Gtr Million Dollar Question

[donkeypunch]

hello all,

so ive put this problem up before but nobody could figure it out, no mechanics here in NZ can figure it out either.

IN A GALAXY FAR FAR AWAY...........

I bought an STI WRX from auckland (auckland being at sea level) with the usual extras, the most notable one being the aftermarket Link computer, and brought it down to queenstown where i live (about 400m above sea level).

When it started getting warmer after winter (air getting warmer/thinner) the car started running rich, popping, backfiring, fouling plugs. sold it about 1 1/2 years later cause no one could fix it

I bought a GTR from auckland, usual extras, power fc etc. same problem, starts running richer when i get it to queenstown, got a Link put in it when i got it more heavily modifed and it fouls plugs real quick.

first thing in the morning the car is un-driveable, i took it to my mechanic yesterday (in christchurch sea level) where he said it started and ran perfectly, he is going to retune it and lean it off, as the first was tune was rich (safe)

i know that the sensors should adjust to the atmospheric conditions, but whats the problem?

ive spent so much coin on this car, and dont want to sell it

any advice/help would be great

cheers robbie

[Guilt-Toy]

I will PM you my bank account details, put the million in there. I will fly over there and fix it for you.

[brother_david]

Got same prob but at a smaller scale.. I live in Sweden, cars running in Japan runs great, gets here and then goes rich and/or eats up sparkplugs, guess its due to other air conditions, density, temperature etc.

Could you please send the million in Swedish krones? 1 000 000,00 AUD gives 6 136 000,00 SEK.

Thank you. .. .....

Edited May 5, 2009 by brother_david

[cosmic starz]

a difference of only 400 meters above sea level can be considered totally insignificant so far as air pressure / density is concerned

you need to look elsewhere - dodgy fuel is one possibility among about several .............

lol

[donkeypunch]

a difference of only 400 meters above sea level can be considered totally insignificant so far as air pressure / density is concerned

you need to look elsewhere - dodgy fuel is one possibility among about several .............

lol

hey i think you may be right, queenstown i think i have heard gets alot of shit fuel? hmmmmmmmm, but than why did it start in christchuch the next day sweet as?

Edited May 5, 2009 by donkeypunch

[Bumblebee]

could be the tuner.. my mates got a heavily modified evo in nz... he hasnt got any problems like what ur describing and his ride makes 800hp+

[donkeypunch]

could be the tuner.. my mates got a heavily modified evo in nz... he hasnt got any problems like what ur describing and his ride makes 800hp+

yeah both cars had different tuners

[paulr33]

hello

we need more information to be able to work out what is wrong, but it sounds like, without no further information you have a map sensor based setup thats been tuned in different atmospheric conditions, so when you move the car to a large variance in atmospheric pressure, the tune is off-whack

this is certainly possible with mathematics to occur, but i am unsure how much pressure difference sea level is vs 400m above

at sea level pressure we are 1 bar or 735mmhg or 94.8kpa

at 400mb above pressure we are 711mmhg or 99.4kpa

so its enough to drive a change in the map sensor by 5% difference

depending on how its tuned, may make it run like a bucket off poo

so

with your current setup is it AFM or map sensor?

if its link, we are assuming Map sensor

when you had the powerfc, was it AFM or Djetro?

did you have any issues with the powerfc?

if you did have issues, what setup was it,? afm or djetro?

[paulr33]

but i would hope in the real world, a 5% pressure change, wouldnt make the car run like a bucket of crap

that would seem unreasonable, so it could be a poor state of tune, or a very quick and nasty tune?

i woudl expect a typical map sensor / djetro system would compensate for a pressure change such as yours

much like an AFM would when temperature changes from summer to winter etc

[donkeypunch]

hello

we need more information to be able to work out what is wrong, but it sounds like, without no further information you have a map sensor based setup thats been tuned in different atmospheric conditions, so when you move the car to a large variance in atmospheric pressure, the tune is off-whack

this is certainly possible with mathematics to occur, but i am unsure how much pressure difference sea level is vs 400m above

at sea level pressure we are 1 bar or 735mmhg or 94.8kpa

at 400mb above pressure we are 711mmhg or 99.4kpa

so its enough to drive a change in the map sensor by 5% difference

depending on how its tuned, may make it run like a bucket off poo

so

with your current setup is it AFM or map sensor?

if its link, we are assuming Map sensor

when you had the powerfc, was it AFM or Djetro?

did you have any issues with the powerfc?

if you did have issues, what setup was it,? afm or djetro?

hey paul33,

this is what im talking about, cheers for the reply, yes the power fc had AFM's, it is now running the new Link G4 with map sensors, and yes you are correct it was tuned in christchurch at sea level, and as i posted it started perfect this morning in christchurch, but where i live in queenstown (400m above sea level) it starts badly.

when i got the car back from christchurch about 6 months ago it ran real well for about 3 mths, then started running badly. just before i took it to the drag race meet i put new plugs in it, it ran perfect. i did the plugs in while engine was hot so it wouldnt run full choke and foul them, drove about 25k, did about 7 passes drove home, did about another 30k, plugs fouled

Edited May 6, 2009 by donkeypunch

[donkeypunch]

oh yeah the power fc was tuned in auckland, sea level too

cheers

[STATUS]

should not do that at 400m, i have used cars here in dandenong that live / compete on mt buller and mt Isa (google that one ) and the differrence is enough to effect the tune but not enough to foul plugs. It should be factored for though.

Edited May 6, 2009 by URAS

[Adriano]

Does it have an air temp sensor, where is it located, and do you have a copy of the compensation table?

[donkeypunch]

Does it have an air temp sensor, where is it located, and do you have a copy of the compensation table?

hey will get that info

cheers

[Keeper]

Isn't the benefit of a F/I car that it can detect the pressure and temp difference and adjust as required the basemap?

We were cranking 6000ft, or 1800m density altitude (pressure altitude adjusted for temperature) in Toowoomba the other day, that's not crazy unusual for here and cars run fine at the top or bottom of the range.

[donkeypunch]

Isn't the benefit of a F/I car that it can detect the pressure and temp difference and adjust as required the basemap?

We were cranking 6000ft, or 1800m density altitude (pressure altitude adjusted for temperature) in Toowoomba the other day, that's not crazy unusual for here and cars run fine at the top or bottom of the range.

hey thanks for that

[joeyjoejoejuniorshabadoo]

but i would hope in the real world, a 5% pressure change, wouldnt make the car run like a bucket of crap

that would seem unreasonable, so it could be a poor state of tune, or a very quick and nasty tune?

shouldn't do that over a pissy 400m...

was the tune in summer on a hot day?

logically if you think about it, as trent said, the buller hillclimb is a vertical kilometre.... and my car runs that bottom to top no worries

[Beer Baron]

from the little info we have I would say it's a poor tune. simple as that. the car should not run poorly over a change in altitude of 400m.

[donkeypunch]

from the little info we have I would say it's a poor tune. simple as that. the car should not run poorly over a change in altitude of 400m.

cool thanks for that, if i get the new dyno readout could you guys let me know if it is a bad tune or not?

cheers

[Guilt-Toy]

who gets the cash?