4agze build questions

[TERRA Operative]

Okay...we're getting turned around here I think.

I have this 4agze engine running off the ae86 4age ecu, wiring etc. There's no where to plug in the ISCV...there's no signal to be had. No it doesn't run on magic...please don't be like that. I had assumed that because the previous 4agze throttle body idled just fine while having the ISCV disconnected, that this one would to. The 4age throttle body will not idle on the 4agze. I do not know why that is, but it does not. You said so yourself, above.

Do you have any idea why the 4agze throttle body would idle, but not the 3sgte one if they both "require" the ISCV? Is there another alternative that I have missed?

Secondly, does anyone know of a way to lean this thing out? This 3sgte throttle has caused the car to run very, very rich. I assume this is because the flap door on the airflow meter is maxing out well before it should due to air volumes. I was going to try and swap in a larger AFM off a supra to see if that would help. Funny, it didn't run rich off the 4age throttle...could it be some annomaly associated with the 3sgte throttle? I can't see that doing it, but I am unfamiliar with such things.

First thing first, use the correct ECU and wiring loom. You're in for a rough time trying to use a 4AGE ECU which isn't designed for a boosted engine.

Second, that ECU will not work with the ISCV on a 4AGZE or 3SGTE throttle body due to the missing ISCV wiring and outputs.

Third, just put a 4AGE throttle back on until you get the correct engine management system installed. It uses a wax pellet for idle control so needs no ECU intervention and is the same size as the 4AGZE and 3SGTE throttle bodies anyway.

And lastly, when I said the 4AGE throttle body would not idle on a 4AGZE, I said it only caused problems for me when the A/C was being used etc. Otherwise it drove fine.
Your problems run deeper than just the throttle body, sort out the correct ECU and wiring and then I can help you further.


I don't understand why people bodge things up and then wonder why other things don't work.
You are trying to figure out why the idle doesn't work when using a 4AGZE or 3SGTE throttle body with a 4AGE ECU, WHEN YOU HAVE NO WAY OF PLUGGING IT IN!!!???

Like I said, it doesn't run on magic, how else do you think the electrically operated idle valve will work when you cannot provide it an appropriate signal?.....

[ae86boy]

I'm glad to see you believe that this won't work and is being done incorrectly. I've heard that noise from people about this for nearly twenty years. It idled perfectly and drove like a dream until this throttle body upgrade...even at 15psi...even with the 4agze throttle body on it, with no wiring connections to the throttle body of any kind even though you say it can't.

It has nothing to do with me not "understanding why things don't work when I bodge something together". It has everything to do with me saying..."well it worked before, what has changed?" The ecu doesn't know what it's doing...it takes sensory inputs and uses them to allocate outputs based on a preset system of reference, not witchcraft. As long as it stays in the appropriate ranges, it will work fine no matter what engine I connect it to as long as it is a 4 cylinder that operates on a conventional cycle. The linearity of the supercharger only augments its responses.

This isn't the first car I've built, its not the first engine I've tuned. I'll send you vids if you don't believe me. I have hundreds of witnesses who will vouch for its potency. Hundreds. This hasn't been some lucky shot in the dark that I've pulled off and if the car dies I am prepared to handle it. Consider it a science experiment.

I appreciate all the help the fine people on this board have been to me in my quest for more power and solving the problems along the way. Especially yourself, because you have been very informative and helpful...you really have! But, I'm not about to be talked to that way. If you don't like it, you don't have to help me. The bottom line from what you're saying is that one throttle body can't work because the other one can't...even though it did. I'm asking "why" is that?...that's it.

"This can't work."

I always retort "I know...that's why it works so well".