Technical Megasquirt construction project

[arc]

thats something worth checking yeah. it will also mean differnt settings in 'engine constants' too. I still stand by an IR thermometer as a handy bit of kit when testing engines, checking the exhaust ports should give a good clue as to what cylinder is doing what.

ahh, i see what you are saying re timing and that makes sense now.

when wiring your VR sensor, which way round did you do it? I assume you use twin core sheilded cable, and then sheath is grounded at both ends? from my loom notes for my build;

07	Shielded (red core)	TDC negative signal
24	Shielded (white core)	TDC positive signal

 

[randomizered]

yeap, thats what i did.

The shield goes to ground. the -ve goes to pin 7 which is infact just another generic ground. I chose the red as the +ve which i ran from the ms to the engine bay, and linked it up to the original loom. It's all shielded.

The confusing bit are the original loom colours, i have yelloy, green and black.

On the crank sensor connector, are your pin 2 + 3 earth/-ve, and pin one the +ve connector?

Cheers for your help arc

Kristian

 

[arc]

erk, now you're asking. lemme dig through some paperwork and work it out. i'd check on the car, but i left my keys in bob_in_disguise's car. doh!

 

[arc]

ok, all i do here is give you SPI stock info -

11	blue/red	TDC sensor Negative
28	yellow/black	TDC sensor Positive

the other (black) is earth yeah.

they don't tie in too great with your colours though.

 

[randomizered]

hehe, I'll compare it to the cinq haynes i have and hopefully conclude it was right all along, although, id love and easy fix

no rush though, will have to buy a weekly bus pass for this week

Cheers again

Kristian

 

[arc]

np

you are of course assuming haynes diagram is correct!

 

[randomizered]

I've gone back to basics now.

Reflashed the ECU and set up the temperature sensors. removed and reinstalled MegaTune, and am following the guides to getting a new engine idling.

Once i know I can get a reliable idle with my settings, i can look at the VE, spark tables etc, and work them to fit my config.

Sadly the battery has dies again on the first try, so no more until tommorrow.

One thing I have noticed though, my TPS calibrates fine, but only reads 136 at WOT. According to the technical info this is too low, as its around the flood clear value. Should I be seeing more like a 0 - 256 range on this?

Cheers,

Kristian

 

[arc]

My TPS has a greater range than that. is the 5v vref for the TPS coming out right?

how are you controlling idle at the moment? Mine is done with closed throttle and a vacuum leak on the back of the TB.

what happens when you do open the throttle, have you got any logs from it you can upload?

 

[randomizered]

I'll measure the vref later, I have a different TPS to you though, as my intake is different, so that may be it. I also have a k series throttle body, not fitted, that i can link up and see how that one works.

Idle at the moment is just the throttle cracked open a bit, I was going to install the idle valve but i've heard of problems getting them setup right, and didn't want to throw another variable in there. How big is your leak? brake servo size or just a small nipple?



I had one or two logs, but got rid of them as I couldn't get much information from them.

Tomorrow night I'll hopefully get it started, idleing, and then get a log produced ...hopefully lol....

If i can't get the TPS running right i may ditch it for now, and run MAPdot instead, as it doesn't need a tps at all......just hope my map sensor is working ok lol. reads 98 without running, not really noted what it does when cranking though.

Cheers,

Kristian

 

[arc]

mapDOT is only to do with acceleration enrichment, suggest you disable the acceleration enrichment for now.

airleak is nipple rather than brake servo sized.

it uses the map sensor to pick which ve bin to be using though, it doesnt need the TPS reading to be able to do that, unless you are using alpha-n.. which isn't a good idea on a road engine.

 

[randomizered]

thats what i read on the MS official pages, but i've read of others driving without TPS

I'll create a vacuum leak rather than cranking the tps, and try and get the tps running well.

nope, not using alpa-n, 'nuff problems as it is

cheers again,

Kristian

 

[arc]

the engine can run without the TPS.. but for normal running it works better using the MAP value to select the VE bin and then using TPS value to control acceleration enrichment. but to get it running and idling, you do not need the TPS. Without any form of acceleration enrichment though, it'll stall if you rapidly open the throttle.

 

[randomizered]

On the brink of calling it quits, and jacking in the whole thing...scouring the breakers for OEM ecu looms I've gained faith again!! :slayer: :devil:

I rewire the crank sensor again with shorter wires but at the same time i measured the resistance....1200ohm. Considering the sensor worked before i stripped the car, i presumed it wouldn't be a cause of problems.

The punto manual said that it should only be 600ohm though So i swapped it with an old cinq one i had kicking about.

Fired it up again with very little hope and ...



Heres the video of it firing.....before i took this video it had only run properly the once, and only for about 5 seconds. So this is almost as good as its first ever fire up

https://www.fiatforum.com/gallery/data/500/MOV00078.3GP


I'm a happy chap now....still a lot more to do but real progress has been made

Kristian

 

[arc]

well done

now the fun of tuning it begins

 

[Asteris]

ok, all i do here is give you SPI stock info -

11    blue/red    TDC sensor Negative
28    yellow/black    TDC sensor Positive

the other (black) is earth yeah.

they don't tie in too great with your colours though.

Arc, is that for sure? Where did you get this info from? Neither Haynes manual, nor Seicento service manual distinguish positive and negative pins of the sensor. I have them wired the other way around and the engine starts fine without resets. Haven't revved it more than 3000rpm thought.

Today was the first day the engine started on MS-II. I had MS pin 36 at Marelli 19 and MS 6 to Marelli 1 and was trying for 2 hours without success. After using a strobo, found out that there was 180 degrees difference. Switched coils and started after 2-3 tries.

 

[randomizered]

http://www.megamanual.com/ms2/wheel.htm

near the bottom

 

[Asteris]

It doesn't say anything on the 11 and 28 pins of Marelli 8v ECU's...

 

[randomizered]

It won't, because they can only be fitted the one way around, so there is no point mentioning polarity. It makes sense though as its an AC signal.

I haven't tried reversing mine, so don't know what would happed.


Managed to get the fan fireing up tonight. I rebuilt the driver 3 times, and it turns out that the fan relay + switching voltage must be wired to int rather that permanent like the fiat loom does. Otherwise it won't let the MS start up if wired, and trips the relay like mad, if you wire it up after a start up.

Took me a few nights of fiddling to finally realise

Thats about it not though, hoprfully get on the move tomorrow

Kristian

 

[randomizered]

Just a quickie....have you all got your tachometers working? It looks pretty simple and I'll give it a go in the morning, but anything specific to look out for?

Kristian

 

[Asteris]

Yes, all gauges are working fine, i managed to fire it up but runs rough and refuses to rev.

Did a little search and common behavior of a reversed VR polarity, is rough idle, refusing to rev and rpm dropout to zero and back. Also a synched-not synched green-red flashing block at the low right corner of Megatune, is definitely a reverse polarity issue.

Will try it again tomorrow.