16v earthing

[Tim.duncan]

hey

i have a 4agze in a ae86 and im pretty sure the earth on it sucks! i have a big heavy cable going to the battery from the motor but a pretty week little cable then going to the body.

just wanted to ask where is the best place to earth the motor to the body?
i was also planing on running lots of differnt smaller cables from as many places as posible to one place then earthing that to the body.

any info would be great

cheers

[cky767]

just the body next to the battery should be fine, same as factory with a 10mm bolt

[LittleRedSpirit]

Run a big heavy cable from the block to the body near the battery. Bolt a big heavy cable from where this attaches the body to the negative terminal. That should be all you need. If you are still having issues then try another cable on the other side down to the chassis rail under the inlet.

[jaz_ae86]

Factory AE86:
Battery to block(on engine mount passenger side) Big cable (later Toyota run a Y cable. Both meet at battery, one to chassis near battery, other to block, $0 upgrade).
From driver strut tower to inlet manifold
From body to gbox.

This has an even spread of earths over the body rather than one point.

[Tim.duncan]

the main problem im having is on a cold morning she will not start. im pretty sure this is because my coil packs are bolted ontop of my cam covers, which have a rubber seal under them. i ran a dodgy cable from them to the fire wall and he presto away we go.

the other thing is my tacho moves all over the place but reacts to when i turn things on and off (eg light, rear demister) would this be because my motor is not earthed well? or another earth problem to do with the dash cluster?

[jaz_ae86]

I have my coil packs attached to the cam covers as well. No earth issues. And don't know why you would need to earth them. Power and earth come from igniter.

What tacho converter are you running?

Sound like you have general earthing issues. Try increasing the number of earths, and ensure the ECU earth(on inlet manifold is good). Earth from near this point to body is a good idea.

[Jonny Rochester]

The coil packs don't need to be earthed with their body. Infact some coil packs are plastic.

But the igniter often does need to be earthed. It has a aluminium body, so if it's mounted securely with a metal bracket, it will be earthed.

The earth straps on a AE86 (and most Toyotas, and many cars) go like this.
The neg terminal of the battery is attached to the body, with a very short fat wire.
There is a earth wire between the chassis rail and the engine block (gets past the rubber mounts)
Earth wire between the firewall and the head.
Earth wire between the chassis rail to the gearbox.

You don't need a aftermarket earthing kit.

[Cerby86]

i had one on my old ae86 and it was fully sik!!!


nah itwas gay

[Tim.duncan]

hey guys

well i pulled into jcar last night a bought a whole heap of stuff to make some earth leads with. i made one up for the coil packs to the inlet then to the strut tower like jas suggested (i already made it for the coil packs before reading your post) i will do some more this weekend and will check out the ignighter to see what that is like.

another cold morning this morning and she did not want to go (even with my dodgy earth wire in place which seemed to fix it last time?) i pulled the fuses for the ecu, motor, charge. and still nothing, i then pulled the relays that are in the fuse box and gave them a quick tap and after that she fired?

am i suffering from a earth problem? or could it be somthing else? a faulty relay or moisture in something?

its a real pain becuase the car is so reliable and has no problems starting till its 6 in the morning and freazing cold then it does not want to play?

[sundee]

^^ that last relay u gave a flick(tap) .. find it.. replace it.
as for your earths.. the main thing about the earth is that it actually has one.
their is no point bolting up an earth strap to a dirty/rusted/painted piece of metal..
if i were u i would:
1.replace that relay u gave a tap.
2. take off all your earths and give them a good sand with sand paper, make sure their nice and shinny and bolt them back up.
3. if your using an aftermarket bosch coil. cylinder type. take some paint of the cylinder to make sure it has a good earth to the bracket... this will give u a better spark.
4. test your start time switch with a multi meter. (the one at the back of the head next to the water temp probe)

[Tim.duncan]

hey guys

well i installed the new earth wire from the inlet to the strut tower, made sure i removed a small bit of paint so it got a good conection. i also replaced the battery terminal with a new one and made sure also that i had a good earth there. now the motor seems to start up straight away (have to wait for another 3 deg morning) and maybe even run better (it might be in my head) i was pretty happy to see my tacho behaving its self and not waving around its needle like it just dont care. untill my thermo fan kicked in..... then the needle was like it had a bad case of ADHA again

just some more questions

my thermo fan is operated from the water temp sensor in the rear of the the head, i have split into the white wire to give my unit the voltage signal. The unit im using is a kit from jay car that sensors falling rate voltages and flicks on a reley at a set voltage. now my questions is

1. the tacho is working fine until this unit turns on the thermo fan, why would that affect the output to the tacho? (jas i dont know what tacho coverter it is running?)

2. by splitting into this sensor is it going to affect the way the ecu operates?

i have not got a big back ground with auto electronics but im enjoying learing some more about it all if you can help me that would be good cheers

[Tim.duncan]

any one care so shed some light?

[jaz_ae86]

Where is your signal comming from to run the tacho? You have to modify the signal or cobine the trigger outputs, or you cluster has been modified.

It sounds like that the noise (signal interference) when the fan is on is interfering with the tacho signal. If the power to the fan runs parallel or wraps around the signal wire that runs the tacho, the tacho will go crazy when the fan is running.

If you know where your tacho signal is comming from, then you can trace the problem back.