Wednesday, 9 June 2021

E30 318i M40: GUIDE - Replacing lower inlet-manifold gasket - rough idle and stalling fixed!

After all the diagnosis and testing from THIS POST, I found the cause of my rough idle and stalling out when cold was a damaged paper gasket on the lower inlet-manifold allowing unmetered air to be drawn in to the plenum at will and confusing the AFM and DME over how much fuel to deliver. 

The engine just about ticked over when warm, albeit with a slight misfire. On cold startups however, the misfire was a lot more severe and at low revs the engine just couldn’t hold on, stalling out due to a way over-lean mixture. It would drive though, but there was no throttle response until about halfway up the rev range and power would arrive with a bang. It is amazing how sensitive these older engines with analog electronics are to unmetered air leaks!

IF YOU HAVE THESE SYMPTOMS, CHECK HERE!

I ordered a new gasket from eBay, it was a snip at £6.88. Be careful when ordering, older M10 engine gaskets are far more plentiful, so ensure yours is the right one for the M40... they have a funny shape which is quite distinctive. Choice was limited, in fact I could find one more gasket for sale of the right type and that came with a full £30 set including a head gasket, so be sure to check out carpartsinmotion, they have rare-fit stuff.

GUIDE:

1. Undo the jubilee-clip and disconnect the large rubber duct from the throttle-body using a flat screwdriver or 7mm socket.

2. Unclip the throttle-cable from the throttle-linkage and remove the two 10mm screws holding the metal plate to the throttle-body so the cable assembly can be moved clear.

3. Remove the wiring connectors from the throttle position sensor [TPS] and idle control valve [ICV].

4. Remove the rubber hose from the bottom of the ICV.

5. Remove the vacuum air hose from the front side of the throttle-body by undoing the jubilee-clip and teasing it off carefully with a flat screwdriver.

6. Remove the two coolant hoses from either side of the throttle-body by undoing the jubilee clips and teasing them off with a flat screwdriver. 

7. Remove the six nuts from the upper inlet-manifold using an 11mm wrench [9 in diagram] and two locating studs in the centre with a 10mm wrench [13 in diagram]. 

8. The upper inlet-manifold can now be lifted out of the engine bay.

9. Remove the wiring connector from the fuel-rail / injectors. 

10. Remove the metal fuel send and return pipes from each end of the fuel-rail by undoing the jubilee clips. (This is where it gets messy, you may wish to plug or clamp the ends of these hoses). The send pipe is attached to the fuel pressure regulator [FPR] at the front of the fuel-rail and the return pipe is at the back of the rail.

11. Remove the five nuts holding the ports of the lower inlet-manifold to the head using an 11mm socket [4 in diagram].

12. Remove the two bracing bolts from the lower inlet-manifold using a 13mm socket. (They point towards the right side of the car) [11 in diagram].

13. The lower inlet manifold is now free to be removed. This can be a bit tricky as the rigid fuel pipes are routed through one of the gaps in the manifold ports. Also make a note of how the hoses to the throttle-body are routed through around the lower manifold, as it can be confusing once the upper manifold is bolted back in.

14. Clean off the mating surfaces of the cylinder head and the inlet manifold.

15. Carefully fit the new gasket to the studs on the head. It only fits one way round.

16. To refit reverse the above steps.

Sunday, 6 June 2021

1988 E30 318i Project - Check List:

 I will update this and cross things off as progress is made:

  • Straighten steering wheel.
  • Speedometer / Odometer inop.
  • Temperature gauge inop. [THIS POST]
  • Washer-jets / pump.
  • No hot air from heater-blower. [THIS POST]
  • Central locking malfunction.
  • Instrument lights flicker / dimmer function inop.
  • Clock inop. [THIS POST]
ENGINE:
BODYWORK:
  • Paint NSF wing.
  • Repair rear valance.
  • Touch up valance corners.
  • Panel above rear lights.
  • OSR wheel arch.

E30 318i [M40]: Massive air leak SOLVED - lower inlet-manifold gasket

I had checked and re-checked the idle control valve [ICV], the air-flow meter [AFM], ignition system, tested for the fuel pressure, performed tests on the DME [ECU] to make sure that was working and even laboriously tested the wiring loom for continuity, but still the engine idles terribly when cold. It ticks over lumpy, shakes the engine side to side and cuts out at will, even when power is applied. 

I checked the timing and all was good, under the rocker-cover showed no defective valves and the cam-shaft doesn't look all that worn. I guess the only thing left to check is the injectors... right?? Now hold on a minute I hear the E30 and M40 engine gurus cry, the symptoms you've described point towards an obvious massive air leak in the induction system! 

This is true and is also the very first thing I looked for and tested. Initially I performed the 'spray' test using a can of brake-cleaner (though 'Easy-start', carb-cleaner or electrical-cleaner work too, anything with alcohol content). This involves running the engine and spraying brake-cleaner around the intake-manifold, ICV, vacuum hoses, throttle-body etc. If unwanted air is being sucked in, say through a split hose, the brake-cleaner will be sucked in and combusted by the engine causing it to rev higher. If you are spraying in one particular place and the engine revs increase accordingly then you have found your air-leak. Thing is, I did this test over and over again and it showed nothing. 

I’ve heard that air can be sucked in past the injector bodies when the rubber sealing rings have degraded over time and that the lower intake-manifold is also a main culprit, but spraying round this area made no difference to the engine revs or affected the poor idle. I did a compression test and the readings were a bit low, but not enough to cause any issues.

At this point I decided it to bite the bullet and begin stripping things down. The removal of the lower intake-manifold is quite complicated because it involves removing the fuel-lines from the rail, which is why I put it off, but clearly if you want to fix something then you need to get your hands dirty so off came the fuel lines and away came the lower manifold to reveal.... well, as you can see from the photo, a virtually non existent gasket. Sigh. 

Cylinder 1 has a massive gap where the gasket is no longer there, so whenever there is a vacuum in the plenum it’s just filling up with fresh air even with the throttle-body shut and this explains why the ICV appears to be doing nothing and leads people to look there first. Whoever was refitting the manifold was obviously in a rush because the broken gasket has folded over on itself, causing the air gap to be even bigger. I guess they just tightened it hoping to make a seal, but alas no. Cylinder 2 is not much better with a noticeable gap and the rest of the gasket squashed flat. Cylinders 3 and 4 are better, but still paper thin. It looks like this may be the original gasket and the past 35 years have not been kind to it (or to me for that matter).

So... looks like I have found the culprit of the rough idle. Finally! New gasket is ordered, a snip at £6.88! Amazing how such a simple thing can cause such a severe problem and goes to show how sensitive these ‘analog’ ‘80s cars are to air metering issues!

Saturday, 5 June 2021

E30 318i: Correct Temperature Sensor fitted (Brown Plug) + wiring/loom issue

The temperature gauge in the dash has not worked since I bought the E30, which was a little worrying on my 250 mile drive home, but the car does not overheat. Oh, it has some issues with the cooling-system, like the heater-matrix pipes fitted incorrectly and an air-lock at the back of the head, but hey it doesn't overheat. Still though, I thought it best to get the bottom of the faulty temp. gauge for peace of mind, particularly with summer coming / just about here.

The M40 has two separate temperature sensors that are independent from one another. The temperature gauge works from the 'Brown plug' sensor to the rear of the head [right in pic]. The forward sensor is the 'Blue plug' [left in pic] and that connects only the DME (ECU) to tell the car if the engine is cool or warm to help with cold-start procedures. A single sensor cannot be used for both purposes on these older engines as the resistance value ranges required for each function differ, the DME being a digital circuit and the temp. gauge still working in analog. [You can read more about this on the E30 Zone Wiki HERE].

MULTIMETER TESTING:

The temp. sensors can be easily tested with a multimeter set to 20k ohms resistance. 

The Blue plug is a two-pin sensor, so test across both terminals with the multimeter and you are looking for a reading of 4-4.5k ohms for a working sensor. This sensor and plug can be accessed easily without removing any parts from the engine.

The Brown plug though will require removal of the lower inlet-manifold to access the sensor for testing or replacing. This is a single pin sensor, so place one probe of the meter to the terminal and the other to a ground-point in the engine bay or against the block/head. Expect a reading of between 1k and 1.5k ohms for a working sensor. To test the Brown plug sensor without removing any parts from the engine, you can apply the multimeter to Pin 4 of the C101 connector (main wiring loom plug in engine bay) which is easy enough to get at, or at Pin 26 of the blue connector to the right side of the instrument binnacle, though the binnacle will need removing to do this.

WRONG SENSOR / CONFUSING WIRING LOOM:

All M40 engine wiring looms use a single pin temp. sensor on the brown plug that earths through the engine block and have only a single wire in use leading to it. Some looms, using components destined for other BMW models, are known to have a second wire leading to the Brown plug temp. sensor which is redundant on the M40 motor, though this is rare and seen more often on 6-cyl. M20 looms. My car has one such loom, however and I realise that this is what has caused confusion in the past and led to the wrong sensor in fact being fitted...

Upon inspection, the rear temp. sensor fitted to my E30 is black, not brown and has two terminals. The second pin means that the sensor body earths back to the loom and not through the block so, if the redundant earth wire in my loom is not connected to a ground-point then the sensor was open circuit. I guessed that someone had ordered a second Blue plug sensor by mistake and fitted that, but it turns out the part number doesn't match and the sensor is for a completely different model engine entirely. The reading from the multimeter was over 11k ohms, something like 7.5 times what it should be! That sensor was never going to work with the E30 temp. gauge circuit whether it was earthed or not.

I ordered the correct single-pin sensor with the brown base from mr-wiper on eBay, who also supplied my Bosch spark-plugs. It was only £7.69 delivered. My temp. gauge now works, but this may also be due in part to removal of an air-lock at the back of the head due to a heater-matrix problem so coolant is now flowing properly round the area of the sensor. 

A BIT MORE ON WIRING LOOMS:

Brown / Violet, brown being the main colour, denotes that the power source provided from the temp. gauge circuit is earthing through this wire and does not need to be a closed circuit back to the gauge. The other wire is either not wired in to the loom or goes to a body-earth anyway, so earthing the sensor through the block will make no difference. This colour coding is the same for all wires in all BMW looms, I would imagine most cars are the same.

Wednesday, 2 June 2021

E30 318i: Noisy exhaust gets a bung / silencer

My E30 has a 4" straight-through Japanese tuner style exhaust back-box fitted, which to the say least is LOUD. In fact, it's one of the loudest I've heard on any car, including a Subaru turbo I had with a de-cat pipe. I figured the centre-box had also been removed from the E30, given the noise level, but find it is still there under the car and looks to have been replaced not too long ago, so I guess the only reason for the volume from this 1.8 litre 4-banger is because it never had a catalytic converter from the factory and is subject to no emission controls that bind (and quieten) modern cars. This E30 is 1988, so must have been right at the end of this phenomena.

While the loud pipe might be fun on a jaunt, working on the engine at home I find myself needing to start and idle the car constantly for testing and this is where the noise causes a problem, mainly with my neighbours and passers-by. They tolerated it for a couple of weeks, but with a few running problems that are still being ironed out and the car unable to move to another location I decided to try and mute it a bit. 

I had two options. Buy a more sociable back-box or get a silencing 'bung' for the current one. I'm not best pleased with look of the Jap-style straight-cut end pipe, I mean I like them but don't feel it suits the boxy E30 and though I'm down with car style juxtapositions all DAY, this isn't the one I would have chosen, so first looked for a replacement. New stock items are not expensive, but too much for this project, so second hand was the way, with twin 'sports' style spurious back boxes and used OEM items going for between £50 and £100. I was tempted by a nice twin square pipe from a German tuner, but the seller had no idea how loud it was and at £55, I still deemed it too pricey at this uncertain stage in the project. People at work fit ‘bungs’ to their motorbikes so I thought this was budget way to reduce the burble by a few dB.

DOES IT WORK?

Yes and no. It certainly takes the edge off the noise level, that ‘crack’ has gone, but it’s still one loud exhaust. The info says it reduces sound levels by up to 15 decibels and I have adjusted to the quietest, most restrictive setting, but without a dB meter I can’t really say if it is that much. In my opinion it’s not to that great an extent but it is somewhat quieter. 

Don’t expect the exhaust to sound as quiet as a stock back box with baffle plates. I suppose you’re never going to get a quiet exhaust tone and still enjoy the slight increase in power a straight-through pipe gives, so as ever there is a compromise, but it has certainly done the trick for me of making the car less anti-social when tuning it in my driveway! Who knows, when I get the E30 out and about over the summer the bung may well be coming back out.

Monday, 31 May 2021

E30 318i M40: Bosch injectors and tips - checking condition

Next on the agenda to find the culprit of the rough running and stalling idle was to examine the injector condition and the plastic tips. The injector bodies are quite rusty and corroded so they could well be the original set, but on closer inspection the tips are fine and they look to be in pretty good condition, so onwards.

To inspect the injectors the lower inlet manifold will need to be removed, which involves de-plumbing the fuel lines and some of the water hoses. 









E30 318i M40: Camshaft and valve condition

I whipped the rocker cover off to check if there was a dropped valve or broken spring that might be contributing to the poorly idle, but no such defect found. In fact, this has to be one of the cleanest top ends I have ever seen. Nice!

BMW E30: Digital Clock quick LED upgrade

The bulb had blown in my E30’s digital clock, so I decided to repair it with a quick and easy LED upgrade. It’s another bulb load of power taken off my 35 year old dash wiring so can’t hurt. 

The bulb-holder is integral to the working of the lamp, with the metal clips that hold it in place also acting as live/earth contacts. LEDs built into such a holder can be purchased specifically for replacing bulbs like this if you want to go that route, but if you have a bunch of cheap LEDs lying round and don’t want to spend any money then read on.

Simply remove the plastic holder and cut the old bulb away from the two pieces of metal. Solder a cheap yellow or red LED onto the metal contacts in the place where the bulb was attached and bend the LED stalks back on themselves so the diode is pointing the right way, as in pic. A pure-white LED would probably be better, but they use more wattage, will probably require a spend and cheaper dome LEDs work fine anyway.

The bulb for the clock has a resistor built in anyway, so the LED will run fine and not pop without modification, but if you find it is too dim or bright to you can ‘piggy-back’ another resistor across the stock one to raise or lower resistance to suit. A calculator to help work out what resistance you need are easily available online, but trial and error is best if you have a bunch of LEDs / resistors lying round.

You may want to cover the recess at the back of the clock with electrical tape to stop light spilling out.

E30 318i M40: Misfire and self-revving - symptoms of major induction air-leak

This video shows the symptoms of an air-leak in the induction system, where unmetered are drawn in after the throttle-body causes a terribly poor idle, a permanent misfire and the engine to rev itself gently. The tendency is to look at the ICV (idle control-valve), ignition coil, AFM (air-flow meter) etc., but chances are it will be an air-leak on the induction. In this case it turned out to be a damaged and disintegrated gasket where the lower inlet-manifold mates to the cylinder-head. 

Sunday, 30 May 2021

BMW E30 Heater Matrix Hoses Configuration - Right and Wrong way round + how to bleed matrix / remove air-lock

My E30 had little or no hot air from the blower inside the cabin. I have heard it is common for the two hoses running to the heater matrix to be fitted back to front, so the flow of coolant through the core is reversed. This causes air locks and severely reduces the amount of coolant flowing through the heater matrix, thus no hot air. 

The reason these hoses so often get fitted incorrectly is due to their location and the way they look when fitted. It appears obvious that the upper hose (back of cyl.-head to heater) goes to the upper stub on the heater-matrix and the lower hose (side of block to heater) goes to the lower stub on the matrix. The hoses look happier this way round, but the matrix and heater-valve are designed in such a way that flow is interrupted and causes the air-lock. 

The correct way round is actually with the upper hose connected to the lower stub and the lower hose to the upper stub, which does of course appear to be back to front, but is essential for correct flow of coolant round the whole engine, not just the heater-core. The correct and incorrect hose configurations are shown in the pictures below.

RIGHT:

WRONG:

How to Bleed system and remove air-lock from Heater-Matrix:

** This is not the normal air-bleeding process when refilling an empty system with coolant, this process is to bleed a system with the air-lock at the back of the head and / or the heater-matrix full of air. **

1. Ensure heater-matrix hoses are fitted the correct way round, if not swap them over. [You should notice if there is an air-lock that no coolant comes out of the hoses when removed from the matrix and the stubs appear dry].

2. Fully tighten the lower [inlet] hose.

3. Leave the upper hose disconnected from the matrix. 

4. Remove the radiator bottle cap. Assuming the coolant level is up to the halfway / max. mark, there should be some gulps of air and the coolant level should drop slightly in the rad. bottle.

5. Cut the bottom off a 2-litre drinks bottle and fill it with water, holding your hand over the lid.

6. Dump the water from the drinks bottle into the radiator bottle, allowing the weight of water to push the remaining air though the system. Water should start to come out of the upper heater-matrix hose from the head. Block this hose with a finger.

7. Continue to top up the radiator bottle with water until water begins to flow out of the upper stub on the heater matrix and quickly refit the upper hose, which can now be fully tightened.

8. Drain the radiator bottle back down the halfway /max. / fill line.

** You should be good to go, but can now bleed / top-up the system using the usual bleeding procedure if necessary. **

Wednesday, 26 May 2021

BMW M40 Engine - how to check timing, where the marks are located

This must be one of the hardest bits of info to find in the whole world of BMW, but there is a great post on BMW Werks on how to do it [https://www.bimmerwerkz.com/threads/m40-motor-timing-info.59059/].

QUICK TIMING CHECK GUIDE:

** Only if crank pulley has NOT been separated from crankshaft! **

1. Remove the distributor / timing cover at the front of the engine.

2. Check the timing mark on the crank pulley. This is an arrow cast into the block which should line up with the sprocket tooth to the right of the gap in the teeth, as in pic below.


3. Check the timing mark on the camshaft pulley. This is a notch/line mark in the pulley and should line up with the right-angle notch in the cylinder head, as in pic below. If this looks good, your timing is fine.


Thanks again to xdrian on BMW Works for making these pics and sharing this secret!

Monday, 24 May 2021

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. 


Sunday, 25 April 2021

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

Monday, 12 April 2021

E46 318i Touring: Back on the road with new battery!

Despite paying road-tax and insurance on the E46 Touring it's been laid up for 6 months and with an improvement in the weather it's high time I put it back on the road. All it really needed was some air in the tyres and the brakes beating up. The battery was totally dead, however. The previous owner had put an AGM [automated glass-mat] battery design for vehicles with Start/Stop technology on it, which was great but clearly the 19 year old alternator and charging setup on the E46 was not up to the job of charging it properly. Ah well, it has lasted for over twelve months... 

I've always sworn by Bosch batteries, but the £100+ price tag these days, yes even with a Euro Car Parts discount code, is a bit too expensive for this car. ECP, as well as the parts dept. at work can offer a budget Lion battery for a little over £50, but I have been warned by everyone willing to give their fifty pence that these don't last five minutes and I should avoid like the plague. Ultra-budget batteries can be found on eBay for as little as £27, but who knows anything about their quality.

At this point I have to hand it to the parts dept. at work here, who loaded me up a Yuasa 3110 series battery [760Ah] for just £60 all in! Yuasa get a good write up, in fact I am told they beat Bosch in tests and are currently one of the best on the market. ECP could offer me a Yuasa for £67, but it was a tiny little square battery and this just goes to show how useful working or knowing someone in the motor-trade can be...



Thursday, 1 April 2021

F10 530d: Water in Battery well / Bootwell / Trunkwell - where is it leaking?

I lifted the boot/trunk floor to jump-start a friends car and noticed that my battery well / spare-wheel well is full of dirty water.... oh dear. I’ve got a leak... but where? Boot seal? Bottom of the rear windscreen? There was a second aerial / antenna fitted in the roof that I removed, so figured it might be leaking through there and running down the C-pillar into the boot, but no water marks in the headlining or signs of ingress... Think I will have a proper look this weekend and try get to the bottom of it!



Friday, 19 March 2021

BMW MOST Bus - Troubleshooting Guide [Vlad on MCA]

 Great guide to the BMW MOST Bus (Media Oriented Systems Transport), used in all BMWs with fibre-optic connectivity. It covers what it is and what it does, as well as troubleshooting a lot of associated problems with these complex systems. It is from Vlad at MCA.org and can be found here: 

https://mca.electricmura.ro/en/blog-bmw-most-troubleshoot/



Sunday, 14 March 2021

F10 530d: N57 EGR / Cooler related fault-code scan results

 Been getting the 'Drivetrain' malfunction message on my F10 530d iDrive and figured it likely to be EGR (exhaust-gas-recirculator) related, so plugged in a Snap-On Modis scanner and these are the codes I got, which are what I suspected to be honest. The EGR and EGR-cooler are known to pack in on the N57 series of engine, the latter of which can leak coolant into the inlet causing a bit of smoke on startup. 


28E200 - Exhaust Gas Temperature sensor before Cat, open circuit

255C00 - EGR Controller, Position Control, Valve open too far

190900 - EGR Mass Air Flow, measured plausibility calculated too high

240400 - EGR Control, control deviation air mass too low

272F09 - EGR, mechanically faulty close to open position

272E00 - EGR, mechanically faulty close to closed position

So, I have the classic two codes of the EGR failing close to open and closed position, which denotes a stuck EGR valve, which is quite common on all diesel engines, along with the EGR mass-air codes where values are higher and lower than they should be, which clearly ties in to the valve sticking in the open and closed position. Faults for the EGR control-module show that it is struggling to position the EGR correctly and this all points to one stuck EGR valve.

I also notice that I am getting a bit of smoke on startup sometimes which I have never noticed before. This also points to a faulty EGR-valve, or rather the cooler itself. The EGR-cooler is fed with coolant to reduce the operating temperature of the EGR-valve itself and these are known to have problems with leaking after time. They crack inside after prolonged use and start to leak coolant into the EGR and thereafter the air-intake, which causes a bit of white smoke on startup, which I have been experiencing the last few weeks and so it looks like this is the culprit and I will be replacing the EGR / cooler unit at some point I would imagine... watch this space.