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Bruce Allert's Avatar
 
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Injectors-To clean or not to clean

I need to change injectors and have some from a motor that ran good before it was taken out of the car. The motor has sat in the garage for 2 years with the injectors in. Do I need to clean them? If so, how do I go about it? I've scanned various past posts on this BBS but have found none that actually spell out how to clean them. I've looked at Brads site and Kjell Nelin's post on injection also.
Any help is greatly appreciated.....
bruce
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Old 10-04-2002, 10:56 PM
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Injectors that have been setting that long can be gummed up or plugged open or shut. As you are aware, gas turns to lacquer after a period of time.

I had one that was stuck open. When you see raw gas dripping from your exhaust system, it's nervous time (can you say FIRE?).

There is a fine screen filter in the injector intake that can plug up.

Find a local injector rebuilder and have them clean yours. They are put in an ultrasonic bath and then cleaning fluid is passed thru the injector under pressure. After the cleaning process they are tested for leakage, flow rate and spray pattern. Wholesale cleaning costs range from $25.00 to $35.00 per injector (I just had 8 done).

or

You can install them and see how they work.
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Old 10-05-2002, 06:36 AM
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injector cleaning

I have had experance with injectors that have sat unused for long periods of time in longterm storage vehicles that has generaly been , but not everytime , not good. The residue that fuel leaves when it dries out can affect an injector to the point where it it may no longer be servicable. As Ron (and he make some very valid points!) said one can try them and see how it goes, with clean fuel and and some qulaity injector cleaner in the tank. I think that Marvel Mystery Oil in small amounts is not a bad thing. A thourgh cleaning with an injector cleaning setup, meaning injectors installed on a running engine, where a quality concertrationed cleaner with out the vehicles fuel system in the loop, can have good results. This can give one the chance to see before and after preformance and tailpipe #s. Usualy some drive time after this is done is needed to see complete results. I have had a what seems like a 50/50 success rate of injectors being serviced and working correctly after the service, but it may be worth a try.
Old 10-05-2002, 08:39 AM
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Thumbs up

thanks guys, I will go with what both of you have said. I've changed these injectors so many times I think I can do it with eyes closed. Last timed injector change was 1 hour. I'd like to try them just for grins (like I try difficult shots whilst on the golf course!) and, if they work... good. If not, then I will take them out and look for an injector cleaning shop. The 2.0 injectors that are in my 1.7 are working good but there's this little nagging voice saying "What if the 1.7's work better?" I just gotta keep mess'n with this thing 'cause it's, well.... fun, right?
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Old 10-05-2002, 09:48 AM
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I've recently had success in freeing up stuck injectors. An bath in an ultrasonic cleaner with an ammonia window cleaner worked for me. It took about 35 minutes for all four to eventually come around. The first one freed up after only 12 minutes.

I was checking them using a 9V battery. This will actuate them and make them click. That's how I was checking them periodically without installing them in a car.

Although I didn't have a pressurized fluid source for the 9V battery test, if you wipe the tip dry before you actuate it, the residual cleaning fluid in the injector will drip out when the voltage is applied (assuming it's freed up, of course). Once you get them flowing, then the flowing/pressurized fuel and injector cleaner in your car can take care of the rest. But you do have to establish some flow before the injector cleaner can flow through to do the in-car cleaning.

One caution I will add to this is to check the temperature of the cleaner periodically. Mine tends to heat the fluid inside. I don't whether that's because of the heat of the motor or from the 'friction' of the fluid under the ultrasonic motion. Either way, I pitched in an ice cube about every 15 minutes to keep it cool.

I was very excited that this worked. My car had been sitting idle for 20 years when I bought it and I couldn't get a drop of fuel out of the injectors. This wound up to be a cheap fix for me since I already had the cleaner.

Hope that is helpful!

--Case...
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Old 10-07-2002, 05:08 AM
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Thanks Case, I never thought to use a 9V. I was thinking about the process of getting a small pump to get some pressure behind a fuel & injector cleaning solution. My wife is in charge of a vet clinic where they have an ultrasonic cleaner but she said she didn't think my injectors should be going in there! I'll try your suggestion with the 9V and see how it goes.
thanks
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Old 10-07-2002, 07:02 AM
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As for opening the injectors with a battery, a 9V might work ok. Be aware, the issue here is what current you're passing through the injector.

You seem to have a D-Jet system, if so, the internal resistance of the injector is about 3 ohms. There is a 6 ohm (5 W rating) load resistor in the ECU that is in series with the injector. System voltage is about 13.5 V, which is dropped down to about 12.2 V through diode drops by the time it's applied to the injector. After the initial transient (due to the inductance of the injector coil) dies down, the current through the injector is about 12.2/9 = 1.35 A.

If you just apply 9V directly to the injector, the steady-state current is 9/3 = 3 A, or about 2.2 times the normal current load. Additionally, a 3 A load on a 9 V battery is probably far in excess of what it can supply, and that the actual applied voltage is considerably less (as would be the current). The battery will likely run down quickly.

From what I've heard (haven't tried it myself), the injector will open with fairly low voltage. High voltage is used in actual operation to open the injector more quickly for precise fuel metering. I've heard that one or two D cell batteries in series will open the injector, and will also keep the current low. You might want to give it a try.
Old 10-07-2002, 07:41 AM
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Buy her some flowers and tell her how 'clean' this whole process would be! Honestly, using the ammonia based cleaner as the media would probably not jeopardize anything in the office (damage equipment, contaminate test results, etc.). It's a better fluid than anything that's petroleum based, believe me..BTDT!

The first time I tried this I used fuel injector cleaner straight from the bottle as the media. "Fuel injector cleaner must be the best thing to clean fuel injectors with, right?" Wrong. Bad idea! At least in an ultrasonic machine, anyway. After about an hour, the stuff got hot and started giving off volatile vapors! There was literally a fog coming off the surface. I didn't realize how hot it was until I reached in to pull out the injectors! Youch! I'm probably lucky I didn't burn my house down!

The ammonia based system seemed to work better and is safer. I think it would be okay in the clinic. I'd offer to do it for you but you'll probably find a quicker method that's cheaper than shipping by the time I could get them back to you.

--Case...
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Old 10-07-2002, 07:56 AM
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I was thinking of getting a spare fuel pump and building a little bench top testing/cleaning station for injectors. Working out the power issues for running the pump and actuating the injector are the "big" problems. Now that I think about it I could use any cheap pump from any car as long as it supplies the 28 psi necessary to emulate normal operation. Anyone know of a particular pump that is cheap and would work?
Old 10-07-2002, 08:30 AM
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Brad, is there anything within the injector that could be ruined by using the battery scenario?
Also, I've been looking for an exploded or side view of an injector just to familiarize myself with the inner workings. Know what site might have it? I looked on your site and, if it was there, I missed it.
(Another also)... in your formula 12.2/9 = 1.35 A, what is the 9 representing?
bruce
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Old 10-07-2002, 10:14 AM
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Bruce--

Check this page out at www.howstuffworks.com .

--Case...
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Old 10-07-2002, 10:36 AM
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Quote:
Originally posted by Bruce Allert
... in your formula 12.2/9 = 1.35 A, what is the 9 representing?
bruce
3 ohms + 6 ohms.
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Old 10-07-2002, 10:39 AM
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I just cleaned injectors that were in a car that sat since '86. First I dripped in mineral spirits and let them sit a few days, but that evaporates quickly. Then I borrowed an adjustable power supply good for 2A. I set the voltage for 3V (per a tech article...forget source), connected about 1 ft of fuel line and filled it with mineral spirits, then connected about 20 lbs of compressed air. I zapped the injectors, which drew about 1A each, and emptied the fuel lines a few times. They seem to spray well and not leak. I'll check for leaks again when I get them connected to the rails and run the pump. I've heard you have to be careful when using a larger than specified voltage because you can damage them by running them continuously. Nornal operation is probably only a 25% duty cycle if that.
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Old 10-07-2002, 11:09 AM
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Hey! Thanks for all the info. I'll try putting all this to good use and post how it turns out. Now... if ya'll don't hear anything in awhile I got blown up
Case, that web site "How stuff works" is great! I can make my brain swell with that one
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Old 10-07-2002, 04:48 PM
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Quote:
Originally posted by Bruce Allert
Brad, is there anything within the injector that could be ruined by using the battery scenario?
Also, I've been looking for an exploded or side view of an injector just to familiarize myself with the inner workings. Know what site might have it? I looked on your site and, if it was there, I missed it.
(Another also)... in your formula 12.2/9 = 1.35 A, what is the 9 representing?
bruce
How's this (from my site):



The only thing inside the injector that's electrical is the solenoid coil. As long as the current passed is below the design limits, there should be no problem.

As someone else pointed out, the 9 is 9 ohms, the cummulative resistance of the load resistor and the internal coil resistance of the injector.
Old 10-07-2002, 09:19 PM
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Thanks mister "B". I saved the injector pic in my special 914 Tech notes folder. (never to be without... ever!)
bruce
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Old 10-07-2002, 09:30 PM
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