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No, fully seat the IACV closed. Turn it until you cannot place the assembly fully seated, then back it off a hair until you can fully seat the assembly in the closed position. I had to do this on mine when I was running the IACV power off a toggle, then the toggle switch broke in the off position while running, wired it up correctly and then tried all methods with the IACV, fully closed is what worked for me, makes sense since the engine is cold when trying to start it, so it is "choking" the extra air.
Ok I'll try this again. Went I say open I meant that the valve was extended all the way out. But I'll give it a go again. I also tried starting it with the valve removed and plugged in. Still no go. What it's doing is starting and running for maybe 1-2 seconds then stalling.
 

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No, fully seat the IACV closed. Turn it until you cannot place the assembly fully seated, then back it off a hair until you can fully seat the assembly in the closed position. I had to do this on mine when I was running the IACV power off a toggle, then the toggle switch broke in the off position while running, wired it up correctly and then tried all methods with the IACV, fully closed is what worked for me, makes sense since the engine is cold when trying to start it, so it is "choking" the extra air.
Ok so I turned the valve all the way closed (valve turned so its going in)and it fired right up again ran for a few minutes with a good but sort of rough idle. I started and stopped it a few times gave the dizzy a small turn hoping to get the roughness out of the idle. Went to start it again and nothing again. I took the valve off again and turned it closed again. Fired right up.

I suppose what's happening is that the valve is opening fully over the few minutes that its running and is causing the no start condition.
 

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does it stay running if you step on the gas? mine wouldnt idle at all unless i step on the gas for a minute until the engine warm up and still would have a rough idle, then i wired up to the M relay and my problem went away.
 

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does it stay running if you step on the gas? mine wouldnt idle at all unless i step on the gas for a minute until the engine warm up and still would have a rough idle, then i wired up to the M relay and my problem went away.
Hey Edgar, yea well while its giving me this "no start problem" I can keep it by giving it gas. Ill see what happens tomorrow when it acts up. Right now it's hooked up the M-relay.
 

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Glad that worked for you, at least you are identifying the troubled area for more troubleshooting, it does however sound like the IACV may not be resetting after you turn it off, which would be a power problem. When I initially wired in my 2JZ and hooked it up to MREL, I had another connection somewhere else that was backfeeding power into the MREL that would not allow it to reset and would kill my battery (hence the toggle switched power to the IACV for a bandaid). I can't remember now what I had hooked up wrong, but eventually I figured it out.

Just saying a small problem like that can occur, and you don't even realize it. So you hooking to MREL may have issues if something else is wired wrong. Also try cleaning and re greasing your IACV, its very easy to do. Aside of that, without being there to see, I cannot think of anything else.

The rough idle can also be caused by a dirty IACV, it is not able to spin freely enough to adjust with the idle fast enough.
 

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Glad that worked for you, at least you are identifying the troubled area for more troubleshooting, it does however sound like the IACV may not be resetting after you turn it off, which would be a power problem. When I initially wired in my 2JZ and hooked it up to MREL, I had another connection somewhere else that was backfeeding power into the MREL that would not allow it to reset and would kill my battery (hence the toggle switched power to the IACV for a bandaid). I can't remember now what I had hooked up wrong, but eventually I figured it out.

Just saying a small problem like that can occur, and you don't even realize it. So you hooking to MREL may have issues if something else is wired wrong. Also try cleaning and re greasing your IACV, its very easy to do. Aside of that, without being there to see, I cannot think of anything else.

The rough idle can also be caused by a dirty IACV, it is not able to spin freely enough to adjust with the idle fast enough.
Thanks for all your help. I will start check checking other things to make sure nothing is back feeding it. I also found a way to check the iacv itself by using like 12 alligator clips and watching it open and close so ill try that just to rule out a faulty valve.

I have cleaned the valve already and made sure it wouldn't get stuck because of that. That sucker was dirty.
 

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Ok so I have noticed that when I take apart the IACV and turn it all the way in and put it back together it runs good. But after a few minutes its starts to fall off. If I removed it and I noticed the stepper was about 1/4 out. Turn it back down and it runs fine again. I guess it's not seating where it should be.
 

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Turn it in like so...



And it runs smooth for a few, take it out after a few minutes of running and it's all the way out. And the car can't hold a idle at all
 

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this looks like an awesome write up! Thank You!

i am just getting started and have a few questions.

i am installing a 94 GS300 2jzge and a W58 into my X7 cressida.

today i started working on my wiring harness. i havent done much yet, just zip-tied the A/T part back out of my way and removed all of the hard plastic BS.

Can you tell me where the end's of E3 and F6 are at on the engine side of the wiring harness? i want to pull them out of my harness and wire them the same way that you did but i am not 100% which wires they are. i am finding a lot of black/red wires.... Also, where my F6 comes out of the IK1 connector its all black. no orange.

thanks!

-Craig.
 

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So I just wanted to update what happen with my IACV if any one else has the problems.

So figured out that valve had no power I took apart the section of harness that runs over the cams and found two black wires that where snipped from their power source. I ran them both to a 12v switch power source and the engine now holds a idle around 1000 rpm once warmed up. I have driven it a handful of times an it's fun as shit lol. I have a slight hesitation When accelerating. I need to get a working timing light on it (mine quit working on me).
 

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Great write up. I've been using it with my swap, and I'm fairly close to finishing the wiring. However, I am using a 95 sc300 harness and a/t ecu. I'm having a difficult time understanding what to do with the neutral switch. Is it basically just looking for a 12v signal? I've read this entire thread over and over but the idea of connecting 2jz STA and NSW to the STA on the mk2, is just not making sense to me. I've located the STA & NSW wires off 2j. But I'm lost looking for the STA from mk2. Thanks in advance


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Never mind. I figured it out
 

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Ok so for what's it's worth I figured I would ask for some advice again...

I took my AT harness out for a 93 sc300 5 speed harness and ecu So far all it does is cranks. I have done or check the following.

Timing is set. Crank on 0 cams lined up, rotor points to #1 , I also check resistance on the dizzy plug they are within spec.


Ecu small plug has ign,M-rel is hooked up and providing b and b1 with switch power. And I have constant 12v hooked up.

I also have switched 12v to my big iacv wire and the 2 injector wires. Iacv and injectors are receiving 12v via the 5m igniter and resistor connectors.

I am getting spark to the plugs.

When I use the jumper near the air filter I can hear the fuel flowing thru the rail and to the return. Check #1 #2 #6 with a noid light and I am getting a steady flash.

All grounds are hooked up that I see. 2 on block. plus the battery ground to the block. 2 on intake. 1 on firewall.

Single wire 02 is not connected.

Any input is appreciated.

Check engine light is a steady flash so no codes stored.

Going to check fuel pressure this weekend and see what that's like.

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Ok I got it running at one point I went for a 15 minute drive and went perfect. It idled around 7-800 rpm and felt good when I gave it throttle. Nice and smooth. We'll see how it acts tomorrow.

I never really could not pin point what I had wrong. But I added another ground to my battery. Re-set my timing and it fired right up. Had to adjust the TPS and fix my knock sensor.

Love this 5 speed harness it's so much cleaner and easier to use then the auto harness. Pics in my thread soon..

Went to start it up the next day and nothing now it won't hold idle again FML
 

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alright, i have a 97 sc300 engine and harness, and i tried following this diagram, but as it has been previously established, the sc300 and gs300 plugs differ from each other, and it seems as if the colors may have changed as well. so now i'm completely lost, and i am in need of some assistance. i just need to know which colors from what plugs go where. if anyone is still on here that could help me, i would greatly appreciate it
 

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isn't the 97 a VVTI engine? you might have a lot of stuff thats different....

i bought the complete stack of lexus SC 300 / 400 books before i did my swap and they helped a lot. look on eBay they usually aren't that much.
 

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isn't the 97 a VVTI engine? you might have a lot of stuff thats different....

i bought the complete stack of lexus SC 300 / 400 books before i did my swap and they helped a lot. look on eBay they usually aren't that much.
no, i believe the VVTI started in 98. but do you have any info you could give me on the swap wiring?
 

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not a huge amount i can do for you online. if you were local i could help. I've only swapped the JZ into a cressida though.

the wires should all have the same Name. or abbreviation. so based off of this guide you should know what your looking for. just find an SC TSRM manual and look up the plugs. the plug may be different but the wires your looking for should be the same.
 
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