AE92 ECU Install
I had finally had enough of the stupid power drop at 5800 RPM. So through the Twincam.org forums, I found an AE92 4AGZE MAP ECU. The AE92 came in 2 variants, the earlier MAF ECU (Mass Air Flow), with the vane type air flow meter, and the later MAP ECU (Manifold Absolute Pressure). The AE92 and AE101 MAP ECU's are almost directly interchangeable, the only difference being the swapping of a few pins.
While I had to ECU open, I thought I may as well replace the electrolytic capacitors with new ones. A visit to the local RS Components trade counter, and I was the proud new owner of a set of top quality Nichicon and Rubycon caps.
There is one small snag I found while doing the replacement, 15uF capacitors are hard to come by. I did find one through RS Components though, so no doubling up of capacitors was required.
Once it was all complete, all I had to do was plug it in and turn it on...
And it worked first try!
I took it for a quick squirt to test it all worked. There was no evidence of any power drop issue and the bottom end seems a little snappier too. The improved bottom end may be a placebo effect, but I'm extremely happy with it anyway.
The following is the nessecary information to complete this mod:
- AE92 4AGZE MAP ECU. (part no. 89661-12612) You need the one with the 26pin plug, the MAF only has a 24 pin plug. (part no. 89661-12171 <- not this one)
- Soldering iron, solder, tinned wire, solder sucker, cutters, etc etc.
- Capacitors. See second list.
- A friggen steady hand.
- Lots of patience and a bright light.
Capacitors:
(RS Components part no.)
- C104 - 10uF 50v - 224-4325
- C106 - 100uF 25v - 421-7101
- C109 - 100uf 25v - 421-7101
- C110 - 220uF 25v - 490-9939
- C401 - 15uF 63v - 491-0412
- C404 - 47uF 100v - 191-8081
It may be easier to rewire the loom, by swapping the terminals in the plugs that connect to the ECU. I decided to internally rewire the AE92 ECU so I could keep my cars loom untouched.
Basically, what needs to happen is you need to disconnect the required pins and extend them to their new locations. If you can't figure it out from the photos and diagrams, it is probably better to mod the loom, or get someone else who is more experienced to royally stuff it up for you... :) (that way you have somewhere else to place the blame..)
Here are the charts that show the pinouts of the 26-pin connectors on the two ECU's. The main differences are on this plug, except for two.
The "G-" pin has been moved from pin-16 on the AE92 ECU's 16-pin plug to pin-17 on the AE101 ECUs 26-pin plug.
The AE101 16-pin plug has a new function at pin-10 called EVP. The AE92 doesn't have this. There is no performance loss without this function, just leave and forget.
Take good note of the pins which are different. some of the PCB ID's are labelled differently for the same function, so go by the description. I have verified the numbers and functions from the PCB's of both ECU's myself, and have a running car, so they are spot on. :)
| Description | Wire Colour |
PCB ID | Pin # | Pin # | PCB ID | Wire Colour |
Description | ||
| Bottom Left of Plug Bottom Right of Socket |
Intake Manifold Earth | BR | E02 | 26 | 13 | E01 | BR | Intake Manifold Earth | Top Left of Plug Top Right of Socket |
| Supercharger Magnetic Clutch | B-Y | SMC | 25 | 12 | #10 | G-R | Fuel Injectors 3,4 | ||
| Supercharger Bypass Valve | G-R | ABV | 24 | 11 | #20 | G-Y | Fuel Injectors 1,2 | ||
| A/C Idle Up Valve | R-W | ACV | 23 | 10 | RSO | R | Idle Rotary Solenoid | ||
| Not Used | N/A | N/A | 22 | 9 | RSC | G | Idle Rotary Solenoid | ||
| Not Used | N/A | N/A | 21 | 8 | HT | B-W | O2 Sensor Heater | ||
| Ignitor | B | IGT | 20 | 7 | N/A | N/A | Not Used | ||
| Ignitor | B-O | IGD | 19 | 6 | FPU | LG | Fuel Pressure Up VSV | ||
| Distributor | G | G1 | 18 | 5 | G2 | B | Distributor | ||
| Distributor | W | G- | 17 | 4 | NE | R | Distributor | ||
| Not Used | N/A | N/A | 16 | 3 | IGF | B-Y | Ignitor Signal | ||
| Not Used | N/A | N/A | 15 | 2 | N/A | N/A | Not Used | ||
| Bottom Right of Plug Bottom Left of Socket |
Intake Manifold Ground | BR | E1 | 14 | 1 | N/A | N/A | Not Used | Top Right of Plug Top Left of Socket |
| Description | Wire Colour |
PCB ID | Pin # | Pin # | PCB ID | Wire Colour |
Description | ||
| Bottom Left of Plug Bottom Right of Socket |
Intake Manifold Ground | BR | E02 | 26 | 13 | E01 | BR | Intake Manifold Ground | Top Left of Plug Top Right of Socket |
| Supercharger Magnetic Clutch | B-Y | SMC | 25 | 12 | #10 | G-R | Fuel Injectors 3,4 | ||
| Exhaust Bypass VSV | G-R | VSV3 | 24 | 11 | #20 | G-Y | Fuel Injectors 1,2 | ||
| Exhaust Gas Control Valve | R-W | VSV2 | 23 | 10 | N/A | N/A | Not Used | ||
| Idle Rotary Solenoid | R | RSO | 22 | 9 | RSC | G | Idle Rotary Solenoid | ||
| Not Used | N/A | N/A | 21 | 8 | HT | B-W | O2 Sensor Heater | ||
| Ignitor | B | IGT | 20 | 7 | N/A | N/A | Not Used | ||
| Ignitor | B-O | IGO | 19 | 6 | N/A | N/A | Not Used | ||
| Not Used | N/A | N/A | 18 | 5 | FPV | LG | Fuel Pressure Up VSV | ||
| Not Used | N/A | N/A | 17 | 4 | N/A | N/A | Not Used | ||
| Not Used | N/A | N/A | 16 | 3 | IGF | B-Y | Ignitor Signal | ||
| Distributor | G | G1 | 15 | 2 | G2 | B | Distributor | ||
| Bottom Right of Plug Bottom Left of Socket |
Intake Manifold Ground | BR | E1 | 14 | 1 | NE | R | Distributor | Top Right of Plug Top Left of Socket |
When it comes to the capacitors, it's best not to use the cheap ones from your local electronics store. They will work ok, but are generally rated only to 85deg or so. The ones I have specified are chosen from the better brands and are rated to 105deg, ensuring a much longer lifespan.
All you have to do is desolder each capacitor and replace it with a new one. Do them one by one so you don't get them mixed up, and make sure you get the polarity right. It's marked on the PCB, so it's pretty easy to get right.
While I was changing the caps, I also stuck some arctic silver heatsink compound behind the mosfets etc. just to help them stay cool. It's not really nessecary, and can be left out, but I'm pedantic and had the heatsink compound there anyway.