Update. Finally. I got sidetracked rebuilding the entire front end, new CM shafts, new 1 ton drag link, better Blue Torch high steer arm, different stabilizer, swapping gears back to the 5.38s from the 4.90s I was experimenting with, new custom soft brake lines all the way around and having the drive shafts rebuilt. Maintenance. Fun times. Still not done. Still have a anti-wrap bar and relocation of the muffler on my plate for this year. <img src="/forums/images/graemlins/frown.gif" alt="" />



I got a wild hair end of June and pulled my 8" IPF lights off the ARB bull bar. The ones that mounted above the winch in front of the grill.

Unexpectedly, this made a HUGE difference with the over heating problem. I never had problems with the lights before and they've been on my big Sport since about 2003. I know that there is an air flow issue with the Sports and the ARB bull bar. This isn't a giant secret. I fully expected to run across a problem when I installed the lights, but when nothing happened I figured I was good. Or, well, good enough. Running Moab in 105+ degrees with no issues on the highway or trail seemed like that meant everything was good.

So, I wasn't wholly blindsided when taking them off improved things on the highway. What completely floored me is that it made an enormous difference on the trail. There's no question of whether it was the lights, because nothing changed for a month before and nothing has changed since and ambient temps have been way up there. Before I couldn't take it off road in sub-freezing temps without overheating problems.

I think there are actually two issues here. One was the restriction of air flow through the grill by the lights at any speed (or no speed at all) and the other is the location of the engine. I mounted the 3.5L EXACTLY where the 3.0L is mounted - using a combination of the 3.0L and 3.5L mounts. The engine wasn't shifted forward or rearward at all. However, when comparing my '03 Limited AWD 3.5L, my stock '97 LS 3.0L and my big Sport with the 3.5L conversion, it's obvious that the 3.5L in my big Sport sits further forward. There is quite a bit of gap between the firewall and the engine. While not having actually measured, it looks like about 2". At least. Sure makes it easy to take the bell housing bolts out. The front of the engine is also noticeably closer to the fans. (which is why I can't switch back to the stock mechanical setup without rebuilding all my mounts and supports)

So, moving the engine closer to the fans restricts airflow through the fans - the air exiting the fans is slamming into the engine before it can bend and flow around. While apparently not enough on it's own to cause a problem, when combined with the restriction of the lights ... well, things just go straight to hell. My reasoning here is based on the fact that vehicle speed has no affect. As vehicle speed increases, so does air flow through the radiator, so the problem should gradually decrease - which is totally not the case. That's what's had the radiator people and everyone else I've talked to stumped. Now cooling behaves as one would expect.

Its interesting. Again, I never would have expected the lights to affect the cooling this drastically on the trail when the vehicle barely moving. If I let it run up to about 215 and flip the fans on it takes less than half the time for the fans to drop the temps into the mid/upper 190s. Less than two minutes at the extreme - more like a minute.

Ok. Moving on ...

I'm still running the AEM F/IC 8. I haven't had time to fiddle with the Montero ECM conversion in the last couple months so everything further is F/IC piggy back and the stock rev. 2 ECM.

I am partially wrong. I'd previously stated that there was never going to be a chance that doing the 3.5L conversion and running the F/IC would ever work. I say partially wrong, because I've managed to get things working to the point I can run in ambient temperatures in the high 90's on the highway in Denver and tool up and down the passes in CO in the middle of summer without the vehicle overheating.

That's taken removing the IPF lights and some tweaking of the on/off/high points on my SPAL fan controller. I changed the on for primary fan to 192, and the full on for both fans to 208/210. With this setting the ECT will run up to 212/213 or so (full open on the thermostat) and then drop down to 203/208 or slightly lower. This is in 70-80 degrees. If ambient temps are lower, everything just sits in the low 200s and then drop to the 190s the minute the load is off.

So, I seem to have the 6000+ ft. highway altitude problem licked. This doesn't work as well in Denver at 5000 ft. The lower the altitude, the worse the problem gets, which tells me that there's still an engine timing problem. The higher you go in altitude, the more timing you need and the lower you go the less timing.

I still want to drop the primary fan on to 190 or 188 to give me a little more draw at low 25-35 MPH in 2nd/3rd gear. It still warms up too much if you're stuck at that speed in that gear going up hill for an extended period, but the fan tweaks have steadily reduced that to the point that one more tweak should put that to rest.

I also think I've run across another problem with the F/IC specifically. I updated everything to the latest ROM releases. I've been running v1.10 since I installed it and that appears to have been 'a BAD THING'. Something go completely crudded up between the F/IC and the ECM so I pulled the F/IC and re-flashed it with both code bases (the FI, and timing/everything else ROMS) and re-uploaded my config. Then I repeated the process only putting the v1.07 code vs. the v1.10 code. The v1.10 code is apparently targeted at multi-pulse injectors - which the Montero and Montero Sport are not. It should work, but that doesn't seem to be the case based on my experience. So far the v1.07 code seems to be working better all around and it does appear that there's less ECT fluctuation.

I also changed my timing config to overall reduce the amount of timing I'm pulling by about 1/1.5 degrees. This SHOULD have made the overheating worse and there was evidence that it had, but changing to the v1.07 ROM seems to have put me back where I was with my unmodified timing config.

This is a good thing, because while my original config was working as far as reducing the timing and mostly eliminating overheating and massive coolant temp swings, it was enough to seriously hork up the ECM over time. Massive misses and stumbling at high vacuum/off idle which gradually degenerated into all over the place. I don't know what the interaction was there but it WAS NOT GOOD. <img src="/forums/images/graemlins/frown.gif" alt="" />

I'm leaving for UT and Moab this weekend for nine days so I'll be able to put some serious mileage on the current configuration and see what happens. I'm keeping my fingers crossed. I'm also hoping that I may be able to reduce the amount of timing I pull by maybe .5 or 1 more degree. I've already tested that - the ECM stays happy at that point.

Anyway, the reason I say 'partially' is because I believe I'm right on the edge of having this for real functional at 4500/5000+ ft altitude both on and off road, but I have serious doubts that this will work at sea level. I'll find out how good this works at 4000 ft here in a couple days since that's what Moab is at and it's still in the 80/90s there. I just don't think the amount of timing I pull will work at half that altitude and I know the ECM won't tolerate more.

So, I was wrong. I looks like the F/IC is a solution in some instances. As far as I can tell. How this works in the long run is still a question. Just 'cause it ain't apparently over heating doesn't mean that there isn't detonation going on and that drastically decreases the life span of an engine in the long run.

Overall, though, with the lights off the bumper, the v1.07 ROM and the new config, I can't complain. Even with the v1.10 ROM and new config, I took it up last weekend for 300 miles in the mountains in 30-55 ambient temps (half deflated tires, of course) and averaged 17.8 MPG and never went above 212 even going over Berthoud Pass at 50 MPH in third gear. Ran like crap with the crudded up ECM/FIC but still did very good. Previews two weekends with higher ambient temps and air in my tires put me at 18.5/19 MPG in the mountains.

I still think the ultimate way to go is with the Montero ECM and for people that are doing a 3.0L to 3.5L swap in an automatic, this should be easy. For a manual trans vehicle, this is a nightmare. I'm going to work on the ECM swap some more next month, but I have a gut feeling that I may never figure this out and my professional help (techs) are going away at the end of this month so I'll be on my own.

Ultimately, if the new ROM for the F/IC doesn't work and the ECM/FIC keep crudding each other up, I think I'll end up using the MS in a piggy-back config. That way I can take the timing completely out of the ECM's hands and program in what I want. CO changed their regulations not too long ago. They don't care about CEL unless its emissions related and don't appear to give a damn one way or the other about add-ons as long as the vehicle passes so I don't see using the MS for timing as being an issue anymore.

Edward