Low boost pressure..

[Fk8_Yero]

During the winter when it was around 50-70F the car would run anywhere from 19-23 psi.. it’s now edging towards summer and I understand fully that in hotter conditions boost psi tends to drop lower but As of right now, in the 80-90F I’ve dropped to 13-14 psi in 2nd 14-15 in 3rd and 15-16 in 4th( this was yesterday today as I’m posting the car is hitting 15-16 full throttle in 2nd-3rd and peaks of 17-18 in 4th and I recall that yesterday night when it was 60F I was hitting 19-21)... but overall the car feels much slower since it got hotter and it’s really bothering me... is it normally for it to drop that much in weather change .. other cars are different but people claim only 1-2 psi drop while I’m nearly at 5-6... if so do I need to get a tune just to boost psi for the summer ? Because i plan on keeping my car for a long time and I don’t want to have to deal with heavy power loss every summer ? Any advice ? (P.s. posting during the day when it’s hot after a few replies I will get back to everyone once it’s cooler outside to see if I’m once again hitting 19-21 psi in much cooler conditions)

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[CanadianFK8]

That sounds a little backwards to me.... In the heat of the summer, the PSI required should be higher than in the winter. (colder air charge needs less pressure to achieve XX torque target) your numbers do seem pretty low for what should be expected..... For me here Alberta, I see around 17 psi in the winter, and come summer time I'm around 19-23psi depending.

 

[PowerPerLiter]

The car is reducing boost as its seeing higher intake air temperature. Completely normal. The lower air temps allow for a higher "safer" boost target. Thinner warmer air is harder to compress so to keep the turbo from overclocking the ecu is reducing boost and trying to make similar power with timing advance and cam overlap changes elsewhere in the ecu(which will only go so far compared to the higher boost in the winter)

 

[tinyman392]

Even if you could tune out the boost drop, I'd advise against it. The car selects boost based on various criterion but will try to hit torque targets. However, there are scenarios where the car will pull boost, mainly if your charge temps are high which is to protect the turbo itself from damage. That said, your boost drops are pretty substantial, it's possible that your running into heat soak issues; most likely with the intercooler.

 

[Fk8_Yero]

The car is reducing boost as its seeing higher intake air temperature. Completely normal. The lower air temps allow for a higher "safer" boost target. Thinner warmer air is harder to compress so to keep the turbo from overclocking the ecu is reducing boost and trying to make similar power with timing advance and cam overlap changes elsewhere in the ecu(which will only go so far compared to the higher boost in the winter)

From everything else I’ve heard this is what I thought was happening but people are telling me 35 different possibility’s and almost all make sense so I don’t know what approach to take ... do I go based off of during the day when it’s 85-100 degrees Fahrenheit my boost drops down to 16-18 max depending on gear and if during the night when it’s cooler it goes back up to 18-21 that weather is the only issue ?

 

[Fk8_Yero]

Even if you could tune out the boost drop, I'd advise against it. The car selects boost based on various criterion but will try to hit torque targets. However, there are scenarios where the car will pull boost, mainly if your charge temps are high which is to protect the turbo itself from damage. That said, your boost drops are pretty substantial, it's possible that your running into heat soak issues; most likely with the intercooler.

With hondata I can get a constant 20-23 psi but then the question of how much damage might that do in hot air conditions comes into play.... I’m still doing tests as for the weather idea on the way to work it was getting from 16-18 depending on the gear I was in.. and when I go home it will be around 90 degrees Fahrenheit and I’m guessing boost will be low again.. during night when it’s 60-70 I will go for a drive and see if boost goes back up to 19-21 and get back to you on that !

 

[Fk8_Yero]

That sounds a little backwards to me.... In the heat of the summer, the PSI required should be higher than in the winter. (colder air charge needs less pressure to achieve XX torque target) your numbers do seem pretty low for what should be expected..... For me here Alberta, I see around 17 psi in the winter, and come summer time I'm around 19-23psi depending.

I’ve personally heard the opposite with turbo car owners... they tend to look forward to the colder days so their cars can run smoother... in California the weather is usually really hot during the summer anywhere from 90-100F and really cold during winter anywhere from 45-60F I got my car in the beginning of winter and it ran perfectly until it got hot lately... only ever since it’s been above 85 degrees Fahrenheit have I had this issue... still running some tests as I see the boost pressure during the hot air maxes out at 16-18 depending on gear.. tonight when it’s 60 I will go for a drive and see if it’s goes back up and get back to this post !!

 

[CanadianFK8]

I’ve personally heard the opposite with turbo car owners... they tend to look forward to the colder days so their cars can run smoother... in California the weather is usually really hot during the summer anywhere from 90-100F and really cold during winter anywhere from 45-60F I got my car in the beginning of winter and it ran perfectly until it got hot lately... only ever since it’s been above 85 degrees Fahrenheit have I had this issue... still running some tests as I see the boost pressure during the hot air maxes out at 16-18 depending on gear.. tonight when it’s 60 I will go for a drive and see if it’s goes back up and get back to this post !!

Oh for sure the engine loves and performs better with colder air charge. There are many variables that will affect engine performance.

I would take a look at your IAT's during these drives, give you a better idea if you are heat soaking to the point that it will reduce boost and drop to those PSI levels to protect itself.... although what you are seeing is oddly low.

 

[Fk8_Yero]

Oh for sure the engine loves and performs better with colder air charge. There are many variables that will affect engine performance.

I would take a look at your IAT's during these drives, give you a better idea if you are heat soaking to the point that it will reduce boost and drop to those PSI levels to protect itself.... although what you are seeing is oddly low.

here’s a link to a video I just posted on Reddit of the dash while doing a pull from 2nd to 3rd

 

[REBELXSi]

here’s a link to a video I just posted on Reddit of the dash while doing a pull from 2nd to 3rd

Are you at 100% throttle?

 

[CanadianFK8]

Same question.

You gotta put that gas pedal to the ground man. That's seems like maybe 60% throttle.. is it just me?!?!

 

[Fk8_Yero]

Are you at 100% throttle?

Yes I am I just let off the gas cause I don’t wanna head into redline but off camera maybe 2 min later I went to redline in 2nd and 3rd with the same result !

 

[Fk8_Yero]

Same question.

You gotta put that gas pedal to the ground man. That's seems like maybe 60% throttle.. is it just me?!?!

Yes I am I just didn’t push it to redline .. soon after off camera I pushed it to redline in 2nd and 3rd with the same output.. full throttle as soon as I went from 1st to 2nd and through 3rd... it kind of felt like it wanted to go faster but something felt pressurized like it was being blocked off and limited to that psi.. definitely feels slower... soon it’s going to be much cooler outside I’m gonna run more test to see if there’s a difference...

 

[Fk8_Yero]

Yes I am I just didn’t push it to redline .. soon after off camera I pushed it to redline in 2nd and 3rd with the same output.. full throttle as soon as I went from 1st to 2nd and through 3rd... it kind of felt like it wanted to go faster but something felt pressurized like it was being blocked off and limited to that psi.. definitely feels slower... soon it’s going to be much cooler outside I’m gonna run more test to see if there’s a difference...

Ok so now that the suns down and it’s down to less then 90 degrees F I’m getting a consistent 19-21 psi ... it seems to only happen when my cars been sitting in the hot blazing sun for hours .. it’s a long shot but maybe after being in the sun for so long could it be that the certain parts of the car/engine are so hot that it causing the ECU to turn things down as a safety measure ?

 

[Lust]

Do you have another scan tool or tuning device to check temps and boost pressure?

It's warm here in norcal and I'm still getting 25-26PSI peak boost.

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