Timing query for 20B
 

I have read a few posts on here and think I have a rough idea what to do but would like some answers on what I have taken off my microtech today. First of all there is the t_rpm Map.This has a drop to 0 at 1000rpm which I am not sure is right? Should the values be consistent to create a curve dropping to 0 or 5 at 500rpm? Or does the value put in at 500rpm depend on the base timing value set?

Attachment 610627

Next there is the T gap map.. If I understand correctly this is to alter the static 10deg separation between leading and trailing plugs. Does this map look fine and what are the benefits of changes? some rough pointers would be great. I have heard people talking about less separation but this seems to show more at lower rpm?

Attachment 610628

Thanks in advance.. I am sure it is something I will be coming back a couple of times.

I need to sort out what on earth is going on with my timing light first as I checked today and it showed 40degs advance for the first mark and 60degs for the second! Something is not right?! That said I think my light only shows advance so I wonder if that is an issue? As I am looking for BTDC not ATDC like a normal piston engine.

The t_RPM should show a linear progression as it is what sets the base timing curve. It is the "mechanical advance" in the stupid virtual distributor model Microtech uses. Bring that 1000RPM point up to be linear with the rest of the curve.

It looks like your t_gap map is the stock setting but I don't know for sure. Trailing gap is a WIDE subject of discussion. Best do a search in the EMS forums for "trailing split" or similar to turn up the discussions.

Basically, it should be either wide or negative split (not possible with Microtech) at idle, narrowing up close to atmospheric, then splitting again to around 15 once in boost.

As for your timing light issues...Sounds like you have a VR sensor connected backwards of the Microtech setup is wrong. Or your CAS is stabbed one tooth off.

You are looking for the leading timing pointer to line up with the mark on the pulley when the timing is locked on the Microtech.

I will try and read some more on timing splits. Are you saying microtech cannot do negative split. Or cannot do any changes other than standard 10deg split at idle. When you say it should be wide or negative that reads as two opposite things or have I misunderstood? Please can you explain with some example numbers to be sure I am following right.
Does my t_rpm look fine other than that one point? Guess I will need to lower the 500rpm one bit?

For timing when you say VR sensor do you mean the signal lead on the timing gun? Arrow point towards the plug on L1? I had timing lock on so any microtech settings should not effect it. Cannot imagine it is a tooth out? Would it run okay like that? Sure my light only has degrees advance and I presume I would need to set the gun 5 deg ATDC to align the leading mark on the pulley? i.e Retarded? The odd thing is the timing marks come up at 40degs advance and then 20 degrees apart when of course they are only 10 degrees right?

Appreciate the help. I am new to tuning and want to start by getting my basic setup and idle sorted. Then progress to off idle low load. The rest has been base mapped already and I will hand it back to a pro for but want to have the understanding of how the settings work and what changes result in what.
I do have a rough idea don't get me wrong. I have used Power FC commander for fine tuning a bit but nothing like this! I am really kean to learn more though.

So I just found a good post on ignition timing and I think it may have partially answered my question. It says that to get the correct timing on a rotary you need to use a 2 stroke timing light? Something I never knew existed. That or you can divide the advance reading on the dial in half to get the correct advance amount. So if my light is correctly reading 40degs advance for the first mark that is in fact 20degs advance at idle. Think the second mark was 60degs which would mean that was 30degs. but now I am thinking the leading and trailing timing marks are 15degs apart not 10degs? is that right? Also I think the dial stops at 60 BTDC and it was not still quite aligned so could be working right from that point of view.
However. 20degs advance at idle I am assuming is not a good thing to have as it should be 5degs retarded?
So if my light does not have a ATDC option on the dial am I just setting the dial to zero and then lining up the first mark with the pointer to net 5degs ATDC leading timing?
I keep confusing myself. I will verify the marks and light are reading right before I move it as it seems to run just fine and has been dyno'd with low boost. Does seem to get a bit warmer than I would expect so that would be a symptom of over advance as I recall?

Thank you for pointers.

Lee

I've never used a 2 stroke timing light.

Don't try and use a timing light with a dial or any other fanciness. Just a regular old timing light that flashes with the spark fires.

The Microtech cannot do negative split, which isn't too big of a deal. It does have a very basic split curve based on RPM and with MAP corrections.

It is very limited in timing because it's essentially a virtual distributer instead of a 3D table.

An example: split at say 4000 RPM would typically be zero at atmospheric pressure. But 15 or so degrees at 4000 RPM under boost.

Your t_rpm will be fine to start with once you bring that 1000 RPM point back up to be in line with the rest of the curve.

The VR sensor is the actual crank angle sensor, which unless modified on your 20B, is a 2nd gen style CAS. Connect them backwards and the car will still run but the timing will be wildly off. It is VERY easy to stab the CAS 1 tooth out. I've done it, everyone has. When installing it you need to take the cover off and hold the rotor with your thumb to make sure it doesn't move.

Do not use the dial on your light. Lock the timing on the Microtech and make sure the dial is set to zero or disabled. Then adjust the CAS until the leading mark lines up.

Thanks for the reply. I am going to double check timing with another light and see. Maybe I need to check he CAS sensor wiring if it still shows way off. All my marks and CAS position seem to line up spot on.
Cheers
Lee

It is even more curious now.. I double checked timing with another light and it shows same as mine leading is around 20degrees advance. If I try and adjust it back it runs out of movement on the CAS just as it comes around correct but also the engine does not seem at all happy idling there where as it does currently.
So I took out the CAS and checked alignment and dropped it in 3 times or more. Still the same. I could really do with a pic to verify where the CAS points once installed.
Mine keeps position pretty well so the points are at the corners of the CAS sensors. Someone told me they should be centre of the sensors which would probably bring the timing back correct on the light but no way I can get it there installing the CAS all correctly aligned. Plus the unhappy idle once adjusted makes me wonder? Please can someone help!
I also heard there was some 20b engines with a different firing order? Not sure if that I true and if it would account for my issue.

Other thing I noticed. If you rotate the engine by hand towards TDC or the leading timing mark should you hit a compression peak at TDC as you would with a piston engine or will compression and exhaust happen just before. Looks to me that compression is peaking around 20 degrees before which doesn't sound right to me. Aligns with the timing I am seeing too. But then all my pulleys and marks seem to tie up?! Confused as hell!

Cheers
Lee

It really sounds like your ignition polarity is wrong on the CAS, or to the coil. Sounds like the exact symptom.

Okay.. So does that actually mean the timing is off or it just appears that way when polarity is wrong?
Presume I can just check continuity from ecu to coil and ecu to CAS using the wiring diagram? Sound like a plan unless there is an easier option?
Not sure where the harness joins are for that as I did not do them.
Anything else I should consider checking? Is there a global correction I may have missed that could be in effect?
Thanks again
Lee

I thought you were on to something Aaron. However, this evening I verified that my coils and plugs are connected the right way around and wired correctly into the ECU. I also confirmed the CAS is wired correctly.
What next.. There is either some global correction at play I have missed or my timing marks are somehow out which I am discussing on another thread.
Thanks
Lee

There is a setting, I think all the way in the options screen (screen 30?) that sets the ignition trigger whether it is on the positive or negative side of the pulse, and whether to trigger the coil on the positive or negative side. Perhaps that has been changed? It would cause the symptoms you describe.

Another possibility...Was your front hub and pulley ever mixed up with one from another engine? Or re-marked?

Hi Aaron, I have never mixed up mg hub or pulley, but it is possible it happened in the past I guess. I will see if I can find this setting. Any idea what it might be called? I read there is TIMtrm in the manual last night for global timing adjustment. Not had Tim to plug in and check that though. I swear timing cannot be too far off as it runs pretty nice. I would guess a touch advanced if anything. If I ever get to the bottom of this we will see. I will check TDC with the oil in the chamber method next week as well and see where it all ends up!

I honestly can't remember what that setting is called and don't have the manual handy. But it is in the manual where most settings are described.

If you are SURE the CAS isn't stabbed one tooth off, and you are SURE the ignition is triggering/firing on the correct polarity, and that your timing light works, then you can verify TDC. If the 20B is like the 13B (I don't know) then TDC is when the keyway of the eccentric faces the port side of the engine.

As I am now not confident in anything not being 100% sure what was done before I owned the engine my best bet is to validate tdc with oil in the chamber method and go from there. I will hook my manual out and see if I can't find that setting. The more I think about it this setting or global correction seems the most likely answer.

Cheers
Lee

I Have found the settings in the manual I think. There are 2 that sounds like they could effect it but I am not sure on which should be changed or checked?
input Trig - Sets ECU to Trigger on either positive or negative edge of input signal. Default Positive.
or
Spark Trig - Sets ECU to fire spark on either positive or negative edge of output signal. Default Positive.

It sounds like they should be preset correctly from factory though and not messed with? So if they are correct (i.e set positive) do I leave them alone or if I check my TDC and everything and still have a problem change one or both of these? I guess there is nothing to say pins have not been swapped around in one of the plugs at some point. Verifying TDC has to be the first thing for peace of mind now either way!

So I checked out my ECU settings today. First looked at the global timing trim setting which is set at 0.
I then looked at the Input Trig setting. This was set to positive as it should be.
Next I checked the Spark Trig setting and ha haaa.. This was set to Negative.

<a href="http://s157.photobucket.com/user/Leeroy_25/media/spark%20trig_zpssuedqv3m.jpg.html" target="_blank"><img src="http://i157.photobucket.com/albums/t59/Leeroy_25/spark%20trig_zpssuedqv3m.jpg" border="0" alt=" photo spark trig_zpssuedqv3m.jpg"/></a>

The manual says this should be set to positive normally. However when I went to change it there was not an option for Positive. the other option shows SER4? See below.

<a href="http://s157.photobucket.com/user/Leeroy_25/media/spark%20trig2_zpswjihlnda.jpg.html" target="_blank"><img src="http://i157.photobucket.com/albums/t59/Leeroy_25/spark%20trig2_zpswjihlnda.jpg" border="0" alt=" photo spark trig2_zpswjihlnda.jpg"/></a>

What does this mean? Do I want this or is something else a miss?

Cheers
Lee

Is this ECU configured by Microtech to run a 20B?

Negative trigger is the setup on stock FC/FD coils. The LTX series uses Microtech coils which trigger differently as "IGBT" which is a stupid way of describing that the ECU is directly controlling the base of an IGBT coil driver and thus has to bring the coil high to charge, then go low to fire. What coils are you using? Can you provide some more information on the setup? Pictures, etc?

I will post a picture tomorrow. I assume they are stock 20b coils. I do not have the option for IGBT in the setup. Just negative or SER4. I have no idea how or who configured the ECU. I bought the complete running setup in an unfinished FC project car which I swapped it all out of.
I checked out my TDC tonight and as best as I can tell the marks are pretty good so the CAS is in correctly. So it only leaves this setting you mentioned I think. Can I harm the motor swapping it? Just tk see if the timing then comes in correct?

http://i157.photobucket.com/albums/t...ps2ij8wyh9.jpg

These are my coils..

Cheers
Lee

as you know a car can idle and rev, but doesn't mean it's running correctly.

I think the seller may have purchased the ecu used, and it's configured for a different CAS? did you check with microtech? they are pretty good at answering specific questions such as this.

The car has been on a dyno and made 420bhp with only 8psi boost at about 5000rpm. It seems to run pretty well! Maybe a little.hot but that could be poor cooling system. And smoked a lot on overrun but I think that is fuel map too rich under vacuum. Maybe it is wrong.. I certainly hope not at this point but it would be just my luck. Messaged Microtech yesterday and hoping to get a reply.

Cheers
Lee

Ah, those are Mazda coils. Which explains the negative trigger. You said LTX-12, so I assumed you were using Microtech coils.

Dumb question but the spark plug wires are on the correct plugs, right? We've all been there.

At this point I'm out of ideas. Your ignition capture settings look correct. Your trigger settings look correct.

Is there ANYTHING connected between the ECU and the coils?

And are you sure, 100%, the CAS is stabbed correctly? The way I usually stab them is to take the top cover off and hold the wheels in place with my thumb during insertion (giggity).

Dam it! I thought that had sussed it! So the negative spark trig is definitely right with the positive input trig?
Pretty sure plugs are on right way! Leading, trailing and numbers wise! And the wires from ECU to coils and CAS to coils appear to stack up with a continuity test. Nothing else connected either? Maybe I need to try the trailing lead and see what that shows.
Did exactly as you suggested when stabbing the CAS. Pointer on the CAS remain pointing at the corners of the sensors once installed with pulley at tdc. Not centre as I have been told before. To be fair mine does not seem to have any inclination to want to go anywhere else but there during install.
I am at a total loss? And do not want to run it in anger without getting this sorted!

Thanks for all the help so far.

Cheers
Lee

I'm out of ideas without actually being able to see it.

Fair enough.. I am stumped. Doing other bits at the mo but will get back on this shortly and try and suss it!
Thanks for the help so far Aaron.

Sorry guy's but I really need some more ideas.. After triple checking everything, verifying with microtech all my wiring and settings are correct and finally getting some measurements from another engine to accurately position and check my timing marks. The issue is not resolved!
I am really at a loss here as I have run out of resources and things to check.

Please HELP!

My timing marks and they are cock on, my CAS stab seems to be bang on too. Pointers just cutting the corner of the sensor. CAS is set about middle of the adjustment slot.
I am running microtech LTX-12 ECU with stock 20B coils direct fire from the ECU. Just to re-cap.
Input Trig +Pos
Spark Trig -Neg
Now when I run the car up and put on timing lock to check with a timing light the timing comes up about 15degree BTDC instead of 5 degrees ATDC. I double checked with the trailing timing mark and then marked all 3 leading positions and they all come up the same.
I cannot see any global adjustment in play on the ECU but it can only be something ECU driven causing the issue now as I have checked and verified everything else!?
If I try and adjust this out there is not really quite enough adjustment on the CAS slot to pull it back in and when I start moving it the rpms drop right off until it stalls at max adjustment. Idle is quite low anyway but as I understand usually idle maxes out roughly at the right timing? Or it is normally a good gauge. My idle drops off as soon as I start pulling the CAS back.

I originally checked it because I felt the engine was running a bit hot and it seems to want to run quite rich on idle to keep a stable idle.. 11.5 ish AFR. Can just about get a low 12 but not consistently. Hence it is quite fumey at idle. I believe these may well be symptoms of over advance but not sure.

Can you shed any light on what it could be or if it is normal to have to put a global adjustment in on a microtech to pull the timing back in? I have checked all the wiring on the CAS and coils numerous times and that is all correct. so I am stumped! Was certain it had to be timing marks wrong but they came up bang on.
Please help. What happens if I swap the input or spark trig settings? will it damage something. or would that setting show a far bigger timing error? Is there any other setting I might have missed that can override the timing lock function?

Thank you

If anyone else running microtech with stock 20B coils can post a picture of the adjustment on their CAS that would be great. I have just had a picture come through that implies the extreme adjustment to one side of the slot that mine seems to want might in fact be correct. Would like to see if that is common for microtech set-ups for some reason.

Thank you
Lee

Extreme adjustment to one side of the slot means that either the CAS input polarity is wrong (in software or wired wrong) or the coil trigger polarity is wrong (again, software or wire).

Having seen this exact problem when LT8s wire wired to trigger CDI boxes without going through the stock ignitor, I'd wager the coil trigger is wrong.

CAS is easy enough to verify. Same settings as 2nd gen, same wiring I believe.

Thanks for the reply Aaron,
Both yourself and Microtech have verified my settings and I have checked and verified the wiring multiple times?
Off hand I have input Trig +Pos and Spark Trig-Neg. It is somewhere earlier in the thread I think.
Microtech sent me a picture of the CAS on there 20B Adjusted the exact same way and I have managed to dig up quite a few threads discussing the same thing which I am working through now to try and figure if this is right or not?!
I adjusted it back today and if anything it makes it want to run richer. I think I might be struggling with 1000cc primary and secondary injectors on that though? I can only get idle down to about 10.8-11.2AFR one click leaner and it stumbles and AFR's start shooting all over the places until it stalls? Smells way to rich for my liking and a bit smokey. That is another discussion though!

Would be grateful for timing thoughts though. Sounds like you don't think it is normal?!
Also when I set timing L1 to leading timing mark should there be a value of 5 in the static timing under screen 30 or should this be 0? what about input timing on screen29? or is this just for temporary global adjustment purposes?

Honestly, I don't know. I don't see why the 20B would require extreme movement of the CAS on a Microtech. Any 13B I have seen with the CAS way off was because trigger polarity or coil polarity was wrong and the CAS was moved to compensate. But the error increases as RPM increases so it is not a fix for the issue.

Oh dear, if you have 1000 CC primaries and are running gasoline then you're never going to have an engine running very well. Those primaries are way too big to control on a Microtech due to extreme lack of injector resolution because of the way they stage injectors. I'd really recommend going down to a smaller primary. 550CC or 680CC. The 1000CC are going to be way too twitchy as you have discovered.

So wait...

I reread your initial post.

You are running an LTX12 with stock coils?

I'm not sure you can do that.

The LTX is designed to run with the Microtech X6 IGBT ignition box and Microtech coils.

If so, that may explain the timing issues. The Microtech X6 probably fires going high while the stock Mazda coils fire going low (at least FC coils do, so I'd assume 20B as it's a very similar ignition system).

You're at the edge of my knowledge as I haven't ever messed with the X version of the ECU as it's such a convoluted system in my opinion.

My honest advice after seeing you struggle for so long is to ditch the Microtech. Sell it to someone else, and buy a Haltech. When you do, you will wonder why you ever wasted so much time with the Microtech. I'm not saying that the Microtech won't work or is the cause of your issues. Just that the Haltech is about a universe better.

Thanks Aaron,
I will stick with the Microtech for now.. Even if just to get me going adequately and maybe chop it in later. I am close after all.
The LTX-12 can run direct fire with the stock coils. Microtech confirmed this directly and said my settings were right. I have googled and searched a lot and a whole heap of people reported the same thing and then tuned and run just fine?!
mis-typed my injectors sizes.. I have 1600CC Bosch EV1 all round currently. I think I need the fuel of at least a 750CC primary keeping the same Secondaries which is what I am currently looking into I a wary of such a big jump in the sizes due to the staging transition issue people report. I was planning on some ID1000 which are reported as very good at low flow rates. They are high impedance though and the Bosch are low impedance so I am not sure if I can run the high impedance on the Microtech or indeed if I can mix high for primary and low for secondary. Do you know? If the ansqer is no, my other option is RC1000 injectors which are Bosch style and Low impedance. So a straight swap.. It is pretty close on the 1600's to be fair just a bit plumey so if I can get it a little better I would live with it for a weekend toy. Value and appreciate your input though.

Thank you
Lee

With 720CC primaries and 1600CC secondaries, I do over 500HP on my 13B with duty cycles around 8mS at wide open throttle and full boost (16 PSI). How much power are you trying to make? 720CC primaries and 1600CC secondaries on a 20B are enough for over 800HP.

As for the transition, that is actually one of the areas where the Microtech does well. Because of the weird way they increase the primary PW when off stage, it ends up making a rather smooth transition. So staging 680/720CC primaries with 1600CC secondaries is no problem.

The Microtech resolution is so poor that it makes no difference whether the injectors are high or low impedance. You can mix and match as LONG as both primaries and both secondaries are the same impedance. The injector driver circuit will handle both.

Honestly don't spend money on fancy injectors with the Microtech. It doesn't have the resolution to control them. Just good old low impedance Denso / Bosch style injectors do the job and they are a dime a dozen.

As for your timing, I really don't know at this point. The only time I've ever seen timing drift during timing lock is when there was a polarity problem at either the coils or the CAS.

But since you've:
-replaced the CAS
-checked the wiring
-checked the coil wiring
-confirmed with Microtech
-posted your settings and had multiple people confirm correct

I just don't know.

Now if you lock the timing and can then move the CAS to line up the LEADING timing pointer, and it stays stable throughout the entire RPM range, then triggering is likely fine.

Thanks for the input.. I don't think the timing wonders if you vary the rpm with the lock on.. I am not sure I have ever checked that. May have given it a little rev but I know you are not supposed to with lock on!? It adjusts and seems quite stable with the CAS swung around!? Go figure.. Will see if it makes no power when I get it on a dyno!

For injectors I see you point about resolution. I will either get ID or RC injectors I think as I would rather get something I know is reliable as well than some real cheap rubbish. Will look into Bosch smaller options but don't want to get used this time around. by the time I get them tested and mess around and get adapters I might as well have just bought a new kit! Also in the event I do change ECU down the road I have the good stuff already!

I was reading a few people complaining about the staging of injectors with big size differences which was my reluctance? i don't want to fix one problem to create another! I am only hoping to push 600bhp flywheel at this point. nothing mega.
Will do some more research on this before I commit to buying anything though. Surely closer in size has to be better? You really think 1000cc will be that bad?
Slight side note, someone mentioned on my other thread about using mixtrim to get a finer adjustment on idle fueling and adjusting the rest of the map to suit? Any mileage in that do you think?

Just absorbed the fact you run 720/1600cc combo! What version ECU if that matters? What is your staging% set at? is it like a straight forwards ratio calc? I gather 50% is setting for same size injectors? So is it ratio/2 +50% or something to work it out? And you have issues as the secondaries come online?

Thank you again

You can rev the engine with the lock on. You can even drive the car. Just that timing will be frozen at the locked value so it won't run very well. Lock the timing and make sure the pointer (L1) doesn't waver from the locked value more than a degree or two through the rev range. If it stays put, then your timing polarity is probably correct. If polarity is correct, then you should be good to go to make your timing adjustments to the map to bring it into sane levels. Of course the Microtech uses a silly virtual distributor model for timing so you will find that your timing map will absolutely be a compromise between safety, drivability and what you are able to set.

Staging on the Microtech is actually very easy. With the RevStage % set correctly it is easy to get a smooth stage. Just keep in mind that more RevStage decreases the primary injector resolution because it is multiplied by the %. So I'd suggest sticking with 550CC or 680CC injectors to give you as much control as you can muster.

The problem with 1000CC is that realistically your minimum injector duration with the Microtech is about 1.8mS or so. That's the appropriate injector time for a stock port engine to idle on 460CC injectors! With 1000CC, you are injecting more than twice the required fuel. More capable ECUs can run modern large injectors down to much smaller PWs.

I'm running an LT8s. RevStage set at 99% I believe. Since Microtech hasn't updated their ECU firmware in 16 years on the LT series, I don't see how yours would be an issue with a similar setup.

Yes, 50/50 is for the same size primary/secondary.

Ohh.. I am nervous.. what do you fiddle with to get a smooth transition? I thought it was the rev stage value.. still cannot work out how that works.. it doesn't sound right.. i imagined it would be s the secondaries come on the primary fuel flow is reduced by the revstage %. for same size injectors you end up with 50% fuel from primaries and 50% secondaries. then ratio accordingly for different sized injectors? This is not how it reads and I don't know why they would make the setting compromise the primary injectors? surely if I go smaller than 720 cc like you I would need more than 100% staging? there must be a point where there is a trade off for just keeping a slightly gibber injector?
On that note I came across Deka Siemens ones yesterday that look like the
ID ones but come in long length and different plug options. Are also about half the price! heard of them? unless I get bad feedback I might go for these. Sizes are a bit limited.. I have been looking for some 725 after your comments. These come in 825cc I think it is. So I might try this and see how it goes for a relatively low outlay. It is nearly half the size of my current ones and they are high impedance which I gather is better. i am prepared for some idle compromise. I would prefer that than transition issues under load. As long as I can pull AFR's into the 12's I think it should be alright. People claim to be doing so with 1000cc primaries on microtech so we will see!

On a side note does the LTX-12 have battery voltage compensation in it? I have not seen it. I read the MT series has it?
Apparently useful for injector set-up and there is some other data you can get which might be useful to input somewhere to optimize the injectors? The guy from ID injectors has been giving me loads of info. Although I am now leaning towards the cheaper options!

Easy question first: as far as I know, as I remember pestering Microtech years ago with this, battery voltage compensation is "automatic". It's done in the ECU without any user adjustment. Another area where Microtech is stupid.

The manual also doesn't describe the RevStage thing properly. Basically, when on the PRIMARIES ONLY the injector time is INCREASED by the RevStage percent. So say at 99% when you tell the injectors to open for 1.5mS the ECU is actually opening them for 3mS behind the scenes. Then at the stage point, the PRIMARY injector time is reduced to the ACTUAL value while the secondaries are brought online.

In general it is one aspect about the Microtech that works very well. It's an odd way of doing it, and it reduces the resolution of the primaries off stage, but it works well. Confusing as hell. While it does work, other ECUs use a much more user friendly method like a staging table (Megasquirt).

You absolutely DON'T want any sort of "idle compromise" to get a smooth transition at load! Never! It is EASY to deal with a bit extra fuel under load as the engine tolerates it. But certainly NOT at idle.

Thanks for input and explanation! That staging does seem completely backwards! Surely it would make more sense as I thought. The staging reduces the ms opening by the ratio in size of the injectors when the secondaries come on? Maybe I have missed a point why that cannot work or be achieved?!
so It does mean the question over smaller primaries must be no benefit at some point if you end up having to put in 100% staging or higher if that is possible to get good transition?
Oh had you heard of Deka injectors? I am 99% made up I am going to go with these as cheap as chips.. Unless someone can give me a reason a not to!

I really don't know why Microtech does the staging like that either. It does work, reasonably well, but seems completely back-arswords and isn't even explained correctly in the manual. One of the mysteries of the Microtech. As near as I can tell, the Microtech has been developed basically by necessity. Features are added years after the market screams for them, but then tacked on to existing code. Once the feature is there, it is never re-examined, re-coded nor improved. Because it just works.

The idea being that by increasing the PRIMARY by that percentage, Microtech can avoid trying to drive large secondary injectors at small PWs which their ECU isn't capable of. So they reduce the primary at the stage point back to normal values and then bring in the secondaries at exactly the value the table says.

Smaller primaries absolutely have a benefit! Would you rather be forced to reduce the resolution of a SMALL injector or a LARGE injector? If your minimum injector time on a 550CC injector is realistically 1.5mS, on a 1000CC injector that 1.5mS minimum is twice the amount of fuel.

Deka seems to be made by Siemens. That's about all I know. Probably used in a lot of OEMs.

Thanks Aarron, point taken! Regarding the Deka, yes they are Siemens and that was my exact thought about OEM use. Ergo they should be reliable. I think have to be worth a punt. If I need bigger or smaller or want to reduce secondaries too at some point nice and cheap to replace!
Shame the sizes are a bit limited is the only thing. I will have to go with 875cc I think as the next some down is 660 or around that. Which I think is maybe close on fueling and I would be worrying about staging issues to with such a large jump.
So is there a formula to work out staging percent by the way? Presume there is something to get you in the ball park? To rpm and hg valued just stay as set from factory?

Thanks for the link.. I found this before. I need to have a thorough read! I a ordering my 80lbs Deka injectors tomorrow. Will let you all know how it goes.

800CC primary and 1600CC secondary use 99%.

I'd suggest setting the stage point to 3500 RPM and 0" of vacuum. The default setting of 2" of vacuum is stupid because the Microtech doesn't have any vacuum bins at that point and interpolation is terrible.

Thank you very much for the tips.. I have seen a few people saying about a 3500rpm point.
Is there not a calc to work out the Rev Stg%? Like (primary cc/secondary cc)/2 + 0.5 x 100?
Seems like there should be?

There may be a formula, but I don't know it. Basically as you suggest, I just linearly increase the % as the injector size goes up. At roughly twice the primary size, 99% is as big as it gets. You'll still be able to get a smooth transition even if the injectors are larger, it will just make a noticeable dip in your matrix table.

Other more advanced ECUs like the Megasquirt have an injector stage table that allows the user to select how much the secondaries start contributing over a 3D table. Works very well.

Thanks Aarron, I will let you know how I get on. Started fitting new injectors today but ran out of time. Think length might be a bit off but will check it out tomorrow and maybe fire up if I have time!