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I've been experiencing rough idling on my 2003 Mitsubishi Galant for the last year or so. It has 182,000 miles on it. About every 6 months now I use seafoam cleaner in the tank and that clears it up temporarily, but then it comes back.

I heard using a pressurized cleaner in a can attached to the fuel rail does a better job, but I'm not sure how to get the hose. I can buy the Pro Cleen can from O'Reillys.

Has anyone tried this? Buying a professional kit is anywhere from $170 USD to over $1000 USD depending on the equipment. It's $100 to $150 USD to have someone do it, but I'd like to do it myself if it's effective.

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Ultrasonic cleaners can be had from $30 upwards, depending on size and features. Some of these are marketed as jewellery cleaning boxes, but will work perfectly for your purposes. As a bonus, your significant other can also use them. – mindcorrosive Dec 10 '12 at 12:57
up vote 1 down vote accepted

Are you sure the rough idling is due to clogged injectors? If so, you might want to consider sending the injectors off to be ultrasonically cleaned. If you really want to do it yourself, get a rebuild kit (new filters / o-rings) and soak them in solvent. You can even rig up a wire harness to cycle them while feeding them solvent. Details here.

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I'm assuming it's the injectors as putting cleaner in the tank gives a temporary solution. Spark plugs, maf, and air filters are well maintained. – James Drinkard Dec 4 '12 at 4:29
So running off a can isn't an option? I had seen some videos on you-tube and they said it works better than adding cleaner to your tank. – James Drinkard Dec 4 '12 at 21:00
Plugging a can of something into the fuel rail might be better than dumping injector cleaner into the fuel tank, but it's not going to change the screens on the injectors. Pulling the injectors should also allow concentrations of solvent that you would never want going into your engine. You'll have to do the math on cost/labor and decide what's best for you. Given the costs you cited for the fuel rail kit, I'd think that could be comparable to sending your injectors off to be cleaned. This is all just my opinion, anyway. – Mark Johnson Dec 4 '12 at 22:49
Have you checked the idle air control valve? Maybe checked your coil pack? EGR Valve? I wonder if the engine just happens to idle better on a seafoam/gas mix regardless of the injectors. Or does the benefit last for a tank or two? – Mark Johnson Dec 4 '12 at 23:00

Actually, I've found that a can/bottle of fuel system cleaner, like say from STP or BG, works great with one caveat - it says to add to one full tank of gas. Add it to a nearly empty tank so that you can drive at least 30 miles or so, and run it as close to empty as possible before adding gas again. The extra bit of concentration makes a big difference, just don't do it very often.

Pressurized treatments, especially when powered by an air hose, can be damaging to a fuel system on a car with a return line to the Tank. I've seen fuel pumps destroyed and gas tanks inflated to the point of rubbing an axle

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I added two cans of cleaner when I had about a 1/4 tank of gas. That is what cleaned it out well the last time. – James Drinkard Dec 4 '12 at 4:05
I'm talking way low though... Like gas light just came on low – Drake Clarris Dec 4 '12 at 19:07

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