Engine power

[CJnDD]

We have 2012 Forester on Ford chase. We had issues on our last trip to CO with power climbing mountains in New Mexico and CO. We never had this problem on previous trip. We were pulling our Ford Escape on a dolly, like always.
I remember reading somewhere that there is something in the engine that needs to be adjusted, to get better pulling power at higher altitude. Before we left DH changed out air filter and fuel filter.
I guess I’m asking the right question, I am DW and I was trying to explain to hubby.
We are looking to buy a used 2018 4 door Jeep as our toad, and I was hoping to get the pulling in mountains issue solved before making another trip out west.
TYIA
DD

[kenandterry]

I’ll be watching this thread. Modern vehicle engines these days......and I’m betting your 2012 Forester is powered by the Ford E350/450 V10 engine.....are sophisticated enough to deal with altitude without having to adjust something. Maybe premium fuel would help at much higher elevations, but that’s all.

I’ll wait and see what others say.

[Canadian Eh]

It has been mentioned before but first to try is to clean the Maf. I'm not sure where it is on a V10 but it will be in intake system between the air filter and the intake manifold. You can use a contact cleaner. The next thing would be if the cats are plugged. That can really suck power.

[avengers]

Did you get a CEL? If so then the power loss can be tracked down. If not something else is happening. How many miles do you have? Dirty injectors or air filter, worn plugs/wires and poor cooling can all create power loss. Have you changed/inspected any of these items?

Did you notice any changes to temps or oil pressure? Trans could be an issue too, last time fluids were changed?

[rsdata]

Someone mentioned this tool and I am now using it. I believe it works... For $10 why not try it now and into the future of your trip.

[CJnDD]

Thank you gentlemen, I will show your replies to DH.
Looking forward to a smoother ride to CO this year!

[D W]

Just a thought here, when is the last time the spark plugs were changed in that rig?

[CJnDD]

Originally Posted by D W

Just a thought here, when is the last time the spark plugs were changed in that rig?

He changed them right before our trip last year. Same time as changing air filter and fuel filter.

[BehindBars]

Originally Posted by CJnDD

He changed them right before our trip last year. Same time as changing air filter and fuel filter.

As a general rule, often when there is a change in performance or operation of a machine just after work was done on it, some aspect of that work is a prime suspect for causing the problem.

[D W]

Originally Posted by CJnDD

He changed them right before our trip last year. Same time as changing air filter and fuel filter.

Given that, and absent a CEL, the only thing left is to put a scan tool on the engine to check everything from the MAF to the O2 sensors as well as short term and long term fuel trims under driving conditions. The readings will at least give you a picture of how the engine is performing. Many of the OBDII parameters are wide enough that it won't throw a code, but engine efficiency will decline. Is your mpg suffering more than it did in the past?

One other thing to consider: Has there been an increase in your transmission temp?

[Sergiop]

There could be a problem with the fuel pump. At first the pump might be producing the correct pressure, but as you drive for hours it gets hot and you press on the accelerator more to pass traffic, go up a hill or mountain, it doesn’t produce enough pressure. So then the engine runs lean and it doesn’t make the rated HP.

It could be like Canadian said a dirty MAF wire. Over many miles dirt gets past the air filter and gets on the tiny wires of the MAF. The MAF is in the air filter housing right after the air filter.

Injector cleaner can help too. The E350/450’s have 55 gallon tanks, most cleaners bottles of 16oz or so, treat about 20 gallons. That means you would need at least two bottles. Or one if you have less than half a tank of gas. I’ve used Chevron Techron with good results. I usually put 2 bottles in on the first tank of a trip, drive it 4 hours or so for it to do it’s job.

[Bdcothran]

Not sure if you are experienced going over mountain passes, but you will lose 3% of your power for every 1,000 feet of elevation gain in a normally aspirated engine. You will loose 1/3 of your power going over Wolf Creek Pass for example. Some passes are steeper than others and will seem much harder on your engine even though the elevations are similar. Also, hotter weather will result in less oxygen in the air and can effect it as well. If you are comparing going over the same passes under the same conditions, then you may have an issue. As someone else stated, watching your MPG over time should warn you if something changes in the engine for the worse. Most motorhomes pulling a toad that aren't diesel pushers, will be doing no more than 25 mph at the top of Wolf Creek or Monarch pass.