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Discussion Starter #21
That is interesting. Like you, I have a fairly decent elevation/temp change when I drive between St. George and Enterprise. (Enterprise 5500 ft. vs St. George 2200 ft.) I make this drive almost everyday, and have never really noticed much of a difference, but I have never logged. Now I'm curious. Maybe when I get back from vacation, I'll do a little logging, and we can compare notes.
Indeed. Now that I have a cable, I should get out and do some proper data logging (I too just got back from vacation :)).

I still need to do some research on how to properly log (best parameters/gear/duration of pull/etc).
 

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Indeed. Now that I have a cable, I should get out and do some proper data logging (I too just got back from vacation :)).

I still need to do some research on how to properly log (best parameters/gear/duration of pull/etc).
Let me know what you find out in that regard, because I am unsure also. I'm thinking third gear pull, though, for some reason.
 

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Yes a hot intake charge can cause the ECU to pull timing by the advance multiplier because it can induce knock.
 

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Yes a hot intake charge can cause the ECU to pull timing by the advance multiplier because it can induce knock.
I was hoping you would stop by. :cool: What parameters would you suggest for logging, with romraider and no wideband? I'm curious to see what happens with my ride, now.
 

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I was hoping you would stop by. :cool: What parameters would you suggest for logging, with romraider and no wideband? I'm curious to see what happens with my ride, now.
engine speed
engine load
ignition total timing
knock correction
IAM
learned ignition timing
mass Airflow g/s
manifold Relative pressure
coolant temp
intake air temp
 

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engine speed
engine load
ignition total timing
knock correction
IAM
learned ignition timing
mass Airflow g/s
manifold Relative pressure
coolant temp
intake air temp
Thank you very much!
 

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Discussion Starter #27
Alright timber, so after we do our multi-elevation logging runs and 'compare notes', who is gonna tell us if our logs look good or not? :rotfl:
 

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Alright timber, so after we do our multi-elevation logging runs and 'compare notes', who is gonna tell us if our logs look good or not? :rotfl:
I'm hoping we can enlist the help of one of these tuning gurus. :D
 

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I've been biting my tongue but it has to be said - have you tried putting your finger in it? :tongue:



Ok, sounds like a pretty good theory. The ECU pulls boost at higher elevation by the pressure compensation table. It is independent of whatever map you are running. It does this to keep the turbo in the area of the compressor map it wants to use (it has to spin faster to pump the thinner air up to the given boost level). Also, you have greater knock resistance at higher elevation I believe because the air is less dense. I know you can run somewhat lower octane safely at least. So you drive down a long ways and the learned values from high elevation are no longer applicable (because your hitting higher boost and your pushing denser air leaning you out), so the DAM goes down while it trys to sort things out.
 

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Discussion Starter #30
Ok, sounds like a pretty good theory. The ECU pulls boost at higher elevation by the pressure compensation table. It is independent of whatever map you are running. It does this to keep the turbo in the area of the compressor map it wants to use (it has to spin faster to pump the thinner air up to the given boost level). Also, you have greater knock resistance at higher elevation I believe because the air is less dense. I know you can run somewhat lower octane safely at least. So you drive down a long ways and the learned values from high elevation are no longer applicable (because your hitting higher boost and your pushing denser air leaning you out), so the DAM goes down while it trys to sort things out.
Nice, thanks. I was thinking along those lines (at least in the ballpark :redface:) I just couldn't put it all together in a thought out coherent manner, as you just did.
I thought elevation probably had something to do with it, I just didn't know what exactly. Also, in the back of my mind I thought maybe elevation had nothing to do with anything since the maniford pressure is just relative to the outside atmospheric pressure anyway. :screwy:

So here's another little tidbit for you guys: Usually when I'm down in the valley, I see peak boost of ~16.8 (map target is 15.8 +/- .5) which is an over boost of .5 psi. This past weekend I was down in San Fran and I hit 17.4 psi on one pull :whoa:. Do you think this was because the turbo/waste gate (ecu, really) hadn't yet "learned" that it can slow it's roll and still hit target boost in the dense sea level air? (also, in that particular instance the load was probably huge - 5 dudes in car, going up a slight incline, 3rd gear WOT)



I've been biting my tongue but it has to be said - have you tried putting your finger in it? :tongue:
I don't get it. :redface:
 

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Children's story about a kid in Holland that saves the town from flooding by putting his finger in the hole in the dike (so the DAMn stays up). It was popular when I was a kid but that was a while ago. It isn't the greatest but here is a link:
The Holland Ring - Hans Brinker Story
 

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I totally forgot we had a high altitude tuning forum. :baaa:

3 threads in the last year. :sadwave:

They all went to another site that I can't name - look in Pace's sig. though.
 

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mycologist.. that is some GREAT info regarding boost at elevation, but how would that relate to timing in this case, do you think? If timing is being pulled at low elevation/high heat as in this case, would that affect boost at the same time?
 

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Discussion Starter #37
I dumped a bunch of information in this thread regarding elevation - you might be interested in the last couple of posts.
http://www.clubwrx.net/forums/high-altitude-tuning/134281264-ap-map-higher-altitude.html
Wow, yeah, tons of good info in there. Some definitely over my head.
One thing I did find comforting though, is that it seems the ECU will basically just figure it all out for itself. I guess if there is one thing the ECU is really good at, it's protecting the motor. :thumbup:
 

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Alright timber, so after we do our multi-elevation logging runs and 'compare notes', who is gonna tell us if our logs look good or not? :rotfl:
You really should spend some time on the RomRaider forums.Seriously,just give it a look.
 
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