Scrutinize my car wiring

[Shnoog]

I drew this diagram up in paint a little while ago. I am currently wiring up my car and just wanted to see if i have made any stuff ups that i may have missed.

The only things missing is the wiring for the oil temp/pressure and water temp but I'm not worried about that on this diagram.

Also this may help anyone who wants to wire up their own car from scratch. The MSD ignition controller could easily be replaced with a fuel injected ecu.

The DASH2 and AEM are the gauges i'm using if anyone is wondering what they are. Also the Davies Craig controller takes care of the electric water pump and the thermo fans.

http://i.imgur.com/DwRFc1g.jpg

[hako]

Maybe because it's Xmas and I've been drinking, but that starter relay is doing nothing.

[Shnoog]

That top relay is meant to shut the power to the lights, fuel pumps, and fans while it's cranking.

[KAL SPL]

If it cuts power to the fuel pump while its cranking you might have starting issues ?

[KAL SPL]

15amp fuse won't be big enough for fans either.

[hako]

I see, completely missed normally closed. As above with the fuel pumps.

[MrSparkle]

This car has a carburetor so i think the fuel pumps shutting down while its cranking won't be a problem.

[Shnoog]

Swapping to 30a fuses for the fans won't be a problem. The wire i have used is more than capable for that kind of load.

[66 coupe]

dont use fuses for your fans, use self resetting circuit breakers 30A.

[ONETEN]

So many relays. Things like lights/brake lights are rarely switched via relays and can be switched directly. Most cars switch these directly in OEM applications. Review these and check your switching load ratings, remove relays where possible as these are just introducing cost, extra points of failure and complexity. Brake lights for example are usually 2 x 27w bulbs or similar, and with Ohm's law applied: 2*(27/12) = 4.5amps of combined current draw. There is hardly a brake light switch under the sun that isn't capable of switching 4.5amp load directly.

I find that a lot of people generally think relays need to be used for all load types without understanding their purpose. Relays are just electromagnetic switches, and as such are really just switches the same as any other. Their designed purpose is to switch a big load using a small load. It doesn't make much sense to use a 30a load capable switch, to switch a 30a load capable relay for a 10a load.

Alt start light probably wont work the way you have drawn, but depends on the alternator type & whats going on at dash2 end thats not in diagram. Some alternators require a load on the charge light wire to excite the rotor field and properly produce a charge, and others are self exciting and generally just use a +12v ign feed for this purpose. For example, Nissan RB are the former and Toyota JZ are the latter (can have the chg light wire left disconnected).

What is the purpose of the resistor on w exactly? Is it a pull down for something?

Fair point was made above regarding fuel pumps. Me thinks you def want them running during engine crank :)

EDIT, just realised this was Alex OP after typing. If this is your 180sx, and you are using the OEM brake pedal/switch & combo stalk for the lights then you can def drop all those relays. No s13 silvia uses any relays for any light operations at all (except for headlight motor controls on the 180). They are all directly switched. The brake lights for example feed a 12v+ from the fuse box via a 10a fuse directly to one side of the brake pedal switch, the other side goes direct to tail lights. Happy to give you a hand with this diagram some time if you want to pop by.

[ONETEN]

On second thought, is this car not carby? Why are you using an 044?

Also, for CAMS regs, I think the fuel pumps need to shut on/off with the engine automatically do they not?

[Shnoog]

Yeh this is for the 180sx. Apart from the 80 relay and fuse all the 40A relays were already on the car so i was just reusing them.

The switch i am using for the lights is a pull type i got from supercheap. It has some pretty beefy connections and also a 30A fuse on it.
I would have used just that for the lights but i don't think it would have been enough. When i tested the modified park lights in the car i found they were actually using spotlight globes too. So on full load it's basically 4 spot lights plus the rear lights on all at once.

Brake pedal is a custom one i made and it uses a switch from a washing machine so i wasn't too sure of its capacity and the 180sx uses 4 globes for brakes.

Only reason I'm using an 044 is i had one already just sitting around and the fuel cell has been modified to take one. It's something i'll change down the track but for now the regulator will be able to drop the pressure down to the 6-7psi.

I had a quick look in the cams manual and found that in Schedule C, 9.
"On each automobile, other than those of the 5th Category, fitted with an electric fuel pump, the pump power
supply must cut off in a maximum of six seconds after the engine stops;"

I'll change that today so the fuel pumps are controlled with the ignition switch instead. Also the way i saw it, disabling the fuel pumps while cranking shouldn't be an issue. With the fuel bowls primed there should be more than enough fuel in the primary to start and run the car for a little while before emptying.

[Shnoog]

Oh as for the alternator, it's a pretty generic one with the battery lead and two pin plug. One is meant to be the charge light and the other is hooked straight up to constant 12v in the commodore.

The dash2 manual just says:

Pin No Description Range Wire Colour
10 Alternator warning 100 Ohms to 12v Slate/Black

http://www.race-technology.com/wiki/index.php/DASH2PROInstallation/ElectricalInstallation?action=dispimg&im=dash2pro_default_wiring.p.gif

[Greg Rust]

I have a switch in engine oil pressure that cuts the fuel pump at 20psi, handy for satisfying the regs and also drops engine power in event of low oil pressure.

[Shnoog]

That's a pretty good idea. How is it setup so it primes the car before startup when there's no oil pressure yet?

Oh and about that resistor on on the W terminal, apparently some isolation switches have it in built others need one wired in.

"supplied resistor prevents alternator voltage spikes potentially damaging the alternator diodes and other parts of the electrical system when the switch is operated (connection via 2 x 6.3mm male terminals)."

[Shnoog]

I found something that should just work just as well as a pressure switch for a fuel safety cut off.

http://www.ebay.com.au/itm/LPG-Safety-switch-Peel-/331611568728?hash=item4d3596fa58:m:myrHQ00R7Z7h6IQ PFoh2wmg

It detects a pulse from the tacho that switches the pump on. So it should work while the car is starting then shut the pump off once the engine dies.

You prob wouldn't need a bypass switch to prime the fuel pump then.

[Shnoog]

Well I think i have the wiring sorted. I attempted to start the car today but i was getting backfiring through the carb and it just wouldn't start. Everything else is working as it should. I added some more timing and a few times it seemed like it was about to start but nope. I don't want to keep adding timing until i rule out any other problems.

http://i.imgur.com/z4k8BEd.jpg

Thanks for the input.

[ONETEN]

Looks like it should work ok mate, nice work.

As for the back firing, check the firing order / spark leads are in correct order. Always first thing i check when engines backfire on crank.

[Shnoog]

I'm going to go through everything i can think of today. Check cam and crank sensors, the reluctor wheel and even if I installed the cam incorrectly.

Also a guy on nisanroadracing mentioned using http://www.summitracing.com/int/parts/prf-80174/overview/ for a brake switch. He had problems with just a normal switch when using a pedal assembly because it would change the height when he adjusted the bias. That pressure switch fixed all his problems.

[S85FI]

Backfire through carbie usually timing out by 180 degrees, firing order or ignition cuircut has voltage drop coming off crank. I.e points, module or what ever you're using might run 12 v on crank and 8 on running and ballast cuircut or what ever is being used is not wired up right?

More likely dizzy cap/leads out by 180 degrees.

Didn't go over the whole thread again but a few posts down something about this car being carbie?

[Shnoog]

yeh its an ls1 with a carbie using a msd 6010 ingnition module. Unless something is wrong with the cam and crank sensors the only real way you could have it 180 out is if I didn't line up the dots on the timing chain. Other than those possibilities i'm not sure.

[S85FI]

yeh its an ls1 with a carbie using a msd 6010 ingnition module. Unless something is wrong with the cam and crank sensors the only real way you could have it 180 out is if I didn't line up the dots on the timing chain. Other than those possibilities i'm not sure.

Compression test? Should let you know if cams set right.

Can cam sensor be fitted out by 180 degrees? That would have same effect? And if capacitor type, I take it you're not running solid leads?

Edited to add cam sensors details.

[Shnoog]

Pretty sure it's spiral core wire. As far as I know the only way it can gout out ui if the sensor is broken or faulty. I prob won't have a chance to check it out until Monday. But I'll make sure to post what I find just in case someone else wants to carb their ls.

I'll do a leak down and compression test just to rule everything out.

[ONETEN]

Easiest way to check both firing order & cam/crank/entire management system is to turn the engine over with fuel disconnected, and use a timing light on each spark lead and confirm that it is firing at the correct engine angle. If its 180 out (which is what im thinking is also the cause) then you would immeadiately see this on the timing light as you work your way through cyls 1 - 8.

Work out before hand what each ign angle should be in acordance with the firing order.

If it is incorrect yet lead firing order is correct i'd start looking at sensors.

[S85FI]

1-2-7-8-4-5-6-3

Some things just stick.... :o) old school 308 firing order... no idea on LS...

[Shnoog]

Well looks like i found the problem. Yesterday i did a compression test and got 0 for cyl1 and 170 for the other 7. At first i thought it was possibly something wrong with the piston but it turns out when i measured the pushrods last year they were slightly too long.

I put in some stock rods in cyl1 and did a quick turn over and cyl 1 then got 200psi. So the for some reason it looks like they are keeping cyl 2-8 on the cusp of seating but cyl1 is completely open.

I'm going to get some replacements sent from america since they are $70 cheaper a set than here in aus delivered, even with the exchange rate.

Once i fix this problem i'll see if it starts.

[Shnoog]

Well the car just fired so i guess that was the problem. It's stalling almost immediately due to the large cam, but once i set the idle screws it should be fine.

[S85FI]

Well looks like i found the problem. Yesterday i did a compression test and got 0 for cyl1 and 170 for the other 7. At first i thought it was possibly something wrong with the piston but it turns out when i measured the pushrods last year they were slightly too long.

I put in some stock rods in cyl1 and did a quick turn over and cyl 1 then got 200psi. So the for some reason it looks like they are keeping cyl 2-8 on the cusp of seating but cyl1 is completely open.

I'm going to get some replacements sent from america since they are $70 cheaper a set than here in aus delivered, even with the exchange rate.

Once i fix this problem i'll see if it starts.

How will this cause low comp? If anything they will hit and cause bent valves?

Or am i missing something here?

[MrSparkle]

If the pushrods are too long the valve wont be able to close and the cylinder wont have any compression.

[Shnoog]

The pistons are flycut so even if the valves are slightly open they won't touch the top of the pistons.

[S85FI]

If the pushrods are too long the valve wont be able to close and the cylinder wont have any compression.


The pistons are flycut so even if the valves are slightly open they won't touch the top of the pistons.


So now really confused.
If pistons are recessed for valves so there is clearance how does this affect compression as valve timing is controlled by crank /cam gear?
Never pulled down a LS motor so no idea what the piston to head/valve clearances are.....:(

In another words closed valve = compression regardless of crank/rod throw?

[RICEY]

The valve can't close because the pushrod is too long so the compression is bleeding off through the slightly open valve.

[Shnoog]

When a pushrod is too long the plunger in the hydraulic lifter can bottom out. The only give is then in the valve. So when the valve is meant to be completely seated it is actually being held slightly open. There is no chance for the cylinder to hold any pressure on the compression stroke.

In my case i am using short travel/slow leak down lifters that have much less movement in the lifter plunger than standard hydraulic ones. They work much better at higher rpm but they have much tighter tolerances. If i had used any run of the mill hydraulic lifter i probably wouldn't have had a problem but the compressed air from cylinder one was rushing out the intake runner and spitting out the carb.

[S85FI]

With you fellas now. The whole time i was thinking i read con rod not push rod. The whole time i was thinking how the fuck?
So i read back to see where confusion started. Then i just laughed. Push rod. .... they still use push rods and hydraulic lifters? Haha

[RICEY]

I'll stab you with a fuckin pushrod you homo BMW driver.

[Shnoog]

we gota stick together against all the haters out there

[S85FI]

I'll stab you with a fuckin pushrod you homo BMW driver.

Lol. Wish i could do the same but wait..... i dont have push rods to do such things. ....cam shaft?i wonder if my car would run on 3 cam shafts?

[MrSparkle]

Shnoog has a set of pushrods he isnt using. Perhaps you can borrow some?