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Mon Oct 01, 2018 12:06 am

Hello,

I am trying to finally program my ECU parameters (i am using an Ecumaster EMU device) on my 2100cc oxyboxer turbo injection engine..
I have one EGT sensor installed on every cylinder so that i can monitor their values.. No wideband sensor yet...

My problem is that i see very low temperatures around 70-100C on cylinders 1 and 3, while on cylinders 2 and 4 the values are more normal around 500C.. These are values after letting it idle for a couple of minutes..

I did a test to make sure that my ignition per cylinder is working consistently and is syncronized and i see that all the ingition angles are correct..
So i assumed that the problem is injection related. I also swapped the injectors between cyl 1 and 2 and the same problem occurs, low EGT values on cyl 1 and 3 and normal values on cyl 2 and 4..

Then I did took off the spark plug from cylinder 2. The weird thing is that in this case, the EGT values on cyl 1 and 3 became normal !!!! around 480C and on cylinder 2 around 80C (as expected) and on cylinder 4 around 180C...
DO you know why does this could happen ?? WHy do I have low EGT values on cyl 1 and 3 , and then when i take off spark plug from cyl 2, why the EGT values on cyl 1 and 3 go normal ???

I am not using any EGT based correction yet on the pulse width of every injector
I am using SIemends Deka genuine brand new injectors
The engine is fresh built brand new
i am using batch fire injection

Please give me your thoughts , I feel i am stucked...

Regards

Mon Oct 01, 2018 12:47 am

Why are the EGT low? because it is not idling on those cylinders.
The reason is probably.... because your intake and/or exhaust manifolds are not symmetrical.

Is this a problem? not necessarily. Sometimes the engine will idle better on two than four. It may show very good fuel economy.....if you can make it work like a "cylinder deactivation"system! But with port injection??? you won't be able to tune it right, so it would be an annoyance you ignore, or, if htis is a problem for you, it means you need to fix the manifolds.

Mon Oct 01, 2018 12:59 am

It might also be a type of lope, if it's a single throttle system with a lot of volume. In which case, it is...... possible to solve with the computer, in theory?
Would very much help to have a picture of this thing

Mon Oct 01, 2018 3:56 am

the EGT sensors are installed in the same depth and the same distance from the exhaust ports of the cylinders (around 10cm) .

It is a dual throttle system.. so, if you say it is a matter of idle because cylinders 1 and 3 are not idling, if i set the rpm to 3500rpm, then the EGT values should be more close to each other ?? and if they do, then for sure it is a matter of idle ??

Mon Oct 01, 2018 4:51 pm

If you have made a fuel injection system with a throttle for each side, then yes it will probably idle mainly on cyls 2/4. Same reason kadrons do.

Mon Oct 01, 2018 10:28 pm

Modok, could you further explain this ?? whats the reason it will idle mainly on cyls 2 and 4 and why the same happens with kadrons ??

THank you

Mon Oct 01, 2018 11:16 pm

This is exactly what I was thinking.. Kadrons.

Think of your firing order 1-4-3-2
That’s also 4-3-2-1 for all intents and purposes, starting on a different hole.

What the 3/4 side of the motor sees is 4-3 then wait-wait,
The 1/2 side sees wait-wait-2-1..

So, the first cylinder pulling after the wait gets the intake charge moving, and the next enjoys the now-moving charge.

Solution is to run the intake manifold to feed both front cylinders with one carb,
And the two rears with the other..

Or,
Better yet,
Get one throat for each hole.. :wink:

Tue Oct 02, 2018 12:19 am

I had a real long explanation back in 2009, with two stoners and a bong, but it seems to be unreachable with the search now.
I don't know why people don't understand it? Must be one of two things.
One thing you might not realize is, you take the valve cover off and look, both intake valves are open at the same time, not just briefly either, a good 60-80 degrees of rotation! Actually THREE valves are open at the same time, the exhaust overlaps maybe 30-50 degrees too.

If you just have an IR system, one throttle on each runner, and you take a VAC reading at idle....what will you see? You'll see a blurry needle on the guage :lol: But if you had super vision, or a map sensor and oscilloscope, or some way to actually see it, you'd see that before the intake stroke, there isn't any vac. In nearly 1.5 engine rotations of nothin happning, enough air has moved past the throttle that the manifold is near or at atmospheric pressure. Once the intake valve opens, and piston moves down it will draw a vacuum, because the throttle is restricting flow. the max vacuum will probably be at BDC, 15" or maybe even 20" mercury. think about it,...intake stroke is 180 degrees and a full engine cycle is 720 degrees. Only flows 1/4 of the time and the other 3/4 of the time is plenty of time to re-fill the manifold, if the volume of it is not huge. That's just how it's going to be. how long, or how many degrees of rotation it takes for the pressure in the manifold to climb back up between strokes does vary, and kinda hard to guess..... but at any condition, it isn't going to be constant. The pressure will be at a minimum at BDC end of the intake stroke, and at a maximum right before the intake stroke, with one throttle right on one runner. "IR"

Now, you've got TWO cylinders under one throttle, and they follow right after eachother. So what's going to happen is cylinder #2, at the beginning of the intake stroke that intake valve is opening and seeing 0 or 5 inches vac in the manifold. At BDC, it's going to have pulled whatever....15", and that's when the #! intake valve is just opened. Did you just get it? So cylinder #1 begins it's intake stroke with strong vacuum in the manifold. Two things are going to happen different because of that. One is that it won't get as much air, because, well, because there isn't as much air in there to start which can be drawn in in addition to what the throttle flows during the stroke. The other thing that's going to happen is it's going to suck some amount of exhaust up the intake, because the exhaust valve is open too at the beginning of the intake stroke.
At idle and with a healthy camshaft, the exhaust contamination is going to be the larger factor. After all that's what's cool about IR intakes.....they don't suck exhaust up the intake much at all, so they idle clean with crazy cams, but with the firing order and kadron kind of arrangement, if's like you have two cylinders with IR throttles, and two with a plenum. So two will run clean but the other two will have a LOt of exhaust contamination.

At WOT, it's a very different story, and it may well go the opposite way like Clatter is saying.

In any case, if it isn't symmetrical, it's not going to act the same for all cylinders, in ANY condition except by luck. A lot of EFI systems they aim to make all the cylinders run equal because all the injectors spray the same amount of fuel so they want all the cylinders to run the same. This isn't needed with a carburetor engine, because a carburetor runs on AIR FLOW, so it just corrects itself mostly, at least far as getting the fuel right.

Tue Oct 02, 2018 7:59 am

Are there 2 throttle plates or 4?

Tue Oct 02, 2018 8:01 am

Take note of readings at cruise and load. EGT at idle will vary.

https://www.hotrod.com/articles/when-do-gas-exhaust-temperatures-become-cause-for-concern/

Tue Oct 02, 2018 11:33 am

Thanks modok that was an interesting expkanation .

Its interesting that the CIS system I have to fit a T1 engine has a large pkenum box under a centremount throttle body which is more central than a centremount carb would be. The box is about the same volume as the displacement of a cylinder.
But then it spoils it by having a dual port split inlet runner.
Injectors spray 100 % of the time straight onto the inlet valves.

I was about to fit it all when I dropped a valve and mashed my engine.

Now I have a mostly new engine it will have to wait for the 12 month unlimited mileage warranty to expire (Just Kampers Preservation Parts 1641)..

Tue Oct 02, 2018 11:10 pm

So here we are..

As a test, I removed the silicon hoses from the throttle bodies so that they could breath physically ...the same problem.. the cyls 1 and 3 still see egt values below 100c around 1500rpm, while cylinders 2 and 4 still have egt values around 500c..I also cross checked this condition of extremely uneven temperatures using a laser gun pointing to the the exhaust ports of the cylinder.. cyls 1 and 3 have temps of 50c and 60c while cyls 2 and 4 have temps of 150c and 180c..this happened also after I have managed to bring the AFR at 1400rpm around 13.2...so, why still that extreme uneven condition between cylinders? It's not only that I am obsessed with the egt numbers but I hear that the engine is not running smooth at those low Rpms..sounds like some cylinders are not functioning properly

Obviously i think the problem is not the center tube that feeds the throttle bodies with air..let me know if I am missing something...should this problem get minimized when rpm are getting higher?

I also started playing and modifying the VE table in the region between 1000rpm and 2300rpm for Map 100-110kpa , so that the actual lambda is close to the target lambda...

Could someone share their lambda or afr target tables that they use? I need to know that my current lambda target table is consistent..

Thanks and regards

Wed Oct 03, 2018 12:37 am

Maybe you should put in a balance tube.

Wed Oct 03, 2018 2:47 am

Chip B.

there are two throttle plates.. one for cyls 1 and 2, one for cyls 3 and 4

Wed Oct 03, 2018 4:28 am

Interesting! I never thought about a two throttle body fuel injection system having the same issues as the twin single barrel carbs but of course they would!

Wed Oct 03, 2018 7:36 am

You can cure this by programming your EFI to spay sequentially rather than continuously or in batch spray. Actually, if it is batch spray, I suspect you can cure this by moving the wires around on your injectors. Switch 1 and 2, or 1 and 3, and so forth. Experiment. If your using just one injector per side, a small plenum might help. Is this MPFI? One per cylinder?

Wed Oct 03, 2018 3:30 pm

i have one injector per cylinder...

i have just checked the valve clearances and all good...no problem there...

no vacuum leaks..

tomorrow i will try new spark plugs..

but anyway, today i was trying to play with the fuel trims per cylinder, so that i could lean or rich the cyls 1 and 3 that have low egt tamperatures...

In the following two videos you can see all the live data and the EGT values that i had... one video is when i was running the engine around 1200rpm and the other when i was running around 2000rpm..
the egt values in cyls 1 and 3 are in both cases quite different compared to cyls 2 and 4...no matter if i was trying to rich or lean cyls 1 and 3 , no big changes would occur...

https://www.youtube.com/watch?v=PMKB0FXEgfo&feature=youtu.be

https://www.youtube.com/watch?v=KfoF01tGzh4&feature=youtu.be

The guy where i took the injection system told me that the fact that i have one common throtthle plate per 2 cylinders is mainly the fact that i have uneven conditions between cyls and unstable idle... He told me that i cannot expect much with that setup.. WHen i bought the turbo injection system from him, my initial plans was to install it on a 1776 engine.. he insists that this setup could work with small engines like 1776 ...

do you agree ?

should i go to individual throttle bodies per cylinder as he proposes (which means more money to spend >:( ) or things will not change much and the problem is hidden somewhere else. ??

Wed Oct 03, 2018 4:49 pm

A lot of high performance cars you tune the idle based on one parameter, and the parameter is.......... does it idle.
Yes? then your ready to drive and get it tuned in where it matters. it's not good to just idle a fresh engine for long periods.
No? screw with it until it quits stalling.

But, I get the feeling your not that type of guy, because you seem to care a lot about getting it to idle smooth. So just based on that I guess you have three options. Fix yourself so you don't care, fix the car with a symmetrical intake, or get a balance tube.

Fri Oct 26, 2018 10:51 pm

have finally managed to change my single barrel throttle bodies to dual ones.
Quite happy about that (my pocket was not) because:

1. The engine completely transformed to a well idling and responsive engine. Now it behaves like an engine where all 4 cylinders are participating to provide power
2. The EGT values are now quite close together even though I haven't started fine tuning the ECU parameters..

https://youtu.be/HHeC-M0dnho

3. They look much better that the previous ones..

Thanks for pointing me to the right direction

Sat Oct 27, 2018 6:21 am

Damn, that put a smile on my face. Good advice and an explanation (above and beyond) was given, the advice was accepted and implemented. Results were the desired ones. Money was spent, but none was wasted. This is how it's supposed to go... Good Job!!!