2005 V50 T5 - Jack Rabbit Starts

Reinie · Post by **Reinie** » 23 Jul 2014, 10:50

My 2005 V50 T5 FWD AUTO has very uneven acceleration. Best way to describe it is "jack rabbit starts". Almost like the turbo is over-boosting at the slightest touch of the accelerator, then drops-out and fluctuates RPM's between gears. The throttle body was removed and cleaned. Recently replaced the fuel pressure sensor (took care of an unrelated issue with the engine temporarily cutting-out). I was told to run a sweep test to diagnose. My thoughts are either the throttle body, turbo TCV, fuel pump, or computer. Anyone had this?

Reinie · Post by **Reinie** » 15 Aug 2014, 07:26

2005 V50 T5 FWD AUTO - Where is the (BPS) boost pressure sensor located?

Reinie · Post by **Reinie** » 12 Nov 2014, 08:46

Still haven't corrected this issue. On start up with a cold engine, everything is normal. But when the engine is warm, the drivability gets worse. It's off to the races again... Most people are complaining about low boost pressures and think I'm crazy. But something is not right. All software is updated. I have done all the general tune-up items and have conditioned the fuel system with sea foam, fuel injector cleaner, and heat. I still haven't identified the location of the boost pressure sensor (bps) and it's function. Any ideas?

Post by **jimmy57** » 12 Nov 2014, 10:09

The boost pressure sensor in on the intercooler outlet, driver's side of intercooler.

Has anyone checked the base setting of the wastegate? Your symptoms can occur with the base boost level being too high.

Reinie · Post by **Reinie** » 12 Nov 2014, 11:52

No, I have not checked any turbo components or settings. I will have someone check the wastegate base boost levels. Is there considerable labor costs to check out turbo settings? Also, it's due for a timing belt, which brought something else to mind. Could this be related to timing or cam issues?

Post by **jimmy57** » 12 Nov 2014, 12:04

Checking the wastegate setting is not complicated.
If a hose to wastegate is cracked, split, or off or if the turbo control valve is sticking you could also hve no boost control and excessive boost.
It could not be related to cam timing without having check engine light on from cam positioning error.
If timing belt is loose enough to allow the cm to change setting then it would be unlikely to not come off and cause severe engine damage.

Reinie · Post by **Reinie** » 12 Nov 2014, 13:07

I don't have any tools or knowledge to check turbo components. However, I'm temped to throw in a IPD turbo control valve and hope for the best ($89.95). Bad idea?

Post by **jimmy57** » 12 Nov 2014, 14:45

No, the failure rate of TCV's is high and that is likely a needed item even if it isn't the problem now.

Reinie · Post by **Reinie** » 13 Nov 2014, 08:56

Jimmy57, what are your thoughts on the boost pressure sensor(BPS). Looks similar to the fuel pressure sensor(FPS) which has a very high failure rate. Should I replace this at the same time?

: BPS1.JPG (22.31 KiB) Viewed 1773 times

: BPS2.JPG (38.58 KiB) Viewed 1773 times

Reinie · Post by **Reinie** » 14 Nov 2014, 08:08

I found the location of the boost pressure sensor (BPS). Also referred to as the manifold absolute pressure sensor (MAP sensor). It's accessible through the fog light cover on the passenger side. The part is $50, so I'm going after that first. The turbo control valve (TCV) is more difficult to get at. It's low, behind the timing belt housing, and to the passenger side of the wastegate. Possible access through the wheel well, but looks easier while on a lift.