Had 2 mechanics say the injectors in my 97 Prix (3.1) can be cleaned using 'acetone'; one mechanic says they can't be cleaned they have to be replaced. Does the acetone create any other problems? If they can be cleaned how do you clean them besides the STP Fuel Clean System or similar? Thanks - Dave

There is a treatment/service sold at AutoZone and Pepboys where you can clean the whole intake system with pressurised solvents that takes out more than 45% of the gum and residue. But if you really want to get the best out of your injectors replace them. The problem here is that with the time the magnets that compose the valves at the injectors get deteriorated and with time they do not close all the way or do not open all the way plus the gum deposits they develop. If your car has more than 100k miles take the time to make the money to replace the injectors if not then try the treatment offered at Pepboys or Autozone. To tell you the truth the treatment is almost as expensive as replacing the suckers

Thanks for the info. kilroypr. My car doesn't have 100k. It's got about 75-80K. Never had a problem before. But had to replace the Intake Gaskets and I'm thinking that that's when the problem started. Maybe I should replace the Injectors. They're pricey.. 'bout $115 a piece. I need 2. If the car shakes at Idle, do you think that might fix it?

Well depends, if the injecetors stick open the car will drawn on gas and will hesitate or stall. If they Stick close then hesitation would arise. If the engine shakes could be a dirty fuel filter, dirty air filter or gum on the intake system. So you should have your car checked to see what the heck is. If you want to do it yourself as Ripn12s says start with the easiest first, clean the TB, replace fuel and air filter and then keep to more pricy stuff

I replaced my valley pan gasket myself. I tried not to get any carb cleaner on the business ends of the injectors while I was cleaning off the gasket, but couldn't help it; after a while crud had run all over them. So I just sprayed them off real well and hoped it didn't screw them up (I didn't touch them with any tools). When I got it back together I was surprised at extra pickup the car had. I really think it cleaning the outside of the injectors helped. I have to admit the carb cleaner did sit in little puddles while the manifold sat upside down on the towel, that may have allowed some to seep in and break up the carbon.

GM recomends cleaning the injectors first and if it doesn't fix them to replace them. Most injector cleaners on the market are snake oil treatments which do not do anything. You need a treatment with TEC in it to clean the injectors.

Some of the chemicals sold are harmful to the injectors and eat the coating on the fine wires inside the injectors.

Following flatratter line, then the only safe way to get a neat injector cleaning would be at a certified GM dealer that has the solvents with TEC. If not then replace them. Anyway I would go replacing them, most of the time you try the cleaning and sooner than later you have to replace them anyway. I have seen instances where the injectors have been cleaned and the cleaning just last few weeks and then some of the injectors start failing not opening or closing properly. SO you would have to invest 2 times. On the cleaning and then on the injectors themselves.

Why do modern injectors fail; or what is the common failure? Total loss of movement (opening and closing), dripping when closed, poor pattern, delayed/poor reaction caused by electical fatigue. It seems to me that carbon build up on the needle would cause the "tiny solenoid" to work harder and eventually fail. If my theory holds, there's a point where the ECM just wouldn't be able to supply enough current to move the weakened injector. At that point the injector would cease to operate correctly. I remember testing CIS injectors on a little test jig we had in the shop years ago. If they didn't pass the patern test. or they dripped when pressure was removed they were failed; and then they were replaced for $20.00.

What I have seen so far is dripping when closed. Or not oppening or closing after all.

Thanks, everyone! All this info is very helpful and I'll use it to get the problem fixed.