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[Stu.C]

If the engine bay loom seemed like a lot to deal with, it was nothing compared to the main body loom    This is a beast and connects all the controls on (and in) your dash to the rest of the car. The plan here is to strip out everything I won't possibly perhaps ever maybe need, one circuit at a time - and just keep going until I run out of things to remove. For the moment, I elected to keep the original cabin fuse and relay panels, so that I didn't complicate the task by then potentially mis-connecting a circuit along the way.


First thing to do then is open up the loom so you can get to all the wires...





If I wasn't doubting myself before, then seeing that lot spread out was the point it kicked in   


Apparently, the absolute worst way to remove loom tape and heatshrink is trying to slice it open with a razor blade or a knife. No matter how careful you are, at some point you're going to either cut the end of a finger off, or slice through a wire without realising. The best way I found to do it was with a variety of different sized seam rippers (or unstitching picks) from the crafting aisle. For a start you're pushing a blade away from you, so much less likely to stab yourself. The pointy bit is rounded off so you can slide it inside the loom tape and it pushes all the wires aside, before a tiny little blade slices open the loom for you. I was as sceptical as anyone, but once you try it, it's speedy and magical...





Stripping the loom back is then a "simple" repetitive process of picking a connector you're not keeping, checking it against the wiring diagram to be sure it's the one you think it is, double checking, and then cutting every single wire on it back to the other end. That other end is going to be either another connector (such as the big ones in the footwells), or a joint in the loom (such as where a load of earths, or the speed signal come together). If you want an easy start to get into the swing of it yourself, go for the bright yellow & purple of the airbag system - you can't miss it (probably intentionally) 


Little by little, that signal-to-noise ratio improves...





Remarkably, there was only one occasion where I realised 8.273 milliseconds after cutting a wire that I was meant to be keeping it 


Eventually, I got to this much more compact version. (I checked the datestamps, and it's three weeks later). The remaining loops of wire here and there are for "things to deal with later", such as all the warning lights on the dash, or all the MID connections.





As I went along, I'd made a note of the major circuits I'd chopped out (on the basis either I wouldn't want them down the line, or a theoretical target vehicle would already have them taken care of anyway);

• Airbags
• Windscreen wipers/washers
• Aircon
• Aerial
• Heater blower
• Horn
• Rear window heater
• Indicators & hazards
• Bulb failure warning
• Alarm
• Powersounder
• Cruise control
• Heated seats
• Traction control
• Ultrasonics
• Electronic Climate Control
• Cabin lighting
• Stereo / amplifier / CD changer
• Power steering
• Exterior lights
• Ignition switch

Blimey, that's quite a lot for a machine to get you from A to B     Once I'd stripped the loom back to this point, I ziptied it all up to keep it structured, dropped it back in the box, connected it back up the engine ... and was relieved when everything worked first time and it fired up again ... 

[STEMO]

You're a glutton for punishment, Stu.

[Stu.C]

   Some people build models of tower bridge out of matchsticks. Some people (for no apparent reason) golf. There's even a group in the next village that knit jumpers for trees and lampposts...


During our various lockdowns (which spanned the story so far), this whole project simply gave me a chance for a half hour break here & there. Research was quite easy on the old interwebs, and any tools or parts I needed were generally only a couple of days post away. Yes I might have taken some long diversions along the way, and others would no doubt have done things differently - but at the end of the day, it's my hobby project not theirs 

[Lizzie Zoom]

  Some people build models of tower bridge out of matchsticks. Some people (for no apparent reason) golf. There's even a group in the next village that knit jumpers for trees and lampposts...


During our various lockdowns (which spanned the story so far), this whole project simply gave me a chance for a half hour break here & there. Research was quite easy on the old interwebs, and any tools or parts I needed were generally only a couple of days post away. Yes I might have taken some long diversions along the way, and others would no doubt have done things differently - but at the end of the day, it's my hobby project not theirs 

Well said Stu and power to your determination, enthusiasm and pure bloody skill that leaves so many of the rest of us in awe!!  Keep going with this fascinating project

[Stu.C]

Because I can play about with it in my head, a hypothetical destination for the engine could hypothetically use the Omega instrument cluster instead of its' own. Logic says that'd be easier than trying to get a whole load of other instruments from a completely different vehicle to understand the output from the ECU, but I've seen some transplants where folks are keen on preserving the retro vibe of original dials. Keeping the original cluster made it easier for me to have a running engine too, so I went with that 


To give flexibility down the line, I worked through the cluster's 26 pin connector and wired up a couple of stub connectors for all the warning lamps, and anything else that wasn't taking a feed from either the ECU or whatever I'd kept in the loom. If you work on the premise that a target vehicle's already got indicators, for example, you could then simply connect that circuit up to the Omega cluster and bam!  Plus, it kept them tidily out of my way for now and I get to claim later on that it was intentional... 





Because - as Stemo notes - I'm a glutton for punishment, I then spent a couple of evenings harvesting wire from the remaining body looms, which run all the way to the tail from the front footwells. The only thing back there I was remotely interested in was the fuel pump & gauge circuits, so 99.87% of this is technically scrap. Don't know about you though, but I hate it when you're following someone else's wiring job and you've got say a circuit on grey with a yellow stripe, and then suddenly it becomes dark green at a joint because that's all someone had knocking about at the time.   


Harvesting the wire now means I can colour match to my heart's content for years to come - and it's free ... 





It's like déjà vu all over again ...     





But the end result was remarkably satisfying, and sooooooooo much easier to store and pick from later 

[Stu.C]

Well said Stu and power to your determination, enthusiasm and pure bloody skill that leaves so many of the rest of us in awe!!  Keep going with this fascinating project

Thanks for the encouragement Lizzie - I've been meaning to write all this down for ages,(as much for myself as anyone else), so it's good to know there's an audience 

[Stu.C]

Right, I promise that's (probably) the end of the loom updates, so let's get back to the engine 


Any destination for the engine will most likely be needing custom exhaust headers. The Exhaust Gas Recirculation system does not form any part of that plan, and besides, it's ugly and too sticky-uppy above the sleek lines of the plenum    To deal with the physical aspect of getting rid of it, there's two parts to consider. The first is a simple blanking plate for the two small ports on the side of the plenum, and the second is a blank for the exhaust manifold. I had a rummage in the plumbing fittings box in the garage, and got myself a 15mm brass compression stop end. It's actually two pieces, and we're only needing the nut. Take the nut, take a coin of the realm, use a smear of exhaust paste to hold the coin inside the nut after you try and put it on fifteen times and it keeps falling out, tighten it up and the job's a good 'un    If I was truly OCD, I'd have made the nut line up or something... 





Which then leaves you with the question of what to do with all the EGR stuff? If you unplug it, the ECU throws codes at you, because it wants to see feedback from the valve. I suppose you could try and tuck the EGR solenoid out of the way somewhere, but that doesn't seem very finessed. Luckily plenty of other folks have already solved this exact problem on a variety of engines, and for the X30XE there's a schematic out there for an "EGR cheater circuit". What this does is take the inputs from the ECU, and produce outputs that are within the range of values the ECU is expecting to see coming back.


Rather than make out like I'm a whizz at everything and I had it solved in a jiffy, I'll let you in on the secret that I'm a bit rusty on my electronics schematics interpretation, so I set all the components out on a breadboard to see if I'd got the circuit right. All you need is some resistors, some diodes and a relay - but like many things, the devil's in the detail. It's dead easy to test, at least - if you plug it in and the check engine light goes out, you're onto a winner 





With a working circuit, I then needed to transfer it onto some copper stripboard, to give me something conveniently small to stash away...





And here's the finished article in all its glory    It's only about an inch square, so it can get tucked out of the way with the ECU and that's another item ticked off the list...

[Migv6 le Frog Fan]

Excellent work. 

[Lizzie Zoom]

Well said Stu and power to your determination, enthusiasm and pure bloody skill that leaves so many of the rest of us in awe!!  Keep going with this fascinating project

Thanks for the encouragement Lizzie - I've been meaning to write all this down for ages,(as much for myself as anyone else), so it's good to know there's an audience 

Oh, yes there certainly is on this forum, which after all is designed for motoring adventures like this one.

I certainly have learnt through the excellent photos, and enlightening explantions, far more about my Omega, and what we drive around in and rather take for granted.  This thread should go into the Guidlines sections for great reference.

[STEMO]

In the maintenance section, entitled'How to totally, completely and utterly destroy an omega'.

[Lizzie Zoom]

In the maintenance section, entitled'How to totally, completely and utterly destroy an omega'.

That is the negative, but with all engineering when you dismantle a machine you learn how it was built, and with this fully referenced exercise it shows areas of an Omega we do not normally see.  For anyone restoring one of these beauties the information given could valuable help.

Whether or not many of us are up to all this is another story!

[cam.in.head]

absolutely and 100% agree . this is the fun part of owning and maintaining "anything that you plan on keeping ".
the best way (as you have found out) of bring able to work on / repair  anything is to understand fully how it actually works in the first place.
well done stuart.

[Stu.C]

I'd go with classifying this thread as edutainment, rather than reference    and freely concede that I'm standing on the shoulders of giants with a lot of the content   


But yes, I've always enjoyed taking stuff apart, to try and get an idea how it works. Admittedly, putting it all back together, not having bits left over, and having it working again at the end is a probably less than stellar track record over the years though... 

[Stu.C]

With all of the plugging things in, unplugging them, chopping bits out of the loom and whatnot, the ECU's got quite a few stored fault codes. Now the old paperclip test is all well and good when there's one or two, but it had got to the stage where I was sat there for six and a half minutes transcribing the flashing of the Check Engine Light into fault code numbers. My cup of tea kept going cold !! 


A search of the options on eBay told me I could have a USB dongle that plugs into the data socket for about twenty quid and upwards. These older engines don't have the more modern OBD2 interface that are common across all manufacturers these days, rather an Opel-specific protocol, so the pocket generic code reader I already had was no use.





There's a bit of dicking about with getting the software to work on modern flavours of Windows, but once it's done, that's it. Instead of six and a half minutes, it now took about six and a half seconds to get a list of stored codes - and then clear them    Yes, they'd have eventually sorted themselves out but it's easier when you're not chasing down ghosts...





The other thing it enables you to do is access some of the live data that's buzzing through the ECU, mostly sensor readings and values calculated from them. Instead of guessing, you can readily see that your intake air is at 18°C, your coolant's at 77 and the O2 sensors on both sides are reading about the same...





You can then also hit the Record button and save the data stream to a file, "for later analysis" as they say. Of course, the analysis is only going to be as good as one's understanding of the data, versus what's good and bad - but other folks can help with that if you've actually got the data rather than guesstimates. 


As a fr'example, one can then map the outputs from one engine runs, compare what you got with what you wanted, and so on and so forth ...

[Stu.C]

Next on the list (and it seems slightly out of sequence) was a game of 'find the vacuum leaks' - a never-ending fun game for one or more players aged 6 and up 


Even though I was running the bare engine inside a small garage that echoed and bounced the noises all over the place - added to the fact that my hearing's knackered and I'm half deaf with no stereo and no sense of direction - the thing just seemed noisier and hissier than it ought to be.    So we started a slow process of working around the top of the engine trying to work out where the holes were, or weren't, or might have been. Some were more obvious than others. The hose from the intake pipes to the Idle Air Control Valve has a tee in it that goes off to the vacuum valve for the plenum multiram. At some point in the past, this tee had split around its shoulder and been taped up. Time passed and the tape dried up with the engine heat (as you see below), so in came a whole bucketful of un-metered air to the intake system. We'll add that hose to the shopping list, but for now I sealed the shoulder up with liberal amounts of superglue and wrapped it in fresh blue tape (as a more obvious aide memoire)...





This then lead me round to the back of the plenum and that vacuum valve for the second multiram. At some point it's got a teensy weensy bit bashed, and not just the cover for the electronics but also the valve body was bust. It wasn't working as a valve, was leaking vacuum (or sucking in air), and wasn't opening the multiram at four thousand and something RPM. Luckily, it turns out I had a spare, as the exact same valve is used for the front & rear multirams and the
Secondary Air Injection system, which I'd already ditched. 





There was still more hissing though, and I couldn't work out where it was coming from. I connected up a vacuum gauge I'd had lying around in a box for years, and checked every connection I could find - from the input & output to the front multiram's vacuum reservoir, the plenum from the output to the charcoal cannister, and the tee off the line that goes from the plenum to the brake servo. I struggled finding a definitive answer as to what the "correct" vacuum should be, but found a few references here and there suggesting it should be around 20 in/Hg or more.





I was still getting a reading somewhere down 18 in/Hg, so there was still a leak somewhere I surmised. It still sounded hissy too, but like I said - no amount of leaning my good ear close to the action was helping me work out what was going on.    Until my young daughter made the terribly modern suggestion of "just record a video on your phone daddy, and move the phone around instead of your broken head". Genius 


That lead me back to the pipe running to the brake servo, and it wasn't until I moved a random clip that it became obvious. I guess that clip's to stop two hoses rubbing - but the irony was the clip seemed to have rubbed through one of the hoses itself. 





With this (giant) hole patched up, I was now getting a consistent 22 in/Hg reading and it seemed like the hissing snakes had been banished from the garage 








Tim reckons we're in the green zone, at least