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Discussion Starter · #1 ·
Hello. I recently bought an Volvo S40 T5 2006 geartronic with 23.000 miles. I love the car but i have some problems with the engine. Today the engine started to lose power after 3000 rpm. If I floor it the car goes like hell till it reaches 3000 rpm and then it enters some kind of limp mode, it revs very slow and i barely reach 6000 rpm. Any ideas what can cause this isue? If i turn off the engine and start it again, it goes fine but after 1-2 minutes the "limp mode" is on again. No check engine light on. Engine starts fine.

Thank you for your answers and please excuse my bad english.
 

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Turbo Control Valve (TCV). Search the site as there are many, many threads on this. Very common problem, and not too expensive to repair either.
 

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I ve had the same problem, cured with new stock tcv and a forge cbv.
 

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Discussion Starter · #4 ·
Thank you for your answers. I will change that TCV. But i am curious, does this TCV problem appear on a diagnoze? I am thinking since the check engine light isn't on the error doesen't appear on the diagnoze. I want to make sure that is the problem.
 

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Thank you for your answers. I will change that TCV. But i am curious, does this TCV problem appear on a diagnoze? I am thinking since the check engine light isn't on the error doesen't appear on the diagnoze. I want to make sure that is the problem.
I had these same symptoms, no check engine light. Replaced TCV and all is well.
 

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Discussion Starter · #6 ·
Guys please help. Changed the tcv and the car still does the same. I really do not know what to do...

Thx
 

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Discussion Starter · #7 ·
Did an obd scan. Got error p0234 turbo overboost. Seems when the turbo kicks in the presure is very big and it goes into some kind of limp mode.
 

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FPS, CBV... maybe not. All vakuum lines ok?
 

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Did an obd scan. Got error p0234 turbo overboost. Seems when the turbo kicks in the presure is very big and it goes into some kind of limp mode.
CBV has nothing to do with turbo overboost. Visit certified Volvo mechanic, he will inspect your engine and do a VIDA check. Everything else is guesswork..
 

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Did you delete the code and have you reset adptation after tcv change?
 

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Discussion Starter · #11 ·
I delete the codes after tcv change. It makes no diffrence. Is there any possibility the turbo is damaged?
 

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Did u reset the adaption when you replaced the TCV? Merely erasing the codes doesn't set the ECM back to zero for the relearn process.
 

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Recheck all your connections on the newly replaced TCV. If you somehow mix up the vacuum lines then I thought I read that the turbo would definitely boost incorrectly. There is a thread somewhere that outlines the correct placement of the lines. Also do the relearn as others have said. Good luck
 

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And how do I do that, need an original Volvo Diagnoze?

Disconnect the battery for 15 sec and that's it.

If that doesn't do the the trick I would also check the wastegate, but as I said, visiting Volvo mechanic seems inevitable in this case to me..
 

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Pull the F23 fuse for 15 minutes. The modules in these cars store voltage for quite a few minutes in some cases which has the ability to retain its stored information. By pulling the fuse you disconnect the ECM from the communication path of the vehicle after its shut off prior to going to sleep.

Have seen people misdiagnose parasitic draws on the battery that were unaware of the modules communicating prior to going to sleep which has an amperage draw.
 

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Can leave the battery connected, all your doing is disconnecting the power supply by pulling the ECM fuse.
 

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Discussion Starter · #19 · (Edited)
Nothing worked, i'm thinking the new tcv althoug is OEM part and it was sealed. it's damaged, or something happend. I've done some tests and discover that the error p0234(turbo overboost), only comes when you push the engine. If i drive the car normal, the error doesn't apear.
Thank you for all your ansewers, i'l keep you posted with my problems and how i will solve it.
 

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I've done some tests and discover that the error p0234(turbo overboost), only comes when you push the engine. If i drive the car normal, the error doesn't apear.
That makes sense as you need a load to create boost (positive pressure). So what controls boost is the wastegate which is controlled by the TCV which is controlled by the ECU/ECM/whatever. So there must be something wrong with one of those or the vacuum lines going to the TCV. That is assuming that there is actual overboosting occuring. Possibility there is a screwed up sensor that thinks you have an overboost situation.

Can the dealership test your new TCV (or heck even old?). If not: claim it is bad, and get a new one. You need to see if there is a correlation for that valve and the problem. Friend with a working car that can spare it for a day or so?

Best of luck.
 
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