jlmounce

I'm trying to plan some of my Mustang related 2010 activities and some of those activities will have me taking the car up and through some extremely high altitudes of the rocky mountains.

My issue here is how my car performed the last time I had it at altitude. During last summer I took my car up to Copper Mountain for a music festival. The altitude there is around 9000 ft if memory serves correct.

At this altitude the car simply ran like crap. Absolutely zero power below 3000 rpm and a lot of surging.

While heading up I70 towards the Eisenhower tunnel I experienced power loss to the extent of having to lower speed down to around 45mph and chug along in 2nd and 3rd gear. I also experienced severe surging in the lower RPM's.

What I mean by surging is that I would be full throttle at about 2000-2500 rpm and the car isn't accelerating at all. However as I start letting off the throttle from wide open the car actually starts accelerating. This is not to the effect of a lessening road grade.

Once on flat ground in Copper the power was so down that the car was incredibly difficult to drive with two other people in it.

Currently on the car, and the same at the time was a JLT CAI with Brenspeed tune and Bassani catted x with Bassani race axleback.

I have a feeling that the symptoms I am receiving may have something to do with the factory charge motion plates. Above the point where they are fully open I have no issue with the car. It feels like they are opening and closing erratically due to changes in road grades mixed with the high altitudes involved.

Has anybody else experienced this type of situation or may have some other insight into what I am experiencing?

I want to get this sorted out before I make any trips into the mountains this year.

cdynaco

Well the issue at hand is you are running rich because of the reduced oxygen content of the thinner air at 9000'. I've had no problems running hard at 7000' so you must have found the limits - or its your tune.

It is my understanding that the charge motion butterflies open at a certain rpm, so maybe that is why you are finding a 'sweet spot' (for lack of a better descrip) where it doesn't run as bad. WOT compounds the problem because now you are asking for max fuel - in a constrained oxygen environment. Its like suddenly 'closing the choke' at WOT in a carb engine and the A/F ratio is just way too rich...

The fact you have a Brenspeed tune may be hampering the PCM's stock ability to adjust. As I understand it, tuners are very careful at higher throttle/WOT settings to avoid leaning out which would damage your engine, and therefore your tune might be on the rich side at those higher rpm's, but at 'regular' altitude it runs great. I would call Brenspeed and ask if they can make an adjusted tune for you above 7 or 8000' to get you up the mountain/over the pass.

I'm at 4200' and my stock PCM & the Bullitt's adaptive spark igintion are flexible enough to operate great from sea level to 7000' nearby at Crater Lake NP. But I have wondered if I would need an 'altitude' tune from a Tuner, since they defeat the Bullitt's adaptive spark system...

Keep us posted.

jlmounce

That could be the case. It's painful how horribly the car performs at altitude. That's the crappy thing about Colorado. It's high to begin with, but it's elevations vary widely and rapidly. I can be almost 2000 ft up or down within half an hour of driving depending on which direction I go.

cdynaco

btw, did you ever go there with the stock settings before you got the Brenspeed tune? I'm curious if the factory PCM can adjust for such altitude swings but a tune narrows the range of peak operation? Like I said, mine (stock) runs great from sea level to 7000'... but 9k is getting up there.

jlmounce

Nope never went un-tuned. The car was stock for 2 weeks before the JLT and Brenspeed tune went on.

My car runs absolutely fine where I'm at which is around 4500 ft to Denver which is anywhere from 5000-6000 ft.

I've often wondered however how rich it's even running at this altitude. I should probably book some dyno time and check that out. Might be some hidden ponies laying around at WOT.

MadMoose

I took my car up pikes peak a couple months back and had similar issues with my brenspeed tuned car, the car barely moves in first gear until 3k+ rpm. I didn't notice the surging you describe though. I'll have to see how my tillman tune does this summer... It has noticeably better low end, I told them I live in denver when I ordered but idk if they actually tuned for it.

Also what's the DA like up there I bet we lose like 35% or 40% power at 9k feet

jlmounce

at 9000 feet during the summer when the air is hot as well, the DA could be around 15,000 ft or above. The DA at Bandimere speedway which is a bit over 5800 feet usually ends up between 8500-10000 ft depending on the day.

It may be time to start shopping for tunes. I'm still thinking I'm going to do the charge motion delete plates as it takes out a variable.

Obviously the car will lose power at altitude, but it's my feeling that what is happening is beyond normal power loss due to atmospheric conditions.

Suntzu

Just FYI, I do not have a tune and I get no noticable loss of power in the mountains.

Antigini-GT/CS

Altitude sucks.

crewcutkid

Hmmm...I have yet to get above Denver's altitude (which is still pretty high, mind you) but my canned FRPP tune seems to be doing the job quite nicely. I'll have to see what sort of results I yield at Bandimere in the spring.
-Jim

jlmounce

This is good info to know. This really does point to a possible tune issue then.

I ran a 14.7@98mph with a JLT and Brenspeed tune only. On the factory tires.

06StangSC

There are a lot of crappy things about Colorado. Like the Avs and the Broncos. Anyway, my car didnt do well at high altitude. Get a spare tune. Call Brenspeed

red pony

I just want to know how your FRPP tune performs as compared to stock. Is it similar to Ford's Bullit tune? What fuel grade does it require? What fuel mileage changes did you see? Was the seat of the pants feel of torque worth what you paid? I might go this route if you recommend it!

Antigini-GT/CS

The best I was ever able to pull out of mine with a JLT/canned tune was a 14.6x@96 or so. Even with the ET Streets, my best time thus far has been a 14.14 at my altitude. Makes me wonder how horrible i'd be in Colorado. This altitude and 3.55's are just a bad combination.

jlmounce

I don't even have 3.55's. I have the 3.31 axle ratio in my GT/CS

I now have added catted x pipe and axleback to the mix. with no other changes I'm sure I can pull teh ET down to a sub 14.5. I'm shooting for a 14.30 this year as it sits.

06StangSC

I think the stock GTs here in Alb were running 14.3 or 14.4. Yeah...altitude sucks.

Antigini-GT/CS

What's the altitude in Albq? I know the DA around here is easily above 5,000. One of our major races in May saw a DA of 7,000+. Dry, hot and thin air is killer. I feel like such a noob when people are running around with ET Streets, intake/tunes and running 13's.

cdynaco

NOAA says 4989'.

06GT

I had similar issues when traveling in New Mexico near Albequerque w/ my Brenspeed tune. Next to no power until 3000 RPM.

jlmounce

So far that's three separate people with Brenspeed tuning having issues with high altitude use.

Is there anybody else out there that may possibly have had high altitude issues with a different tuner, or stock?