Ford Focus ST Forum banner
1 - 20 of 52 Posts

·
Registered
Joined
·
19 Posts
Discussion Starter · #1 ·
I’m about to bring it back in for the third time. I bought it certified pre owned with 10k on it and now has 15k. Here’s my issue. The car falls into some type of boost limp mode when it’s wot in the higher gears. I can drive around while full boosting between 1-3 gear and it has no issues. But if I am on the highway and do a long pull, it cuts off the boost to 7.5 psi on the gauge. I can quickly turn off the car and turn it back on which resets the issue till I go do another long pull. Example, Let’s say I’m in 5th going 75/80mph and I go wot, at about 115 it drops on its face.
The first two times I brought the car in was cause a check engine light came on after a few of those instances. The dealership said the first time was from a boost sensor that went bad. And the second time they said the bov was leaking. And now I’m on here looking for some help because I got off the highway earlier and it did it again. No check engine light is on, yet.
 

·
Super Moderator
2014 ST3. Garrett Powermax turbo, Thermal Turboback, CPE intercooler, JBR intake, Innovative RMM
Joined
·
3,970 Posts
Dont take it back in, any sane tech won't risk going to jail just to duplicate your concern. Get some sort of logging device and try to narrow it down yourself.

I will say that if you're doing a pull from 80 you should be starting in 4th gear.

You could be simply suffering from heat soak by the end of that pull, where the pcm is pulling power to keep the engine safe. We wont know until you get some data logs.
 

·
Premium Member
2018 Ford Focus ST1
Joined
·
1,304 Posts
Like TurboGT said, if you're doing a run from 80 to 115 you shouldn't be doing that from 5th, but 4th gear. If you're on the stock fmic, it's most likely a heat issue.

Even at 30 degrees, I did a pull the other day in 3rd/4th, and by the time I let off the charge temps were around 130 degrees. Not sure where you're at, but I would bet that if you started in 5th and went from 80 to 115, your charge temps were over 200, so it's no wonder it pulled boost.
 
  • Like
Reactions: TurboGT

·
Registered
Joined
·
1,175 Posts
Stop mashing it in 5th.

The car is very clearly trying to tell you that it doesn't like that.

The car has overboost which lasts for 15 seconds. If you're matting it in 5th at 75, odds are good you're using all 15 seconds of that overboost.


Specifically- "Overboost is available only for 15 seconds at a time, which Schoder says is more than enough. If the pedal is held down continuously, the car’s control systems will detect if the turbo temperature is rising too rapidly and shut down the feature."
 

·
Registered
Joined
·
19 Posts
Discussion Starter · #5 ·
Stop mashing it in 5th.

The car is very clearly trying to tell you that it doesn't like that.

The car has overboost which lasts for 15 seconds. If you're matting it in 5th at 75, odds are good you're using all 15 seconds of that overboost.


Specifically- "Overboost is available only for 15 seconds at a time, which Schoder says is more than enough. If the pedal is held down continuously, the car’s control systems will detect if the turbo temperature is rising too rapidly and shut down the feature."
So over boost is over 15psi and then after 15seconds it drops to 7.5psi?
 

·
Registered
Joined
·
19 Posts
Discussion Starter · #6 ·
So I just got home and I was able to replicate it and get it on camera. The car was warmed up and it’s 50 degrees out. I put her in fourth at 80 mph and went wot, before I was even at red line it dropped my boost down to around the 7.5psi mark. And the check engine light came on. Why’s the best way to post the video here?
 

·
Super Moderator
2014 ST3. Garrett Powermax turbo, Thermal Turboback, CPE intercooler, JBR intake, Innovative RMM
Joined
·
3,970 Posts
Since the engine light came on, you definitely do have an issue. What code are you getting currently?
 

·
Super Moderator
2014 ST3. Garrett Powermax turbo, Thermal Turboback, CPE intercooler, JBR intake, Innovative RMM
Joined
·
3,970 Posts
The Launch cr319 code reader is 18 bucks on Amazon right now. I own this model and it's a nice little unit. For as cheap as it is, theres no reason not to pick one up.
 

·
Premium Member
2018 Ford Focus ST1
Joined
·
1,304 Posts
Had you been running it hard just before that pull (this would have made the starting charge temps high)? I only counted 7 seconds on that run before it dropped boost pressure.

Wish you had a Bluetooth OBD2 connector and torque pro, as we could see your charge temps before, during, and after the run. Could also easily see your engine codes.

Without seeing what the sensors are showing, we are kind of shooting in the dark since it's pulling boost before 15 seconds.

ETA:. What octane fuel are you running in it? 93/91, or are you feeding it 87/89. It's entirely possible that the engine is sensing knock if you're feeding it 87/89 and pulling timing, but since it's being kept at wot and the charge temps are still going up, thus making knock even worse, it can't deal with the knock and starts pulling boost. From 1-3rd gears the load probably wouldn't be bad enough, even with 87/89, to pull boost and it can just deal with the knock with timing retard.
 

·
Registered
Joined
·
19 Posts
Discussion Starter · #15 ·
Had you been running it hard just before that pull (this would have made the starting charge temps high)? I only counted 7 seconds on that run before it dropped boost pressure.

Wish you had a Bluetooth OBD2 connector and torque pro, as we could see your charge temps before, during, and after the run. Could also easily see your engine codes.

Without seeing what the sensors are showing, we are kind of shooting in the dark since it's pulling boost before 15 seconds.
I was cruising average speed on the parkway in highly police populated section of highway. I use Waze and know where they sit at, and just past one right before that video was taken.
Which exact model ob2 reader you talking about?
 

·
Premium Member
2018 Ford Focus ST1
Joined
·
1,304 Posts

·
Premium Member
2018 Ford Focus ST1
Joined
·
1,304 Posts
Somebody else might chime in with something that works with an iPhone, but your best bet may be an Accessport then. They're on the for sale board here all the time, but they're a bit spendy at between 300 and 350, used.
 

·
Registered
2014 Ford Focus ST3
Joined
·
231 Posts
Happy Thanksgiving everyone!

To read code, you can use OBD Fusion on your iPhone Phill
 
  • Like
Reactions: Phill_casi
1 - 20 of 52 Posts
Top