1jz won't start

[George]

Though I would double dumbass on trying to replace ECU for a while, I once read on local boards that there were versions of JZX8x ECU not capable of diagnostics (can't recall if it was in regard to scanner connectivity or warning light being tricky). Something like Cresta was good and MarkII was not.

[doommachine]

Though I would double dumbass on trying to replace ECU for a while, I once read on local boards that there were versions of JZX8x ECU not capable of diagnostics (can't recall if it was in regard to scanner connectivity or warning light being tricky). Something like Cresta was good and MarkII was not.

My engines out of a cresta .. anyway, there are probably initial conditions like on the 7m (for example, the ma70 supra manual requires the throttle to be closed and the transmission in neutral with o/d off to make the codes appear). I'm fairly sure my throttle position sensor isn't quite aligned right, I just cant remember where I put my feeler gauges to do it.

My water temp sensor is f*cked, I pulled the plug off to test the resistance and it broke in half. Possibly that might do it, if the car is shoving excess fuel in?

Also I just bought a TT supra pump off the internet (not a dodgy one, a proper denso unit with fitting kit), and a new filter. If its not the fuel and water temp sensor.. has to be the ECU.

But the weird thing is, when it runs, the check engine light turns off, every single time. I have also read somewhere that if there are no codes stored some cars flash the lights so fast that it looks like the light is on solid.. possibly the lack of flashing could indicate there are no codes? I have yet to check for codes with the temp sensor unplugged.

[dumbass]

never take what u read on the internet forums as gospel hehehe
ive never seen light flash so quick it looks like its on all the time
ive always tested ligths this way
car in park or neutral if its man
nothing else on then bridge wires then turn ign on
never had issues where if throttle is not closed it wont flash
y not induce a code like unplug tps and coolant and try start it
it should log those codes
anyway id replace capacitors in ecu jsut for safe keeping
if it wont flash codes u might have to learn how to test sensors and wires with a multimeter then

[crowncustom]

My mates Cressie(JZX 81 Conversion as well) had the same probs,he near pulled his hair out,gave it to me and found that the problem was the temp sensor.$20 fix.Also you dont use feeler guages to adjust the TPS you use battery power and a multimeter.
Cheers Brett.

[doommachine]

My mates Cressie(JZX 81 Conversion as well) had the same probs,he near pulled his hair out,gave it to me and found that the problem was the temp sensor.$20 fix.Also you dont use feeler guages to adjust the TPS you use battery power and a multimeter.
Cheers Brett.

Yes, but there is a certain point that the ECU likes to see as "open throttle"... I checked it out earlier and I reckon that when the throttle is closed, it thinks its open (IDL has infinite resistance). The feeler gauges are to prop the throttle open slightly.

[dumbass]

to check throttle is easy
put multimeter on signal wire
put test light on idle wire
all u need is the idle wire to light up test light and for signal wire to be at 0.6 volts approx
thats how i srt most toyota tps's

[doommachine]

to check throttle is easy
put multimeter on signal wire
put test light on idle wire
all u need is the idle wire to light up test light and for signal wire to be at 0.6 volts approx
thats how i srt most toyota tps's

Hah, well, I gotta wait until I get a water temp sensor before I do anything else, I'll get in and check the TPS and since I have no water temp sensor see if the thing will throw a code/ if I can make it throw a code.

Now to sort the ABS error code and the f*cking door locks haha..

[dumbass]

u might have not wired up rear abs sensor properly
depending which gbox is on there u might not fix abs easily

[Dan_k36]

How long was the engine sitting before you got it running?
I had same issues with my first 3tgte and it was the injectors was hosing fuel in so it wouldn't rev up, put some others in and no worrys

[doommachine]

u might have not wired up rear abs sensor properly
depending which gbox is on there u might not fix abs easily

It's the right gearbox, the only code that the ABS throws is code 51. All the JZX81 stuff is swapped in, gearbox, front hubs, and loom/ abs computer. I think the ABS unit is screwed, luckily and surprisingly JZX81 ABS units are easy to source haha..

How long was the engine sitting before you got it running?
I had same issues with my first 3tgte and it was the injectors was hosing fuel in so it wouldn't rev up, put some others in and no worrys

About a year I think. I agree, I think it's very likely to be a fueling issue, I'll replace the pump and filter first (300,000 and 150,000 km respectively :/) and if that doesnt fix it I guess I'll have to do the injectors. But it has started and run just fine before.. well if the pump/filter doesn't fix it I guess I'll try to swap ECU's out first, injectors is an annoying job it looks like.

[dumbass]

just put fuel pressure gauge on it
its most prob your capacitors in the ecu
i repaired one 3 weeks ago where auto was stuck in limp mode
replaced capacitors and fixed problem
one capacitor was only just blown out

[dumbass]

when u say code 51
are u getting that by bridging te1 and e1 to get ecu codes
or are u axtually getting the codes from abs ecu

on ealry ecus code 51 was start signal or a/c code
and sometimes u cant get rid of that code so i would not worry if its code 51 from engine ecu

[doommachine]

when u say code 51
are u getting that by bridging te1 and e1 to get ecu codes
or are u axtually getting the codes from abs ecu

on ealry ecus code 51 was start signal or a/c code
and sometimes u cant get rid of that code so i would not worry if its code 51 from engine ecu

No, it's from bridging codes TC and E1 - the abs codes. Like I said, can't get any engine codes to come up

[doommachine]

Well, as an update, I received a new water temp sensor in the mail today. Plugged it in, filled up the radiator and the car started first go. Very strange that the 1j won't start without it, my galant VR4 runs a haltech and it's very particular about most sensors except the water temp sensor.. it runs crap without it but it still starts no dramas.

Not complaining too much though, I still had a great excuse to buy a MKIV supra fuel pump.. the thing is huge, hope it fits in the hanger easily

[doommachine]

Well, as an update, I received a new water temp sensor in the mail today. Plugged it in, filled up the radiator and the car started first go. Very strange that the 1j won't start without it, my galant VR4 runs a haltech and it's very particular about most sensors except the water temp sensor.. it runs crap without it but it still starts no dramas.

Not complaining too much though, I still had a great excuse to buy a MKIV supra fuel pump.. the thing is huge, hope it fits in the hanger easily

OK so now I have connected all the pipes up, etc, car starts reliably every time.. but now the idle is ridiculously high and it sort of.. mechanically surges. It goes up to about 2500rpm, makes a clicking noise, drops to 1500, then goes back up to 2500. If I put my hand over the air inlet to limit the air intake it drops down and will sit at a low idle nicely and continually. I've considered a boost leak apart from the surging.. could the IAC allow the idle to go up so high? My searches on the internet regarding this issue have been pretty fruitless.

Now that the car is warm, the idle is low, but it seems like it misfires continually. Throttle causes the car to sputter, and if I don't baby the throttle a little it will eventually die. The revs don't really increase with throttle application.

The inlet makes this weird whistling sound too.


Unplugging the "turbo pressure sensor" makes no difference (i'm assuming this is the MAP), and interestingly the ECU light doesn't turn on when its unplugged. So.. pretty sure now that its the ECU. Dammit. I guess I'll have to pull it and replace all the caps.

If anyone has a jza70/x81 ecu, can you take a look at it and tell me if you have a 3 pin transistor at T316, and also a resistor at R398? It's on the board that has the flying lead attached to it. Mine seem to have been unsoldered, and could possibly be the reason I don't have a functional check engine light.


I've also taken to unplugging coils while its running and it seems to randomly make a difference. Often though unplugging a wire makes zero difference to how its running. Strange.