E30/E28: Faulty AFM (Air Flow Meter) repairs, worn carbon-track quick fix

** FOR ADJUSTING AFM AIR/FUEL RATIO SEE THIS POST **

The AFM or Air Flow Meter uses a metal flap that is opened air entering the engine to move a brass arm up and down a carbon-track. The position of the arm along the carbon track alters the electrical resistance through the circuit and this lets the ECU know how much air is coming in, so it can deliver the right amount of fuel to the injectors. The E30 uses a BOSCH AFM unit, also used in many other BMWs with Motronic or Jetronic injection systems.

The analog electrics in the BOSCH AFMs rarely ever fail, but there are two areas that are failure prone after higher mileage - a worn carbon track and a faulty air-temperature sensor.

Causes of flat batteries on BMWs explained - Great guide!!

If you own an older BMW, no doubt you will have experienced your battery suddenly starting to go dead for no apparent reason. All modern BMWs have a ‘shut-down’ procedure after the ignition is turned off, things can be heard whirring and humming even after you’ve locked the car and this is the most common cause of your battery going dead over night with no warning, but there are others too...

Below is a great guide from Vlad at MCA Blog explaining the reasons BMW batteries go flat over night and where to check. It also details that bane of the BMW battery's life, the 'IBS' or Intelligent Battery Sensor fitted from the '90s on. 

https://mca.electricmura.ro/en/blog-bmw-what-causes-dead-battery/

• Plugged in external devices
• Plugged in OBD-II scanner
• BMW Intelligent Battery Sensor
• The infamous ”hedgehog” (from the climate control panel)
• One of the electronics on your car drains too much power or does not go into sleep mode
• Faulty alternator
• Old battery

E87 LCI: 1er Warning-light woes + dodgy pad-sensor. [How to reset.]

My boss Mike has been dying to get back on the Beemer wagon, so has surreptitiously gifted himself by getting his wife an E87 LCI 118d M-sport as a present. It was time to reset the service lights, which can be done using the 'trip reset' button on the clocks, like other modern BMWs, though with no iDrive the procedure is slightly different.

HOW TO RESET SERVICE DURATIONS:

1. Turn ignition on without depressing the clutch. [Key phase 2 on push-button models].
2. Hold the trip-reset [odometer] button on the clocks until a yellow triangle with ! appears.
3. Single presses of the trip-reset button will now cycle through the service menu options [service, oil, brake-pads etc.]. Stop at the one you want to reset.
4. Hold the BC button on the end of the left indicator-stalk until a clock appears next to the menu-icon on the dash. When the clock stops counting the service duration for that option is reset.

• A red icon is a service duration warning. An orange icon means it is overdue / there is a fault.
• A red/orange icon of the car in the air with a stand under it means there is a fault and it needs to go in to BMW [or get a scanner on it].
• If the handbrake light stays lit up after you release the handbrake then this means there is a fault in the brake system. If you know the discs/pads to be OK and the brakes are fine, then you have a dodgy pad-wear sensor.

PAD-WEAR SESNOR ERROR: [HANDBRAKE-LIGHT]

After resetting the brake-pad service indicator we noticed the mileage count had not reset. The icon in the service menu recommending the car be taken to a dealership [the car icon with a stand underneath] and interestingly, the handbrake light was staying on even with the handbrake released. After a bit of forum scanning it turns out the light staying on means there is a fault in the braking system or one is about to develop. This is common when pads / discs have been changed and 9-out-of-10 times it means a pad-wear sensor has been disturbed and thrown up a fault. If you know the brakes are working as they should then the warning message can be cleared with a scanner and probably wont return. If it does then a pad-wear sensor has failed [scanner will likely confirm this] and will need replacing. You can do both of them for about £10 and it's a really easy job - wheel off, 2 bolts and a push-fit - but if you're truly skint I believe there is a technique online somewhere to just twist some wires together and bypass them.

http://www.babybmw.net/forum/viewtopic.php?t=23763

http://www.e90post.com/forums/showthread.php?t=698040

E46: Inlet full of oil! Re-con time.

Removed the inlet-manifold to check the CCV [crankcase-ventilator], crankshaft-sensor and main wiring-loom / connections. It didn't look too bad underneath, though there are some signs of a stuck CCV valve. I put the manifold down next to the car while I was working and after 5 minutes I noticed a large pool of dirty oil had run out of the throttle-body, so I placed that end in a bowl, jammed the butterfly open and leant the manifold on its end. Another 1/4 pint of oil ran out of it and today I removed the throttle-body entirely and managed to get about half as much again. More is coming, so I've blasted carb-cleaner back through the inlet-ports and left it to run down.

So either the piston-rings are completely shot and are leaking that much oil back up into the inlet, in which case the engine wouldn't run... or it's one heck of a stuck CCV. In this case, it would appear the crankcase-vent valve has stuck closed, which is allowing pressure to build up and pump oil back through the clean side of the CCV-system, dumping it right into the top of the throttle-body! Rather than creating a vacuum in the air-inlet that keeps the car at a decent idle, the CCV is pumping combustion pressure instead and covering all the sensors with hot oil. Not good. This is the most poorly engine I've ever seen.

While the throttle-body is off I may as well give it a good clean, along with all the sensors that had filled up to the wiring-connector with the pressurised oil. Even if this doesn't completely clear the rough running faults, it has certainly given the engine a new lease of like and it never does any harm to flush everything out and eliminate any further problems in the inlet.

The curse continues! 318ti blown head gasket! [E36K]

I don't believe this! Nathan has been using his E36 Compact for work this week while the wheels are off the 330 Clubsport. Yep, the same E36 I was about to borrow so I can get to work with the broken E46 and E60. It's been running like a dream while it's for sale, then this morning he gets 2 miles and the head gasket blows, then he runs round and dries home like a red arrows display, so it looks water related... why? its not like he was ragging it in eco mode. Drat!

It has a minor running fault as it is, where the engine cut out when the auto-box is put in 'D', probably the torque-converter. This I could have lived with, even the 'sport-o-matic' box, but more open-engine is out of the question I'm sure anyone would agree!

3 dead Beemers in 3 weeks! What is going on.

E46: Vacuum-pump severe failure...

With a new servo and master-cylinder, but still no brake assistance, I decided the vacuum-pump must be leaking air. I whipped it off, only 3 bolts and no need to remove rocker-cover etc., and opened it up. This is what I found...

This chamber should be full of air, not oil. The pump bolts on to the back end of one camshaft, which turns a spinning-boss. A plastic-bar slides up and down in the spinning-boss and creates a constant vacuum into the servo to help 'suck' the brake-pedal down when you brake. My plastic bar is missing. Where is it? Well, it's smashed into pieces lying in the oil.

After a clean up it was a decent pump-body and would work fine with a new O-ring and plastic-bar. They sell O-ring kits for the N42 vac-pump separately, but plastic-bars they do not, so I bought the pump from the same donor car as the servo + M/C. All pieces seem to have sheared off with a clean break, the bar was literally blown apart, except for one of the round end-caps (the tiny piece in the middle of the pile in the photo). That had been spread into thin strips as it broke off, so it looks like that end contacted the side of the case, spread into fronds and jammed the plastic-bar, which promptly blew up. How though? Did the timing slip unbalance the camshaft enough to wreck the pump? Or did the plastic-bar break apart and jam the pump, causing the camshaft to stop briefly and the timing to slip in the first place? Hmm...

Another side effect of the vac-pump failing was a terrific oil leak. The O-ring seal had gone completely and the spinning-boss was acting like a mini oil-pump, sending a constant stream down the back of the head onto the hot exhaust [bottom of the pic]. The pressure also made the vacuum-hose connector, normally only filled with air, to leak at the jubilee clip and pour oil onto the gearbox-housing [middle of pic]. After removing the pump a huge third pool of oil arrived. This was what had run out of the vacuum-hose to the brake-servo after disconnecting.

E60: Engine Autopsy Verdict.

Well, contrary to my earlier verdict of no damage to the head, a bit of informed explanation reveals the corroded surfaces in cyl. 6 are in fact battered metal from the where bits of my swirl flap were bouncing around inside it. Not good!

After having my photos pored over by the engine diagnosis experts on BMW Land, the best version of events of that fateful Tuesday are below:

1. Swirl flap no. 4 breaks up and bits enter cyl. 4.

2. Inlet valves jamming open on cyl. 4 cause a backfire and blasts the loose remains of the swirl flap into the intake plenum.

3. The turbo forces the swirl flap remains along the plenum, with bits ending up in cyl. 5 and the majority entering cyl. 6.

4. Cylinders 4 and 5 continue to fire with slight lack of compression.

5. Trapped debris in cyl. 6 begins to ricochet around, causing damage to the alloy piston-crown and the top of the combustion-chamber in the head until the inlet valves cannot close fully and compression is lost entirely.

Worst bits:

• Cylinder-head is finished. Valve-ports on cyl. 4, 5 and 6 need regrinding and fitting with some new valves. The top of the combustion chamber in cyl. 6 needs completely regrinding into shape.

Best bit:

• The engine still turns freely, cyl. 4 and 5 are virtually damage free and do not need replacing.
• Piston 6 compresses in the block still, so no damage to piston-rings.
• There is no damage or scoring to the cylinder walls.

THE REPAIR [in theory...]

• Repairing the head will cost ~£350, the cheapest Birkenhead-Engines can do and may still need further work, so a replacement is needed. Birkenhead-Engines say they have one such in stock, removed from another E60 530d, though what year they are unsure. It is not re-con and they say I can take my chances for a mere £200, but at least they know the valves etc. all work so it looks like this is the way to go.
• As long as I remove any tiny debris from cyls. 4 and 5, I am happy that they are working 99% as well as they should and do not need any repair.
• Cyl. 6 is battered and, although it is compressing in the block, the jagged metal crown will mess up proper combustion even if it fires ok. Worse, bits of the jagged alloy will probably break off during combustion and ping around the cylinder some more, potentially messing up the valves again so really the piston needs replacing.
• Not only is finding a single replacement piston very difficult, the job to replace it requires removal of the sump and big-end shell. This, with all the under-trays and cross-members is a colossal task in itself and, with the car parked on loose gravel, it's looking like a no-go.
• The short-cut solution to piston-6 looks like it's going to be a jenky regrind with the piston still in the engine. I will turn the crank by hand so that piston-6 is in its topmost position and get in there with a die-grinder, removing all the proud bits of metal and re-shaping the 'swirl-pot' and piston-crown as well can be. This ultimate bodge could be the end of a relatively unscathed engine. It could also be the only way to get the E60 back on the road quickly and with a minimum of fuss... Fingers crossed.

COST:

• Replacement cylinder-head: £225. [Birkenhead Engines]
• New head-gasket: £85.55. [Euro Car Parts]
• New head-bolts: £37.48. [eBay: dusty789blue]
• Swirl-Flap Blanking Plates: £20.99. [eBay: myldanautodesignltd]
• New thermostat: £33.99. [I broke the housing - Ebay: carpartssaver]
• Oil: £85.98. [Halfords, own-brand BMW Fully Syn. 5w30]
• Coolant: £22.99. [Halfords, Comma G48]

TOTAL: £511.98.

E60: 530d Engine-Death Post-Mortem:

Had the rough-running / misfire from the vid in this thread [], so I've quickly whipped the cyl-head off [lol!] and this is what I found...No. 4 swirl-flap has broken off and is missing from inlet-manifold. Some technician could have removed or broken this with the mani. off in the past, but this is unlikely so it looks to have been chewed by the engine. With all that intake-pressure it's possible the skinny flap has been totally disintegrated by the valves / piston and blown through the exhaust in tiny pieces...
  Image resized to 50% of its originalize [1600 x 1200]

...because there is no sign of it in the head, or inside cyl. 4 / the exhaust manifold. The turbo is spinning great and there is no play in the spindle. You would imagine the flap getting stud behind the inlet-valves, right down the inlet-port, but there is just no sign of it. I got the inlet valves down using a home-made valve-spring compressor, built from a piece of angle-iron and an M10 nut/bolt and sent pipe cleaners through. There is no obstruction in the head at all. Ima
 resized to 37% of its original size [1200 x 1600]

Slight marking on piston 4 suggest the flap has been mashed through the cylinder, or that the inlet-valves have gingerly contacted the piston while that was going on.
  Image resized to 37% of its original size [1200 x 1600]

In the block, cylinders 1-3 appear to be working perfectly. All cylinders are in the right position and the engine was running [badly] so there is no seizing. Cylinder 4 appears to be firing correctly, despite the marking to piston-top. Cylinder 5 appears to be firing ok, but there was a small pool of neat diesel in it. This may have just spilled over from cyl. 6 when the head was removed, as 5 appears to be firing. 

Image resized to 50% of its original size [1600 x 1200]

Cylinder 6 was full of neat diesel to the brim. There was no sign of 'hydro-locking' or the neat fuel affecting the crank, so it seems to have been gushing straight into the turbo/exhaust. Exhaust-port 6 on the head is wet / oily with diesel, whereas the other 5 are bone dry and sooty, so it looks like only cyl. 6 was in fact not firing.

Image resized to 50% of its original size [1600 x 1200]

The top of piston 6 is quite badly corroded, as is the top of the combustion chamber in the head around the valves. I wonder if excessive fuel from a leaking injector could cause this?

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Image resized to 52% of its original size [885 x 1143]

Injector 6 appears fine [as is always the case].

Image resized to 50% of its original size [1600 x 1200]

There is no sign of damage to the head, cams, block, manifold and turbo, so I have to give the head a clean bill of health and will be putting it back on. New gasket is £80-£120 on its own!

No loss of compression on cyl. 6 or damage to head-gasket. 

My best guess is that as exh. port 6 on the head is wet with fuel, no. 6 injector has flopped it in a big way and been flooding the back cylinder with fuel and not firing, which could still explain the sudden nature of the fault.

If this not the case, then I can only imagine the dropping swirl-flap has caused untold damage to the engine, knocked the timing out somehow affecting only cyl. 6 completely, but 4 and 5 to fire improperly too.

Yeah, so looking like a truly broken injector then! Guess I will be replacing all 6 when I refit, about £40 each, along with some swirl-flap blanking-plates for £7.50. I also broke the thermostat-housing as I removed the feed-hose, so that's another £40 down the drain, oh and more oil and coolant of course. Think I'll re-use the head-bolts!

E60: Second fault already... Front Parking-sensor!

How ironic! Just as I put paid to the E39's rear parking-sensor issue, a front sensor goes on the E60... they do seem to be temperamental little things those same sensor-units used from the E38 up until 2008 - they can be working fine one moment and then just fail over night!

 A few years ago one of my company directors had an E65 730Li, which started to spend a lot of time in our workshop under diagnostic. He blamed CANBUS issues and his symptoms were the car's electronics having a mind of their own, then as soon as one fault was rectified another would pop up straight away. I'm guessing the E60 uses the same technology as the E65, so can be forgiven for thinking mine might have the same issue seeing as the 'PDC' (parking-sensor) error came up the second I turned the key after fitting my new sidelight bulb...

Blown fuse?

The first thing to check, but mine wasn't blown and chances are yours won't be either, it's never the fuse with these BMW parking-sensors. The fuse is No. 21 in the glove-box, a green 30A.

Wet control-modules?

The sensors then fixed themselves for a day or two and then gave up completely, leading me to believe it was not just a failed bumper-unit. I hear on forums that intermittent PDC problems can be caused by a small amount of water being let in to the spare-wheel well while the boot is open and, without any drain holes, this can pool right where the PDC control-module is. Just a drop in the wrong place can cause erratic PDC behaviour and the module is fitted right at the bottom of here wheel-well, a bit of a design flaw, but it's only casually fixed in place on long wires so it's a good idea to move the module to a higher piece of ground somewhere else in the boot. I'll be putting up a guide for this as soon as I get round to it.

Broken sensor?

Yes. Those with vast experience tell me in 99.9% of these cases it's simply one of the bumper-sensors has thrown its hand in over night, which renders the entire system inoperable, as they work in a sort of daisy-chain. The only way to check which sensor is at fault is to kneel down at the front and rear of the car and put your ear to each sensor. As they work on a sonar principle the working sensors should emit a (pretty loud when your close) clicking sound. When you find the one that isn't clicking, that's your duff sensor - a lot easier than plugging the car into a diagnostic! 

Sure enough, all my sensors were clicking away save for one - the front driver's-side centre one, ironically one that happens to be located under the headlight I removed to sort the parking-light issue, so I can perhaps see what happened there. It's too much of a coincidence for that sensor to fail right at that point in time, so it looks like I've disturbed something or allowed water into the back of the sensor somehow. I gave the wires to the sensor a good wiggle and traced them back to the loom, but still nothing, so got straight onto eBay and bought a replacement sensor. It's pre-painted in Titan-silver, having been pulled off an '04 E60 and was £33 delivered. This was a bit more than the E39 sensor, but I know it's the right part and it's still a lot cheaper than the £125 from BMW, plus the 2-3 week wait and fitting charge.

REPLACEMENT PROCESS:

For Front-Centre Sensors:

** This couldn't be easier. The official procedure and internet forums recommend removing the 'bumper-skin' to replace the middle-front sensors, which is basically the whole bumper. This is totally unnecessary! You can get to them through the lower grille and don't need to have tiny hands or be double-jointed. This is for non-M-sport bumpers, I assume the larger mesh-grille on M-sport models is attached from behind and would need the bumper to come off, but if it is detachable then this would be even easier. **

1. Remove the black plastic grille-bars from the lower grille by unclipping the horizontal bar from the lug at either side. This is done by lifting the bar and pulling it forward. The vertical bars simply pop off.

2. Reach into the grille aperture and up towards the corresponding sensor, you will feel the wires about 5-inches up.

3. Remove the wire-connector by pressing in the clip at either side and the plug should easily wiggle off.

4. Remove the parking-sensor from its mount by wiggling it from behind and slowly pulling it towards the rear of the car. At the same time, gently apply pressure to the exterior-face of the sensor with your thumb. Once it is about 2mm into the bumper it should slide out easily.

5. Push in the new sensor from behind, ensuring it is the right way up - that is with the single small lug and wire connector at the top (12 o'clock) - then plug the wiring connector back in and replace the grille-bars.


For Front-Corner Sensors:

1. Remove the headlight that is above the corresponding parking-sensor by referring to Steps 1-6 of THIS GUIDE.

2. The parking-sensor is located just beneath the outer corner of the headlight and is easily accessible from above. Refer to steps 3, 4 and 5 of the above guide to replace.

E21: Front indicators - a common problem?

Is your front corner-indicator not working, but the bulb and fuse are fine?

Mine wasn't and it turned out to be the metal live-clip that sits against the bottom of the bulb. Not the best of designs, connection is lost to the bulb if the clip is bent back slightly, causing the indicator to fail intermittently [denoted by faster clicking of the turning-signal]. The clip having a little corrosion or crud on it is also enough to stop the bulb getting a signal.

A quick clean up with emery-cloth and a slight bend forwards so it sits tight on the bulb was enough to get mine working solidly again. This could be a common problem, especially in the UK and Europe where grime gets pushed everywhere in an E21, so if your fuse and bulb appear fine, but the indicator won't work, you can bet it's the live-clip.

PROCESS:

1. Dis-connect the corner indicator wiring by sliding apart the plastic-clip located behind the headlamp under the bonnet and push it through the hole to the outside of the wing.

2. Remove the two crosshead screws holding the corner-indicator lens and lift the lens off.

3. Remove the two crosshead screws holding the indicator-housing to the wing. The housing should now slide forwards and clear the wing.

4. Use nose-pliers to remove the metal live-clip from where it sits in the plastic-housing.

5. Bend the prong [denoted by the arrow] in towards the other prong, bringing the flat-edge down.

6. Clean up the face of the prong and the metal-contact on the bulb with emery-cloth.

7. Replace the live-clip to the plastic-housing and reverse Steps 1-3 to re-fit.