My Engine Bay Renovation Thread, AE111 ECU conversion, wire tuck, and more... Options

[Coomer]

Over the past few days, I've finally had time to touch my car after months of not being able to work on it because of school and work.

A while ago, I came across a good deal on an AE111 ECU. I bought the ECU, and have been working to get my silvertop 4A-GE running on the new ECU. This thread will document some parts of the AE111 conversion.

First things first, I had to get the old wiring out of the car. Because of my stupid old wiring setup, the harness was squeezed between the intake manifold and valve cover, so I had to remove the valve cover to get the harness out.



Then I removed the passenger seat and parts of the dash for easy access to the ECU and body harness plugs.



I took notes of where every wire went on the ECU plugs and body harness plugs, and I then proceeded to start unlooming the harness. Some things had to be cut, so I took good notes and labeled wires before I cut them.



I continued removing stuff...I found it easier to work with the throttle cable and stuff out of the way. Individual throttle bodies...mmmmm...



Finally, I got the entire harness unloomed. As I took notes and unloomed the harness, I came across some interesting things. First off, my knock sensor was spliced into a ground wire before it made it to the ECU...I'm sure that wasn't good. Also, my oxygen sensor was wired incorrectly, with both white wires of the Bosch four-wire oxygen sensor going to the HT pin on the AE101 ECU. Also, the black ground wire of the oxygen sensor was grounded to a chassis ground point, not the sensor ground pin on the ECU.

Here is the unloomed harness. You can see some of my notes on this photo. I took tons of notes so that I could put everything back to the way it was if desired.



Once I had everything unloomed, I began modifying the harness to suit my new ECU, which has a significant number of changes as far as where wires go on the ECU plugs. Also, I had to remove the AFM plug and add plugs for an intake air temperature sensor (that I got from a fifth gen. Celica ST) and a manifold absolute pressure sensor (that I got from a sixth gen. Celica ST.) None of the body harness plugs had to be changed, except for the circuit opening relay, which now gets its FC signal from the ECU, rather than the AFM on the old setup.

To minimize soldering joints and keep things clean, I de-pinned my ECU plugs, removed un-necessary wires, and moved pins around. I highly recommend that you do this, as it keeps things clean and it's easy once you know how to de-pin those plugs.

For most Toyota plugs, there is a lock that pries up with something small and pointy, like a safety pin. This must be pulled up before pins can be removed.



On a Honda plug (I found my 22-pin ECU plug from a '94 or '95 Honda Accord because I couldn't find a suitable one on a Toyota,) the locks are different, and are simply flaps at the back of the plug that must be pried open, like in the photo below.



Once the lock is unlocked, you can see tabs in the side opposite of the wires (the side that plugs into whatever...in my case, the ECU.) These tabs must be pried up with something like a safety pin, and then once they're up, the pins will pull out from the wire-side of the plug. It takes some patience to get the hang of it, or at least it did for me, but once you've got it figured out it becomes easy.

And by the way, the pins just push right back in and snap into place. And I found that the Toyota pins are not interchangeable with the Honda pins. And also, the pins vary in size and not every pin will work in every connector, or even in different parts of the same connector.

With the ECU plug pins moved, I completed most of the connections on my harness. I then triple checked all of my connections, tracing them out by hand and with the multimeter to ensure correctness. Once I was pretty confident that my wiring was correct, I taped the harness up a bit, plugged everything in, and prepared to hook up the battery and start up the car.

I hooked up the battery and listened and looked for anything out of the ordinary, like wires getting hot or burning, etc. Everything seemed fine, so I put the car in diagnostic mode. To do this, you short the TE1 pin on the ECU to the E1 ECU pin, at least in my case, because I removed my diagnostic box. Once in diagnostic mode, I turned the car to on, but didn't start it yet. The check engine light began flashing, indicating that I have a code 21, or a miswired oxygen sensor.

After talking with Dr. Tweak, he kindly told me that I shouldn't have had both white wires of the oxygen sensor wired to the HT ECU pin, and that one of the wires should go to ignition power. Once I made the change, my code went away, and I had no more codes, which is indicated by a constantly quick flashing check engine light when in diagnostic mode.

With no more codes, it was time to start the car. I made sure all my wiring was out of the way, vacuum lines were in order, etc., and then I cranked the car, and it fired right up instantly. I ran around ensuring that everything looked normal and nothing was burning or acting strangely, and then I let the ECU adjust itself over a period of a few minutes. At this point, the bay looked like this.



With wires everywhere and things like the IAT and MAP sensors just sitting there, I couldn't drive the car, so I just revved the car a couple times, and wow, the sound of the open throttle bodies is amazing.

Everything seemed to be in order, so I turned the car off, checked for codes again in diagnostic mode, and found none. I then removed the battery and removed the harness so that I could finish it up and loom everything up.

Before the weekend, my velocity stacks arrived, so I had to modify them to fit my intake manifold.



As you can see, the place where the holes were was cut, so that now there are notches. This was done because the holes didn't match the holes on my intake manifold, which are a little bit further apart than the velocity stacks.

I then bolted them on, loomed up the harness, cleaned up some vacuum line routing, installed the VVT plug and OEM Toyota coil (from a ST164 Celica with a 3S-GE,) and then hooked the battery back up. When all of this was done, the bay still wasn't complete, but it was clean enough to go for a drive.



So I started the car, checked for codes, found none, and proceeded to let the car warm up and adjust itself. Once adjusted and warmed up, I went for a drive, with mixed emotions.

First off, the car absolutely screams at wide open throttle. The sound of the air rushing through the velocity stacks and into the individual throttle bodies at full throttle is indescribable. It's crazy loud and sounds kind of like DOHC VTEC on steroids. As you reach the 6700 RPM to 8000 RPM range, the noise is deafening. And it's not just loud and mean sounding, but at WOT, it is fast...much faster than before!

That said however, the car is running like crap. At partial throttle, the car has virtually no power, and when you do floor it you don't get instant throttle response like before. Instead, the car feels like it bogs down and hesitates for a moment, and then it gets fast and runs well until redline. Also, the idle remains at 1500 RPM.

I'm pretty sure it's a vacuum issue, and this is the point that I'm stuck at right now. Here is my current vacuum setup.



First off, take note of vacuum spot circled in yellow. First, I had that spot connected to a line, to a metal tube, to another line, to another metal tube, and finally to another smaller rubber line that was open. When I first had the car running on the new ECU, this was how it was, and the car idled at 900 RPM just as it should and revved just fine.

So when I was removing extra vacuum lines, I removed the extra lines and tubes and crap from that vacuum spot that eventually just were open. But I'm thinking that the smaller line that eventually just went to the atmosphere must have restricted airflow a bit.

This vacuum spot initially went to the intake manifold plenum, after the AFM and before the ITBs, and is supposedly the "power steering rack and pinion's vacuum idle up valve / compensator return hole" according to this site.

But anyway, after reading the explanation on that site, I tried capping that vacuum spot, pulled the EFI fuse so the ECU could reset, and then started the car and let it adjust. Idle was fine, at about 900 RPM, but when I revved the motor, the response was VERY laggy. So as the car was running, I removed the cap, and the idle went up, but immediately, the engine would again rev instantly.

I shut off the car and reset the ECU again, and the car idled very high on immediate startup (like 2500 RPM...about 500 higher than normal when it's first adjusting) and once it was adjusted, the idle was still at 1500 RPM. This is the current state that the car is in, and when I was driving the car, this is how it was.

I'm thinking that perhaps that vacuum line has to do with my high idle and bad driveability problems. Anyone have any ideas there?

Or, perhaps it could be my three foot long vacuum line to my MAP sensor I'm thinking. On the Toyotas I've seen, it's typically been short, like 6-9" or so, but mine is quite a bit longer to accomodate my hidden remote mounting location for the MAP sensor. I'm guessing that three feet is too long...anyone have any input?

Keep in mind that the car idled and ran beautifully before I swapped in the new ECU. And I'm not throwing any codes at all at the moment.

What do you guys think? And any comments thus far are welcome as well...I'll be adding to this thread as I accomplish more on the car.

[Coomer]

Today in class I was bored, so I drew up my basic wiring schematic for my new harness. It should be nice when it's all said and done. Just have to figure out what exactly I need to order as far as connectors go.