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Discussion Starter · #1 ·
Hello all,

I'm looking for any insight anyone might have on an issue I've been having on my 2004 S60R M66 the last few weeks. The issue is when I build boost and let off the throttle when shifting or just letting off the gas the car almost jerks forward like a light tap on the brakes. The car runs and drives fine with no engine codes. I hooked up VIDA and checked all the throttle and air related data and it all seems normal. Fuel trims are normal as well. I checked over the engine bay and couldn't find any leaking or air hoses or fittings and no vacuum leaks that I could see. I checked the CBV with a vacuum pump and it releases at about 7 psi which if i remember correctly is normal??

I travel for work so the car doesn't get driven very much so when it does get driven it's usually a bit spirited. This issue started after a particularly hard run, then the car was parked for a couple weeks and I noticed it the next time I drove the car. Not sure if it's related to this problem but the MAF went out at the same time this issue started. I replaced it with a bosch unit from FCP and the engine runs perfectly except for this issue now. Also, the engine does not use an abnormal amount of oil and doesn't lose any coolant. I appreciate any input and thank everyone for bearing with me as I ramble on.
 

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Do you hear a clunk when the car jerks forward?


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motor mounts?
 

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Check your clutch position sensor. It can become dislodged making things jerky.
 

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Discussion Starter · #5 ·
I do not hear a clunk when this happens, I think the motor mounts are in good condition still, and I will check the clutch position sensor this weekend when I get back home. Thanks!
 
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