1jz wont rev past ~2500rpm *SOLVED*

[Hydra]

Rob, i'm almost not ashamed of the patch job I did... it's really only there to get me to the exhaust shop without being pulled over for noise! Ground clearance is probably more of a concern!

Lexsmaz, it was on top of the fuel filter, so fuel coming into the engine. The plugs were black but it wasn't running too well before I had this 2500rpm problem - you see I forgot to connect the IGSW pin to anything, and while it would run it would not even attempt to throw a code etc, as you would expect when the ECU doesn't know the ignition is on. It ran, but rich as all hell

The fuel pump is the original that came with the car. I have the walbro ready to go in but I need to find a non-rainy day (not parts of days as it is right now...). Plus I have about 1/4 tank of fuel left Might be ok I guess.

[CrUZida]

WTF?!!

A correctly wired setup will not do anything without the IGSW pin connected.

IGSW input on turns the M-REL output on, which turns on the EFI MAIN RELAY, which inturn turns on the +B and +B1 pins (which is what the ecu uses for power)

[rob]

WTF?!!

A correctly wired setup will not do anything without the IGSW pin connected.

IGSW input on turns the M-REL output on, which turns on the EFI MAIN RELAY, which inturn turns on the +B and +B1 pins (which is what the ecu uses for power)

not if u wire +B and +B1 straight to any ignition power wire u can find

which whats prolly been done

[CrUZida]

I realise that, hence my 'correctly wired setup' comment.

[Hydra]

IGSW is power from the key barrel to the ECU telling the ECU that the ignition is on, not the other way around.

I cannot deny the facts, it was the one wire that caused the problem. Connecting it to ignition switched power fixed it.

[CrUZida]

Yes, it tells the ecu the ignition is on, which in turn turns the EFI MAIN RELAY on (through the M-REL output), which then provides power to all the engine sensors.

[Mos]

I've seen engines run without any power connected to the ECU at all.... the power feed through the injectors was enough to provide power supply to the rest of the circuitry through the flyback and protection diodes.
Having engines "sort of" run doesn't promote the notion of wiring things up correctly. It shits me tears the amount of people who ask for help when they haven't covered the basics.

I've rewired one certain MA61 with a VVTi 1JZ that seemed to have a "if in doubt connect all these wires to power" train of thought.

Mos.

[Hydra]

I've wired mine up correctly, wires to the correct wires, power from the correct power sources. It still ran without the IGSW pin getting any signal, but not at all well. Perhaps that was before I rewired it though (first attempt was more or less as Mos described, as we REALLY needed to get it moving at the time, at which point we encountered what ended up being the fuelling problem!).

The one thing that isn't quite right is the BATT pin - the connection for that enging loom wise is somewhere in the engine bay, while it comes from under the dash in the chassis loom. I just gave it power from the battery via a fuse. Easier.

[Mos]

I've wired mine up correctly, wires to the correct wires, power from the correct power sources. It still ran without the IGSW pin getting any signal

If you didn't wire IGSW and it was getting +B/+B1 then you *didn't* wire it correctly. Chances are M-REL wasn't wired either.
Unless you mean "you've NOW wired it correctly" you're statement is contradictory.

The one thing that isn't quite right is the BATT pin - the connection for that enging loom wise is somewhere in the engine bay, while it comes from under the dash in the chassis loom. I just gave it power from the battery via a fuse. Easier.

There's nothing wrong, or not quite right, with that - BATT is literally just a fuse off the battery. It's nicer if you follow the toyota topology that it comes off the EFI fuse but then not all toyotas had it off that fuse either and it doesn't make it incorrect electrically.

Mos.

[rob]

for interest sake, what is the disadvantage of not wiring in M-REL and using the main efi fuse, but wiring everything requiring ignition power from post ignition barrel and everything requiring constant power from a single constant source?

[wilbo666]

for interest sake, what is the disadvantage of not wiring in M-REL and using the main efi fuse, but wiring everything requiring ignition power from post ignition barrel and everything requiring constant power from a single constant source?

Your ISCV won't fully open when you turn the engine off. --> shit cold start etc.

The ECU knows the engine is off (via IGSW) but it leaves the Master relay on for a few secs (and hence +B to ECU) so that the ECU can fully open the ISCV and put it in a know state for the next engine start

Wire it properly. No reason I can see not to.

Cheers
Wilbo

[Hydra]

Yes, sorry, now have wired it correctly because we ended up towing it

I chose not to run a wire from the engine bay all the way back to the green-white wire under the dash to avoid having another wire running the length of the loom, through the hole etc. It makes sense to me at least!

Wiring it properly isn't hard when you aren't pressed for time - there are ways to just get it working too, mind you

[Hydra]

In case there is any confusion, the BATT wire ends on a plug in the engine bay, not in the dash like on the MA61.

[Mos]

for interest sake, what is the disadvantage of not wiring in M-REL and using the main efi fuse, but wiring everything requiring ignition power from post ignition barrel and everything requiring constant power from a single constant source?

Can't believe you're suggesting this
Apart from what Wilbo said, other than being a slackarse there's absolutely NO reason why you wouldn't do it properly.

The other reason for having separate supplies to things like ignition coils, injectors and computer is that ignition/injection is pulsed power, whereas ECU is mostly constant (or constant relatively speaking).
The pulsed supply produces high currents which introduce pulsed momentary drops in voltage on the power supply to those devices. The power devices such as coils and injectors are not detrimentally affected by the pulsing voltage, however the ECU is more sensitive to the power supply hence the provision of a "cleaner" supply.

The common connection, from the battery and the alternator, is thick and short resulting in a relatively low cable resistance meaning the pulsed currents don't produce significant voltage drops. From this common source, though, the remaining conductors are usually thinner and longer, with higher cable resistance, meaning any pulsed currents magnify the voltage fluctuations. Hence these thinner power supplies are separated so the fluctuating power doesn't affect the constant power.

For this reason it is not advisable to run *all* of the engine components from the same switched ignition power source.

In case there is any confusion, the BATT wire ends on a plug in the engine bay, not in the dash like on the MA61.

Yes but so does MREL and +B1, even though they are all available at the ECU and can be connected in the cabin, you just need to tap into the wire in the cabin and add a plug.

Mos.

[Hydra]

Yep fair point - could have done so too... Buuut I didn't!