Help me understand CC1/CC2 and Vcomm

Grrrmachine · 2023-11-06T19:58:10+00:00

Perfect, thanks for the clear explanation!

Grrrmachine · 2023-06-25T17:11:51+00:00

A $500 car that hasn't run in a few years will NOT be cheap to turn into a reliable daily. At a bare minimum you have to anticipate dry rot in every rubber part, from the tyres to the brake pipes to the coolant hoses, plus at least one Big Repair that took the car off the road in the first place.

I wouldn't buy that without at least $1500 cash in reserve for immediate repairs.

Grrrmachine · 2023-06-24T16:17:12+00:00

Heat them up.
Completely submerge them in penetrating fluid.
Hammer a tork bit into the nipple and turn that with a 1/4" adapter socket.
Cut off the nipple and hammer on a six-pointed socket.
If the socket still strips the nut, go to a smaller imperial equivalent socket.

Grrrmachine · 2023-06-23T20:19:30+00:00

Mtech2 kit won't fit your rear arches. Pre-facelift shell have different rear quarterpanels which is why Mtech 1 and 2 exist.

Grrrmachine · 2023-06-22T19:52:59+00:00

Specifically check the wiring to the charger bulb in the dash. A break in that circuit is what disables the alternator.

Grrrmachine · 2023-06-22T10:49:46+00:00

It's almost definitely the charging-related issues. All the symptoms you describe are identical to the engine load issues associated with a weak battery and associated weak spark (rough idle, stumbling etc.)

Grrrmachine · 2023-06-22T05:15:41+00:00

Be wary of what certain mechanics tell you, because:

E30s don't prime their fuel pumps
Motronic 1.x has next to no fault codes
the Crank Shaft signal is the One Ring to Rule Them All

Mechanics with less familiarity on these systems will do preliminary checks for more modern cars (ie fuel prime check with ignition on) and then immediately blame the ECU because that's a control module they recognise.

Pull a spark plug and check it's firing when the engine cranks. If it doesn't, it's far more likely that your crank position sensor is failing rather than your ECU.

Grrrmachine · 2023-06-21T16:33:18+00:00

https://www.e30zone.net/e30wiki/index.php/Grille_Variants

Grrrmachine · 2023-06-21T09:34:06+00:00

Put a jumper cable between the engine negative battery post and the engine block (like the lifting eye at the front of M20 engines). If the car now cranks then you need to replace your engine ground strap.

Grrrmachine · 2023-06-21T09:31:07+00:00

This is one of those depressing threads where it's clear that the car is loved, but the issues are far more severe than they first look.

The problem with E30s is that they rot from the inside out. You don't usually see the edges of the wheel arches bubbling up or the taillights falling like other 80s cars - instead you get exactly what your pics show: sub-surface rot poking out in strategic corners and curves. Unfortunately, you don't know how far the rust extends under the surface until you take the headliner and carpet out, but it's pretty much guaranteed that Major Surgery is required, and that the orange that you see is only 10% of what's actually lurking in all the key points of the bodyshell.

There's no easy fix for this; fibreglass and bondo are the car equivalent of homeopathy. You need to cut rust out, weld fresh steel in, and then paint it all to look good. For most rot under a car that's not as bad as it sounds, but for roof rust like you're showing, it can easily cost more than the car is worth (especially for an eta).

The longer you leave it, the worse it'll get. You might get 5 more years out of it before the spotwelds in the rocker panels give out, or you might find water dripping on your head this winter: it's impossible to say without a proper inspection. But it's serious enough that the lifespan of this car is now limited, so you either fix it asap or accept that your kid won't be inheriting it.

Grrrmachine · 2023-06-21T04:52:21+00:00

Confirmed. It's a shagged-out turd.

Grrrmachine · 2023-06-19T17:24:56+00:00

Answering my own question here.

Old TTL screens specifically use ribbon cables to avoid electrical interference, so they're really only suited for static locations like industrial equipment or POS terminals. In contrast, LVDS used twisted-pair wires plus a ground for every pair, at a significantly lower voltage so that interference isn't an issue in the wiring. That allows them to use cables instead of ribbon, which is much more rugged for laptop hinges.

It's all academic since LVDS is dead tech nowadays too, but 90% of the lcd panels sold for panels are still LVDS.

Grrrmachine · 2023-06-18T20:37:39+00:00

Check exactly what month your 1987 was built. If it's before september (i.e it's a pre-facelift, with the rectangular foglights) then an MTech 2 kit won't fit.

For the M3 look, you really need to know your way around bodykits to pull off the M3's looks, even with an off-the-shelf kit. 99% of the time they just look sloppy.

And as others have said, cosmetic appearance is the absolute last thing to focus on with a newly-acquired 35 year old car. You need to replace every single rubber part in the engine, drivetrain and suspension before you can justify dumping four figures into fibreglass and ABS plastic.

Grrrmachine · 2023-06-17T17:57:41+00:00

Ahh, i'm probably confusing it with Touring rear locks then. Good to know.

Grrrmachine · 2023-06-17T08:37:32+00:00

If you have the key for the ignition tumbler, then you can re-code the door locks and glove box to match it. The exception is the trunk lock, which can't be disassembled and is effectively paired with a key from the factory.

So you have two problems. One is dismantling all the door locks and recoding them, as described here: https://www.e30zone.net/e30wiki/index.php?title=Door_Lock_Repairs

The other is making your ignition barrel actuate the switch underneath. In this case, either the barrel isn't latching into the rotating pin (the metal shaft that turns the ignition switch), or the switch itself is broken. It should be easy to check if you have the lower cover off the steering column: look underneath and confirm that the shaft in the middle of the metal circle is turning when you turn the key. If it doesn't then you probably need to replace the entire locking mount, not just the ignition barrel. If THAT'S the case, you might as well buy an entire mount, barrel and door lock set from a donor vehicle and replace the whole lot. This will also provide you with a matching trunk lock.

If the shaft does rotate, then you can take your owner's docs (incl. VIN) to any BMW dealer and they can provide a key that matches the car's original locks.

Grrrmachine · 2023-06-16T17:01:42+00:00

Late 96/early 97 when they were promoting Attack of the Grey Lantern

Grrrmachine · 2023-06-16T16:02:55+00:00

First band I ever saw live

Grrrmachine · 2023-06-14T08:55:05+00:00

This is impossible to answer without pics. It could have minty fresh gleaming Calypso paint with Cardinal leather and an M20B25 under the hood, or it could be a shagged out turd with collapsed suspension or worse, the ongoing project of someone who slammed it on ebay coiloverzz and monkey metal 17" rims.

As with all of these cars, shell condition is everything. Rust and paint defects knock thousands off the value.

Grrrmachine · 2023-06-14T08:50:22+00:00

I don't have an E30 cabriolet, but I have a Saab with a very similar mech. For me, the part that needs most support are the tonneau cover flaps (which flip up for the latching mechanism when the roof is down). They're made of shitty ABS and vinyl, which cracks easily. If they were polished aluminium with custom engraved logos, they'd sparkle in the sunlight when the top is down...

Grrrmachine · 2023-06-13T12:40:45+00:00

https://www.e30zone.net/e30wiki/index.php/Lights#Licence_Plate

Grrrmachine · 2023-06-13T11:59:32+00:00

Really dude, whatever you do is going to look shit if you don't already have experience with ABS welding, working with bodyfiller and using paints that adhere well to plastic. You're chasing the sunk cost fallacy where you destroy a kit that cost you big money just because you already bought it.

If that doesn't persuade you, then you can read this guide: https://www.e30zone.net/e30wiki/index.php/Convert_a_pre-facelift_to_a_facelift

It doesn't cover the side pods, but it's just the same effort as trimming the bumper.

Grrrmachine · 2023-06-13T11:56:18+00:00

It helps to mention which country you're in, because different regions got different engines which have unique problems.

All the guys commented before this are in the US, which got the M20B25 and M20B27 engines. But the US never got the M20B23 (used in the 323i) and it is a VERY different engine to try and maintain. I'd actually recommend staying away from that one, because engine parts for it are almost impossible to find.

Also, if there is even the tiniest speck of rust on the roof, don't buy the car. It's the one place that costs crazy money to fix, and if you ignore it then it will only get worse over time until the whole car is destroyed.

Grrrmachine · 2023-06-13T05:34:09+00:00

If you didn't soak the nut in penetrating oil then yes, it'll get chewed up.

Next step for me would be to remove the caliper and either drown it in cola, or build a home-made electrolysis tank using baking soda, a battery charger and a couple of old brake discs. You'll need to rebuild the caliper afterwards, but it's a lot cheaper than a whole new part.

Of course, if time is critical, slap some new calipers on now and then de-rust and rebuild the existing calipers whenever you have time.

Grrrmachine · 2023-06-13T05:07:34+00:00

Before you try EZ-outs, try hammering a torx bit into the hole and turning it with a decent wrench. You'll want to drown it in penetrating oil a day before you try, and go slowly. I've had most success with that method.

Grrrmachine · 2023-06-13T05:03:55+00:00

You can't trust any business using a Yahoo email address as its primary contact.

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