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View Full Version : Poor mans fuel injector rebuild DIY


Bullet Ride
11-21-2009, 12:33 PM
I say poor mans because the legitimate way to rebuild injectors is to take them to a shop that specializes in injector rebuilding (i.e ultrasonic cleaning, rebuild, and flow matched). That would typically run you about $20-$30 per injector

Here's what I did (In total cost me ~$40)

Tools needed:

- brake cleaner
- clean rags, old tooth brush
- o-ring removal tools (really small flat screw driver will work if you don't have an o-ring tool)
- flat screw driver
- properly sized wood screw
- bench vise
- hammer
- heat gun or blow dryer

Parts needed:

- set of injectors
- injector rebuild kit (I bought mine from http://stores.ebay.com/Mr-Injector for $35 US shipped to my door)

The process:

This is something I should have done before I did any of this work, but I forgot. Check the impedance of all the injectors using a digital multimeter (analogue multimeter is not accurate enough). You can find the impedance values for most injectors here http://www.witchhunter.com/injectordata1.php4 or here http://users.erols.com/srweiss/tableifc.htm. If the impedance is way off what it should be the injector is probably going south so don't bother rebuilding it http://www.witchhunter.com/injectorimpedance1.php4.

These injectors are supposed to be 14.2 ohm so they are within range (make sure the contacts are clean because these readings are very sensitive)

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01298.jpg



Most of the stuff you need in one picture (p.s. I'm not French)

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01271.jpg

The candidates:

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01273.jpg

you can see there is an upper o-ring, a lower o-ring and a retaining cap for the lower o-ring

The rebuild kit, new o-rings, filters, and retaining caps

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01274.jpg

Now use the flat screw driver to pop off the retaining caps and the lower o-ring will simply roll off. Be careful around the pintle area because any dings or scratches can seriously affect the spray characteristics of the injector.

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01276.jpg

Now use the o-ring tool to remover the upper o-ring. Be careful not to damage the lip that holds it in place (the brown ring in the picture below).

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01277.jpg

Now to remove the filters put the wood screw in the bench vise. Make sure that the wood screw that you use can thread in nice and snug. In the picture above you can see the filter and the 3 black ribs on the inside, this is what the wood screw will be grabbing on

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01278.jpg

Thread the screw into the filter so you have a few threads grabbing the filter.

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01280.jpg

It takes a bit of force to get the filter out so get a full hand grab on the injector wiggle slightly and pull upwards

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01281.jpg

Close up of filter

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01282.jpg

Bullet Ride
11-21-2009, 12:34 PM
New clean filter vs old dirty filter

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01286.jpg

Repeat for the rest of injectors.

Now take your injectors out to the garage or outside and hit them with some bake cleaner to get the grease and crud off of them. Use an old toothbrush and come clean rags to help agitate and wipe off the crud. I sprayed brake cleaner into the injector and then used compressed air to blow it out. Make sure to focus on where the o-rings sit those are the most important areas to clean

Once you've decided the injectors are clean enough for your liking take care to make sure you don't get any sort of debris inside of them because this debris will be stuck inside the injector once you put a new filter in... sort of defeating the purpose of rebuilding them.

Roll on the new o-rings

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01293.jpg

To insert the new filter get a full hand grab on the injector and drop the new filter in

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01291.jpg

Now grab the hammer and tap the filter in until it's flush with the top. You'll know it's flush when the sound of the tapping from the hammer changes to a more metallic sound because you're tapping the steel at the top of the injector rather than the brass on the filter.

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01292.jpg

Now use a blow dryer or heat gun to heat up the retaining caps one at a time as you use them (they can crack of you don't heat them up first). I used a blow dryer, I put the cap on a screw driver so it wouldn't blow away, and hit it for 30 seconds. Then put the cap on a flat surface and press the injector onto the cap

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01294.jpg

Repeat for all injectors and you're done!

http://i575.photobucket.com/albums/ss191/StevoM5/injector%20rebuild/DSC01295.jpg

Hope you guys found this useful!

Bliss
11-21-2009, 05:15 PM
Great job! Props for tackling the rebuild yourself. The satisfaction alone of being able to do an injector rebuild is priceless...so not exactly a "poor mans" project.*th-up*

Did you test them out yet?

tg07lq
11-21-2009, 06:56 PM
im interested in tackling this. time it took and difficulty?

Bullet Ride
11-21-2009, 07:56 PM
Great job! Props for tackling the rebuild yourself. The satisfaction alone of being able to do an injector rebuild is priceless...so not exactly a "poor mans" project.*th-up*

Did you test them out yet?

Haha thanks *wave*.

Not yet, I'm planning on installing them along with an M30 AFM and wideband o2 (and eventually a MarkD chip). I have the AFM, the wideband is on route, I just need to fab a bracket to hold it in place and get a cone filter. Next weekend they will go in most likely. Can't wait to hear an unsilenced intake and feel some hp gains *rockout*


im interested in tackling this. time it took and difficulty?

It's pretty easy. On a scale of 1-10 where 1 is doing an oil change and 10 is doing and engine swap I'd say it's a 2, maybe 3 max. The hardest part is finding the right wood screw for taking the filters out lol. It took me about an hour to do. the bulk of the time being cleaning the injectors.

tg07lq
11-21-2009, 08:03 PM
hmm in that case maybe ill have you mail me the wood screw hahaha.

Bullet Ride
11-21-2009, 08:24 PM
hmm in that case maybe ill have you mail me the wood screw hahaha.

I think it's a 7 gauge wood screw

ScotcH
11-22-2009, 03:39 PM
Excellent DIY ... the way they should be posted! Nice work and thanks for taking the time!

Bullet Ride
11-22-2009, 09:00 PM
Excellent DIY ... the way they should be posted! Nice work and thanks for taking the time!

Thanks *th-up*

It's too bad I had to post it under the general discussion section because it didn't fall under one of the MaxTech sections.

Maybe there should be a "general engine tech" under the MaxTech section?

Ihavenocar
11-22-2009, 09:50 PM
did you feel a difference after ?

Bullet Ride
11-22-2009, 09:59 PM
did you feel a difference after ?

as said earlier, I haven't installed them yet. They are #19 injectors and I plan to install them with a larger AFM. So I better feel a difference or I'll be pissed lol.

Steve30
11-22-2009, 10:27 PM
is there a rebuild kit for e36 m3 injectors? while doing my manifold swap one of the injector tips (plastic tips) broke. i know people run it with broken tips but i'd like to have them rebuilt.

http://www.pelicanparts.com/BMW/techarticles/E36-Injector-Replacement/pic3.jpg

Bullet Ride
11-22-2009, 10:38 PM
is there a rebuild kit for e36 m3 injectors? while doing my manifold swap one of the injector tips (plastic tips) broke. i know people run it with broken tips but i'd like to have them rebuilt.

http://www.pelicanparts.com/BMW/techarticles/E36-Injector-Replacement/pic3.jpg

Probably. Contact this guy and ask him if he sells a rebuild kit for your injectors bjcda2000@yahoo.com his name is Bill Johnson.

ScotcH
11-22-2009, 10:45 PM
They're just Bosch injectors ... I'm sure there is a kit. Like 75% of cars use these!