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Thread: DIY - Injector Replacement / Upgrade

  1. #1
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    DIY - Injector Replacement / Upgrade

    Today I was snowed in from doing any work, so I tackled those injectors.

    Wasnt really all that bad, just tedious, slow and dirty.


    I've suspected since I got the car that the injectors might be not so good and could use replacing. So I first thought about putting late 80's Mustang injectors in.. I have a set.. but they didnt look so good and needed a good cleaning.
    But then I ran across a set of '99 328i/M3 injectors and figured I'd give them a go instead.. they are very clean and alot newer.



    And before I ventured out in the snowstorm to get camera batteries.. I managed to take it down completely to injectors removed before I started taking pictures.

    So I removed the AFM/air box and put it aside.. then came the snorkel and ICV.
    Vac hose taken off the snorkel and put snorkel aside by front drivers headlight.. ICV set aside for a good cleaning.
    Lower ICV hose was disconnected from ICV, but left in place where it runs under the intake.
    Little hose from snorkel to valve cover was disconnected from both valve cover and snorkel, but left the little vac hose in place and set the two together on top of the valve cover for the time being...


    I unbolted the two diagonal brackets at front and rear of intake.. the rear bracket had two, almost identical plugs in it. I used a paint pen to mark which was the top set and which was the bottom set.. I foreseen confusion later on since they were so similar and almost identical in length.
    Removed brackets and set aside.. careful not to lose the little washers with the bolts and nuts.

    Then I started unplugging the connectors at the front.. blue,brown,grey and two small white ones.. no confusion as to what goes where here.. so no need to mark the connectors.

    I think I might have gone ahead and unbolted the Fuel Pressure Regulator, removed the little vac hose, popped the regulator out of the fuel rail and set it to the other side with the return fuel line still hooked on.
    The supply fuel hose at the rear was removed from the rail and set over by the master cyl. for the brakes.
    The cold start valve fuel hose clamp was also loosened.... we'll get back to this PITA in a bit.. for now it has the clamp off, but it wouldnt come off for me yet...

    So now I'm down to mainly just injectors and fuel rail to get out.. but the wiring harness didnt want to move out of the way.. so I had to dig around it to continue.. and I had to unbolt the throttle body and move it up outta the way to give room to move the fuel rail up.. dont drop those washers from behind the TB nuts!
    Careful with the little vac hose at the bottom of the TB.. I disconnected the little vac hose from the plastic bobber looking thing(check valve).. kept the 1" vac hose on the throttle body and left the check valve in the longer vac hose that runs to the front of the engine alongside the vac hose that was on the snorkel.

    Now, after looking around for a tool like a dental pick, I managed to pry the little clips back for the injector connectors.. all but that #6 connector I could get to OK.
    These injectors were in TIGHT. I was using a med. sized prybar to try and wedge them out..
    I finally just slowly unclipped all the injectors from the fuel rail (DONT DROP THOSE CLIPS!!!!). Again, using the pry bar and a shoprag to protect the intake metal from getting scratched.. I applied pressure up like a lever to get the fuel rail off the top of the injectors.. it finally pops off the injectors and gas pours out the rail all over the place.


    Back to that little fuel hose going to the cold start valve... it was the last part to pop off the rail.. it was in TIGHT.. I even buggered up the top edge of that hose trying to pry it off.. but it was reusable for now.

    Pic of me squatted over in my engine bay, with one foot on the strut tower and the other.. I forget.. NOT INCLUDED!
    All I know is I just about straddled the engine.. I may as well had one foot on each strut tower to get a good enough grip and leverage to get the fuel rail free from that stubborn hose!!


    So now, I can finally get to that wiring connector on injector #6 at the back.. no problem now that the rail is off of it and outta the way.

    And of course, now I can pop out the old injectors.. they all come out and then I pull the fuel rail out.


    What I found inside was so horrifying, that I had to stop and go take a break.. jk.. I took a break and went to fetch some new camera batteries..



    Below are pics before I continued..
    Attached Images Attached Images

  2. #2
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    The injectors were horrifyingly disgusting!!

    pics speak for themselves.. and the seats they go into on the intake.. were just as nasty!
    Attached Images Attached Images

  3. #3
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    I slowly cleaned out the seats for the injectors.

    Using qtips, an old toothbrush, degreaser and brake cleaner... I went at it.


    Trying not to use too much cleaning agent.. I soaked the carbon/filth and started with the tooth brush and finished with the qTips.

    The toothbrush is the purple plastic thing in one of the pics..

    below are pics of cleaned up seats and casualties in qtips

    third pic down shows my nice mushroomed cold start valve hose
    Attached Images Attached Images

  4. #4
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    Now's a REALLY good time to replace those 268K mile rubber vac hoses.. heck, I wouldnt even call them rubber anymore... they are so OLD they no longer have any elasticity to them.. they just stretch and stay stretched..

    So I got me about 10ft of small vac hose at NAPA and replaced them one by one.


    Here's my old set:
    Attached Images Attached Images

  5. #5
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    So.. having that all out of the way, I cleaned up my ICV.

    It was all carboned/gunked up and hopefully soaking it in brake cleaner and WD40 helped it free it up and work better.

    no pics taken..

    On to the injectors!


    Robbed all the '98 M3 injectors off the other fuel rail.

    I managed to make some quick connectors to hook 12V up to each one and gave them a quick shot of brake cleaner followed by a blast of air.
    Make note of which side is + on the injector!

    I used a battery charger for 12v power.. the moment you power an injector, you hear it CLICK.. then you can get solvent and air to flow thru it.
    Careful not to create any sparks while messing with the solvent!!!!
    Attached Images Attached Images
    Last edited by Seeker; 07-29-2010 at 07:33 PM.

  6. #6
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    So having them all cleaned up, I decided on replacing the O Rings for another time.. right now I'm not even sure if these M3 injectors are even gonna be compatible with my engine!

    So I went with what they came with.. had to replace one pintle cap (the yellow one) and an O ring w/spacer. Wiped some motor oil on the O rings and put them all in.

    Basically reversed everthing I did when going in.. I put the injectors in first, then got the fuel rail back on, rail clips, injector wiring connectors and so on until it was all back together.
    Attached Images Attached Images

  7. #7
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    By now you are probably wondering..









    Did it run?













    .........





    Well.. actually it does! Runs fine.

    It still has a slight rough idle though!

    But it idles much better I think, and seems smoother and sharper throttle response.


    I didnt get a chance to drive it though.. we just got hit by snow and it was really late evening by the time I had it running.. so I just snorkeled the exhaust under my garage door so I could stay warm and not CO myself to death while I let it warm up and run a while in my garage.

    I'll report back to this thread after I get a chance to drive it on the road.


    Pics below of exhaust snorkel and my recent garage favorite.. the Rubbermaid Janitor Cart!!
    Attached Images Attached Images
    Last edited by Seeker; 01-30-2008 at 04:24 AM.

  8. #8
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    UPDATE-


    I forgot to report back!


    These injectors appear to be working fantastic!


    I found out later that my O2 sensor was disconnected. So I replaced the original one with a new one while messing with it. I found out that a 1986 Ford E-150 4.9L engine used the same exact sensor($30 vs. $120 for one with BMW connector!).. just had to resplice the BMW connector from the old one onto the new O2 sensor.
    Put the new one in, hooked it up and the difference in idle was like night and day. No more rich mixture.


    But anyway.. the old girl lights up like a rocket now when the pedal is stomped. It's an auto and it immediatly kicksdown and lights up. The performance is top notch.. even for having 280K miles on it. In fact it will suprise me just how quick it can be on the highway and a 30mph stomp will break the rear tires loose and start a fishtail
    Good thing it has LSD!

  9. #9
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    That's a great write-up! And the pics really bring it home.

    I replaced all of my injectors with new units ('82 uses a different style than the 635 motors). I found that all of my connectors were brittle. Every one of then disintegrated upon removal so I spliced in new ones.

    Not a tough job but well worth it. A little more effort such as yours can save someone a ton of money by not having to buy new or rebuilt injectors.

    Good job!

  10. #10
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    I would pay you to do this for me, but if you're anywhere where you're getting snowed in, I think I'm out of luck down here in Texas haha

  11. #11
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    Quote Originally Posted by Substream View Post
    I would pay you to do this for me, but if you're anywhere where you're getting snowed in, I think I'm out of luck down here in Texas haha

    For an e24 you have or your e36?


    E36 injectors came out easy smeasy for me compared to the old crusty 6ser.


    You can do it. Popping the rail w/injectors on a e36 is like a ten minute job. Then it's the tediosness of undoing those clips.

  12. #12
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    do you have a video of your car running with the injector(s), and WOT. My problem is that on my m30 engine cylinder 5 is misfiring because of a bad injector, so im weighing in on putting upgraded injectors while im there. I go on a drive and it's boggin down within the range of 3k 4k rpms. I do know it's a fuel delivery problem. any performance, torque gains. drive ability and gas mileage? And last but not least does it burn rich.

  13. #13
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    With a higher flow injector set you may need to upgrade the fuel delivery system (pumps, pressure regulator, etc). If you do upgrade them I would stay with the more common 19lb mustang injectors unless youre making big power. In that situation I would assume the stock fuel pumps can handle it.

  14. #14
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    i might have to do that, my o2 sensor that regulate the gas mixture i cant find it, i don't know where to trace it, i think it got burned off from the exhaust heat. does run up over the bell housing? Yeah i have an old fuel pump on there. i've been having fuel delivery problems even with the old injectors. These work fantastic. the ecu is probably just dumping fuel in there and then it cuts out. This car leaves me with mysteries sometimes

    - - - Updated - - -

    im looking to sell it btw. It's a 1983 Euro Spec 635csi Cherry Red interior. The interior is in okay condition; needs some TLC. Odometer and OBC is written in German and the exterior needs body work. Original Engine only has 49k miles. I just don't have enough time ( This car is now considered a vintage classic according to legislature 25 Years over which makes it a classic car).
    Last edited by Im635csi; 10-26-2013 at 05:18 PM.

  15. #15
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    This is an old thread but does anyone have the photos used in the write up? I need to R/R the injectors on my 1985 635CSi and while the write up itself is great, the photos would certainly help!

  16. #16
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    Quote Originally Posted by Piperbill View Post
    This is an old thread but does anyone have the photos used in the write up? I need to R/R the injectors on my 1985 635CSi and while the write up itself is great, the photos would certainly help!
    I see the pix - if you're using an app or a phone, try a PC-based browser.

  17. #17
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    Quote Originally Posted by e24mpwr View Post
    I see the pix - if you're using an app or a phone, try a PC-based browser.
    Thanks! That was the problem. Driving me crazy until now!

    Cheers,
    Bill
    1999 Z3 2.8 Coupe - Boston Green
    1998 Z3 1.9 Roadster - Boston Green
    1985 635CSi - Arctic Blue
    2006 325i - Burgundy

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