SOLVED!! - 1UZ Stalls, but not when bridging FP and B+ AND 12v to B+

[Cresleepa]

OK ive searched for a while but no real answers

I have a Cressida, with a 1UZ conversion.
Driving along (in teh rain) and it started running really low RPM, like 250 RPM

Pulled over, upon decelerating it stalls.

tried to re-start, wouldnt. Kept trying, stil no-go.
After waiting for a while, it did start, but wouldnt idle, still running at really low RPM.
Only would keep going if throttle depressed slightly.

I was tinkering around to fix. If I add 12v to the B+ pin, and then bridge B+ and FP, it will start. Exhasut smells very rich.

I assume that there isnt power (or intermittant power) going to B+ as it wont start unless I add a lead from the 12v Batt to B+

I have had the EFI relays tested, they are fine.

Im thinking also there is a Fuel Pum ECU somewhere. Since Im the 2nd owner of the car (3rd since its project life started in 2005) Im not too sure if there is a Fuel Pump ecu, or where it is.

Also, is it ok to have wires bridged (from 12v to B, and B+ to FP) as I really need the car running, and not sure if I'll feck something up. Plus it would be great to actuall fix whatever is buggering up, not just bandaid it!

Any tips or trick s are welcomed.

[Cresleepa]

Ok after fiddling a bit more, car will start with B+ connected to 12v batt.
Once running, idle is smooth. Have checked efi relay, it is really hot!

[EldarO]

Check CoR wiring.

[4th surf]

First thing to do is find the ECU and see if it it a Stock Toyota one then find the part no off it which should start with 89661-***** so we can find what model the engine is out of. Then try to work out how it is wired up, some DTC checks and go from there

[Cresleepa]

Thanks for the replies.
I should add, the engine is a Crown Majesta, the ECU, well Ive been told its from a soarer, but I will check.

Can you clarify what 'CoR' wiring is? This is my first toyota!

[Cresleepa]

Sticker on ecu is earshot, last 4 digits are:
2?280


Have found a blown 20amp fuse in lower left passenger footwell too, nfi what it's for?

[CrUZida]

B+ is one of the main power wires for the engine/ecu
If you don't have +12V on B+ then something has gone wrong in the wiring.

[Cresleepa]

I traced the B+ back to the ecu, it's 3x40 pin, wire goes to 1st plug, bottom row, 3rd from left.

[CrUZida]

Get a wiring diagram and have a look.
+B is fed from (normally) a relay.

[George]

"B+" terminal in the diagnostic connector is power line from main relay to MAF, oxygen sensor, vacuum valves, fuel pump (which has additional dedicated relay for it), the ECU pin you've just traced and maybe something else

Hot relay indicates one (or both) of the following
-too much resistance when relay is on
-too much current flowing thru the relay

by shorting +b and 12v you actually bypass the relay (you can even extract it from fuse box and car will keep running)
so I would recommend
1 double check relay's "on" resistance
2 check for excessive current thru your efi relay
to do that, replace your bond-aid wire with ampermeter that is capable of showing say 20amps without blowing
your main consumers are fuel pump and ox.sensor heater, their total current usually does not exceed some 6 amps.

[4th surf]

CoR I would assume is "Circuit Opening Relay" (if it even has one)

I'm also taking an educated guess on the ecu being 89661-24230 which is a UZZ30 SC400 (US spec) and I have factory wiring diagrams in PDF format for those. Shoot me a PM with your e-mail addy and I'll send you a copy

[CrUZida]

Hot relay indicates one (or both) of the following
-too much resistance when relay is on
-too much current flowing thru the relay

George, if the relay in question is one of the Toyota metal bodied ones, then they get very hot by just being on. Pretty much too hot to touch.

[George]

CrUZida, ok thanks...actually haven't ever seen those relays. The ones I source from local Toyota wrecker are only 1998+

[CrUZida]

These are the ones.

[Cresleepa]

Thats the one relay yes,.
Guys thanks heaps for your help so far.

Just to add. If I leave it alone for a few hours, then come back to it, it will start, idle rough, then die. All in about 5 to 10 seconds. In my mind thats a similar time for the O2 sensors to pre-heat/clean too... hmm

I have looked at the main engine loom, at the rear of the bay. O lord its not pretty. There are random connectors all over the place, some with cut wires hanging of the back etc. Seems like the sparky was trying to retain the 7M connectors or something. Cleaning it all up is very messy!
I 'jiggled' the loom while the engine was running with the band-aid wire to the B+, and upon removing the wire the engine kept running for a few seconds (whilst I jiggled the loom)
So I am in the process of removing the shitloads of blue electrical tape, that has been rattle can sprayed black (bloody hell) and wiping the goopy glue that has melted.
End result will be clean wiring loom, clear indication of the connectors and what goes where.
Im guessing that is a step in the right direction.

Thanks for the offer of wiring diagrams, I'll pm you my email address.