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switch type TPS + single cam sensor


CMSport
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Hey guys, I'm wiring up an old 3 cylinder dinosaur that has two unknowns to me and I am trying to find the simplest way forward...

The first is the throttle position sensor - it uses a switch type TPS i.e. a throttle closed switch and a WOT switch. I'm wondering if the Atom will allow me to wire the WOT switch wire to TP(main)? and possibly the throttle closed switch to digital input? I do have a linear position sensor type TPS that I could retro-fit but that would mean machining up an adapter plate which is not a 5 minute job... even if the resolution is not great, I'd rather stick with what's on there just to get it started and mobile. 

The second is that the distributor has only a single 3 tooth trigger wheel and a N+ and N- and no other crank or TDC position sensing. This seems very strange to me but surely it's not the only one in the world like it. Is my only option here to fit a crank-mounted trigger wheel and cut off 2 teeth from the distributor, leaving a single TDC trigger? or is there another solution? I have wiring diagrams, albeit it in Japanese, and can take pics if it would be a help :)

Cheers!

Tim

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For The TPS you would be much better to convert to a proper viable TP sensor.  You get better accel enrichment using TPS, with the switch type TPS you will have to use MAP to detect transients for accel which is slower to respond and more difficult to tune.  The Variable TPS will also give you a bit more adjustability for functions like idle speed control lockout etc.

If you are sticking with distributor ignition then the stock 3 tooth trigger signal will be fine.  If you want to go to coil on plug or sequential injection then you will need some sort of unique TDC sync such as the separate crank/cam sensors you mentioned or a missing tooth wheel in the dizzy.

 

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Hey Adam thanks for the fast response - well that's going to save me a whole world of pain to start. I know none of the current setup is really ideal but it's a very new build (a fresh engine combined with a rather unique and untested combo) so I just want to get it running and then focus on the finer details to tune.

Cheers

Tim

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  • 1 month later...

Hey Adamw I am just trying to setup the timing on this car now and am having some trouble getting a signal from the trigger... I have stuck with the single 3 tooth trigger at the distributor for now but don't seem to be getting any signal from it

Can you tell me what trigger setting I need to use for this setup? It's a 3 cylinder with one tooth per TDC so I figured that I would use the "1 tooth per TDC" setting but no joy.... any help would be appreciated! 

Cheers

Tim

 

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Here's a copy of a log file plus my pclr file for reference... I pulled the plugs after this and they weren't soaking like it had flooded and then turned the fuel off, cranked over with the timing light connected to each spark lead and all cylinders were firing so I'm a bit puzzled... 

G4+ Atom Mira EF-JL.pclr

Log 2018-06-16 5;43;11 pm.llg

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Yes 1 tooth per TDC would be the best mode for this set up.  Make sure trigger 2 sync mode is set to none after that change.  With 1 tooth per TDC mode you will need lots of dwell at cranking speed.  Set the dwell table like my example below.  Also lower your trigger 1 arming threshold to match example below.

Can you make those changes then confirm you have a realistic RPM displayed and a spark when cranking.

4NIJ0Bk.png

WmP6NVu.png

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OK so I've made those changes and the log is returning sensible revs while cranking at approx 300rpm

it spluttered once but other than that no real sign of life. I have made some significant changes in the fuel table ranging over 30% VE

I am a little suspect about the TPS calibration. it doesn't seem to be returning sensible numbers and jumps from 0 to 100% sometimes ( you can see this in the log ).. in my mind this shouldn't really stop it from firing?? I have set accel enrichment to MAP and figure that for starting and idle it's only going to be looking at calculated mass flow for fuelling, regardless of what it thinks the throttle position is, is this correct? 

latest log and data file attached... 

cheers

Tim

Log 2018-06-18 5;30;55 pm.llg

G4+ Atom Mira EF-JL.pclr

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You are right the odd TPS reading wont stop  it from running.  The voltage on analog 2 is sitting near zero volts so that may suggest there is a wiring problem (or is it still a switch type?).

Trigger looks like it is happy.  Did you check the base timing with a timing light?  With 1 tooth per TDC mode you have to rotate the distributor to adjust the base timing.

Otherwise, to make broad fueling changes in modelled mode I normally just adjust the engine capacity setting rather than mess with the VE table.  Make big changes like +/-50% normally gives you a good clue whether your issue is fuel related or elsewhere.

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thanks for looking at that so quickly - yes, I'm using switch type TPS for now. will see how it drives before I throw that away. I have pinned the idle switch wire to DI1 and the PWR (power?!) wire to TPS main... looking at these now, nothing seems to be happening at the DI pin and the PWR wire ain't doing much when I depress the throttle so I'll go back and check that wiring for sure

I set base timing by making a [#1 cyl] TDC timing mark on the front pulley when building the engine (not ideal I know but I can't access the flywheel with it all together), then set the timing configuration on the ECU to 0deg and adjusted the dizzy to suit. does this sound correct to you? 

I may have flooded it early on without knowing so I'll leave the plugs out over night and try again tomorrow. they're brand new so a little difficult to see if they're wet or not when I pull them. can definitely smell fuel though so it's getting through alright and the expected 300kPa is showing at the reg, as I've entered into the ECU fuel settings...I'll persevere for now

thanks again!

Tim

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1 hour ago, CMSport said:

I set base timing by making a [#1 cyl] TDC timing mark on the front pulley when building the engine (not ideal I know but I can't access the flywheel with it all together), then set the timing configuration on the ECU to 0deg and adjusted the dizzy to suit. does this sound correct to you? 

So did you check it with a timing light while cranking?

 

1 hour ago, CMSport said:

thanks for looking at that so quickly - yes, I'm using switch type TPS for now. will see how it drives before I throw that away. I have pinned the idle switch wire to DI1 and the PWR (power?!) wire to TPS main... looking at these now, nothing seems to be happening at the DI pin and the PWR wire ain't doing much when I depress the throttle so I'll go back and check that wiring for sure

Note it should be conected to an analog input, not digital right?  Since it is a switch you will also have to set your error high to 5.0 and error low to 0.0 for it to work.

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Hey there.. yes, I set the timing with a timing light, while cranking and sorry yes the TP main (PWR wire pin) is connected to AN Volt not DI.. my mistake

Just had another crack at it and no joy but noticed that it was reading 85% ethanol... I have never had a sensor connected to this setup but I assume that it has taken the ethanol sensor fault value from a previous setup (this particular ECU was not brand new for this car) and applied this because it couldn't see a sensor reading....?? I can't imagine how it would alter fuel because of this given that dual fuel table or any fuel corrections for % ethanol are not active but it's the only thing I can see that's out of place... 

any other ideas would be great!

here's another log from cranking over tonight and adjusting fuel table

 

 

Log 2018-06-20 5;29;46 pm.llg

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one more thought, I have set the injection mode to group / staged, is this correct for my triggering mode? 

I've just read the configuration help file again on injector mode setting and am wondering whether I should be using multi-point group? 

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1 hour ago, CMSport said:

but noticed that it was reading 85% ethanol...

Ignore that, it is just a default value, the ECU wont use it unless it is in multifuel mode with blend tables setup etc.

 

24 minutes ago, CMSport said:

one more thought, I have set the injection mode to group / staged, is this correct for my triggering mode? 

I assumed you had more than 1 injector per cylinder when I originally looked?  If you only have 1 injector per cylinder then it should be set to multi-point group and you will also what to set active drives to 1-4.

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27 minutes ago, CMSport said:

it's also wired to run batch so all 3 nozzles are wired to inj #1 pin

Ok, original settings wouldnt have prevented it from running in that case.

 

4 hours ago, CMSport said:

yes, I set the timing with a timing light, while cranking

So you have a spark at the right time.  That means it must be fuel, air or compression that is missing from the equation - so which one? 

Fuel is easy to test - you can just spray some ether into it - if it then coughs or fires you can conclude it is fuel that is missing and look closer at what is causing that.  If you dont get any signs of life with an alternate fuel source then you are going to have to look for the missing air or compression (cam timing, stuck valves, rings, etc)...

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thanks I'll go over the basics again. there's definitely fuel because the plugs are coming out wet

there is spark.. and the timing is as per my mark but I could have been having a dull moment and set up the mark poorly.. dunno. even if that were the case, I wouldn't have thought a few degree would make much difference.. will do a compression test, too which will answer any questions of cam timing but it's a freshly built engine with factory tolerances so should be OK

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  • 4 weeks later...

*update* still banging my head against the bench with this one! have double checked the wiring to the ECU, drained the fuel system and cleaned, including the tank, pulled the head off and checked clearances then re-fitted and triple checked cam timing and the thing still won't fire... I'm sure something will jump out eventually but I'm really at odds. while the head was off I also checked the timing mark on the front pulley with a DTI, on no.1 piston, and it's bang on at TDC

any other thoughts and ideas would be really appreciated!! 

related... I checked the TPS wiring again and it's a very strange setup. there's no +5v, only a sensor earth then I suppose an earth switch back to the ECU for IDL and PWR... is this normally how the switch type TPS operate? 

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I tried wetting the plugs before fitting and this didn't yield any response but I haven't tried an alternative fuel, no. I would have thought fresh 98 would be more than enough but maybe a bit of ether wouldn't hurt..

it does occasionally 'pop' when I turn the key off after cranking which sort of suggests to me that it's a timing issue...? maybe I've looked at it too many times and can't see my own mistake :wacko: 

 

just to double check... base timing on these engine's is normally 10deg BTDC but I've set a timing mark at no.1 piston TDC so, when I am setting the base timing at the distributor, the correct way is to go into the "set base timing" function and lock ignition timing to 0 degrees BTDC then adjust the dizzy to the TDC mark with the timing light, correct? there's no logic in my mind that I should be setting the locked angle to 10deg, right?

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2 hours ago, CMSport said:

just to double check... base timing on these engine's is normally 10deg BTDC but I've set a timing mark at no.1 piston TDC so, when I am setting the base timing at the distributor, the correct way is to go into the "set base timing" function and lock ignition timing to 0 degrees BTDC then adjust the dizzy to the TDC mark with the timing light, correct? there's no logic in my mind that I should be setting the locked angle to 10deg, right?

The way you have done it will work, but it means when you are cranking (ECU doesnt control timing below 400RPM with the 1/TDC mode) you will be sparking at 0BTDC.  It may be a little slow to start like that but I expect it would still fire up fine. It only needs a small cough to get the RPM above 400 where the ecu will start controlling igntion to whatever is in the ign table.

Since you know original base timing was 10deg, It would be better to put a new mark at 10BTDC on the pulley, then in the set base timing screen, set the "lock timing to" 10deg.  Then when cranking adjust the dizzy until your 10deg mark lines up.

 

2 hours ago, CMSport said:

I tried wetting the plugs before fitting and this didn't yield any response but I haven't tried an alternative fuel, no. I would have thought fresh 98 would be more than enough but maybe a bit of ether wouldn't hurt..

You need more than just wet plugs.  The idea is to eliminate to possibility that the injectors either arent working or arent injecting enough.  If you dont have a can of easy start or something then pinch some gas out of the lawnmower and squirt in it to the manifold with a squeezy bottle of some sort.  A teaspoon or two full would be ballpark. 

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ahhh OK I didn't know about the 400rpm threshold. I've got an adjustable timing light so bumping it to 10deg is easy

I'll try the timing tweak first then add some juice in the intake and see what transpires 

 

thanks again!

Tim

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still no joy on either front... BUT... I'm willing to how my arse here a little... as it were

I somehow overlooked the fact that the factory IGN wiring does not include an igniter and therefore the setup is currently wired so that IGN output 1 from the Link is directly coupled to the -ve on the coil. I have not looked closely at this solely due to the fact that there seems to be spark but perhaps only a very weak one??? should this setup work or do I need to add an IGN driver? I have plenty of them and my goodness that would be an easy fix if that's the culprit !!

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Ok well that's good news to hear! I was led off that scent completely because there was spark when I checked the plugs sitting on top of the engine and never thought that the igniter would be built into the ECU! Stupid of me to assume. 

Hopefully I'll have a clip to share of it running soon!

Yup sure enough one little Fuji Electric ET 424 transistor tucked away on the board

 

https://photos.app.goo.gl/p5XDzxzm3KzU246p7

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