I'm posting this seperately because it wasn't getting answered as "question #2" on another barely-related thread.

I bought an RX7 with ~105,000 miles on it. A forum member recommended getting the fuel injectors cleaned, since it probably hasn't been done before. So I called a mechanic. It's an $80 job, which is a package deal that includes cleaning/replacing associated parts/hoses. Given an average of ~17mpg, very clean emissions and otherwise smooth running RX7, is it necessary? Or should I dump some fuel injector cleaner in the tank (or do nothing) and forget about it?

 

Lucas Oil or redline fluid.

 

Lucas oil = snake oil
Redline = I don't know

As far as injector cleaning it sounds like your car is running fine. Cleaning them certainly wouldn't hurt, but don't take it to the mechanic and have it done. Remove the injectors yourself and send them to a local injection shop (Yellow Pages). They'll clean, balance and "rebuild" them (basically replace the rubbers) generally with a day's turnaround.

 

That sounds about the same as what this mechanic is going to do in about 2 hours. And since the car is my only mode of transportation, getting back from such a place would be a pain in the butt. I could read a school book for 2 hours. Am I wrong here? Is there something my mechanic won't do? Is such a place cheaper than $80?

Last owner says he probably didn't get the fuel injectors cleaned. He says he's not sure because he did so many things when he first got it. So I plan on getting them cleaned just in case.

 

You can certainly take the injectors out but if you want to avoid some labor and expense 3M makes an injector cleaner that is very potent. We use it at my shop for some fuel problems. All you have to do is disconnect your fuel in remove fuel pump relay and the car runs off the can. It got me 4 MPG on my 24000 mile hemi.

 

Most injection shops use an ultrasonic cleaning rig, and then a flow testing bench in order to check their work. I doubt your mechanic is so equipped unless injectors are a major part of his business.

 

I didn't think I had a fuel problem. I had a spare set of injectors I was going to sell, so I had them cleaned. Seller backed out, so I installed them for fun. I actually noticed a difference, smoother idle and delivery of power.

I had a local turbo and diesel shop do it. $18 each I think, got them back the same day I dropped them off.

 

Already called the shop and made an appointment. It's a rather small shop. Maybe I should call them and see if they use ultrasonics?

Unfortunately I can't go with out my injectors for a day. I'd have nothing to drive back from the shop with except my bicycle. $80 seems reasonable if it works. But if, let's say for example, they only use the 3M stuff, am I throwing my money away?

 

Most of the fuel injector cleaning solutions that work without pulling the injectors out, don't work that well. They'll help, but they're not as good as a proper reverse flow ultrasonic flush cleaning.

Will it help? Possibly. I wouldn't waste my money on it, though. For about the same (if not a bit less), you can ship your injectors out to be cleaned, blueprinted, and basically restored to original condition.

-=Russ=-

 

Here's my thought. 17 mpg is a little low. But there is a simpler approach, to start. Last winter I installed a new O2 sensor and new plugs. I gained 3 mpg with that one. Went from 16 to 19 mpg. The o2 sensor had not been changed in 120,000 miles. Then my car set over the summer while I drove my FD. First tank out this fall with my FC and I had about 15 mpg. The power seemed really low so I added one bottle of fuel injector cleaner and now I'm back at about 18 mpg. I'm also having far fewer problems with the automatic transmission hunting for the right gear. If those three items combined don't improve things, I'd go have the injectors cleaned by your local shop. Keep your expenses low until you've eliminated the cheap, easy fixes such as basic maintenance. Then go out and spend serious money if you haven't fixed it.

 

If the vehicle is running reasonably well, just use the over the counter FI cleaners. Stick with the better(more expensive) stuff like Amsoil/Redline/Regane/Techron....... IMO, this is more cost effective and just as good as any 'shop' cleaning.

The problem with "on vehicle" servicing is: which injectors or firing when??????

Unless you are having problems, its not worth the hassle removing, shipping, waiting, and then reinstalling the injectors from a injector cleaning shop. But, IMO, this type of service should be mandatory when rebuilding engines or recycling injectors.