BMW M5 Forum and M6 Forums banner

1 - 20 of 49 Posts

·
Registered
Joined
·
457 Posts
Discussion Starter #1 (Edited)
Hi Everyone - I've been hunting down various issues on my M5 to try and help the low RPM stumbling feeling + vibrations at 2.5k-3k RPM (UK motorway speed in 6th).

So far I've updated just about everything in the drive train inc the flywheel and clutch last week. Surprisingly I now have a super light clutch as the throw out bearing was very tired indeed and wearing the gearbox shaft cover tube away. The issue has not actually helped the vibration as the new dual mass flywheel is less 'loose' that the old one so i'm still hunting!

One of the areas I've been meaning to look at was getting my fuel injectors cleaned & refreshing the seals - I've known others who have said this has helped their cars, especially in the case of high mileage vehicles like my M5 which is almost at 130k miles. I've always used quality Shell V-Power fuel in the car since I've had it (18 months) however it has 10 previous owners who'd not necessarily been quite so fussy. Anyway to this aim I decided to remove the injectors and send them away for professional cleaning as I had a weeks holiday where the car could sit on the drive.

So - back to fuel injectors - I searched around the forum and found minimal content and no DIY which surprised me so I decided to share my learning's for the benefit of others who may wish to do the same. I've found so much of the content on here useful I wanted to try and fill a gap in the DIY section for others. I've included lots of pics and borrowed some others - these have been marked to show non-M5.

Searching the net I did find one item on another forum which was a useful reference:

https://www.bimmerfest.com/forums/showthread.php?t=571302

Doru on Bimmerfest has completed an injector removal and replacement on a 6 cyclinder petrol Beemer - though their's is not an M5 and the injectors are Siemens units - there are similarities between the models with the holding clips and the electrical connection clips. I've borrowed several of the pics (so they continue to work on this board) and linked above to their item which I found most useful as a reference + their pictures were way better than mine!

One item to note is their were various models of injectors used on the M5 - if you are looking on RealOEM then you ideally need to use the last 7 digits of your VIN to help it select only the relevant items. The early Siemens units used in some BMW's of this era have a known issue where they swell and leak internally over time - I'm not sure if these units are used on M5's but something to be aware of.

RealOEM fuel injector info can be found here - my car is a 2002 UK model and uses the Bosch injectors shown in the last picture.

RealOEM link: RealOEM.com Â* Diagram Selection


Remove fuel relay module and / or fuse / or Battery. Once this lot ius removed the fuel rails will be open so you do NOT want the fuel pump running at all. Remove air intakes, Plenum cover, Plenum itself. Remove cabin air intakes if you need the room. Once that lot is removed it should look something like this:



I removed the plenum to throttle body gaskets - it may be possible to remove the injectors without however it only takes a few minutes to do - undo the band straps under the gasket around each throttle body - there is just enough access. Carefully pull up evenly above each throttle body and the rubber gasket will slide up and off.





Once removed it'll expose each throttle body and give you more room to fight with the next bit. Wet patches on my clamps is just where I put some 3-in-1 on them to ease re-installation.



Now we need to release the electrical connections to the injectors. It seems others have said you simply need to pull firmly upwards along the rail and the connectors will un-clip. I found this not to be the case and would have broken something expensive if i'd tried even harder! I used the technique Doru used on Bimmerforums and partially un-hooked the connector springs - this allowed the connectors to then release and lift up an centimeter or 2. Note access to the rear connectors is much more difficult but doable - if the injector > fuel rail clips are in the way they can be rotated around if necessary. Eventually and after much muttering I managed to release the electrical connections - others have had trouble with breaking / bending the connector springs, I didn't though and they simply popped back into place afterwards. Should you break one completely it was suggested on another M5Board posting I read to use zip-ties to secure the electrical rail down to the injectors by tying around the fuel rail. It's all very solid so should work fine. Note the next 2 pics are NOT from an M5...





These pics are not the clearest but should give you an idea what to expect. I used an iphone only as oil, petrol and expensive DSLR's don't really mix in my book with one person doing the job.







Next step is to remove the injectors from the car - I found mine were pretty solid and again to avoid breaking anything I decided to remove the fuel rail from the injectors first, then remove each injector at a time from the inlet manifold. To do this you remove the 2x 10mm bolts holding the rail down, then lever out the injector securing clips like below (again pic is not M5 but clip is identical:



Be careful doing this - the clips have a habit of flying off - I lost two - glad I ordered 8x replacements - they were 40p IIRC so dirt cheap.

If you now pull upwards on the front most injector on the rail it should pop off. Expect some fuel to pour out so have a rag underneath to catch it. Work along the rail until they are all undone. 2 of my injectors came out of the inlet manifold instead of the rail. Either way they will all come off - any left in the inlet manifold can be removed by pulling them - I found it helped to twist them a little and wiggle them out.



Once all the injectors are removed the fuel rail can be lifted out of the way while you clean up the injector holes in the inlet manifold - don't strain the rubber connecting hose. The upper seals will most likely still be in the fuel rail and can be removed (hook them out) if you are replacing - mine looked in great shape.





One rail down - another to go. Once completed I had 8 removed injectors - they looked a little sorry for themselves externally however the 4x tiny holes inside the tips looked very clean. The oily gunge is I believe from the crankcase ventilation oil. The inlet manifold holes they were pulled from were also slightly oily and I cleaned these with throttle body cleaner and swabs.

Note the lower seals are very gunked up - these are air seals only and seem to attract the dirt - remember though these are from a 130k mile car and nothing in the service history says they've been touched before. I'm hoping a clean and refresh in this area may aid my search for smoother low revs running alongside the cleaned injectors in case any un-metered air is leaking by (minimal chance I know!).



Note the very end is clean - I assume this is because some petrol blows back and keeps it clean:



A word on the seals. I removed the lower seals as I wanted to clean them and possibly re-use if in good condition. Your now thinking what a tightwad, however read on - I initially thought 'replace the lot, they'll be cheap', then I looked up BMW's UK prices... madness is perhaps the best way to describe these seal costs. As of today (April 2014) Upper fuel rail seals for my car are just over £4 each (not too bad I suppose compared with usual M5 bits) and the lower ones are, wait for it, £12.20 each. For an o-ring! So over £130 for 16 seals... hmmm. Anyway I looked up and ordered a selection of viton seals near the size listed on RealOEM for the lower seals (9,3X2,62) - £0.24 each.





The seals I removed cleaned up well and appear in good condition - I may re-use, will compare with the online order of non-BMW seals when they arrive. As of now my injectors are about to wing their way off to a UK company to clean & test. They provide new upper seals, new filters and a report showing flow rate, resistance etc etc. Testing and shipping for all 8 is £107 which seems reasonable.

Re-installation is the reverse of removal to quote a well known car maintenance manual - I will be inserting the injectors into the fuel rail first then push them 4 at a time into the inlet manifold. Then resecure the electrical connectors with a small push down once aligned. Don't forget to bolt down each rail first. Once they are in (both rails!) it's very important to replace the fuel relay / fuse and prime the fuel pump a few times by turning key to position 2 - don't start the car yet. Now check for leaks around the fuel rail to injector seal area. If it's all good try starting the car - it'll probably run pretty rough as the air metering will be all over the place with no plenum and MAFs in place. Start the car and hunt for leaks between the rail and the injector. Be careful nothing gets in the throttle bodies or near them if revving the engine. I suggest run the engine briefly then switch off and again check for leaks.

I'll update this once I receive them back with my findings - even if it does not help my initial issue it's a worthy PM I think given the miles.

If anyone has any questions, comments or feedback please feel free to ask. First time doing a DIY type post so open to any comments.

Simon
 

·
Registered
Joined
·
2,271 Posts
Thank you for the detailed and pic-heavy write up, quality stuff.

Lots of pics and description helps enormously when you're tackling a job like this, and you've never actually seen the parts before.
 

·
Registered
Joined
·
457 Posts
Discussion Starter #3
Hi - thanks for that. I prefer a lot of pics - even if the words don't make sense at least the pics might! bit worried they were too big but they seem ok - not sure on any recommendations we have on this board for pic size, thumbnails etc. Seems less important now with even mobiles having good download rates.
 

·
Registered
Joined
·
2,271 Posts
I think most browsers resize to suit once the image is loaded, all good with me. And no-one uses dial-up any more, despite people still putting '56k warning' in thread titles.... ;)
 

·
Registered
Joined
·
72 Posts
Great DYI, I just did this not 2 weeks ago with my injectors. I sent them to Mepeh Bimmer out in California. He did a great job and it was crazy cheap to have the injectors cleaned. He told me to keep using the gas I was using since my injectors really didn't need cleaning. Though I may change my fuel filter again soon.

I did do one thing differently than you did as far as removing the electrical connections to injectors. The work area to unclip the connections from the injectors is insanely tight. I searched and searched this forum, watched youtube videos trying to find an easier way. Buried deep in one of the treads I was reading I found the answer. Use a long screw driver (sometimes I used 2) and put leverage close to where the electrical connection and the injector connect. Then use the leverage to pry up the electrical connector. The force you have to apply is quite a lot to get the connection to disconnect from the injector. I had 8 injectors out in the span of 20 mins. I probably could have done this faster but I was convinced with amount of force I was using I was going to break something.
 
  • Like
Reactions: curtissp321

·
Registered
Joined
·
814 Posts
Thanks for the write-up.

Just one comment, instead of starting the engine to test for leaks, it is much safer and easier to turn the key in the ignition switch to the ON position as this will turn the fuel pump on and pressurize the fuel lines. In case there is a dodgy seal or improperly seated injector, the resultant leak will be much easier to take care of, minus the risk of the spark plugs igniting the fuel.
 

·
Registered
Joined
·
457 Posts
Discussion Starter #7 (Edited)
Thanks for the write-up.

Just one comment, instead of starting the engine to test for leaks, it is much safer and easier to turn the key in the ignition switch to the ON position as this will turn the fuel pump on and pressurize the fuel lines. In case there is a dodgy seal or improperly seated injector, the resultant leak will be much easier to take care of, minus the risk of the spark plugs igniting the fuel.
hi - thanks. Funnily enough that's what i'm going to do on testing - just turn key to prime fuel pressure a few times... don't know why I didn't write that! Amazing the bits you skip out - documenting processes is a skill in itself i've found working with people who do it for a living. I've altered the text to add in this method.
 

·
Registered
Joined
·
457 Posts
Discussion Starter #8
Great DYI, I just did this not 2 weeks ago with my injectors. I sent them to Mepeh Bimmer out in California. He did a great job and it was crazy cheap to have the injectors cleaned. He told me to keep using the gas I was using since my injectors really didn't need cleaning. Though I may change my fuel filter again soon.

I did do one thing differently than you did as far as removing the electrical connections to injectors. The work area to unclip the connections from the injectors is insanely tight. I searched and searched this forum, watched youtube videos trying to find an easier way. Buried deep in one of the treads I was reading I found the answer. Use a long screw driver (sometimes I used 2) and put leverage close to where the electrical connection and the injector connect. Then use the leverage to pry up the electrical connector. The force you have to apply is quite a lot to get the connection to disconnect from the injector. I had 8 injectors out in the span of 20 mins. I probably could have done this faster but I was convinced with amount of force I was using I was going to break something.
That's a good idea - as you say the access is not good in there at all - especially the rearmost connectors. I wasn't comfortable prying on much in the area as it seemed flexible - will take a closer look when i'm putting them back in.
 

·
Registered
Joined
·
457 Posts
Discussion Starter #9
Great DYI, I just did this not 2 weeks ago with my injectors. I sent them to Mepeh Bimmer out in California. He did a great job and it was crazy cheap to have the injectors cleaned. He told me to keep using the gas I was using since my injectors really didn't need cleaning. Though I may change my fuel filter again soon.

I did do one thing differently than you did as far as removing the electrical connections to injectors. The work area to unclip the connections from the injectors is insanely tight. I searched and searched this forum, watched youtube videos trying to find an easier way. Buried deep in one of the treads I was reading I found the answer. Use a long screw driver (sometimes I used 2) and put leverage close to where the electrical connection and the injector connect. Then use the leverage to pry up the electrical connector. The force you have to apply is quite a lot to get the connection to disconnect from the injector. I had 8 injectors out in the span of 20 mins. I probably could have done this faster but I was convinced with amount of force I was using I was going to break something.
Hi - did you pull injectors for cleaning because of a specific issue / code or simply pm?

Simon
 

·
Registered
Joined
·
72 Posts
That's a good idea - as you say the access is not good in there at all - especially the rearmost connectors. I wasn't comfortable prying on much in the area as it seemed flexible - will take a closer look when i'm putting them back in.
Yeah it's pretty flexible, but if you get the screwdriver close to the connectors its really not too bad. I just carefully worked my way front to back.



Hi - did you pull injectors for cleaning because of a specific issue / code or simply pm?

Simon
I just pulled my injectors for PM, I'm in the process of finishing a spring tune up so I did injectors, plugs, belts, filters, wheel refinishing, and an evolve tune. Looking at your injectors they look very very similar to how mine looked when I pulled them out.
 
  • Like
Reactions: curtissp321

·
Registered
Joined
·
457 Posts
Discussion Starter #12
Update for this DIY thread now I have my cleaned injectors back and in the car.

For anyone UK based I would recommend the services of Injectortune.co.uk - good email comms from Steve there to all my various questions re. seals etc and a very good turnaround speed. I sent my injectors Tues for next day delivery and received them back on the Friday. £107 all in.

Service provides a clean, flow test and clean again if required + new basket filters and upper seals. Lower seals were advised as dealer only. I replaced these with Viton items from Polymax.co.uk for 18 pence each as against the £12.20 BMW wanted each! Luckily for some parts RealOEM list the dimensions which helps when second-sourcing standard seals etc.

Looking the at the report provided re. flow rate etc (see pic below) my injectors were in really good shape and the benefits of using good fuel seem to have been born out. I wish i'd noted which injectors came from where on the engine as it seems 3/8 were a little worse overall (tiny amounts though).
Even though my injectors were not blocked my much i'm pretty sure the engine seems to run smoother on refitting. This could be down to new filters and possible better sealing of the new lower seals - not had a long run yet either to really test. The old filters were returned - I didn't even notice the injectors had them when I sent them off. The mesh is damaged on a few though this is probably down to the removal process - bin job anyway but interesting to see.











My plan for re-fitting was to clip the injectors into the fuel rail then push all four of each bank into the inlet manifold at once and bolt down - this proved easier said than done... It may have been down to the Viton seals I was using being slightly stiffer than OEM. Anyway I applied a little automotive grease to each injector lower seal and individually pushed each one into the inlet holes. I then push the fuel rail onto all four with little effort and secured the injector clips. The electrical connections went on far easier than they came off - line them up and a small thump and they clicked on.

From then on I did the second bank and then checked for leaks by putting the fuel relay back and priming the ignition to position 2 several times to allow the fuel pump to create pressure in the fuel rail. No leaks found - then started engine for a bit and checked again - no leaks again so good to put it all back together.

Overall a worthwhile and interesting exercise.
 

·
Registered
Joined
·
710 Posts
BTW, I would use vaseline (petroleum jelly) to lube seals on injectors rather than engine oil.

Good write up. It must feel better to have perfect injectors. I wonder how well the ECU deals with changes to individual flow changes by way of fuel trims?
 

·
Registered
Joined
·
457 Posts
Discussion Starter #14
BTW, I would use vaseline (petroleum jelly) to lube seals on injectors rather than engine oil.

Good write up. It must feel better to have perfect injectors. I wonder how well the ECU deals with changes to individual flow changes by way of fuel trims?
Hi - yes it's one thing off the list I can be sure of! I used some general purpose grease (tiny amount) on the seals to get them into the inlet manifold holes. I think whatever you use will disipate quickly with the heat in the engine bay so no issues there.

I reset the adaptions and have now added a few hundred miles on since - INPA shows 0 fuel trim adjustment being made with the multiplier being 1 if iirc... Data before was a 4% alteration I think - have to check old records.

Certainly seems smoother to rev anyway so I'm happy - less bogging down as well though this may be due to the plenum all being sealed up better.
 

·
Registered
Joined
·
1,831 Posts
Did you happen to peak down in the throats of the throttle bodys?
 

·
Registered
Joined
·
1,831 Posts
Thanks Simon,

The replacement engine I got for my project car is pretty black and dirty down there leading to the intake valves.

I did some work on our 540 last year and it was similar.

I cleaned it up real well and plan on doing the same to the s62.

:cool:

PS- do the injectors come apart to replace/clean the screens?
 

·
Registered
Joined
·
457 Posts
Discussion Starter #18
Thanks Simon,

The replacement engine I got for my project car is pretty black and dirty down there leading to the intake valves.

I did some work on our 540 last year and it was similar.

I cleaned it up real well and plan on doing the same to the s62.

:cool:

PS- do the injectors come apart to replace/clean the screens?
I'll be honest i could not even tell they had screens when I removed them - it's not obvious as the filters slide into the fuel rail end very neatly. The guy who cleaned mine pulled them and returned them to me, probably to show they had been changed. Simple push fit I understand - i've seen pics on the net of people using a large, pointed thread from a hook or similar to grab them and pull them out.
 

·
Registered
Joined
·
564 Posts
Do you have the part numbers for the lower seals & tiny square metal clips that connect to the connector? I cannot find it on realoem .
 

·
Registered
Joined
·
457 Posts
Discussion Starter #20
Hi - this is the realoem page you need

RealOEM.com   Diagram Selection

select one of the 2 levels down depending on your year - worth putting your VIN number into start of realoem for this as injectors were changed part way through i believe.

lower seals will most likely be fine - size detail is listed on real oem so you can second source viton seals the same size elsewhere for pennies. BMW want ridiculous money for them in UK - may be better for you.

for the clips - do you mean the wire clips on the electrical connector or the injector to fuel fail square clip?

fuel rail clip is on realoem, electrical ones not available seperately i believe - others have suggested a few zip ties will hold the electrical rail down if yours are broken or you could extract clip from another car at a breakers if your really keen.

Simon
 
1 - 20 of 49 Posts
Top