hello guys...i have a 2009 xc90 3.2 model....i bought this car with this same problem after doing thousands of dollars in repairs...it still has the same issue...it runs great but sometimes on 2000-3000 RPM it looses rpm ....if I ease my foot off for a little it recovers. sometime it happens, sometimes it doesnt..vehicle has zero codes what so ever.. I replaced the entire exhaust system front to rear. intake manifold gasket, new fuel pump, fuel filter, air filter, new fuel pressure regulator, new air filter, new o2 sensors.....i even took it to a volvo specialist....no codes. it only does this on high speed...please tell me what you think...

 

sorry you decided to throw parts at this issue within a complete diagnosis. When you said a "volvo specialist", did you ask if they have all the factory tools like a VIDA DICE set up? Sometimes these issues need to be trapped via real time data (ie a test drive with the monitor tools recording live. Note many of the fault codes are averaging over time, meaning a short hiccup won't trigger a code. Are you doing any of the work yourself, has any been done by a dealer or just by your local indys?

 

thank you so much for responding to me! the mechanic who did all of the work had his device plugged and it seems like when this starts to happen..the fuel pressure drastically drops, we replaced fuel pump/filter/fuel pressure sensor and same issue...I took it to the famous PRO VOVO in jersey as a last resort. the car ran fine and had no issues....few hours after leaving their shop..the nightmare started again...

 

Was the tank checked for contamination when the pump was out? Does your shop know about the duty cycle and is he checking the duty cycle of the pump? Is that changing when it runs bad? That car has a PEM, a fuel pump controller. Early cars those were mounted exposed and were subject to water/corrosion - where is yours mounted? (they may have solved that by 2009)

 

he had his tool plugged in while this happen...fuel pressure dropped drastically. we replaced pump...my car is has a fuel pump module under back seat. we replaced it with a used one...same deal...no im not sure what duty cycle is...this is a real nightmare...car runs like new until it starts to stumble...

 

Duty cycle is the roughly the percentage of time the fuel pump runs. That's controlled by the PEM with input from the fuel pressure sensor. For instance when the fuel pressure drops drastically, if the duty cycle goes higher than normal something could be preventing the fuel pump from pumping. What's in the bottom of the tank?

 

thanks so much for helping...we did not check the duty cycle...any idea what can cause the pressure to drop ? also the tank seems clean...

 

Pulling straws here -

"The process of the water and ethanol separating from the gasoline and sinking to the bottom is called “Phase Separation”. Phase Separation is a real problem because the water from the bottom of the tank is sucked up and sent to the engine it causes a lean condition"

Short of removing the pump and taking a sample from the bottom of the tank - put some dry gas (alcohol) in the tank to mix with the water (if there is some) and that mixture will combine with the gas and hopefully be eliminated from the system.

 

hello guys, just wanted to follow up with my xc90 issue....the issue was the fuel pump. the after market fuel pump that was installed did not work correctly...after installing a volvo pump, the car runs like it should , i'm very happy

 

What's that old saying, reliable, cheap or something - pick two?

 

Sounds painful😳😳