Well, it sounded like a good idea ....
After replacing all the electronics on the engine (except the MAF and IAC, which will go in this weekend) and both O2 sensors, I've got it back to running virtually like new. I need to replace the CAT, too, here shortly. Hoping that'll finish straightening out my fuel trims. Overall, it runs like a top. Lots of power - lots more torque than the 3.0L, that's for sure.
Problem is, that fixing everything has just created more problems. The better the engine runs - the more timing the ECM dumps in. Swapping back to the 5.38s got my ECM back to sane, but the ECM adds more timing because engine load isn't as high. And, the more the temperatures fluctuate, the more impossible it is to compensate with a static map. Maybe I could do some more by tweaking the O2 to run the engine a tad richer, but that's at best a poor band-aid.
I'm reasonably certain that I could get this to work if I did like the DSM/3g/EVO/GT guys and forced it into OL-Drive all the time, but that's a pretty stupid idea for a street driven vehicle. Might as well just yank the F/IC and put a MS in and give it full control of the timing and fuel.
Hate to say it, but this idea is dead. <img src="/forums/images/graemlins/frown.gif" alt="" /> I have to give AEM credit. The F/IC is an awesome box. It does exactly what they say it will and it does it well. If I were running a turbo or supercharger, this would be my first choice. But, its just not working out as I'd hoped. There is such a huge variation in altitude and temperature here in CO that unless you have something that makes constant adjustments - its just not workable.
On the plus side, its working out enough that I'm not going blow the engine up and it helped me troubleshoot a bunch of issues I didn't even know I had. But, that's about as far as it goes.
So, off to transplanting in a different ECM. Again. <img src="/forums/images/graemlins/frown.gif" alt="" /> Since the 3.5L Montero Sports only came with PCMs - and swapping one of those in hasn't paned out - I'm moving over to the Montero ECM. I've gone through a bunch of Montero stuff with the help of others here on the forum. (Thanks, guys!!) The following is what I've come up with so far ...
3.5L SOHC A/T Montero (NOT SPORT!) ECM (FED)
1997 MD338137
1998 MD343513
1999 MD361885
2000 MD365261
The 1997 is the 92 pin (4-plug) connector, just like the '97 Montero Sport M/T (green).
The 1998-00 is the 100 pin (3-plug) connector, like the '98/99 Montero Sport 3.0L A/T (black).
These four are all ECMs - no integrated TCU (Transmission Control Unit).
The '00-05 Montero Sport 3.0L and the Sport '99-05 3.5L use the 130 pin (4-plug) connector like the '01+ Montero, and these are PCMs - integrated TCU (besides other things, hence the extra 30 pins)
A quick tell-tale to distinguish between an ECM and PCM - ECM = 92/100 pin connector and PCM = 130 pin connector.
As best as I can tell, these break down into '3' groups. '97, '98/99 and '00. I THINK - based on my research - that there are internal programming differences which MIGHT make using the '98/99 or '00 preferable to the '97, but I have no actual evidence at this time. It'd be interesting to find this out, though. There's a significant difference between the Sport M/T rev 1 '97 ECM and the rev 2 '97 ECM.
So, back to the drawing board, so to speak. I now have a Montero '97 and '98 ECM. Sets of FSMs for both are on the way - they're supposed to be in tomorrow.
I've already gone through the '98 electronic FSMs and generated a spreadsheet with the pin-outs and so far nothing earth-shattering has shown up. So far this is it ...
Not sure what these do yet (or what affect they have if missing):
1. ABS Control Unit (pin 66)
2. ELC-4 A/T Control Module (pin 87) (C-140 pin 45) - engine coolant temp signal
3. ELC-4 A/T Control Module (pin 88) (C-140 pin 46) - MIL request signal
No equivalent on M/T:
1. Park/neutral position switch (pin 67)
2. 4WD Operation detection switch (pin 65)
Unless the P/N connection does something stupid like keep your vehicle from starting, I think it can be left unconnected. Not sure if it actually triggers a code and CEL. I don't think so.
The 4WD Operation/detection switch just grounds to the t-case when closed (in 4WD). The 4WD Operation/detection circuit does something - this has nothing to do AFAIKT with dash lights, t-case, transmission operation. Could be something as simple as a trigger for limiting speed in 4WD or it could trigger changes in fuel/timing maps OR do something funky with the IAC. OR it could be a trigger for a whole bunch of things. I can think of half a dozen things just off the top of my head. <img src="/forums/images/graemlins/frown.gif" alt="" /> If its necessary, at least there's a dirt simple fix. Just add a switch.
Once the FSMs show up, I'll confirm what I have against the wiring diagrams (which are missing in the electronic FSMs).
I'll start with the '97 ECM. Put together the pin-out diagram and then have Boomslang do up a conversion harness. The '97 ECM I have has the plugs still attached so I can confirm that I'm not missing pins - something(s) not documented in the FSMs.
If I can get that working ok, I'll move up to the '98 ECM (since I have one) and see if there's any difference. But, first, I need to get something working. Otherwise, it'll be time to start considering yanking out the 3.5L and going back to the 3.0L. <img src="/forums/images/graemlins/angry.gif" alt="" /> <img src="/forums/images/graemlins/frown.gif" alt="" />
Guess I could consider swapping in a M/T SOHC 3.5L ECM from a '96. Maybe that would work if there is such a beast. I'd still have to swap out for emissions testing, but in theory I'd have something that works 99% of the time. I think I'd be more inclined to just go back to the 3.0L. <img src="/forums/images/graemlins/frown.gif" alt="" />
As an aside, I found documentation in the '98 Montero FSMs that explicitly says that the pre-CAT and post-CAT O2 sensors are BOTH used in calculating long term fuel trim (LTFT). Which means that a bad CAT or no CAT at all will screw with fuel delivery. Based on my experiences over the (many) years, Sports are no different.
Link to more Montero stuff related to this thread ...
Montero 3.5L 5-speed? Edward
