Quote Originally Posted by sefiro View Post
Slightly, slightly off topic. Theory on why US ecm has STJ while others do not. Prove the theory though and it might help with the op problem.

Toyota had to deal with tighter emissions/greater mpg requirements of the US vs non US. it's possible that they put small main injectors in the US vehicles. The larger Japanese injectors could support cold start fuel requirements with a longer pulse width from the ecu. However, the smaller US injector could not be pulsed long enough without risking a burn out. So Toyota solved it by having the ecu take over the cold start injector after its timer expired.

Or, the US cold start injector timer has a shorter timer length than non US to ensure that excess fuel would not be dumped into the system. The ecu would take over sooner. This implies that the ecu was controlling parts of the fuel system even though it was had not switched closed/open loop.

In either case, the above would require checking part numbers across the builds. Ideally, the injectors, cold start and o2 circuits would be capped on both builds to verify control activity.

Sent from my XT1053 using Tapatalk
I think the injectors are the same. The replacement injectors I've seen on US parts sites looks the same as what I have. And I have a spare cold injector that looks the same that I bought off someone here, don't know what his setup was tho. It's most likely something with the cold start circuit. My JDM setup has no STJ pin on the ECU and the injector is not getting ground while cranking. According to the shop.

How about this. What if I spliced a wire to the cold injector ground wire? At least to see what happens. Would that hurt anything? It only gets power while cranking.