The Tuning Talk Thread - Forced Induction EFI & JZ Tuning.

[thechuckster]

rpsil13: remove the coil pack in question off the head, ensure it has a decent earth, then use a short length of (good) plug lead to go from outlet(s) to the spark plug(s). Put timing light sensor on that short length of lead and see if it's getting triggered/sparking.


edit: do the same if you want to check base timing for the ECU (e.g. set spark angle to fixed amount, do above to #1, check timing light against crank and adjust ECU trigger angle on ECU so fixed amount matches what is showing on the crank).

[1gjet]

ripsil, just run the spark check on the microtech, you can do the same with the injectors. I cant remember whats its called at the moment, but i have it on the ltx12s

[1gjet]

If the coil in question still isnt firing, when you run the sequence, trace the signal wire .

[midnight_purple_GA70]

spark check? ive not yet heard of this interesting

[1JZ-Rolla]

Yep, there's a test mode in the handset/software for LT models that allows you to trigger all ignition and injector outputs simultaneously. Don't do it with your injectors connected or you'll flood your motor

Its quite handy for fault diagnosis. Instructions are in the manual.

[rpsil13]

aaarrrggghhh, dont you just hate fixing other peoples crappy work

so far 4 of the injectors were wired wrong, 2 coil pack plugs were switched, and 2 of the injector wires werent even soldered, they were TAPED together wtf!!!

thanks for all the great info, you guys have been a tremendous help, i cant thank you guys enough,

well im almost there, the car runs A LOT better, but its still a little off, the last thing i need to check it the crank and cam sensors, heres where im at so far

Cam sensor

According to wiring diagram
Orange-blue
White-green

What I have
Orange-green
White- blue
(not sure if the diagram i have, already has them switched or if the wires have already been switched)

Crank sensor
According to the diagram
Red-Red
White-Yellow

I Have
Red-Yellow
White-Red
( i think this one is backwards)

if the crank sensor is wired backwards, would my car even start?

[midnight_purple_GA70]

there are a couple of combinations of how they can be... i think 2 combinations the car will not start
the other incorrect combination i think it will cause it to miss and carry on around 3000rpm

if it is incorrect it should throw the error home/ref and sometimes rpm

you might need to rev the car to above 3000rpm before it fails though

[midnight_purple_GA70]

ok just because i have a photo of my cam sensor wire on my phone...

if you are looking from the intake manifold side at your centre cam sensor (while plugged in)

them microtech green wire goes to the left (in my case orange/blue wire) and the blue wire goes to the right (in my case white/blue wire)

[rpsil13]

there are a couple of combinations of how they can be... i think 2 combinations the car will not start
the other incorrect combination i think it will cause it to miss and carry on around 3000rpm

if it is incorrect it should throw the error home/ref and sometimes rpm

you might need to rev the car to above 3000rpm before it fails though

100% correct, i tried switching the cam sensor wires and even the cam sensor position and it wouldnt start,

ok just because i have a photo of my cam sensor wire on my phone...

if you are looking from the intake manifold side at your centre cam sensor (while plugged in)

them microtech green wire goes to the left (in my case orange/blue wire) and the blue wire goes to the right (in my case white/blue wire)

awesome information, so my cam is wired correctly, now i think my crank my be reversed, it runs but after i revved it, it gave me codes "hom, ref, rpm"

THANK YOU +++++

now i just need to find a tuner and figure out how to check the timing, i dont know where to connect the timing light magnet/pickup

[thechuckster]

now i just need to find a tuner and figure out how to check the timing, i dont know where to connect the timing light magnet/pickup

as noted above - you do the following to the coilpack supplying cyl # 1

rpsil13: remove the coil pack in question off the head, ensure it has a decent earth, then use a short length of (good) plug lead to go from outlet(s) to the spark plug(s). Put timing light sensor on that short length of lead and see if it's getting triggered/sparking.

edit: do the same if you want to check base timing for the ECU (e.g. set spark angle to fixed amount, do above to #1, check timing light against crank and adjust ECU trigger angle on ECU so fixed amount matches what is showing on the crank).

[midnight_purple_GA70]

Well as most probably already know check your fuel pressure...

turns out its been the biggest point of failure in my whole system...

i didnt suspect it as the car started and idled fine and ran normally until attempting to make positive pressure

fuel pump had a busted outlet from incorrect installation (not done by myself)

so was only seeing 10psi fuel pressure at idle and very little more under any accelleration

so now i should be able to get the car up and running today/tomorrow if i get a pump
happy days

[1JZ-Rolla]

oops..............

[midnight_purple_GA70]

yeah fucking oops indeed... got a stock jza80 tt pump in it now... havent started it but ignition on 40psi fuel pressure so ide say my fueling problems are gone... worst part is spending about the last 18 months fucking around trying to fix my wiring so it wouldnt lean out etc making sure eveything else was spot on... and to find out the pump was the issue...

[thechuckster]

^^ it's a good example of why it's so helpful to fit a pressure gauge to your FPR if it's externally mounted from the rail. Can help you enormously when you have strange AFR and lean-out behaviours.

[JZA70 R]

(in future) if you have an electronic fuel pressure gauge (or just a sensor), you can run the output back to the ecu and then set failsafe parameters so when fuel pressure drops below say 40psi, the engine goes into limp mode. this would still allow the car to start but should fuel pressure drop any other time the engine would protect itself.
obviously this would also alert you to the fact something is wrong (if you didnt have a gauge). you would then check ecu logs and see there is a fuel pressure problem.