Megasquirt earthing points

[SILICONEKID340HP]

I have conflicting afrs`s, the LX1 digital guage runs a lot richer than the Tuner studio ,The tuner studio sits at a nice 15.5 on steady cruise but the LX1 shows less than 15afr .Been told it could be the earth points .

Trigger wheels.com told me the LX1 will be correct beacause it`s reading direct from the lambda`s, so does this mean the whole map is wrong ?

Where do most megasquirters fit the earths ?




Earthing points


LX1

[MADMAX2]

what i do know Daz is.. if you want a proper earth go direct to the chassis easy to make one drill and tap.. end of....

[SILICONEKID340HP]

MADMAX2 said:

what i do know Daz is.. if you want a proper earth go direct to the chassis easy to make one drill and tap.. end of....

Could i come off those earths with a nice thick cable ? been told the engine but where can it be earthed on the engine ?

[MADMAX2]

SILICONEKID340HP said:

MADMAX2 said:

what i do know Daz is.. if you want a proper earth go direct to the chassis easy to make one drill and tap.. end of....

Could i come off those earths with a nice thick cable ? been told the engine but where can it be earthed on the engine ?

its an earth cable so thickness isnt an issue there are earths on the engine but for something as important as megasquirt have it on an earth by itself

[spitfire4v8]

What's that wire just above the date in the earths picture? looks like bare cabling showing? and paint on your earth ring terminals? looks all wrong to me.

[SILICONEKID340HP]

spitfire4v8 said:

What's that wire just above the date in the earths picture? looks like bare cabling showing? and paint on your earth ring terminals? looks all wrong to me.

There are 4 earth cables ,i can clean that one up by re crimping it ..Where are all these earths from and where should they be ..This is not my work ,done by a specialist !!!

[Simon says]

All MS earths/grounds to go direct to the block Daz in one place otherwise you will get voltage offsets, there is a stud on the rear of the nearside cylinder head and all the MS grounds should be secured here (all of them together) as mentioned already you have them fitted to a painted/insulated surface not ideal the WB problem you have is either because the WB needs calibrating in Tuner Studio or you have a voltage offset i.e the wide band should take it's grounds - and live feed + from the same place as your MS ECU otherwise there will be an offset on the readings form one to the other

Edited by Simon says on Thursday 9th August 21:15

[SILICONEKID340HP]

Simon says said:

All MS earths/grounds to go direct to the block Daz in one place otherwise you will get voltage offsets, there is a stud on the rear of the nearside cylinder head and all the MS grounds should be secured here (all of them together) as mentioned already you have them fitted to a painted/insulated surface not ideal the WB problem you have is either because the WB needs calibrating in Tuner Studio or you have a voltage offset i.e the wide band should take it's grounds - and live feed + from the same place as your MS ECU otherwise there will be an offset on the readings form one to the other

Edited by Simon says on Thursday 9th August 21:15

Do you have a picture of the Stud ? or give me an exact area.. Yes it is painted but the metal is bare under the crimped connectors. Im going to trace the live feed to see if it comes from the same place ..

There are four earths so maybe they are for the ECU and lambdas ..Once i have re connected the earths will it change my tune ?

If it`s earthed to the block how does it get to the chassis because its on rubber mounts .

Edited by SILICONEKID340HP on Friday 10th August 08:05

[jeboa]

You should have another heavy duty cable near the front of the engine connected to the chassis. You need a heavy duty cable for the starter motor earth.

[paulathome]

Daz as mentioned before, all your ecu earths should go to the same point ON THE ENGINE BLOCK.
That earth you have there is a heap of possible problems. Mounted to the plenum throttle bracket. So between there and the engine block you have several mating surfaces. Bracket to plenum, plenum to trumpet base, trumpet base to inlet manifold and inlet to engine block. Most of these joints have gasket sealant of some sort, which is not a good conductor.
Im sorry but who ever decided to mount the earths there wants a slap.
Find an earth direct to the engine block, take all the earths to this point, and this point only and i think your problem will go away.
Have a read of phils install manual to explain in better detail.
Paul

[SILICONEKID340HP]

Thanks for that ,the problem is there are four ,there is a possibility one of the earths maybe nothing to do with the lambda and ECU.

Im going to have a good search through the rats nest to see if there is one supply feeding the ECU and Lambda sensors.!

Can someone post the engine earh position

Edited by SILICONEKID340HP on Saturday 11th August 21:06

[blitzracing]

From what I know of audio electronics you need to be very careful how earths are wired when the signal levels are low and sensor internal resistances are high. Ideally you want an earth on each sensor being fed back to one common grounding point at the ECU end-(this is what the 14CUX does)or basically a star type configuration and you don't want to join the earths so they can form a earth loop of any kind, whether it be through the block, chassis or whatever. OK, a car is basically a DC world where induced voltages through inductive loops should not be an issue, but things like the HT and the alternator output still have an AC component in them that can get picked up in earth loops. If you do ground every sensor at one point on the engine block, then use a good quality single sensor ground wire to go from there back to the ECU, (dont use chassis) but its still not the best way to go about it. I dont pretend to know how the internal grounding of the MS is wired, but the above is just good practice.

[Simon says]

Its fine to share an Earth point with something not relating to MS Daz as long as its a good-un i.e engine block/cyl head and as Paulathome said

[SILICONEKID340HP]

I can just get to it ,does anyone have an engine out of the car to find out the bolt size, it could be imperial. ..I can get to it but can`t see it cheers .

[macdeb]

You may find it easier with the plenum off Daz. That's where my MS earths are at back of engine block. As has been said, where you have them at the moment is not good at all.

[SILICONEKID340HP]

macdeb said:

You may find it easier with the plenum off Daz. That's where my MS earths are at back of engine block. As has been said, where you have them at the moment is not good at all.

I can get a bolt in no problem ,its the one on that picture ,think its the head not engine block ,just need the thread size because i can`t see it ..

[macdeb]

Corrected, yes, it's the head. Should already have an earth on there, so should be able to take the nut of and see. Unless yours is missing of course.

[SILICONEKID340HP]

macdeb said:

Corrected, yes, it's the head. Should already have an earth on there, so should be able to take the nut of and see. Unless yours is missing of course.

I don`t have an earth on the head but i can see one way down on inlet manifold ,There are plenty of places to earth in this area,two female threads spare the other side of the inlet manifold.One just at the side if the large nut ..Im wondering if this area could be used .

Edited by SILICONEKID340HP on Monday 13th August 18:15

[SILICONEKID340HP]

Can someone put me in the picture where the earth cables come from

I have one from the Air temp sensor ground joined on to a red one which disapears uner the plenum

Four coming from the footwell then joined together

Two more coming from the footwell separate

I can`t seem to find a decent place to ground them, pictures and help will be appreciated.

Other than that can anyone reccommend somewhere i could take it to get it sorted.

The live feed needs to be the same one which feeds the ECU and Lambdas to keep the voltage the same ,can`t seem to find them ..

Sick and tired of it ! Im on the brink of getting rid .

Edited by SILICONEKID340HP on Thursday 23 August 20:11

Edited by SILICONEKID340HP on Thursday 23 August 20:13

[Alexdaredevilz]

I earthed mine on the fuel rail tabs that bolt on the intake, I think there 10mm's never had a isssue, nice and easy to get to