F10 530d: New O/S / driver’s side rear spring.

Did both of the rear struts and springs a few years ago, but find the right side one has broken right at the top and will need doing for this years MOT test. As usual with 5 Series models when the spring snaps at the top or bottom, there was no tell-tale clunking or change in driving characteristics, so who knows how long it's been like that. At least it is not a big job.

*GUIDE: F10 Rear Shock / Spring Replacement*

*GUIDE: F10/F11 Front Shock / Spring Replacement*

The rear struts were replaced several years ago from a car with 80k miles. Their combined run in both cars has still added up to less than the mileage on the original ones!

E30 318i: Replacement Speedometer/ Odometer

Had to bite the bullet and buy a replacement speedo / odometer for project E30 this week as after many different attempts to fix the original one [THIS POST], I had to declare it totally junked. These are not cheap and sit around the £65-70 region, but I got a deal on one for £59... still an unwanted cost but at least I no longer have to tape an old iPhone to the dash with a speedo app!

Now the question is, do I swap in the number row from my old odometer or leave the ones in from this one, some 100k miles less.... Hmmm.

As per the pics, the areas of concern on my old speedo are not problem on the replacement, with resistors, capacitors and other components all looking mint. There is also no charring to the back of the PCB, so no sign of this unit overheating in the past and the odometer gearing is perfect. This unit has still covered 154k miles over the last 35 years, but has clearly had an easier life than the one from my E30!

Showing the healthy resistor on the newer speedo on the left and the burnt out one to the right.

E30 318i: Speedometer / Odometer faults + check list

If your E30 speedometer is broken, your odometer isn't turning or both, then here is a troubleshoot check list to find and fix the fault. Doing the work yourself is a bit fiddly, but totally doable if you are handy with a soldering-iron.

** A more detailed guide / thread all about E30 speedometer / odometer faults by 03IRM3 on r3vLimited.com is here - https://www.r3vlimited.com/board/forum/e30-technical-forums/general-technical/59019-e30-speedometer-repairs-failure-modes, which was a great help. **

NOTE: If your speedometer is not reading, before starting to diagnose the instrument the first thing to check should be if there is a pulse being generated by the speed-sensor in the differential, see E30Zone Wiki here.

Broken Odometer drive gear.

This is the most common problem when the odometer has stopped turning. The drive gear from the stepper motor that turns the larger cogs tends to split on higher mileage cars causing it to skip teeth and not turn the odometer gearing. Replacement gear sets can be bought from eBay for a few quid.

Burnt out resistor.

This is the main power resistor on the 12v + input to the PCB and it's never usually failure of this component that causes it to burn out. Instead, failure of a component further upstream is usually the culprit by drawing way too much current, causing the resistor to work double-time and overheat. This one was still working amazingly, given the heat it had been producing that charred everything around it, but I threw a new one in anyway. The value was about 150 ohms, so that's what I went with.

Blown capacitor.

Sudden failure of both speedo and odometer can often be down to the main power capacitor blowing. This is visible in the above pic to the right of (and next in sequence to) the burnt out resistor. It's a basic 220uF electrolytic capacitor and is very simple to replace with only two pins needing de-soldering, so should be the first step in troubleshooting a dead unit, even if the cap itself doesn't appear blown. Mine had been scorched by the overheating resistor, but seemed ok. I replaced it anyway, but it did not help with mine.

Snapped wire on Odometer stepper-motor coil.

This is rare, but does happen as 03IRM3 has seen one and mine had this too so I guess it does happen, where one of the single strands of copper coil for the stepper-motor snaps off its pin on the PCB. It’s possible that this happens due to time/age and vibration in the vehicle, but could likely be due to manhandling the unit while it is out for other repair work. Either way, it’s an easy fix to just solder it back in place and will be stronger than it was before at least.

UAF chip blown.

If none of the above fixes have worked and both speedo and odo are still not working, the likely culprit is that the UAF I/C chip has malfunctioned and is not processing inputs and outputs correctly, which leads to the resistor burning out, caps blowing and the odometer coil overheating. These UAF2115 chips are common, used in many speedo/odo units, taxi-meters, tachographs etc., so replacements can be found on eBay or electronic component sites for a few £/$, but this is probably the most advanced fix needed for these units and the question at this point is whether it's worthwhile. 03IRM3 has replaced chips as a last resort only to find the unit still won't work, so I decided that with all other fixes not working and my odometer still needing new drive gears that it was time to junk it and seek a replacement unit... [THIS POST].

E30 318i: New Bosch spark plugs + correct coil fitted

With the car still misfiring a bit, I turned my attention to the plugs and HT leads. All appear fine. The coil works because there is a spark. I inspected the plugs, a set of NGK R that don't look particularly ancient, expecting one or more to be wet with unburnt fuel from a combination of misfiring and running an over-rich mixture from tweaking the air-flow meter [AFM]. I noticed that the plugs were in fact all dry and totally black with soot at the tips from over-fuelling, but their condition seemed fine. This matched the points in the distributor-cap, which were also blackened.

The spark plugs were working, but they didn't seem to fully igniting the mixture and performing weakly, so I turned my attention back to the coil. A previous owner had fitted a universal 'Sports coil' and judging by the shiny casing it doesn't look too old, so I couldn't see how it could be at fault. Thats when I noticed the terminal connecting it to the HT lead. It's about 10mm wide and has a metal inner lining. There is a screw at the bottom holding it in. This is obviously designed for a different type of HT lead than fitted to BMW, as the lead has a rubber plug where

it contacts the copper casing of the terminal in the coil. The metal terminal in the HT lead is designed to fit over a stud inside the coil-terminal, which is what I've always seen before, not just in BMW. This means the only contact being made by the main HT lead was its very tip touching the screw at the bottom of the coil-terminal.

I swiftly ordered a used OEM Bosch coil unit from eBay for £15. A 'Sports coil' type with the correct end was about £35, but I figured it was best to go original, at least for the time being while I iron out the M40 engine's running problems. While I was at it, I bought some OEM Bosch spark plugs for £13, which is cheap and I thought I may as well rule out plug condition as a factor with not knowing how long the incorrect coil has been fitted to the E30. 

BMW Common Engine Error Codes / Fault Codes List 2740-2772 [E46, E39 etc.]

2711-273F, 2740-2772, 2773-279F, 27A0-27FF, 280A-29FF, 2A01-2CFF, 2D00-2FB7, CD87-CDAC,

2740 Pedal-travel1 permanently
2741 Pedal-travel2 permanently
2742 Misfire detection cyl.1
2743 Misfire detection cyl.3
2744 Misfire detection cyl.4
2745 Misfire detection cyl.2
2746 Misfire detection cyl.
2747 Misfire detection cyl.
2748 Misfire detection cyl
2749 Misfire detection cyl
274A Misfire detection cyl
274B Misfire detection cyl
274C Misfire detection cyl
274D Misfire detection cyl
274E Misfire detection, Checksum failure
274F Misfire, Checksum failure, service rel.
2752 Pedal-travel half plausibility
2753 Monitoring ign. coil 1
2754 Monitoring ign. coil 3
2755 Monitoring ign. coil 4
2756 Monitoring ign. coil 2
2757 Monitoring ign. coil
2758 Monitoring ign. coil
2759 Monitoring ign. coil
275A Monitoring ign. coil
275B Monitoring ign. coil
275C Monitoring ign. coil
275D Monitoring ign. coil
275E Monitoring ign. coil
275F Pedal-travel defect
2760 Secondary air system
2761 Secondary air system bank2
2762 Secondary air valve
2763 Secondary air valve bank2
2764 Controll sek.air pump relay
2765 Controll sek.air valve
2766 Phase generator1 time duration
2767 Phase generator2 time duration
2768 Phase generator positioning failure
2769 Spring test DK-controller open spring
276A Control-unit recognition
276B Secondary air valve output stage bank2
276C Phase generator2 positioning failure
276D Tank-ventilation functional check
276E Tank-ventilation functional check bank2
276F failure within secondary air system
2770 failure within secondary air system
2771 Secondary air system locked
2772 Controll gas ventilation valve