Injector replacement without removing plenum

[symposer]

Hello all,

 

Here's a description of how I replaced number 2 injector using the dremel method, without removing the plenum. There's nothing new here and it's all been done before, but I thought it might be useful for somebody to see pictures of another example.

 

The screws holding the injectors are covered by the plenum, so normally you need to remove the plenum just to change one injector. The dremel method involves cutting away material from the plenum to allow access to the screws. After 16 years the pipes and wiring around the plenum on my zed are well and truly baked hard, so I didn't want to attempt to remove it.

 

Here are the most useful links I found on this topic:

http://www.twinturbo.net/net/viewmsg.aspx?forum=technical&msg_id=1014990

http://www.zcar.com/forums/read/3/1157376/1157376#msg-1157376

http://www.zcar.com/forums/read/3/1939562/1939704#msg-1939704

http://www.zcar.com/forums/read/3/1185546/1185574#msg-1185574

 

I would really recommend this process, especially for the easily accessible number 2 injector (front right, looking at the engine).

 

The symptom of my failed injector was a permanent misfire - rough idle, vibration, lack of power, audible misfire from one exhaust and 5 cylinder combustion noise (sounds like a Subaru).

 

By touching a screwdriver on the injector cap and listening at the handle I could hear all the injectors clicking away, except for number 2. When I measured the resistance across the pins on the injector it read open circuit, whereas the other injectors measured 10-15 ohms. So the injector had failed electrically - time for a new one.

 

I got a used TT injector for £41.75 all inclusive from Zedworld. Thanks, guys! Next stop was Maplin for a 9.6V "dremel" tool - on offer for £20:

 

 

I used the small sanding head which cut through the aluminium quite easily. It took about 20 minutes to do, taking it slowly:

 

 

Here's a closeup - it looks like a lot of material was removed, but it's the bare minimum to get access to the screw, and even then the screwdriver is at an angle:

 

 

I read about a lot of problems with the screws being difficult to turn, so I soaked the screwheads with WD40 a few times and I didn't try a normal screwdriver in case I damaged the heads. Instead I got an impact screwdriver for about £8 from Machine Mart. There wasn't enough space to use this directly, so I got a £6 set of screwdrivers from the same place with hex heads intended for impact use.

 

 

I used the dremel tool to narrow down the shaft of the screwdriver slightly to help with clearance, and used a half inch socket with the impact driver to drive the screwdriver. A couple of taps was enough to easily loosen both screws, with no damage at all to the heads. Half way there!

 

 

The next step was to remove the fuel pump fuse and crank the engine, to release pressure in the fuel rail.

 

 

Now came the tricky bit - removal of the old injector. Actually it was a lot easier than I thought it would be, using the same leverage method shown in one of the threads above. At first I used locking pliers to hold and twist the injector around, while spraying silicone spray into the gap. With it loosened I tried to pull it straight up, which broke off the plastic housing with the connector. This was the point of no return - with the plastic broken off, fuel started spraying out gently from the holes where the leads go into the injector body. At this point I realised it would probably be a good idea to have a wet towel handy in case of fire. After a few seconds the remaining fuel pressure was gone and no more fuel came out. Now I could use the grips directly on the metal injector body, and with some gentle upwards leverage using a screwdriver for support it popped right out.

 

 

Closeup of locking pliers pulling the injector straight up:

 

 

These were the pliers I used - £7 from Machine Mart. The old injector was pretty dirty:

 

 

Both sealing rings looked in good shape so I reused them. Here's the new injector with vaseline on the seals to help it go in:

 

 

To fit the new injector I dropped it into place, then tapped it gently in using a small length of wood with a hole drilled in the end to accommodate the pin on the end of the injector. Once in place it would twist quite easily with the lubricated seals.

 

Next it was a case of reinstalling the injector cap and screws - some people replace these with hex head bolts but I just reused the screws, since the heads were undamaged. There's not much clearance to get the screws in and it helps to put the screws into the cap before you fit the cap.

 

Finally I replaced the fuel pump fuse, switched on the ignition a few times to run the fuel pump and check for leaks, then started up. All working!

 

Overall the process went much more easily than I thought it would! I'm so happy to have the power and smoothness back! Good luck if you try it.

 

Tim

[TonyC]

Nice one Tim,seen it before but worth posting , was looking at me injector tops last week and was thinking of replacing them(was replacing my inj connectors at the time) i like the way you levered them out:)

 

Tony

[AndyP]

Yep, nice detail there. Unfortunately, when I had a problem it was with an injector that wasn't as accessible and so it was a plenum off jobbie.

[lcridford]

Thats a ood write up, nice one. I think it would be worth moving this in the FAQ's section for future reference?

[AC49er]

Good write up, its always nice to see someone take time to do these with good pics to help other people, thanks.

[FASTREDZ]

great write up there i have done injectors 5 & 6 using this method,

only thing i would add is to be very caerful about how deep you cut into the side of the plennum if you go through your screwed try it a bit at a time.

[TopLess]

Some little extras for anyone reading this, try to buy new petrol O rings from nissan, and oil based lubricant rots rubber.

[santa]

Some little extras for anyone reading this, try to buy new petrol O rings from nissan, and oil based lubricant rots rubber.

 

What lube would you suggest? I`m going to be replacing all mine shortly.

And don`t say k.y.:winkiss:

[TopLess]

I should imagine any silicon based lubricant would be preferable ;)

[santa]

cool, cheers!