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Mysterious Transmission Issue

About a year ago, my Volvo XC70 started hesitating as it increased speed from 0 to about 30mph. After the hesitation it jerked forward. This problem is worse if the gas tank is full. I took the car to a highly recommended transmission garage and they said it wasn’t the transmission but the throttle pro-actor and I would have to go to a dealer for that because Volvo has proprietary rights on the computer in the car. I took it do the dealer, paid $1,200, and the problem persists. My regular mechanic is doing some research about the problem but I would like to know if this sounds like a complete transmission overhaul or if only part of the transmission or a connection needs replacing. I would like to be prepared before I go to the mechanic.

From your description, it is difficult to figure out exactly what your car is doing, but it sounds to me as if the problem is an engine-related driveability problem, rather than a transmission problem. Certainly the level of gas in your tank has no relationship to the transmission, and apparently the trans shop agreed that the transmission was not at fault. So–why you seem to think that this issue is transmission-related is something that I don’t quite understand.

You did not tell us the model year or the odometer mileage of this mystery Volvo, nor did you tell us anything about its maintenance history. However, since you paid the dealership for those expensive repairs, it does appear that the car is at least old enough to have run through its warranty. That means the car is also old enough to need certain maintenance procedures, but we don’t know if they have been performed.

In the absence of all the above information, my best advice is to take the car to an independent foreign car specialist (not that Volvo stealership), and have all of its maintenance brought up to date, focusing especially on items such as spark plugs, all filters, and–possibly–cleaning the Mass Airflow Sensor (MAF).

A check of the Evaporative Emissions System (which IS related to the level in the gas tank!) is also a good idea. Even if proper maintenance, cleaning, and checking the evap system does not improve the situation, at least it will then be easier for a qualified mechanic to diagnose the actual problem.

Since your current mechanic appears to have no clue, I suggest that you seek a new mechanic, preferably one who is used to working on Volvos–hence my suggestion to look for an indy foreign car specialist. The Yellow Pages should give you some leads, and then you can check the reputation of these possible mechanics via the “Mechanics Files” on this site. Near the top of the page, there is a link to the Mechanics Files.

You are focusing on the transmission, why? A transmission shop says the issue isn’t the transmission. A full tank of gas making a difference is another reason to not blame the transmission.

The Volvo dealer did not identify and fix the problem. What did they do for $1,200? What is the model year of the XC70? What motor, 5 cylinder turbo? The problem could be in the fuel system, which is very complicated on the XC70’s. The '98 to 2002 models have 2 fuel pumps and lots of plumbing to move gas between 2 fuel tanks. Fuel pump(s) and filters could be a problem. Also the 5 cylinder motor requires a complete tune up every 30K miles, plugs, wires, and distributor cap.

I owned 2 of these beasts, a '98 and '00, and both were so expensive to maintain and repair that I sold them just to get my budget back under control. By far the most expensive cars I’ve ever owned. If your XC70 is 5 years old or more and off warranty my advice is to sell it, or budget about $4,000 a year for repairs.

Thank you for your comments! My car is 10 years old and it just reached 110,000 miles. It has surpassed its warranty but I haven’t had any major problems in the three years I have owned it. I’ve replaced the tires, front brake pads, rear sway bar links and some lights. My mechanic specializes in Mercedes but I have been investigating Volvo specialists. This has all been so helpful!

Sorry, Uncle Turbo, I did not answer your question. The Volvo dealer replaced the throotle proactor, a device that links the transmission to the computer in the car. I had to go to the dealer, something I would never do, to get this fixed because Volvo has proprietary rights on the computer in the car.