P0238 Overboost. Need help.

[Kyle09TC 0]

I have read plenty of dead end threads on here around this issue. Recently pulled intercooler out and patched it, but have still been getting the P0238. The car revs over 3000rpm, really struggles in 4-6th gear and loses a lot of speed on hills (don't think this is normal). There is oil in the hose from the turbo to the intercooler. I will be checking the turbine shortly to check for movement and shaft play. The wastage does move. To lower the pressure do i spin the nuts for the wastegate left or right?

[dmoonen 54]

Remove the rear end and work the wastegate back and forth with a big adjustable. . my bet its gummed up and isnt opening

[dmoonen 54]

Make sure it moves first, off the top of my head I dont remember the adjustment I'll have to dig in

[tolsen 630]

To lower wastegate boost pressure setting you must lower preload on wastegate actuator spring. Do this by moving adjuster nuts to the right on rod.

[Kyle09TC 0]

I have moved the wastegate, it will open with a fair amount of pressure but seems to still open. I read to spare it with graphite spray and i have. I will move the nuts over a bit tomorrow and see if that helps any. I will also continue to work the wastegate and make sure it is opening fully.

Might be unrelated, I am getting a squealing noise from about 1800-2800 and goes away above that, not sure if its a belt or something else. Anything i should look at while i have it all apart tomorrow that may be related to this?

[tolsen 630]

Wastegate springs generally do not become stiffer over time so perhaps you should check wastegate hose for splits and leaks.

[Ronfire 0]

My wastegate moves ok, I lubed it up and maybe it is a little more free, Seems like I do this every 2-3 months to keep the codes away. Could the actuator be getting bad, could not detect any leaks in it or the hoses.

anyone have intermittent problems with the sensor? And where is the sensor located?

[tolsen 630]

Boost pressure sensor sits on rubber mounts at right hand side of valve cover.  Sensor is connected to inlet manifold by a rubber hose.

[cadillacman 927]

2 hours ago, Ritchie said:

Is there a sensor for this mdoel or Is it that no one knows or is it no one cares to be helpful?

It can be frustrating.

 

Do you assume that every thread will always contain all the information ?

In another topic ,I mentioned the location of this sensor, about 4 weeks ago.

I also try to post x-ref links in topics, to find related stories, that might be related.

 

You need to do more searches to find the answers, because not everybody on here is perfect.

 

Gads, I try, but I'm not either.

[Nigel 287]

Ritchie

Will your scanner show boost or map numbers while driving?  I think the maximum map should be about 2.1 bar or max boost be about 16 psi.  If you can’t get the numbers you are welcome to come up here and try my Scangauge.  I’m about  20 minutes north of 400/401.

 

Nigel

[tolsen 630]

6 minutes ago, GRP151 said:

Had the same problem. i removed actuator hose cleaned it up to the sensor and it hasn't reappeared  

Which sensor?  There is no sensor on waste gate actuator.

[Nigel 287]

Ritchie

I will try but I may not get it exactly right.  On your first picture, on the left side of the Turbo there is a hose about a quarter inch diameter going from the Turbo to the wastegate actuator.  The pressure travels through the little hose and pushes against a diaphragm and spring in the actuator and when there is enough pressure to overcome the spring the actuator rod moves the wastegate towards the open position.  As the pressure drops the spring in the actuator moves the wastegate back to the closed position.  By moving the nuts on the rod where it is attached to the wastegate lever will change the preload on the actuator spring therefore raising or lowering the maximum boost.  I don’t remember which way you would turn them left or right to lower the boost.  Since your problem is intermittent I suspect your adjustment is pretty close within a turn or two.  Also if you have a crack or hole in the little hose full boost may not be getting to the actuator and therefore not opening the wastegate and causing an over boost condition.  

 

Clear as mud?

Nigel

[tolsen 630]

Moving nuts on waste gate actuator rod to the right lowers turbo boost pressure. 

Carefully inspect hose on waste gate actuator for possible cracks or splits. 

[LooseLugNuts 557]

^thats sounds about right except i wouldnt say air pressure is generated by exhaust turbine...id say the exhaust turbine is powered by the engine exhaust flow....which in turn generates pressurized intake flow

 

 

11 hours ago, Ritchie said:

 

What controls the boost pressure sensor? Pressure, vacuum, electrical?

Do you have a picture please?

 

 

 

i may be wrong but

 

 

i think the confusion is that the "boost pressure" sensor is actually a map sensor ...only used for ecm 

 

the other wastegate actuator system is completely separate pressure operated system that works on its own (no ecm involved)

Edited November 21, 2017 by LooseLugNuts

[tolsen 630]

See your own post no 18. Inlet air pressure sensor sits about an inch forward of rail pressure sensor. It is connected to inlet manifold via a small diameter rubber hose. 

[tolsen 630]

1 hour ago, GRP151 said:

 

Actuator hose had some obstruction within, oil or carbon,  Problem hasn't returned.

 

Wrong word since that is a sensor, not an actuator. Proper description surely must be “sensor hose”.

[LooseLugNuts 557]

why post pictures of map sensor and then talk about actuator hose?,..

 

its almost like youre trying to confuse this person on purpose

[tolsen 630]

You are again muddling the water GRP151. 

Cracked and leaking actuator hose will cause overboost and possibly limp mode. Oil in actuator hose causes no problem at all. 

[tolsen 630]

4 hours ago, Ritchie said:

 

If crack hose gives overboost  what is actually happening?

Is it not enough pressure to retrack the actuator or to extend it?

You don’t need to be particularly smart to figure that out. 

[booneylander 37]

If the hose to the actuator is cracked, or if the diaphragm in the actuator itself is torn, the boost leaks out and can't build enough pressure to compress the spring in the actuator. So the rod doesn't extend and the wastegate doesn't open, boost keeps climbing, and you get an overboost code and limp mode.

[smartdriver 49]

My car had this error occur after driving about 2 km and going up the same hill while going to work every day.

 

Removed the rear panels and freed the wastegate.

[Nigel 287]

Ritchie

Turbocharger boost changes with engine load from a slight vacuum at idle to max boost going uphill with your foot into it.   Unlike a supercharger where the boost is directly linked to engine speed.  So if you drove with light throttle all day long you probably wouldn’t set the code.  

 

Nigel