited on 15/11/14 by Ivan]

Ivan - 15/11/14 at 04:26 PM

Your O2 seems very high maybe implying the things are too lean and if you have it the knock sensor is retarding the heck out of your ignition causing all your problems. Are you using a wideband lambda sensor?

theconrodkid - 15/11/14 at 04:27 PM

way too rich,try measuring the values of temp and lambda sensors and is the thermostat working ok,engine getting up to temp

meewisse - 15/11/14 at 04:35 PM

When looking at lambda (from ECU but also from different gas-analysers) and O2 you wouldn't say too rich...

Thermostat is working good. We have two temp sensor and engine stays at around 90C

No knocking sensor. We will check timing tonight with stroboscopic lamp.

EDIT: Timing is stabile. Ten degrees of pre-ignition at idle

[Edited on 15/11/14 by meewisse]

MikeRJ - 15/11/14 at 06:24 PM

quote:
Originally posted by meewisse
When looking at lambda (from ECU but also from different gas-analysers) and O2 you wouldn't say too rich...

Thermostat is working good. We have two temp sensor and engine stays at around 90C

No knocking sensor. We will check timing tonight with stroboscopic lamp.

EDIT: Timing is stabile. Ten degrees of pre-ignition at idle

[Edited on 15/11/14 by meewisse]


An exhaust leak could cause a high lambda and O2 reading, but on an open-loop system it can't cause a high CO level. You CO level suggests you do have a very rich mixture, which ties in with the poor fuel economy.

Check fuel pressure (esp. if running an aftermarket pressure regulator, many of these are junk) and the coolant temperature sensor.

snapper - 16/11/14 at 08:20 AM

I thought 1.06 panda was lean!
You should check lambda sensor and coolant temp info to ecu
The gas readings are also inconsistent with physics of combustion products