FORD BA XR6 TURBO BOOSTING PROBLEM...

[Greendaddy]

No worries will give it a try in the morning. None of it makes sense, I changed the actuator awhile ago and it fixed it for a few days then went back to rubbish, I put a second hand boost solenoid in and it worked. Although on reds / accessories it was making a clicking sound constantly I thought it was stuffed too but it actually worked. The original one never made this clicking sound, So I bought a new genuine one put that in and that one also clicked when accessories were on, so I thought it was normal to click. I did some work on the car which it was off road for a few days, punched the broken cat out, engine mounts power steering line drove it home started breaking up through high revs, I've already replaced coil packs and plugs before this, so I replaced both the map sensor and the boost pressure sensor, since then the boost solenoid has stopped clicking and no longer works, I'm not sure if it's just a coincidence or what but it's really got me stumped 

[BeerTurbo]

just think of the solaniod as a really fast on/off air valve.

 

When the car reaches the boost it want - it will open to let air thro, but you can modulate it so it runs more boost (on of on off)...

so you turbo actuator might be a mechanical 4.5Psi spring, but with the controller it can modulate the air in supply to actuator so the car will run higher boost

I believe the Peak boost a BA computer will aim for is somewhere in the 6Psi range.

 

so just think of it like that, mechanically the car will try for 4.5 PSI, but with the use of the boost controller it will try for 6...

with the use of the boost controller you can bring on boost quicker and run like a variable boost through the RPM, the electronics are pretty fancy.

 

so if you boost controller is stuck closed, or not responding correctly due to bad wiring, there could be a limitation on the level of boost sent to the actuator.if nothings sent to the actuator it will over boost like crazy (same as if the actuator was broke (they can leak or if your rear valve was stuck).

 

when you add in a less restrictive exhaust and sh*t like that, all this will happen faster and things will tend to run more boost because the turbo is able to spool up considerably easier than it could before....... but like I said, mines 3inch straight though and can still manage to sit under 5psi, I cant see why yours wouldn't be able to do the same or similar if you removed the computer control of the boost.

Edited 09/06/18 09:57 AM by BeerTurbo

[Greendaddy]

Yeah I see what you're saying. It's all complex just a matter of figuring out why the wastegate is staying closed, the boost solenoid has power going to it I checked that today. But I'll do the bypass tomorrow and see what I come up with. If that fails what next? Haha

[Greendaddy]

Hey mate put a hose straight from the turbo to the actuator still seeing at least 15 psi .... No idea what to do now. 

Still got me wondering what could possibly make the wastegate stay closed and force overboost 

[BeerTurbo]

when you connected your tester to the actuator and it opened around 5 psi, was the actuator leaking at all? like a faulty diaphragm? 

[Greendaddy]

Nah no leaks or anything of the sort, actuator was changed not too long ago. The diaphragm is still good. Maybe take the turbo off and take it to a shop get it flow tested or is that a bit overkill? 

I have no catalytic converter either it sh*t itself so I punched it out to get me out of trouble, any chance this could be causing me problems? 

[BeerTurbo]

Mines got no cat, only straight thro and its fine.

But ive read lots from people saying they do over-boost with free flowing exhausts. but yours seems a bit extreme to me.

 

your issue will be around that actuator not opening the flapper enough - its the only mechanical thing to control boost.

see they offer flapper valve enlargements for these cars, possibly to control your kind of issues...the more air it can divert from the turbine the more solid the boost curve can be.

 

nah, that overkill.....get it flow tested, maybe having the flapper enlarged is a half decent idea.

 

If you want to try extremes...disconnect the actuator from the flapper valve, the use some wire to hold the flapper valve all the way open. then test it.

[Greendaddy]

Ahh yeah makes sense. You wouldn't believe how hard it is to find a standard cat to put back on haha I'll try and get the turbo off and go get it flow tested hopefully somehow that flapper is just getting caught or something. There's nothing else electronically it could be or even mechanical 

[BeerTurbo]

I did a bit more reading, seems anyone who modify s the exhaust on a x6t gets over-boosting issues.

If you going to keep the aftermarket or high flow exhaust maybe look at a larger flapper valve or adding external wastegate.

or go back to stock exhaust

 

I dont know how I got so lucky.

 

good luck.

[k31th]

Check the actuator with a compressor to see if it cracks at the desired pressure. It sounds like you've got a stuck/sticking actuator, especially if it overboosts on connecting the compressor to the actuator.

 

Also, get any 200 or 300 cpsi catalytic converter welded into place because the punched cat will definitely cause it to overboost on a stock car.