EOI Timing Need Help

[aceperformance]

I am trying to understand EOI Timing in HP Tuners with no luck. I have read for hours and still it makes no sense to me. Is there some formula for this? I see 3 tables (Boundary, RPM, ECT) which do you change? do you increase the number or decrease it? How much?
My cam is 224/236 581/601 on a 114+4. I have the raw fuel smell at idle and my afr's are rock steady at 14.5 with e10.

[Phil@PnP Tech]

EOI = Boundary - (ECT+RPM)

EOI (End Of Injection). This value is 0-720º which represent the 4 stroke combustion cycle. 0 being TDC at the beginning of the intake stroke. 720º being TDC at the end of the exhaust stroke. This value is when the ECM will END the fuel shot for that cycle.

ECT. This is an adder. As engine temp increases, this value falls off. This allows the fuel more time to phase change into a vapor in a colder engine.

RPM. This is an adder. As the RPM increases, this value increases. This allows the fuel more time to phase change into a vapor due to the increase of airflow.

Basically, you want to inject the fuel earlier in a cold engine and inject it earlier as RPM increases

I have the raw fuel smell at idle and my afr's are rock steady at 14.5 with e10.

Is this 14.5 based on E0 with a stoich of 14.67? This would be slightly rich
Or, Is it 14.5 based on E10 with a stoich of 14.11? This would be lean.
Learning to work in lambda is much easier.

It is very common to get a lean reading but still have a rich smell. The oxygen sensor reads oxygen content of the exhaust. If you are getting fuel/air charge short circuiting the combustion due to cam overlap, you will get the fuel smell along with lean reading on a WB.

The factory L76 cam has -29º of overlap (@ 0.050"). The exhaust and intake valves are never open at the same time. This allows the OE calibrations to really increase injection timing without short circuiting the fuel/air charge.

My cam is 224/236 581/601 on a 114+4.

This cam has 2 degrees of overlap (@ 0.050"). So now you have some overlap and your intake valve is opening 19º sooner than stock.

The first thing I like to do is adjust the boundary based on the intake valve timing. In your scenario, I would subtract 19 degrees from the boundary table.

The next part is to figure out when the start of the injection happens based on your ECT and RPM. You will need to know injector pulse width (IPW) and rpm. To convert pulse width into degrees of engine rotation = 0.006*IPW*RPM. So at a 725rpm idle with a 3.4msec IPW, the injector will be firing about 15º of engine rotation.

So now you know the end of injection {boundary - (ECT +RPM)} and how long it takes to fire the injector, you can now figure out when the injection starts.

If EOI = 425º and IPW = 15º, the injection will start at 410º

You can build a spreadsheet to start and see when your start of injection happens before the exhaust valve fully closes. To remedy this, you will need to reduce the ECT adder. With your cam, you will need to reduce the ECT adder to about 115º from -40 up to 133 degrees F and stock the rest of the way up.

[STL_G8GT]

Very cool, tweaker, thanks for the help.

[Phil@PnP Tech]

Forgot to mention... If you have removed the catalytic converters, zero out all of the Cat Lightoff tables in Engine>Advance>Cat Lightoff. These tables remove timing during warmup to warm the cats up faster. With reduced timing, not all of the a fuel/air mixture is burned in the cylinder but rather in the exhaust to generate heat downstream. This can skew WB readings as well as produce fuel smell. Once you remove the Cat Lightoff timing modifiers and fix the EOI, recheck your MAF tune in the idle cells. Tweak if necessary and your fuel smell should be greatly reduced.

[aceperformance]

This is what I was looking for. Thanks a lot. Everything else I have read has made me more confused than anything. I have got it now.


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[blkscooby]

I know how you feel. I spent weeks playing with EOIT with my first cam.

[aceperformance]

when I started playing with eoi timing I started taking the boundary table down. I think it was around 525 to begin with. I first went to 500 and it was much richer in the idle area so I went down until it quit getting richer. It ended up being 475. So you are saying to go back up to 506 and pull my ect table up to 115 from -40 to 133 from upwards of 200? would that not be going the opposite direction? Still trying to understand this stuff. Am I missing something? Should I do nothing to the rpm table.
What I have done now is return everything to stock pull 19 from the whole boundary table and and changed my -40 to 133 ect table to 115 is that correct.

[Phil@PnP Tech]

With your cam, the exhaust valve is closing at 360º. Now that is at 0.050" so depending on your lobe profile, it's probably not fully closing until 385-390º. So you want to shoot for no injector pulse starting before 390º in the idle rpm's.

Now moving the boundary up 19º (decreasing from 525 to 506) is not moving in the right direction but you want maintain the same EOI to Intake valve timing.

Next is to figure out the pulse width of your injectors idle at to know how long they are firing in degrees of rotation. My stock 42# idle around 3.4msec at 675 rpm. Using the equation from above 0.006*3.4msec*675rpm = 13.77º

If you want to maintain at least an injection start of 390, you want to find out what the max ECT adder you can handle.

Injection Start + Pulse Width = Boundary - (ECT + RPM)... 390º + 13.77º = 506º - (ECT + 0º) ---> ECT = 102.23º. Your ECT adder can not exceed ~102º at idle. (This is all assuming your RPM adder is stock at 0º at idle). Look at your ECT table and you will probably have to change to complete table to 102º. Leave the RPM table stock.

Now that you have the EOI timing set, you need to make sure the rest of your tune is good.

First off if you have the cats removed, make all of the tables in Engine>Spark>Advance>Cat Lightoff are set to 0º. These tables reduce timing on warm-up to burn some of the fuel in the exhaust to aid in the heating up of the cats so they can do their job sooner. The delayed timing will show a few points rich on a WB and could produce some fuel smell.

Next, make sure your are idling around 13-18º of advance and your adaptive idles is only swinging a few degrees. MAF only tunes have a hard time keeping a steady air calc when the idle is isolating RPM.

Next tune your MAF again in the idle frequencies.

During warm up, the car will be in Open Loop until the O2's are ready to start providing trim. Depending on the start temp, warmup will be rich and decay until stoich. You will get some fuel smell here but it can be minimized with a good tune. Once the engine warms up, your STFT should be +/-0.5% with a good tune.

Be careful with the AFR gauge. If stoich is set to E0 at 14.67 AFR, even with E10 stoich will be 14.67 on the gauge.

EOI is only part of the solution for a good idle. As you see, there are a lot of other factors. I've seen O2's come on too early and trim bad to bad MAF signals. Good Luck.

[aceperformance]

Thanks for all the help

[blkscooby]

I have a very similar Comp Cam in my new G8 and I don't have raw fuel smell at all. It does have high flow cats though. I haven't adjusted the EOIT at all.