injection angle for emissions

Hi - running 6cyl inline bmw turbo engine withh 1000ccm injectros and 290 degree cams.

I want to get my fuel economy during idle in better shape - although I am running lambda 1.00 (afr 14.7) during idle, I guess this value is a false lean due to the cam overlap - standing behind the vehicle is burning eyes to tears and you can smell fuel in the engine bay. Also spark plugs read gives me the indication to be on the rich side of course.

So I will lean out the mixture in idle for testing, but I also want to try injection angle since should have an effect during idle on emissions.

I did watch the seminars but did not find it spot on. So what is from theory the best injection angle in idle for emissions? I do have all possibilities within maxxecu to set this up (reffering to tdc , start or end of inj)

Looking forward for your support - thanks

You have to test this for yourself. Things that can influence the "ideal" injection angle -- injector position from the valve. Injector spray pattern (which can be affected by fuel pressure), cam overlap, intake runner length, manifold design, injection pulse width.

My suggestion for finding the best injection angle at idle for what you have:

-- Set injection timing to end of injection.

-- Disable any closed loop fuel control.

-- Start with either the default injection timing, or somewhere between 300 and 480 degrees.

-- Tune the idle fuel cell (you should set the table up so idle conditions are in the center of a cell) with the engine warmed up to hit your target Lambda 1.0

-- Adjust the fuel timing by 10 degrees (up or down), and wait for the Lambda reading to stabilize (at least 4 or 5 seconds).

-- If the Lambda value is going down (richer), then we are burning more of the fuel and you're going in the right direction.

-- Continue to change the fuel timing by 10 degrees until you find the lowest Lambda reading possible.

-- Tune that fuel cell for Lambda 1.0.

-- Now adjust the Lambda target (just in the low RPM / idle area) to find the leanest the engine will run smoothly. If that's Lambda 1.1 due to your aggressive cams, then that's OK.

-- For extra credit, find someone with a 5-gas analyzer, and tune using that, with similar steps as above.

Guten tag.

David has some good advice for you there so id do that first. I would like to add that it sounds to me like you have a misfire or the fuel not burning properly. Those BMW coils loooove to fail silently on you.

If your car has normal power and drives like it should and you just want a more efficient fuel usage. The post below is NOT your problem.

First id ensure that mechanically the car is good. Check compression on all 6 cylinders. All injectors work and spray pattern is proper. All coils work and spark strong. This is to avoid false positives.

So what happens is the wideband measures the remaining Oxygen in the exhaust. Not the burnt fuel (carbon monoxide). So whats going to happen is that if a cylinder doesnt fire properly that charge of Oxygen is going to pass through the engine and to the lambda without burning creating a lean mixture signal when in reality it isnt lean but rich. Exhaust temperatures is a good indication of this because that unburn fuel usually ignites in the catalitic converter and gets glowing hot.

So reason im saying that is you say it shows it runs rich so then you tuned it to run 1.0 lambda thinking it was lean. So if a cylinder isnt firing you are morelikely running at like 0.8 lambda because of thar air charge not burning.

As for ideal it varies from engine to engine. About 8 to 12 deg for 4 cyl and 6 to 10 for a V6 (on mine at least) bur ib seem some run as low as 3 deg and otgers as high as 18 deg. It really does vary.

Im assuming you are having some emmisions trouble with local laws? If you want better fuel economy your power wont be around 14.7.

What you want is the most efficient burn not compelte burn. Adam did a webinar on it a while back. To get better fuel economy you actually need to get it on a dyno and measure where the most power is. I think there is a free lesson on it in the webinar or youtube. Misconceptions about fuel economy. Basically if the car is tuned efficient and has more power it needs less revs to get the driver to the speed he wants to be in turn it uses less fuel.

In other words if you have more power you dont have to floor the car for as long to get to the same speed and then you use less fuel.

Hope this helps

https://youtu.be/JzbLrn-2jyw

We can assume you're running full fuel sequential?

As the others have said, until you have reliable ignition you cannot expect to tune accurately by the lambda.

You appear to be making the very common error of mistaking a mis-fire for a lean condition, and just making things worse. The spark plug condition should have tipped you of, with the rich/fuel exhaust smell also indicating this. You can check this by disabling the lambda feedback and just manually pull fuel witht he lambda used just for reference - you should see little change until you reach the point where the mixture in the firing cylinders reached their lambda 1.0 points, and a fairly consistent increase from there and/or a point where a possible rich mis-fire get to the point where ignition now occurs, and there may be a noticeable drop in the lambda number, relative to what it was, with a improvement in the engine performance.

Under light load, you should be looking at 1.05 to as far as 1.15 as the lambda range. The fuel doesn't provide the 'power', as such, it's the expansion of the gas in the cylinder as it's heated by the combustion process and the burned fuel adds to these gases.

So what you need is to balance the amount of fuel burned to the power from the expansion of the gases. This means the stoich' 1.0/14.7 may give the best combustion efficiency, but the best "expansion efficiency", and hence power per unit of fuel, can be in that range - some engines can even have AFRs close to 17:1 for best fuel economy.

I'm not familiar with the engine, but if there are reports of poor coil/ignition characteristics I'd make sure the coils, leads (if used), and any suppresion resistors are all within spec's - maybe upgrade if possible, the spark plugs are the correct heat range, and the spark plug gaps are where they need to be - wide gaps are better for light and/or lean running as they have a greater spark, but under boost smaller gaps require less voltage to fire - a compromise may be 25-30 thou', and maybe the lower side if you have an underload mis-fire.

To check the best injection angle(s), it's going to be quite difficult without a 4/5 gas analyser, but there may be work-a-rounds. Adjust the timing of the injector and monitor the fuel usage at a constant, set rpm and load would be the easiest thing.

Do not overlook the importance of the ignition timing - there can easily be 20, or more, degrees of advance requiring to be added under light running than under load/boost for best efficiency.