Long time, no post. So, here is where its at ...
I ran the new Boomslang/AEM F/IC 8 harness installed with the loop-back plugs installed for a week to make sure that there weren't any apparent miss-wiring problems. No issues there, so apparently I got something right. <img src="/forums/images/graemlins/smile.gif" alt="" />
I will get back in touch with Boomslang after I'm done and get them my documentation so they can wire up a complete Boomslang/AEM F/IC 8 harness for anyone that doesn't want to go through the headache and expense of doing their own at least for the '97 and '99. If I can find a set of '98 service manuals, I'll add the wiring for '98.
There are two problem with installing a piggy-back. The first is making sure that the unit is grounded perfectly and in the same ground loops as the ECM/PCM. This is REALLY, REALLY important!!!!!! There's lots of documentation regarding this and not just for the F/IC so I won't beat the whys and wherefores into the dirt. My wiring diagram explicitly addresses this.
The second problem that no one ever points out is that when building harnesses to plug into or wiring in a harness to the stock ECM/PCM wiring is resistance. I'm sure with a little digging it wouldn't be hard to figure out that this is a big problem and likely at the root of a lot of barely working or flaky installations where the correct wiring has been checked dozens of times and there's still bad behavior.
Lots of sensors on a vehicle change resistance as conditions change. The ECT is the perfect example. So, any change in resistance between the ECM/PCM and the sensor changes the actual data ariving at the ECM/PCM. The manufacturers factors in added resistance between the ECM/PCM and sensor in the ECM/PCM - for the factory installation, some degradation, variation in sensor output, etc.
I've already run across this. I'm getting a CEL (P0203) for injector 3 on ignition on with the F/IC plugged in, but not with the harness installed on loop-back. Several things are tested on 'ignition on' before start for 'presence' - resistance through the circuit to confirm that they're 'there', 'good' and reading withing a pre-defined range. Injectors and transmission solenoid system valves are two things that Mitsu clearly documents.
In this case it appears that I have an injector that's right on the hairy edge and the extra resistance of the F/IC is JUST enough to push it over.
My suggestions to those wanting to do this (or anything like this): Make sure you're real good with a soldering iron and are capable of making 30 odd perfect joints. Have and know how to use a good multi-meter 'cause you're going to need it to check and confirm every one of your joints - if they're measuring over 1.3/1.4 ohms you probably screwed up and it/they need to be redone. Get a good, lighted magnifying glass 'cause this is intricate, tiny work. <img src="/forums/images/graemlins/smile.gif" alt="" /> And, most importantly - be patient and TAKE YOUR TIME. Believe me, this is NOT something you want to have to tear out 10 times before you get it right. <img src="/forums/images/graemlins/frown.gif" alt="" />
AEM F/IC 8 Harness for Montero Sport
![[Linked Image]](http://www.4x4extremesports.com/modifications/AEM_FIC_8_ECU_Piggyback/IMG_20140309_Montero-Sport-AEM-FIC-8-Harness-Pre-Completion.jpg)
The green wiring and ECM connectors make up the Boomslang straight-through harness. I know guys have 'sucessfully' done this but there's no way I'd try hacking the stock wiring. I can't imaging trying to do all the soldering required while wedged under the dash. <img src="/forums/images/graemlins/frown.gif" alt="" />
You never use all the wires that come on the AEM F/IC harness, so I snipped off the 'never gonna be used' wires at the F/IC plugs. Those were the wires for all the alternate things like cam and crank sensors, etc. The small group of unattached wires are the ones that I MAY use in the future so I want to keep those around. They'll get bundled inside the sheath so I can pull one or more out in the future if necessary.
I did maybe make one 'mistake'. I sniped off bank 2 O2 sensor wire. I wired in bank 1 O2 to the harness in case I ever wanted to change the fuel delivery to other than what the ECM does on it's own. In hindsight, I probably should have wired in bank 2 just in case. Some ECMs use the post-CAT O2 in combination with the pre-CAT O2 sensor when calculating fuel delivery. I don't THINK anything pre-'05 does that on Montero Sports or Monteros - but I've already run across at least one thing with the post-CAT O2 that isn't supposed to do something it obviously does. <img src="/forums/images/graemlins/rolleyes.gif" alt="" />
Completed AEM F/IC Harness for Montero Sport
![[Linked Image]](http://www.4x4extremesports.com/modifications/AEM_FIC_8_ECU_Piggyback/IMG_20140309_Montero-Sport-AEM-FIC-8-Harness-Completed.jpg)
This is the completed harness plugged into a spare ECM for picture taking purposes.

The flat Weatherpack connects to the coil of white and black wires. The white and black are the actuators for logging on the AEM and the calibration/indicator for the Innovate LC-1 Wideband O2. The flat Weatherpack is also wired for an intake air temperature sensor (IAT). So, two for the WB O2, two for the AEM logging and two for the IAT. The round gray connector goes to the Innovate LC-1.
Test install AEM F/IC Harness for Montero Sport
![[Linked Image]](http://www.4x4extremesports.com/modifications/AEM_FIC_8_ECU_Piggyback/IMG_20140314_Montero-Sport-AEM-FIC-8-Harness-Test-Install.jpg)
Everything except the Innovate LC-1 plugged in for my first test run last Saturday. I had the vacuum hose for the on-board AEM MAP sensor running out the window and under the hood - that has since been fixed. <img src="/forums/images/graemlins/smile.gif" alt="" /> Totally 'getto' - you have to love it! <img src="/forums/images/graemlins/lol.gif" alt="" /> Good thing the AEM isn't that big - even so it's going to be a PITA fitting everything back together and mounting it. <img src="/forums/images/graemlins/frown.gif" alt="" /> If I get real enthusiastic next weekend, I may mount the two lighted switches (AEM logging, and Wideband) in the dash. Not looking forward to drilling two more holes. <img src="/forums/images/graemlins/frown.gif" alt="" />
I already had my base map built so I loaded that in the F/IC, ran the vacuum hose, cleared the ECM and drove it to work last Friday. So far, so good.

I started tweaking the fuel and timing last weekend.
Fuel is at -7.8% so far. LT trims are coming in +/- 2/2.5% on the outside. That's all good so far. 'course long term fuel trims are the easy part. <img src="/forums/images/graemlins/smile.gif" alt="" />
I'm really working on the timing now. As I expected, that's turning out to be much more difficult. It was reasonably easy to get a map that works decently on the street, but getting on that works on the street AND on the trail may not be possible.
The big problem is the amount of gearing in my big Sport. Its extremely difficult to work out a static map that will accommodate high-medium load (low vacuum) and very low load (high vacuum). For instance, on the street its in the 4-15 psia range while driving, but on the trail its in the 1-6 psia range. Since the Sport doesn't have a MAP per say (if at all), its coming up with an Engine Load data point somehow.
When on the street Engine Load is high, so the ECM pushes the timing down. However, when in Lo, Lo-Lo, or God forbid Lo-Lo-Lo, Engine Load is almost non-existent and vacuum is in the .5-3/4 psia range so it cranks the timing WAY up.
So, I need to pull a lot more on the trail, versus on the street. I have a lot more work to do on it is what I know. <img src="/forums/images/graemlins/smile.gif" alt="" /> If the weather stays good this weekend I'm going to take my laptop with ScanXL and the custom OBD maps I've built for this up on the trail and see what I'm getting.
I suspect that this isn't going to work EXACTLY like I hoped and that I may end up with two maps. One for the street and one for the trail. While I hadn't planned on this eventuality, the F/IC 8 has the capability to have two completely different maps loaded and two switch between the two at the push of a dash button. That means that I'll have to give up my ability to do logging on the F/IC independent of a laptop, but its not that big a deal for me anyway.
So far, though, everything is working as AEM advertises. Its completely transparent to all the factory electronics. Everything in the ECM clears as it should - no interference with any of the OBD drive tests. Guess the reall test will be in two and a half months when I go in for emissions testing. <img src="/forums/images/graemlins/scared.gif" alt="" />
Below is a link to the wiring doc on
www.4x4extremesports.com. I've confirmed everything I have wired up to the vehicle so far (so, non-aftermarket stuff like the WBO2 yet), except the connection to the factory (forward) O2 sensor. At some point I'll have to try playing with that before I know if the resistor is needed or not. According to one of the members on the Montero Sport forum with the supercharger install its not supposed to be needed on Sports (and I presume Monteros), but ....
'97/'99 Montero Sport -> AEM F/IC 8 Harness Pin-Out DocI'll post a base map for the F/IC 8 for DL on my site when I'm done.
If anyone has any ideas on working through the timing map, feel free to chime in. I can post screen shots of timing maps from ScanXL if its wanted.
Edward