1UZFE gurus please help :)

[ae92gtapex]

Hey guys,

Bit of a long winded one here so bear with me. Did a 1UZ swap into my 92 4Runner, specs are:

UCF10 Celsior Engine (the one with the cold start injector under plenum)
26/16/22/26 ECU (upside down 26P)
Single wire Oxy sensor model
VZN130 with r150F manual

Now it all runs sweet as, and has been for a while now. Just with a small niggling problem. It 'sometimes' wont start. Will just crank and crank and crank. As soon as I let off the key and try start it again, engine starts instantly and runs smooth as. No amount of 'pumping' the throttle will help (which some people say works for them). This can be when its dead cold, or warm, or both.

If i turn it off after its been running for a minute (or after driving), and start it within say 10 minutes, it will fire straight up (turns over maybe once or twice). Now this is the annoying part, some days it will start perfectly when cold, and start perfectly when warm. Other days its a pig. There is no reasoning behind it. Well, there is, I just dont know what it is :/

Example: Yesterday morning, jumped in, dead cold, and it cranked for about 3 seconds and then fired and fast idled. Beautiful. This morning, jumped in, it cranked for about 6 seconds with nothing, i released the key for about 1 second, cranked it again and it fired and fast idled straight away. No rough running, smooth as a 1UZFE should be. Now I did nothing different yesterday and today. Herein lies my dilemma.

Have done alot of searching on various forums, and tried most of the things that have been relevant to my problem. So its time to ask the smart people.

This engine has NO performance problems, no cold idle problems, no rough running. It has a very very occasional single dead miss when under full load in 5th gear and low rpm (~1,500), this doesnt happen very often. Other than that its sweet, albeit thirsty on fuel but again from reading everything 16L/100 is quite normal with high gears, manual and 33x12.5's. This I can live with, especially with the sound it makes.

1. I have checked all my wiring again, and again, and again. STA and NSW are wired to +12V starter (black/white). Tried it with no NSW connected, no diff. One website says NSW to 12V, one site says NSW to GND. Mine will still start fine with this disconnected.
2. Fuel pump runs as soon as starter turns (this does not prime when the key is switch on, which I have been told is correct for this ECU by a number of people), and turns off a few seconds after the engine stops. No problems there. I have tried bridging the fuel pump relay to 'prime' it , and still no start. So that isnt the problem.
3. Checked fuel pressure after turning the engine off, it drops a few PSI after an hour, maybe a few more after another hour. Took all the pressure out of the line, then hit the key with the pressure gauge on, full PSI within 1 or 2 engine cranks. So its not the pump.
4. IACV is working properly. When cold engine will fast idle at 1,500 and drop to ~550 when warm every time. Also when I switch the engine off, the ECU MREL is keeping the main relay on for a few seconds to 'reset' the IACV (can hear it 'tick tick tick tick' after a few seconds of key off). So that is working fine.
5. Brand new Coolant Temp Sensor. Have pulled it out and checked it. Its within the specs. no problem there.
6. No error codes when in diagnostic mode. Just flashes its 'normal' code.
7. Was told possibly leaking fuel injectors, but pressure drop would be more and the thing would run rich when it fires. It doesnt.
8. Was told possibly leaking Cold start. Same thing as above though.
9. Was told ECU is faulty. Pulled it apart and none of the caps have been bleeding. I highly doubt its this as everything else works fine with it. Could be wrong.
10. Was told AFM is faulty. Pulled the plug off while the engine is running, runs like a bag of sh/t and CEL comes on. No problem there.

Ill be borrowing a set of noid lights so I can see if the injectors arent triggering when its having its tanty. There is so much conflicting information out there, some say that the early 1UZ's rely solely on the cold start injector to start? Some say they batch fire the injectors once and then wait for a few engine revolutions from the crank sensor before it turns the ignitors and injectors on? F'd if i know. Maybe someone can shed some light on this?

Could it be bad coil reserve? Its fine under load, with a very very occasional single dead miss in 5th up a hill at low RPM.

Does anyone have the TSRM for the 91 Celsior so I can see what voltages and resistances should be at every ECU pin?

So thats where I am. Its something I can put up with , but would be good to get it right. Maybe I should just bolt a supercharger to it, i'm sure that would fix it.

I would highly appreciate any input or suggestions.

Cheers Guys

Gaz

[DX20VT]

I would check the battery voltage to the ECU under cranking.

Have struck on toyota's where the starters are so good the wind over fine with low voltage,
but there is not enough voltage for the ECU.

Easy enough to check with costing anything.

[dumbass]

maybe its wired wrong to the ignition key
so maybe put a separate start button so the key isn't going to start and dropping ign circuit off


spray abit of aerostart down throttle body to see if it always starts first go with this
then u know its fuel related

[ae92gtapex]

Thanks for the replies boys.. Appreciate it
@ DX20VT : I did check the voltages at the ECU a while ago under crank and it was normal. I was thinking the same as you. I'll check again over the weekend just to be sure. Cant hurt.
@ Dumbass : I'm leaning to something like this mate. As the donor celsior it came out of didnt have this issue. And the old V6 didnt have this issue. I havent changed anything at the ignition key side though, and i'm not a complete nufti with wiring and reading diagrams. Its like on first crank something is getting feedback and holding a relay open. Will put 12V to the starter wire at the ECU and see if that helps anyway.

Will have a crack at this over the weekend . Too bloody hot at the moment. Time for a beer. Cheers again

Gaz

[dumbass]

just spray extra fuel down throttle body when cranking
this will tell u if cold start injector or poor fuel pressure at start up is the culprit

i know of afew 1uzs with isseus over past few months as ive been trying to help them

[ae92gtapex]

Dumbass: For the past two days on dead cold start I have been spraying aerostart in the pod filter and its been starting straight away every time. Interesting. When the coolant temp sensor is below a certain temperature, does this particular 1UZ start purely on the cold start injector, and then switch to the main injectors (have read this somewhere). I might be pulling the inlet manifold off and getting the cold start rebuilt.

Cheers

Gaz

[dumbass]

cold start injector only helps a tiny bit so if its not working then it takes afew more turns to start
u could also have fuel pressure problems
maybe try running pump of ign for a test to prime the fuel lines and rails then once rails are full then start it
so maybe fit one way valve in fuel lines

so maybe u might have fuel pressure dropping back when car is off and then also bad cold start injector


I doubt its power to injectors cause the coils and ignitors run of same power and u always have spark since it starts on aerostart

start signal to ecu helps with timing when cranking and im not sure but it might even pulse main injectors abit more

maybe try run cold start injector directly of a ground and start signal for testing

[ae92gtapex]

Dumbass: Fuel pressure is fine and only drops a few PSI after a few hours. As i said in my first post, I bled the line of all pressure using the bleed on the pressure guage, then cranked the engine over with zero PSi in the line and it come up to 42psi within two revolutions. I'm assuming there is plenty of flow and line pressure as it is perfect running and I can hold it pegged under full load for ages with no power loss or sputtering.

Definitely +12V at injectors while cranking.

Just tried the cold start injector ground trick. The CSI already gets its +12V from STA wire, and gets GND through the CSI Time Switch. I pulled off the brown plug to the CSI time switch, and grounded the red/black wire (the other wire is black and goes to STA). Cranked the car and it started pretty quick from cold..BUT.. for some reason the starter solenoid stayed engaged while the engine was running until I removed the GND wire for the CSI.. ??? Maybe I need a diode somewhere in there.. :? Stupid thing

Just FYI, this engine loom is not a crappy importer hack job. It was/still is a complete loom from the celsior.

[dumbass]

not sure why it would be getting feedback
try it without it brdged see if it goes back to normal

most looms ar ecomplete

its how they are mated to the vehicle they r fitted to that causes most headaches
70% of people can get them running but only 2% know how to diagnose properly
and that only comes from experience

[ae92gtapex]

Yeh i can appreciate experience dont worry. Every engine has its own secrets. Done plenty of conversions over the years so have learnt most of the toyota logic. Its just one of those gremlins that comes and goes. If it did it all the time that would make thing easier.

Gotta get back to basics I guess, it'll be something stupid. Its freaking annoying that somedays its perfectly fine like it should be, and others its not. There is just no obvious reasoning behind it. Keeps my life interesting i guess.

Anyways, Plugged everything back to normal and it started fine. Cranked for about 3-4 seconds and off she went. Tomorrow could be a different story. Will have to wait and see.

Appreciate all the input mate. I'll keep pluggin away at it.

[George]

The start button advice looks prominent to me, while it does cost nothing. Here's my short example. When I wired my own car, I didn't pay much attention to ignition barrel having 2 "IGN" (or "15") outputs. I thought they were just connected together but they were not. In fact, one of them is disabled during cranking to reduce current drain, and by accident it was the one I hooked ignition system and injectors to. Apparently it didn't start, which took me a whole day to investigate.