A few weeks ago I took a road trip to pick up my new trailer... a 600lb pop-up. I drove the 700+ miles from Dallas to the eastern side of Tennessee, hitched up the trailer and drove back the next day. These were 99.9% highway miles on the trip. My Car: a 2006 MCS with the first cut of engine mods... 16% pulley, CAI, JCW Injectors, cat-back exhaust, GMRS Intercooler and RMW dyno tune. No internals have been changed. Lots of other cosmetic and suspension mods, but the engine upgrades have been fairly tame when compared to others in this crowd. On the way back, after 3-4 hours on the highway, I got a CES (Check Engine Soon) light. I pulled over at the next safe place and pulled out the code reader. I can't remember the exact code #, but I had 2 codes to bread and both said that I was running rich. I cleared the codes (turning the car on and off a few times in the process) and got back on the road. The CES light went out. About an hour later, the CES came back, along with the same 2 codes. I erased them again. When they came back an hour or so after that, I just waited until I got home and parked the trailer to reset again. Since I've been home and driving without the trailer, I have driven 500+ miles and have not had the CES light return. Any ideas why I might be running rich when towing the trailer? It's possible that the car just didn't like the gas that I was running, but the first light came on with 1/8 of a tank of fuel left and the second and third lights came on after I refilled at a different station, so that's probably not the case. Another bit of information: I dropped from 30-31 MPG to 25-26 MPG per the OBC on the way home, but the trailer is a bit wider than the MINI, so there is more wind resistance. I'm wondering if the extra momentum when I lift (engine being pushed even more than normal by the extra weight of the trailer)... Any thoughts?
You need the freeze frame data this will tell you the engine load and RPM when the code was thrown. I'm guessing that you just have to pull more stuff all the time and you're wandering out of the allowable trim band... This actually means that the engine can't lean out the car enough to get to what it wants for the load and RPM you are running in closed loop mode. Under engine braking, the ECU cuts all fuel flow off, so it's not rich then! Matt
Well Aaron MM.org just ordered one of them BavTech Pro things from DocO for the club toolchest. Should be here by the weekend. Looks like you might be the first to make use of it.
I think Dr. O is onto something. Load/RPM when cruising along just falls outside of fuel trim. My car has done this sometimes but I haven't isolated the conditions. No biggie.
With our 08 Clubman S, we haul our teardrop, which weighs in at 600lbs, 80 lbs on the hitch, when it is empty. We probably add 200lbs loaded for a trip, with maybe 50lbs added to the hitch weight. I notice(now that we have the Garmin HD) that it goes to boost sooner, so things are working harder, and it shows in a drop of MPG, which when cruising at 75mph, high 20's low 30's. Without the trailer we get mid to high 30's. Our trailer is 4' wide, plus the wheels, and is 5' tall. Bit more here; http://www.motoringalliance.com/forums/roadkill-other-musings/1689-mini-motorhome.html#post11678 Mark
I'm not as tall (I can just see over the top of the trailer in the rear view), but I'm much wider... the box is 6' wide... 7.5' if you count the wheels.
IF there is no tune on the engine... you might want to look into a good "water/meth" system to keep it all safe when you are UNDER a load and pushing it in the heat?? yes?? Just a thought.. Just me................................. Thumper
Let me try this..... IF the engine is working harder at a lower RPM, and developing a detonation, the ECU will retard ign timing and ADD fuel. Or Rich!! IF you have a system that will cool the combustion/ add fuel octane ( research Methanol.. to get correct nomenclature, cool)..Keep the chambers cool, prevent detonation, which will keep the ECU from retarding the ign timing ( power loss) and adding rich fuel ( power and MPG Loss)!! Water/Meth is perfect to loading engine when at work!! Actually THAT was the intent of w/m - achol systems all the way back to the old farm tractors in the 30's. Nothing new here.. just better! cool>? Just me.......................................... Thumper
Might try running in 5th gear keep your rpm's up a little higher. That is why you don't tow in overdrive in a truck it creates more heat,in your case it might be reading more heat so it gives it more fuel.
Yikes! Have you measured the tongue weight yet? It looks like your rear suspension is telling you that it's a bit (lot) high. Having that much sag in your rear suspension will actually toe the tires enough to add additional load to the engine in the form of tire scrub resistance. You may be able to move the trailer's axle forward enough to roughly balance it out. Raising the hitch so that it sits level on solid ground will help as well. You should only have 5-10% of the trailer's weight on the hitch.. which translates to a non-sag-inducing 30-60lbs on your 600lb trailer.
Our teardrop's tongue weight is about 100 lbs, with the trailer loaded, at about 800 lbs total. Virtually no drop in the rear when I put the trailer on the hitch. I load the trailer with most of the added weight on or behind the trailer axle. The axle on that pop-up does look to be set rather far back. Ours is much closer to the center of the trailer. Loaded, I can easily pick the tongue up with one hand. Mark
Sorry if I was not more clear. The issue at hand is engine safety. Everything you mentioned above about Water/Meth is true, and it would certainly be a great addition to this situation. But as far as engine safety goes, the MINI's ECU will do what is required to keep the engine safe, in this case it is likely retarding ignition and definitely adding fuel, so the engine is already safe. Is it running optimally, not at all, but that was not the point. You initially mentioned engine safety, and for all intents and purposes for this situation, the engine is already safe as it is running rich. Will a Water/Meth kit help, damn straight it will, but don't get one because of concern that the engine is being damaged (i.e. not safe) while pulling the trailer. If you pulled the trailer on the track, that would be a different scenario.
http://www.motoringalliance.com/forums/roadkill-other-musings/1689-mini-motorhome.html#post11742 Mark
My tongue weight is only 125lbs or so... My rear suspension is a beta set of TSW springs and it rides mighty low without the trailer! TSW added at least 1cm of height to their final production design. The addition of the trailer lowers the back a bit, but not too much. I've also got a lot of gear in the back of the car during this pic. I drove out to pick up the trailer w/ the boot full of stuff for camping on the way home. I'm planning most of my camping gear to go into the trailer so I don't have to clutter up the MINI when heading out (only a cooler and a 45lb generator will go in the MINI, though I'm working on a way to get the cooler onto the tongue of the trailer). Most of the heavy gear I've situated over the axel of the trailer.