CraigD0404 Posted November 3, 2015 Share Posted November 3, 2015 So I put a 1uz in my supra and it was running on 6 cylinders. the mechanic checked it over and found that 2 injectors where not getting a pulse from the ecu. so I got that checked and found that one of the transistors that fire the injectors was blown, so changed that, started the car up and we're on 8 cylinders. I thought great problem solved. turned the car off then go to start it again, now its back to 6. First thought that the ecu has blown again but checks confirm that its all ok. so now it intermittently runs between 6 and 8 cylinders. Just wondering if anyone has any ideas what could cause this? I know this isn't a 1uz forum but thought maybe this might have happened to someone on here? Also not sure if I posted this in the correct place, if not my apologies. Cheers. Quote Link to comment Share on other sites More sharing options...
Style Posted November 4, 2015 Share Posted November 4, 2015 These run distributors don't they? I would start there, I was running between 4 and 6 cylinders on my NA engine and it turned out to be knackered HT leads arcing out and not firing at all. New leads, cap and rotor arm and it was good as new Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted November 4, 2015 Share Posted November 4, 2015 Leads, caps, arms, plugs. They are expensive, thats why nobody does them. Bite the bullet, spend the cash, transform your car. Quote Link to comment Share on other sites More sharing options...
CraigD0404 Posted November 4, 2015 Author Share Posted November 4, 2015 Changed the leads and plugs at the beginning before I got it properly checked, the caps and arms wouldn't cause the injectors not to get a feed though, or would it? Quote Link to comment Share on other sites More sharing options...
Style Posted November 4, 2015 Share Posted November 4, 2015 It could be. The arm may be occasionally missing the contact for the cylinders that aren't firing due to being worn out. Quote Link to comment Share on other sites More sharing options...
CraigD0404 Posted November 4, 2015 Author Share Posted November 4, 2015 Ahh ok yeah that makes more sense to me now, I'll give that a go. Cheers Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted November 4, 2015 Share Posted November 4, 2015 How do you know the injectors arent firing now? Wasnt that the problem with the ECU? And did you buy new leads? Quote Link to comment Share on other sites More sharing options...
CraigD0404 Posted November 4, 2015 Author Share Posted November 4, 2015 He put a diode on the injector plug which showed the pulse, before the Ecu was fixed obviously there would be no flashing light, then once fixed all injectors where pulsing. But now it intermittently pulses between 6 and 8. I bought new leads right at the beginning of trying to sort it which was months ago going on a year. Quote Link to comment Share on other sites More sharing options...
Guest Sketch Posted November 7, 2015 Share Posted November 7, 2015 So is there any reason you can't pick up an ECU off another LS400 (I'm assuming its an LS 1UZ non vvti) - There's plenty of those things breaking, it's not a transponder ECU on the non vvti's I don't think is it? Having a spare ECU would allow you to rule this out as a cause, perhaps you could also get an engine bay loom too - the ECU loom is pretty much self contained on them. Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted November 7, 2015 Share Posted November 7, 2015 Same reason a Supra ECU will work in an Aristo, but will flag up errors, theres many subtle differences an ECU controls. Surest will fire up the engine and run the gearbox, but you'll no doubt get a spurious warning lamp for something like ABS or TRC Quote Link to comment Share on other sites More sharing options...
Scott-tt Posted November 7, 2015 Share Posted November 7, 2015 Craig I'm having the exact same problem trying to diagnose a misfire on a 1UZ if you get it sorted let me know what it was How's your car coming along asides the misfire mine seems to be taking forever Quote Link to comment Share on other sites More sharing options...
CraigD0404 Posted November 9, 2015 Author Share Posted November 9, 2015 So is there any reason you can't pick up an ECU off another LS400 (I'm assuming its an LS 1UZ non vvti) - There's plenty of those things breaking, it's not a transponder ECU on the non vvti's I don't think is it? Having a spare ECU would allow you to rule this out as a cause, perhaps you could also get an engine bay loom too - the ECU loom is pretty much self contained on them. I did pick up another ecu which I was told was working, but this never fixed the fault. both where tested and found they both had the same faulty transistor. either a big coincidence or something blew the ecus. I have since got one of the ecu fixed and its now going between 6 and 8 cylinders, but hasn't as yet blown the transistor. I am currently on the lookout for another ecu but most that come up haven't got the same connecting plugs. Quote Link to comment Share on other sites More sharing options...
CraigD0404 Posted November 9, 2015 Author Share Posted November 9, 2015 Craig I'm having the exact same problem trying to diagnose a misfire on a 1UZ if you get it sorted let me know what it was How's your car coming along asides the misfire mine seems to be taking forever Mine has been an absolute nightmare, the conversion was originally done by another mechanic then I had to get someone else but no one wanted to touch it as they didn't want to take on anyone else's mess. I have had it running on 6 a while now but this is the closest I have got to finding what the problem is. Have you any idea whats causing your misfire yet? Have you ruled out the usual suspects? ive searched for hours for everything that generally causes this on the 1uz but none was helping me, not until someone thought to test the transistors in the ecu. Quote Link to comment Share on other sites More sharing options...
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