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Pete
Pete, Technician
Category: Car
Satisfied Customers: 25801
Experience:  17 years automotive training and experience.
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Volvo: I have a 1999 Volvo Cross Country Wagon V70XC AWD 2.43.

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I have a 1999 Volvo Cross Country Wagon V70XC AWD 2.43. The car was running terrible. I replaced the mass air flow sensor, 4 NGK spark plugs, cleared the codes and the car performed better. I checked the intake & all vacuum lines with Carb & Choke cleaner and found no external vacuum leaks. After the car comes to operating temperature, the idle goes up and down from 800 RPM to about 1600 RPM and continues until you drop in gear. Since we can't find external vacuum leaks what could cause this? The codes P0101, P0722 & P1633 came back after driving 60 miles.
My name is XXXXX XXXXX I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would ask to see if you still need help with this.

P0101 will set for a mass air flow sensor fault,excess air entering the engine that is unmetered by the mass air flow sensor possibly or it may even be an electrical issue with wiring to the mass air flow sensor.One common issue can sometimes be carbon build up in the throttle body itself.I would check and see if this is the case here and if it is then it needs cleaned to see if it corrects this fault.The other two codes are set for a transmission speed sensor fault,this can be caused by a defective transmission speed sensor itself,wiring issue to the transmission or sensor,internal electrical fault in the transmission control module.In some cases this can end up being a faulty speed sensor causing this issue on this vehicle.

All of these need checked into to see if the fault is located,this may require some testing as well using some diagnostic equipment for the speed sensor issue.

I hope this has helped in some way here.If you need anything else don't hesitate to ask thats what I am here for.

Thanks Pete
Pete and 2 other Car Specialists are ready to help you
Customer: replied 3 years ago.

How do I clean the throttle body and where is the speed sensor located?

On most throttle bodies you can remove the air inlet tubing coming from the air filter box connected at the throttle body and take a shop rag with some brake or carb cleaner on it and wipe out the throttle body bore and open the throttle body plate to wipe out the plate itself.If there is allot of carbon then it may take more then one rag to do this.

Unfortunately my info isn't showing the exact location of this speed sensor,usually they are mounted externally on the transmission but in some cases it can be an internal part inside of the transmission as well.Since my info does not show the location you can try and contact a shop or dealer and they may be able to tell you the exact location of it.

I hope this has helped in some way here.If you need anything else don't hesitate to ask thats what I am here for.

Thanks Pete
Pete and 2 other Car Specialists are ready to help you
Hi,

I am following up with you to see if you still needed help with your question you had asked.If my help didn't satisfy your question please let me know so we can continue.

Thanks Pete