JZA70 wont start...problem is very very wierd

[Jt_70R]

Matt, had you tested that stocko ECU in another car? any possibility it might have cap issues also?
I'll send it back down in the next few days when i get a chance anyway.

I reckon i might have to ask Santa for a microtech (or equiv) this year....

[JZA70R_92]

You say it runs fine from cold start then 15mins later screwed...what happens if you turn off the car as soon as it runs shit and restart problem gone??? could it be your cold start injector is still running at operarting temp causing the car to run shit/rich?? maybe try unplugging the cold start injector and double checking all earths to ecu, fuel pump.


My old AUTO ecu in the GA had issues where at operating temp it ran but heavliy missed under loaed so one day i pulled over ripped off the plug to the cold start ijector and she ran sweet

[Jt_70R]

nah it doesnt run fine from cold start. just randomly sometimes It starts normally, and i can drive it around normally for a while until it starts doing it again.
sometimes i start it from cold and it will do it straight away.

the problem is likely dodgy earth/wire/joint/plug somewhere, unfortunately problems of that nature can be very hard to track down, particularly when half the loom is hidden within the guts of the car.

[MR 1JZ]

oh?

10 char.

ya rly...srsly...

the other ecu came from a running car dude...worked fine

microtech will be the easiest way to stamp out these issues...and also get max power from that turbo...its half scary on 11-12 psi...it would be lethal on 21psi

[JZA70R_92]

man maybe the car is cursed? best thing if possible is grab working sensors like cas, map, knock sensors, ignitor, and try them out also check coil pack plugs make sure they have good connection!

[MR 1JZ]

ill bet you $50 its the cas again

[JZA70R_92]

bloody EFI shit give me push rods and carbies anyday best thing sinced sliced bread

[Jt_70R]

yeah im hoping its not the CAS again.

looks like it might indeed be microtech time, it was going to happen anyway sooner or later.

[Jabtronic]

My 1J has the same problem, exactly as you've described.. my wiring loom is butchered though so I'm currently in the process of replacing it with a good condition one.

My alternator died last time I drove it too, have you checked your alternator and are you getting 14v with engine running?

[EldarO]

ya rly...srsly...

the other ecu came from a running car dude...worked fine

microtech will be the easiest way to stamp out these issues...and also get max power from that turbo...its half scary on 11-12 psi...it would be lethal on 21psi

evidence?

and it sounds like my ignition issue.

[Jt_70R]

welcome to weirdshitsville, population: me

plugged the stock ecu back in, bridged the main relay so the ecu was getting full B+, car started up and ran fine! actually more than fine, it ran fkn perfect!

what i dont get is why the stock ecu is only putting out ~9.6v on the main relay coil side. which doesnt seem enough voltage to pull that main relay solenoid over. otherwise everything would be perfect.

[JZA70R_92]

can that main relay soleniod be replaced if so maybe happy sexy time?

[MR 1JZ]

well thats good to hear...have you tried bridging the main relay with the blitz ecu?

[wilbo666]

what i dont get is why the stock ecu is only putting out ~9.6v on the main relay coil side. which doesnt seem enough voltage to pull that main relay solenoid over. otherwise everything would be perfect.

I recall JP mentioning that he had a couple of ECUs that did the same!

Transistor that sinks M-REL was blown...

Cheers
Wilbo

[Jt_70R]

i recall someone mentioning about M-REL voltage too. ive replaced the relay with several other good replacements, same result each time.

shouldnt need to bridge the main relay with the blitz unit, as it gives the full M-REL voltage; also I can hear it clicking the relay in and out.

Whats even weirder, is I put the blitz unit back in and started up, straight away it jumped up to around 2g and started idle hunting. Engine itself sounded fine though, no backfiring or running rich. Still flickering the cat temp sensor light.
(No unusual lights what so ever with the stocko ecu).

Matt, maybe I should send the blitz unit back down, and you could try it in another working JZ powered car?