Leeroy_25

I know there are plenty of threads as I have been reading them and getting most of the answers. But could still do with a little help here please. So I have a Microtech LTX-12 ECU for reference. I am running the 20B pulley hub with a 13B pulley set-up. but I cross marked the 13B trigger wheel with the marks from a 20B pulley and double checked last night that these line up by swapping from one to the other. The marks are spot on. I then thought I would add a TDC mark to the pulley which if I am correct is just a case of getting a protractor and measuring 5degs clockwise from the leading mark on the pulley and that is TDC?
So these questions largely arise as although I have never touched my CAS I thought I would check the timing. a couple of things lead me to think it might be a little advanced. it runs fine, starts fine, idle maybe a bit rich and hard to trim out.. Had a dyno session with low boost and made decent numbers. all be it spool seemed a little slow but I had a wastegate issue too.
So I took my Gunson timing light and connected to L1 and set the Microtech to timing lock on. tried to line the marks up and they were way off. The gun only has advance on it no retard adjustment.. but when I turned the advance dial it came around so the trailing mark which was the first it got as coming from the wrong side of the marks lined up at 40degs and then the leading hadn't quite come around at 60degs where I ran out of dial! I assume there is no way it could be that far out and still run okay? Also the angle separation does not work out from trailing to leading. Over 20degs? and it should be 15degs? So I found a post that said something about using a 2 stroke timing light to ge the right readings (which I have never come across) and if you use a 4 stroke one to divide the advance value in half. So that could give me a something a little more manageable and probably solve the large degree of separation my light shows. Anyone confirm that is definitely the case?
So if the reading was right I would be on something like 35 degrees advance when the leading line came up and 20degs for the the trailing. To get round to TDC mark would be 40degs I assume to put those all into perspective.
So can the engine run seemingly fine with that amount of advance or do I need to get another light and check it out?

The other thing I can try if I know my TDC mark will be accurate is take the top off the CAS and see what is pointing where inside? if that looks wrong then maybe pull it out and reset it which does worry me slightly having never done it!
In the above case what would be very helpful would be if someone could post a picture of their CAS with the top off and the pulley aligned to the leading mark please.. Then I can see what points where. Maybe as a backup if someone has TDC marked a picture of the CAS with TDC aligned too.
I have seen lots of pictures of CAS's but nothing to verify they shown what I am asking so would be real grateful if a fellow 20B owner could help me out as I don't want to make a boob!

Thank you
Lee

hsmidy

Setting your CAS back up is as per any rx7 manual on the net... can send you one if ya want.
I can also send you a pic of the CAS aligned BUT not installed. might still give you an idea of what you're looking for.

Don't worry about a timing light with a 2 stroke function (some of the expensive ones have this) the issue that it relates to is that the leading plug fires twice as often as the trailing. This might give you a false rpm reading if your timing light has that as a feature

Setting the TDC mark can be done the way you have described or if the pulley measures 360mm in circumference then its a matter of 5mm to the right.

Leeroy_25

Thanks for the reply and yes please to the manual. I only have one for the FD. Assuming the picture you can send will show how the CAS should look with the engine at TDC or on the leading timing mark when it is installed that would be awesome. So is it possible timing could be that far off and still running?
See I have a PM from you. I will hook you up with some info and a contact shortly.

Cheers
Lee

hsmidy

Will flick you an Fc3s manual and a shot of the cas setup prior to being installed in the engine, you may see some rotation due to the helix of the gears, will have to wait till tomorrow though as its 11pm.

stickmantijuana

iTrader: (1)

so let me get this straight. You have 20b hub and 13b trigger wheel and made sure bolt lines up ok. Did you compare FD trigger wheel TDC to 20b pulley TDC when bolted up? Did you lock timing on microtech LTX unit before checking with timing light?

Leeroy_25

Thanks dude.. I am sure it would help although a pic to verify what a correctly timed and installed CAS looks like would be helpful if someone can post this. I found a couple I think are what I am looking for. Just want to be sure. Stud roughly centre of the adjustment slot and pointers on top of the rotor close to the corners of the sensors inside the CAS.

Cheers
Lee

Leeroy_25

Hey Stickman.. Must have posted at the same time.. I can confirm 20B hub and 13B trigger wheel. I checked all my alignment marks. I basically marked them by bolting them together on the hub at the same time and transferred the marks from one to the other. I double checked again last night by lining up the leading mark on the trigger wheel and then swapping the old 20B pulley back on.. All good. And timing lock was on when checking the timing.

t-von

iTrader: (8)

Did you check this thread here? https://www.rx7club.com/20b-forum-95...quest-1091664/


I'm a little confused. Are you running the fd front cover and trigger setup? In one sentence you claim 13b trigger and in another, you claim CAS?

hsmidy

Trigger wheel is fitted but not being used

Leeroy_25

Yes... As above. I have the trigger wheel as I am using 2/13b pulley setup but 20b timing marks on it to time engine. Appears to be a timing light issue as all marks and CAS alignment appear good. Need to borrow another light and check it out. Will check I had the timing lead connected the right way. Arrow pointing towards plug? Pretty sure I did. Only other thing I can think of though.

Thanks.

Leeroy_25

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

Monsterbox

iTrader: (6)

Hey lee,

replying to your post in my thread.

I dont know how microtech works, but alot of ECU's do have a global adjustment. Its the same as moving the CAS by hand. So you should be able to change the global adjustment, and it will move timing, and yes, it should be noticed with the LOCK function engaged.

You need to check that the LOCK function is for -5 BTDC and not some other locked number.

The engine should not be out of time by 20* if you lined it up and stabbed it in. My car was only off -1* from -5 BTDC when I stabbed it in. All I had to do was offset it 1* in the global adjustment using the adaptronic software.

I know you said you have the 20b hub with 13b pulley. Take the pulley itself off and trigger wheel and put the OEM 20b pulley onto the oem 20b hub and line them up while you stab in the CAS. Check your timing off ONLY the 20b pulley.

Leeroy_25

Thanks for the reply here. The microtech manual just says check leading timing ensuring lock is on. So one assumes it is for the 5 ATDC. I can swap the 20b pulley over but if I do the marks line up exactly where my trigger wheel marks are. So I am 100% they are all right. Besides I cannot run it without a water pump belt?! I need to check for a global adjustment just in case. Also it would be great if anyone can verify where the CAS pointers line up once installed and engine on leading mark and also if the engine peaks compression at TDC mark as I would expect it to. Or of in fact it peaks and exhausts before this?
Thank you
Lee

Monsterbox

iTrader: (6)

OK as long as your pulley's line up perfectly than you should be fine.





Found this pic for your, should look like this, installed, with pulley at -5btdc

Monsterbox

iTrader: (6)

One more for good measure

Monsterbox

iTrader: (6)

If the timing is still 20* off, I'd assume the ECU is the problem. Are you sure the coils are wired correctly and that L1 is actually L1 output from the ECU?

You can also check timing using the second mark. With the timing lock engaged, the second mark will light up on center if you use the T1 plug

Leeroy_25

Thanks for that. I had found one of those images and that is exactly how the CAS looks installed. So maybe there is a global adjustment on the ECU. L1 certainly goes to L1 plug I assume it would be more than 20degs off if the coils were wired wrong? And wouldn't run right at all? Ot runs and makes power?! But I guess over advanced would make power! Maybe I will try T1 as you suggest and try and align the second mark.
I just don't get it?! Everything seems to line up and I have used two different timing lights?!

lastphaseofthis

iTrader: (8)

theres a known issue about fd pulleys on 20b cranks.. if you havent been aware of that yet. you are know. causing this timing problem.

sorry scanned thru saw not ur issue. glwp

Leeroy_25

Sorry guy's but I really need some more ideas.. Posting here as well as in ECU section as it is 20B related!
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 **** 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?

On a side note I will be doing a write-up on a nice easy way to find leading timing mark on pulley with engine in the car or built up.

Thank you

Leeroy_25

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

haydenw

Did you get this resolved ? , i am having the exact same issues with same setup (microtech ltx12 and factory coils)

Leeroy_25

To my knowledge this is sorted but I have not been on a dyno in anger since getting it setup. After multiple checks of everything and finally getting a response from microtech on it. It turns out the CAS will be pretty.much hard over one way when timing is correct on the LTX-12. It must be something different in how the ECU reads the trigger signal compared to the stock ECU. Seems to run just fine and it definitely runs much cooler which is one of the reasons I started checking this out in the first place?!

haydenw

After messing around with it i found the wiring diagram wrong from microtech. The ecu was bought 10 years ago for the project and all the leading and trailing ignition trigger confiquration from microtech was wrong. Or the circuit board in the ecu has been messed up somehow. I know it sounds odd but i have had so many wierd issues with these useless ecus in the past it doesnt surprise me.

Leeroy_25

Really? Please can you elaborate on this? Are you saying you have changed your wiring around and with the exact same setup as me you now get your CAS about middle of the adjustment slot and you are 100% sure want you have done is correct? Micro tech themselves said their own car has the CAS adjusted around to one side and I have read quite a few posts on here reporting the same thing. In the end I assume as long as the spark is happening at the right time it doesn't matter where the CAS is. As long as the ECU knows!

haydenw

Well i checked on a pico oscilloscope with a pressure sensor in rotor 1 and checked the leading and trailing ignition event vs pressure tdc and found the trailing event happening 120deg after the leading (wired the way microtech listed in there wiring diagram) , and thought to myself well if the trailing wiring is messed up i wonder if the leading is out and thats why the CAS is out. Well sure enough we aligned the CAS how it is intended with the nub on the housing and dot lined up on shaft and the front pulley marks we slipped in the cas and i scoped the ignition event vs pressure tdc location and found the leading trigger was also wrong. So then i just went through all the triggers and aligned them how they should be.

I have not yet checked the injector events yet to make sure they are firing at the right time.

Just a note. We changed the coils to HEC715 as i didnt have faith in the factory 25 year old coils and made changing around the coil triggers a lot easier.

With the triggers wrong the car sounded to the ear to be running fine but i encounted knock when tuning on the dyno which lead me to here.

And the cas is over hard to one side like the S5 rx7s i have done in the past

It seems you can run these engines 3 ways and to the ear sounds like its running fine. But its not.