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2012 fx4 boost cycling

677 Views 53 Replies 6 Participants Last post by  Gord0
my 2012 fx4 is cycling boost on factory tune 15psi-7psi over and over around like 1/2 to 3/4 throttle. I put a 5star tune on it i also get the same thing but with pressures being 20-13 over and over. I have done new plugs, coils, timing, factory turbos, exhaust manifolds, all sensors. I checked for leaks and see none. It does not throw a code at all, It is getting quite annoying trying to figure out. i even drilled the 1/16 hole for condensation. I also have been reading form after form checking all and double checking with no solution. i am just at a loss and am about at witts end. I am hoping someone else has had this issue and has figured it out.
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Ok but as far as the vacuum port on the back left of the intake that goes to the canister and wg, is yours slightly loose by chance? If not I may need to buy and intake but the ones I can find don’t come with that port
Not sure about the vac port. I've got a 2013 so our systems may be different, and I can't go check it right now.
If the connection to this part of your turbo has a leak, that is the pressurized side and could be the main cause of your WG oscillation issues for sure




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If the connection to this part of your turbo has a leak, that is the pressurized side and could be the main cause of your WG oscillation issues for sure

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That side was torn all to heck may have had a crack in it when I put it back together? Maybe. But I got all new cvf tubes coming and a new intake from ford that’s all going on this weekend
That side was torn all to heck may have had a crack in it when I put it back together? Maybe. But I got all new cvf tubes coming and a new intake from ford that’s all going on this weekend
Hopefully that solves it for you!
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Hopefully that solves it for you!
I hope so too I will let you guys know once I get it all put on. Thanks for all the responses
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FYI, on a 2012 (being a MAF truck) a leak on the intake side can cause issues too, but it's usually fueling related. Air that is unaccounted for throws off the calculations. Any leaks in the system can be cause for concern with a MAF though.

It's not entirely related to the issue at hand but is helpful info regardless.
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Only the 2011 has the MAF by the airbox. 2012+ have the MAP. Tho everyone thinks it’s strictly for IAT - my FP calibrator told me it helps dial in the airflow calculations. Which is why you want airflow to not be turbulent.

But the wastegate PID feedback loop controls your boost. It tries to adapt based on your airflow. Doing so allows the calibration to provide consistent Boost/load during TIP in. If there is an intake leak/boost leak, airflow can be different each time you go into boost. Hence the discrepancy in PSI.
That goes to your BPVs. It connects to the vacuum reservoir and T’s to each turbo. There’s a check valve there to top off the reservoir but prevent pressure. That check valve does fail and you can actually use a IWE check valve to replace it. But just have to cap off one of the ports.
Ok but as far as the vacuum port on the back left of the intake that goes to the canister and wg, is yours slightly loose by chance? If not I may need to buy and intake but the ones I can find don’t come with that port
Notbat all loose. If yours is loose, might get a new clamp on there and see if that helps. Guessing your torn hot side boot is the culprit… unbelievable the dealership techs were unable to find such an obvious problem 🤯
So update it was a torn intake boot at the turbo but replaced all the new tubing with cvf which I am not a fan of should have went afe. But replaced the intake because that port was broke. Got it all back together and still have this issue I am lost.. and debating setting it on fire in a corn field.
Did you do a KAM reset and throttle body relearn after you were done?
You may be trusting new parts, and one of them may be the issue. Engine calls for x load which requires a certain amount of boost. The amount of boost your turbo puts out is controlled by throttle, and wastegates, unless your bov's aren't holding. Wastegates are controlled by the solenoid in the "spider assembly" and should start to open at 5psi. Have you monitored your throttle position to see if it's doing anything funky in relation to boost? It'll move around a bit, and never be at 100%, but throttle bodies cause all sorts of issues with these engines.
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Also adding that there's obviously map sensors measuring said boost as well.
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