Emmissions test and VEMS

[lost]

On emmission test i hot too high HC reading (unburned fuel out of exhaust-bad smell) it was around 1500ppm at lambda 1 and after playing with timing and warming up i got down to 600, pass is 300ppm.

Was at test for 45min, tried lambda 1.02 0.98, switched from lpg to petrol, tried different injection angle,  moved timing from 8-50degress.
Im using 115r vag cop, added additional resistor in vems ign out.
Dwell was 2ms at testing, i got it changed to 3after, didn't test but it looks same as before

My EGT is 350-400 at idle and on 1 bar boost i gets around 1000 on LPG.

How to fix unburned petrol problem?

[Sprockets]

What engine/mods are you running?  Is this a stock engine but with VEMs?

Cam timing, compression, general health of engine, correct injector spray pattern and location all play a key part in emissions.  If you alter any of them you will alter the emissions of an engine.

-Gavin

[lost]

Stock alfa 2l v6 turbo except for added cam sync and VAG   VAG 115R COPs intead of distributor

spark plugs are new NGK -7 heat range (as on stock car only shorter plug to fit COP)

-primary trigger vr 60-2 -stock alfa
-secondary trigger hall homemade 1 tooth
-alfa v6 fire order: 1,4,2,5,3,6
-injectors bosch-702 cca 186cc - stock + LPG barracuda 130
-engine alfa 164-v6 turbo garret t25 1996ccm 8:1CR
-Max. output:   209.8 PS (207 bph) (154.3 kW) @ 6000 rpm
Max. torque:   289 Nm (213.1 lbft) (29.4 kgm) @ 2750 rpm
turbo mitsubishi td05-12b stock IC BOV

[Kamuto]

Stock alfa 2l v6 turbo except for added cam sync and VAG   VAG 115R COPs intead of distributor

spark plugs are new NGK -7 heat range (as on stock car only shorter plug to fit COP)

-primary trigger vr 60-2 -stock alfa
-secondary trigger hall homemade 1 tooth
-alfa v6 fire order: 1,4,2,5,3,6
-injectors bosch-702 cca 186cc - stock + LPG barracuda 130
-engine alfa 164-v6 turbo garret t25 1996ccm 8:1CR
-Max. output:   209.8 PS (207 bph) (154.3 kW) @ 6000 rpm
Max. torque:   289 Nm (213.1 lbft) (29.4 kgm) @ 2750 rpm
turbo mitsubishi td05-12b stock IC BOV

not sure what emision limit is, but usually you will need cat to pass it

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Car has stock cat and pre-cat.

Fact is there is fuel smell from exhaust.

Is there anything i can do to fix it with config.

.300 is pass my car has around .700

Fuel consumption is also 30% higher
I ordered simple "coil spark tester" maybe spark is too weak?

 

[Sprocket]

what does the injection end angle curve look like? Injecting on a closed or open valve?

What ignition advance in idle and fast idle regions?

Cylinder leak down test? OK?

[lost]

what does the injection end angle curve look like? Injecting on a closed or open valve?

What ignition advance in idle and fast idle regions?

Cylinder leak down test? OK?

I tryed to change ignition while on tester from 5-50 degrees.
Injection angle curve was on 720 deg, tryed to change it and maybe it runs little better at 420deg.

What angle shound i use to inject on closed valve?

[Sprocket]

In the main, idle advance is usually around 15 degrees.

Injection end angle on a closed valve is usually better for emissions as the fuel sits on the back of a hot valve and has a chance to vaporize. The quality of the injector spray pattern is also important.

Liquid fuel does not burn, and will end up as hydrocarbons in the exhaust (much the same reason that you need to inject more fuel on a cold engine to maintain the same lambda target, that extra fuel is going out the exhaust or onto the inlet port or cylinder walls). Injecting fuel on an open valve with a poor injector spray pattern will see higher HC content in the exhaust.

There does seem to be an equal argument for injecting on open or closed vlave, but most say inject on a closed valve for good emissions. A 4 gas analyser is the tool of choice to best see how injection angle affect emissions.

You can tune injection end angle by swinging the angle until the richest Lambda is experienced for the same injector pulse width. I'm not sure if this is the result of the extra fuel no longer leaving in the exhaust as HC, or whether is the result of a lower fuel film on the inlet port.

I've just bought a 4 gas analyser for this very reason

Vems end angle is degrees BTDC. Recommended is 210 -370 degrees http://www.vems.hu/wiki/index.php?page=GenBoard%2FManual%2FConfig%2FInjectorTiming  I'm not sure which BTDC this relates to, the compression stroke or the exhaust stroke

Found the answer here http://www.vems.hu/wiki/index.php?page=PortInjected%2FSequentialInjection It's BTDC on the compression stroke, so the ignition and injection are using the same reference point (Makes sense)

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TDC is top dead center
BDC is bottom dead center

[lost]

according to diagram, intake valve closes 59 degrees after bottom dead center is that 360+59 or 180+59 ?

[fphil]

I think that BTDC means Before Top Dead Center. In any case, I am with you, I have not fully understood the explanations for the "Injector timing " parameter

[lost]

You are right:

BTDC-Before Top Dead Center

TDC   -Top Dead Center

BDC  -Bottom Dead Center according to diagram.

[Sprocket]

You have two options on injecting on a closed valve or a closed valve. Either before the valve opens, or after the valve closes. Injecting before the valve opens, the fuel sits in the port for only a short period, while injecting after the valve has closed, the fuel sits in the port for nearly one full cycle.

It appears that there is no point going lower than 210 BTDC  which is on the valve closing side, while 430 degrees+  is on the valve opening side.

One other thing to consider is if injecting on an open valve, is the valve overlap period where the exhaust valve is still open. Fuel can go right out the exhaust at this point. This is one argument for injecting on an open valve, as fuel can be delayed until the exhaust valve is nearly closed and cylinder scavenging is complete.