I found this on the Motorvac:
"Time for a Tune-up?
Time to Try MotorVac
Do the fuel injectors need tune-ups?
Until 1995 I always said no. Then A representative from Snap on Tools showed me a MotorVac Machine. We had a 1994 Ford Escort in the shop that had been to the dealer a number of times for the same problem. It had a miss at idle. We diagnosed it as a bad injector. The Snap on Tools representative asked us to try the MotorVac before replacing the injector. We did and when the job was done for a third of the original quoted price, and We acquired a happy new customer and a new Motorvac machine. They retail for around $5500 so you won't find it in most shops. I recommend cleaning them every 10,000 miles 0r 12 months. The price of a cleaning ranges from $80 to $150. I wouldn't have my shop without one.
This MotorVac machine cleans the air plenum, throttle body and plates, air bypass valve, injectors, carburators, intake valves, combustion chambers, oxygen sensor and catalytic converters...without having to remove any engine components. A CarbonClean system cleans the entire air intake, fuel system and exhaust system, fuel rail and the injector screens. It is the only fuel injector cleaner that does this. I call it "god 2" (with a lower g). It never fails to amaze me, and it comes with a "money back guarantee"!
I've compared it to other machines and injector cleaners and theirs don't come close. The additives that are sold to â??clean injectors by adding to the gasâ? only bring all the junk to the injectors. Leave the junk in your tank just clean the injectors.
The MCS245 is the first gasoline engine system of its kind to clean the entire fuel system. When used with the proprietary MotorVac CarbonClean Fuel System cleaning detergents, the MCS245 cleans the air plenum, throttle body and plates, air bypass valve, injectors, carburators, intake valves, combustion chambers, oxygen sensor and catalytic converters...without having to remove any engine components. A CarbonClean system cleans the entire air intake, fuel system and exhaust system.
A MotorVac CarbonClean service will help your engine function more efficiently by unclogging accumulated carbon deposits from fuel injectors and other engine components."
Taken from the 700-900 Faq on
www.brickboard.com (the Volvo equivalent to the CEG)
Problems With Valve and Injector Deposits. [Motor Magazine, Dec 2002] As a vehicle approaches higher mileage, you can generally expect intake valve deposits (IVDs) and injector deposits. Their onset can vary widely, depending on driving conditions. Engine operating temperature, intake manifold gas speed (rpm) and hot soak cycles are some of the critical operating parameters affecting these deposits. To lubricate an intake valve, tiny amounts of oil have to run down the valve stem. Over time, this oil is deposited and heated on the intake side of the valve, forming a carbon cone. This has multiple effects on the intake event. The carbon changes the aerodynamics of the intake event - causing higher gas speed and a change in the direction of intake and swirl - which affects the combustion process. The IVDs also act like a sponge, creating a delay in fuel control. This delay not only creates a temporary enleanment on acceleration but also causes a temporary enrichment on deceleration. When the throttle is closed, the intake manifold vacuum goes high, pulling the fuel out of the carbon sponge. This affects fuel control. When the engine is shut off, a small amount of liquid fuel is left on the tips of the injectors; this fuel evaporates and leaves behind solids that were originally dissolved in the fuel). Eventually, these deposits cause an injector to act like a squirt gun rather than an atomizer. Aggressive drivers and drivers with long highway drive cycles may not have deposit issues until very high mileages. Stop & go drivers, especially delivery drivers with many hot-soak cycles, are more likely to experience deposit problems sooner.
This explains the effects of carbon.
Injectors can be "bench" cleaned. There's a how-to that I found for Volvos that might work for the Contiques. However, I would do the Motorvac first. If there's a problem with still leaking injectors, I would bench clean them. This was fairly popular with the Volvos, but keep in mind that the 740/760 Volvos can be 20 years old with several hundred thousand miles on the cars.
Wow, I just realized that I'm getting long winded.
I hope that all of this helps.?
Eric...
Mystique 1998 V6 MTX Sold.
