1jz won't start

**roadkill** · 12-06-2012, 01:45 PM

Hi,

that being the case - recheck ALL your injectors, make sure that they are connected to the right ones. Also, see if you can setup a new fuel supply - ie jerry can to fuel pump to filter to rail. Try and rid yourself of the old lines all together and isolate the problem.

bEn

**doommachine** · 12-06-2012, 04:25 PM

Originally Posted by roadkill

Hi,

that being the case - recheck ALL your injectors, make sure that they are connected to the right ones. Also, see if you can setup a new fuel supply - ie jerry can to fuel pump to filter to rail. Try and rid yourself of the old lines all together and isolate the problem.

bEn

Pulled out the fuel filter - looks brand new inside. No gunk comes out of it. Certainly no problem as far as fuel pressure, even when I had cranked the car to drop the pressure there was still plenty of fuel flow.

I'd like to eliminate the lines but I don't really have the bits and pieces to do that at the moment, I'll try to eliminate injectors first. Already checked and made sure they all go to the right place.

**dumbass** · 12-06-2012, 07:01 PM

did u end up checking your ecu on another car
i kow its a pain to find someone but maybe even send your ecu to someone on here
i never trust it when ecus get repaired as they cant check them 100% until u plug it into another car
the main things that determine fuel injector duty is map sensor which is very hard to get weird signals compared to air flow meters
and maybe the tps
so u would have to get some fkt up fluctuating signals to do what yr explaining

**doommachine** · 13-06-2012, 12:29 AM

Originally Posted by dumbass

did u end up checking your ecu on another car
i kow its a pain to find someone but maybe even send your ecu to someone on here
i never trust it when ecus get repaired as they cant check them 100% until u plug it into another car
the main things that determine fuel injector duty is map sensor which is very hard to get weird signals compared to air flow meters
and maybe the tps
so u would have to get some fkt up fluctuating signals to do what yr explaining

I know, I am organising a known working ecu to check it against before I start pulling the thing apart. It does seem like its missing, the idle is fairly rough even though its stable. But yes, the ECU does seem to be the culprit because before I replaced the ISCV the thing would happily sit at 2000rpm as an idle speed and rev freely to at least 4000 rpm (dont really like to free rev engines).

Ah actually, this is interesting and I forgot about this - the idle was at 2000 rpm and I put it in drive with my foot on the brake to see if loading up the engine would cause the RPM's to drop - after that it started to idle lower and rough. Anyway replacement ECU shortly, I don't know if I'll be annoyed that i paid to have the caps done and its still screwed or relieved if thats the problem hahah...

**doommachine** · 20-06-2012, 02:10 PM

Originally Posted by doommachine

I know, I am organising a known working ecu to check it against before I start pulling the thing apart. It does seem like its missing, the idle is fairly rough even though its stable. But yes, the ECU does seem to be the culprit because before I replaced the ISCV the thing would happily sit at 2000rpm as an idle speed and rev freely to at least 4000 rpm (dont really like to free rev engines).

Ah actually, this is interesting and I forgot about this - the idle was at 2000 rpm and I put it in drive with my foot on the brake to see if loading up the engine would cause the RPM's to drop - after that it started to idle lower and rough. Anyway replacement ECU shortly, I don't know if I'll be annoyed that i paid to have the caps done and its still screwed or relieved if thats the problem hahah...

OK so, I replaced the ECU with a known working unit -car is perfect now.

I also got some "spare" aka faulty ecus to play with as well.. interestingly one of them has exactly the same problem as my original one- car starts, but the idle is very high and pulses, and also the check engine circuit does not function. The light comes up, when the car is running it turns off, but earthing TE1 has no effect.

My thoughts on why this happens - when you want to check the base timing, you earth TE1, correct? So somewhere within the guts of the thing theres an IC that controls timing, and is also connected to (of course) the IC that looks at diagnostics. Perhaps its the same IC? Who knows.

Anyway, if this stops functioning correctly, the timing is always advanced or retarded, causing a high idle... like when you turn a dizzy too far one direction (long time since I played with a carby car so I can't remember which way will increase the idle speed).

Sound reasonable? So if I can work out which IC connects to both diagnostics and the ignition timing, I can look for a dry solder joint, or likely a fried IC or something similar. It's very odd that both ECUs behave in identical ways...