• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


Boost loss at lower temperatures? (13-15 PSI)

Messages
287
Likes
62
Location
Clarksville
#1
To give you an idea of my car as it stands:

Injen CAI
Cobb RMM
Cobb Catback exhaust
Boomba BOV adapter
Glowshift Boost gauge.


So I was driving today after being snowed in for about 3 days. I notice my gear shifts are stupid smooth and the car feels really "tame" compared to the norm. IE: boring.

I get on the highway and put some WOT around 4th gear and I notice that my boost gauge would get to 15PSI then drop to 13PSI and go back and forth between the two as I held WOT for about 3 seconds. I could hear the Injen CAI sucking in the air and it confirmed to me that the car is hesitating after hitting 13-15 PSI.

What I am trying to figure out is it due to the snow? Is my Turbo misbehaving due to a failure? Or do I have something stuffed too close and clogging up the system maybe? Perhaps a tube or two are a little loose and need to be re-tightened?

I put stability control into sports mode to make sure it wasn't the ESC being silly and making the car run a little slower at those PSI or something silly like that.
Still had the same issue.

I'm going to check all my tubes tomorrow and jack the car up when there isn't so much snow underneath the car falling on me. If that doesn't fix it...looks like the dealer is gonna learn about my mods when I take it in.

Any of you have the same scenario happen?

Normally the car will go to 15 PSI then max out around 19-20 PSI in overboost before tapering off. This is concerning and I would be mortified if something were to happen to this car.
 


rodmoe

5000 Post Club
Messages
5,810
Likes
580
Location
wausau
#2
Sounds like a boost leak for me but i have been wrong before so let us know what you find underneath it
 


MOFiST

Active member
Messages
724
Likes
74
Location
Adelaide
#3
I've found this little tester invaluable over the past few years.





I have a small tank compressor but you can also attach a schraeder bike valve and use a hand pump if you're desperate.
Then you just pulse air into the sealed system. I've not had any leak issues but have used this to check.
Be aware if using a compressor you'll build pressure very quickly so be careful and wear eye protection just in case.
You should be able to quickly hear where your boost leak is coming from.

*note this will pressurize the valve cover so you may wanna crack open your oil cap a little. (but then air will bleed out from there)
I find you dont need to test with full boost pressure as you'll hear the air farting out well below that.
 


OP
S
Messages
287
Likes
62
Location
Clarksville
Thread Starter #4
Alright so update. I've talked to a few people and also to the Ford guys. Sadly they weren't able to take me today and I have an appointment for next week. However, the common thing that was stated by everyone I talked to was that the cold weather could be making either my actuator go wonky or the super condensed air could also be effecting my boost.

I also tightened everything I could get my hands on just to be sure and that includes the intake as well as all tubes going to the intercooler, turbo, everything I could. My boost has now managed to stay around 15 and doesn't fluctuated as much but it still doesn't go past that and still feels held back.

It seems it's probably just the cold weather and I should stay off the boost to make sure I don't blow something up and hate myself for hurting my baby.

I'll wait out the weather and get back again to see if things get better. If they do I'll let you guys know.

Pro tip: Keep all your tubes tight!
 


CanadianGuy

4000 Post Club
Messages
4,097
Likes
942
Location
Southern Ontario
#5
Well if it is the weather you could try leaving it in a garage and warm it up to see it it disappears. If it does it is the cause and also something hard to fix if it gets warmer between now and the appointment. Keep us posted and good luck.
 


haste

1000 Post Club
Messages
1,222
Likes
1,262
Location
Eastern
#7
Yeah, I'm running Stage 1 tune from Mountune with a drop-in filter and the car feels amazing in 15f weather. Something is wrong with your car, OP.
 


OP
S
Messages
287
Likes
62
Location
Clarksville
Thread Starter #8
Just thought I would make another update.

I went underneath the car once more and tightened 3 more spots a bit. I managed to scoop up an insane set of tools and was able to reach some hard to get spots. I did one more test run and now I am consistently running 15 PSI on my boost gauge.
When in second gear and dropping the hammer it will ramp up to about 16-near 18 before plopping back down like it normally does in 2nd. So I can confirm that there are probably a few things loose. Looks like I'll have to give the dealer a call and let them know to cancel my appointment and move whoever was next up the list I suppose.

I'll be taking my front bumper off later to give a full look at it in the future. Summer is not here yet and my garage is both cramped and cold at the moment. So when summer comes around then It will be much more fun and I can hopefully have more time to do such things.

Or maybe I'll wake up stupid early anyway and make my way over there to give it the last test. It's a decent drive out and I suppose I can truly make sure it's consistent before giving it up for a whole day. I think my appointment was at 8 in the morning lol.
 




Top