TPI Speed dencity. wont run in altitude?

NORCALFJ40 · 05-23-2006, 10:06 PM

Well I dont have this problem but... We recently swaped in a TPI 350 into a 73 landcruiser fj40, We havnt had a chance to run it in the altitde yet , but i have heard a few rumors that speed dencity doesnt like to run in the in the altitude, Due to it being a MAP instead of a MAF fuel injection? i might e way off but just wondering if any of you guys heard anthing or experenced anything like this before? BTW its a stock computer setup that i am running not a programmable one. Thanks , Kodi

JeepinDoug · 05-23-2006, 10:48 PM

Sounds like you're expecting the worst.
If this was the case, all MAP sensored FI set ups wouldn't work at altitude.
What's the reasoning behind this?
Vaccum pressure is comprimised when air density is lower?

If all is set up properly you should be fine, just expect a small amount of power loss at altitude.

Ghetto Fab. · 05-23-2006, 10:55 PM

Should run just fine. The slightly lower map sensor values will lean out the mixture to compensate for altitude. My speed density fuel injection system(early jeep 4.0) does just fine at altitude(dusy ershim 10,000ft?). What do all those poor souls crossing the rockies through the eisenhower tunnel on I70 through colorado do? How high are you planning on going?

Kevo

NORCALFJ40 · 05-23-2006, 11:01 PM

Its set up right, runs exellent at my house at about 100 ft above sea level. I had just heard some rumord about this. i guess they are just rumors then. Thanks for the help so far

Eagle-Mark · 05-25-2006, 12:31 AM

I think the Mythbusters would bust this myth!

Bubba_Jeep · 05-25-2006, 07:23 AM

When you first turn the key on, before the engine starts, the ECM uses the MAP signal to calibrate for altitude. It's built in. No worries, mate.

MrWillys · 05-26-2006, 11:30 AM

Quote:

Originally Posted by Bubba_Jeep

When you first turn the key on, before the engine starts, the ECM uses the MAP signal to calibrate for altitude. It's built in. No worries, mate.

The only thing here that should be kept in mind though is: If you start at sea level and drive continuiously without shutting off the vehicle it will continue to adjust for sea level. I always make sure and stop at some point and shut the vehicle off and restart to allow the computer to reset. Some have said newer vehicles do compensate for this when at WOT. It's said they take a new reading at this time of no vacuum. I do know that no provisions for this exist in the early TPI ecm's.
My scanner reads 4.72 millivolts here at 400 feet, and at 10,000 feet it read around 3.9.

Balsax · 05-26-2006, 11:58 AM

I live at around 10,000 and run a MAP TPI on my 383 without any problems...My TPI system has ran fine above treeline (about 12K') without any issues. It's much better than any carb setup as far as self adjusting for changes in altitude.

05-23-2006, 10:06 PM	#1
NORCALFJ40 Registered User Join Date: Aug 2005 Member # 51625 Location: California Posts: 903	TPI Speed dencity. wont run in altitude? Well I dont have this problem but... We recently swaped in a TPI 350 into a 73 landcruiser fj40, We havnt had a chance to run it in the altitde yet , but i have heard a few rumors that speed dencity doesnt like to run in the in the altitude, Due to it being a MAP instead of a MAF fuel injection? i might e way off but just wondering if any of you guys heard anthing or experenced anything like this before? BTW its a stock computer setup that i am running not a programmable one. Thanks , Kodi

05-23-2006, 10:48 PM	#2
JeepinDoug Zeus of the Sluice Join Date: Jul 2002 Member # 13028 Location: So.S.F., CA Posts: 3,130	Sounds like you're expecting the worst. If this was the case, all MAP sensored FI set ups wouldn't work at altitude. What's the reasoning behind this? Vaccum pressure is comprimised when air density is lower? If all is set up properly you should be fine, just expect a small amount of power loss at altitude. __________________ I may lack much in way of integrety but I make up for it with pure denial. [URL=http://www.pirate4x4.com/forum/showthread.php?t=377480][B][COLOR="Red"]Malvado Grande #1[/COLOR][/B][/URL]

05-25-2006, 12:31 AM	#5
Eagle-Mark Web Wheeler For Hire Join Date: Feb 2004 Member # 26999 Location: North Idaho Posts: 1,062	I think the Mythbusters would bust this myth! __________________ Founder North Idaho Off Roaders Webmaster North Idaho Trail Blazers KAT Team Member Blue ribbon Coalition Member Idaho State 4x4 Association Kootenai County Idaho Off Road Advisory Committee Member Former Idaho Executive Director PNW4WDA

05-26-2006, 11:58 AM	#8
Balsax Registered User Join Date: Aug 2003 Member # 22345 Location: Breckenridge, CO Posts: 409	I live at around 10,000 and run a MAP TPI on my 383 without any problems...My TPI system has ran fine above treeline (about 12K') without any issues. It's much better than any carb setup as far as self adjusting for changes in altitude. __________________ my weekend rides... just another 1 ton CJ being towed by a '52 M-37.

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05-23-2006, 10:55 PM	#3
Ghetto Fab. Registered User Join Date: Jul 2001 Member # 6170 Location: A-town Posts: 487	Should run just fine. The slightly lower map sensor values will lean out the mixture to compensate for altitude. My speed density fuel injection system(early jeep 4.0) does just fine at altitude(dusy ershim 10,000ft?). What do all those poor souls crossing the rockies through the eisenhower tunnel on I70 through colorado do? How high are you planning on going? Kevo

05-23-2006, 11:01 PM	#4
NORCALFJ40 Registered User Join Date: Aug 2005 Member # 51625 Location: California Posts: 903	Its set up right, runs exellent at my house at about 100 ft above sea level. I had just heard some rumord about this. i guess they are just rumors then. Thanks for the help so far

05-25-2006, 07:23 AM	#6
Bubba_Jeep Oldnewbie Join Date: Oct 2004 Member # 37184 Location: Santa Barbara, CA Posts: 1,054	When you first turn the key on, before the engine starts, the ECM uses the MAP signal to calibrate for altitude. It's built in. No worries, mate.