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Hello, E28 528i M30 L - Jetronic engine guru's! Help needed


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46 replies to this topic

#1 e34525isport

e34525isport

Posted 24 October 2008 - 10:12 AM

Hello all, i'll start off by saying the car in question is an E30/E28 transvestite... :o

My car is a genuine 1985 (pre-facelift) E30 Hartge H28. The conversion took place when the car was new and it was based on the then of the range 323i.

The base engine Hartge used for the conversion was the 2.8i M30 with L-Jetronic management, yes you've guessed it, the same setup used in the E28 5 series... So that will explain why i'm posting on here and not on the E30 Zone! :D

The problem...

With the engine stone cold it is quite difficult to start, you either have to keep it turning over for approx 5/6 seconds in order for it to fire up OR give it some throttle and it will start quicker. Once started it will be lumpy for a short moment and then all of a sudden it will settle at a very constant idle speed and run perfectly (but strangely enough occasionally the engine will fire up perfectly, especially if it has been left for a few days :?)

When the car is warm i can shut the engine off and start it back up again on the turn of the key, it runs beautifully, but if i leave the engine off for 20 mins/half hour or so it will gradually become a little more hesitant to start, the more so the longer i leave it.

Am i right in saying the injectors, dizzy cap, rotor arm and spark plugs are ok as if one of or a few were inop the engine would run terrible all the time? The sparks were actually only replaced about 2000miles ago.

Am i also correct in saying the fuel pump relay, fuel pressure regulator, fuel pump and filter is ok as the car runs A1 with no defect whatsoever once its been running for a short while, even before it reaches operating temperature. The only issue is the initial start up period when cold.

What would one suggest i should replace next?

The cold start injector?

So far i've replaced the coolant temp sensor and thermotime switch with no avail.

The car only has 42000 miles so it should not have any major wear problems

Thanks

#2 Steve_H_

Steve_H_
  • LocationKingsclere Hants
  • Occupation:Witch finder General

Posted 24 October 2008 - 11:27 AM

Sounds like you have a rather cool car, not sure it really classes as being a transvestite though! This is of no help but my E28 528 has very similar start up symptoms at times. As I don't drive mine an awful lot and it hasn't caused me any real issues I haven't done anything about it but it would be good to know what is causing it.

By the way, I have been strongly advised against prodding the throttle on start up as it can cause damage.
1985 E28 528I cheap chariot!

#3 Robbo

Robbo
  • LocationDubai, UAE

Posted 24 October 2008 - 11:36 AM

You need to look at the cold start injector yes.

If you are sure the time switch is ok, and the correct one as there are different types.

You are probably aware this is what tells the cold start injector to fire.

I thought loss of pressure at the fuel rail as well tbh, sure that side of it is ok?
Posted Image
No BMW now, just a V8 VW :(

#4 e34525isport

e34525isport

Posted 24 October 2008 - 12:14 PM

Right a little update, i started the engine just now having left it overnight and i purposefully did not press the throttle. It was a pig to start :evil: it would fire up eventually after a few somewhat lengthy attemps but once it fired it ran VERY lumpy to the point that i had to press the throttle or otherwise it would stall, but after giving it a little gas for a few seconds it ran fine. Also i have found that if i crank the engine up with a little gas on the first attempt it will fire up straight away.

Also when it's been running after a while it will start no problem at all, even if i left it for half hour/hour it would become hesitant in starting but no way as bad as when starting it up when its been left for overnight and is stone cold.

I'm open to any suggestions, it could even be any of the things i suggested it could not be, who knows :roll:

Robbo, i have replaced the thermotime switch if this is the same thing?

Another thing to mention is that after i crank the car, even if it doesn't start ii still get a strong smell of fuel around the engine? Would this suggest that maybe this side is ok?

#5 Sir Anthony Regents-Park

Sir Anthony Regents-Park
  • LocationSheffieldshire

Posted 24 October 2008 - 12:56 PM

It sounds like it may be losing fuel pressure when stood. Although I've never seen one, don't some 528i's have a fuel lift pump? This sits in the tank and supplies the main fuel pump. A 1985 E30 never had such a thing. Really you need a fuel pressure gauge to measure the residual pressure in the fuel line. If you find it's dropped to nothing, the pump has to work like hell to build the pressure up again to around 2.5 bar.
A bad set of plugs will make it a cow to start. So, you need to check the fuel pressure (residual and running) and plug KV's.
A dying fuel pump relay will cause similar symptoms.

Classic BMW Service and repairs.


#6 andyb

andyb
  • LocationIlford, Essex

Posted 24 October 2008 - 01:34 PM

What he said ^^^^^

My old 528 was a pig to start from cold, and pretty sure fuel lines/hoses were allowing loss of fuel pressure over time. And yes it had both a fuel lift pump in the tank and a main pump above the diff/axle.

The cold start system is supposed to operate the separate injector when water temp is below a cerain point, and the injector could be faulty or even leaking, and so the smell and overfuelling. Believe the idle revs should be raised as well when cold start operates, but mine never idled at more than about 800rpm (neither does my motronic 3.5)
1986 Lachs silver E28 535iSE on 70k and now GONE Posted Image
Fitted 740 front and 540 rear calipers, disks, braided hoses and yellowstuff pads
Sitting on H&R and Spax lowering springs and 17" Alpinas

Posted Image

#7 JohnH

JohnH
  • LocationJ6 M25
  • Current Car:E28 527i

Posted 24 October 2008 - 04:52 PM

I have exactly the same symptoms with my 520i, and have had for a number of years. I don't think its a (lack of) fuel pressure problem as L-jetronic runs the fuel pump for one second when you turn the key to the run position to build up fuel pressure prior to starting. All the symptoms point to an excessively rich mixture at start up. I think the problem is a weeping injector. Either a main or cold start injector (I don't have one of these as I run LE2-Jet). I think the solution is to get your injectors professionally cleaned and rebuilt.

#8 Warp One 535is

Warp One 535is
  • LocationHalfway up the left side of Lake Michigan
  • Occupation:Damned Lawyer

Posted 24 October 2008 - 05:06 PM

Assuming you need to mess with the CSV (Cold Start Valve) or the fuel line going to it, here is a description of how I go about the job.
C.R. Krieger
Posted Image

#9 JAM172

JAM172
  • LocationEast Sussex.
  • Occupation:Projects manager
  • Current Car:E28 528i & E28 M5 (Track car) & E39 530d

Posted 24 October 2008 - 06:18 PM

I have a very nice 55000 mile 528i and it has always been a bitch to start in exactly the way you have all described, I am inclined to agree with JohnH, i think it is down to leaking injectors, i have replaced the Cold Start Valve, had the fuel pressure checked all to no avail :evil: At the very start of this post it was stated that sometimes it would fire up on first turn of the key, mine is exactly the same albeit not very often, i have learn't to live with it :roll:
Posted Image
87' E28 M5 (Nr172), 87' E28 528i, 87' E28 525e

#10 tandino

tandino
  • LocationWestfield East Sussex

Posted 24 October 2008 - 06:38 PM

My M535i was exactly the same as yours and Jamie's.
Now owned my Mark (Splondike) and im not sure if he ever got to the bottom of it?
93 E34 Lagoon Green M5 Hartge - Gone but defo not forgotten,
95 E34 Fjord Grey 540i/6 - Gone to a mate,
85 Agate Green M535i - Gone to Splondike!
86 Arctic Blue 525E - Not gone!

"If you ain't broken it you ain't trying hard enough!!"

#11 smokeydan

smokeydan
  • Locationmanchester
  • Occupation:sound engineer

Posted 25 October 2008 - 02:01 AM

Another thing to mention is that after i crank the car, even if it doesn't start ii still get a strong smell of fuel around the engine? Would this suggest that maybe this side is ok?


I experienced a similar thing with my 528, I think that the strong smell of fuel around the engine is a sign that you have a fuel leak, which is not ok!! and might be the cause of the problem. Maybe the csv is defunct or the fuel hose running to it has perished. (a fairly common problem) Its hidden under the inlet manifold, so not easy to spot/get to
Posted Image

#12 Sir Anthony Regents-Park

Sir Anthony Regents-Park
  • LocationSheffieldshire

Posted 25 October 2008 - 12:04 PM

If an old LE Jet engine's injectors were leaking enough to flood the engine, the residual fuel pressure would drop. One of the first things you look at.
Does it have a cold start injector? If so, does it work? You need to test for voltage, and if there's nothing there, check for voltage at the temperature time switch - this is the big screw in sensor on the thermostat housing. If it's failed (and they do), the cold start injector won't work and it'll be like trying to start an old Mini with no choke. Voltage comes from the starter motor and ECU pin 4, into the temp time switch and then to the cold start injector. Chase volts all the way back to terminal 50 on the fuel pump relay if you have to.
Later cars did away with the time switch and the cold start injector and did everything from the ECU and coolant temp sensor.

The coolant temp sensor is the small one the same size as the sender for the temp gauge, the time switch is a big bastard, something like a 22mm iirc.

The smell of fuel could be a leak, and could be the stink of a flooded engine. These need a really good ignition system - what are the plugs, cap and rotor like?

Classic BMW Service and repairs.


#13 JAM172

JAM172
  • LocationEast Sussex.
  • Occupation:Projects manager
  • Current Car:E28 528i & E28 M5 (Track car) & E39 530d

Posted 25 October 2008 - 01:20 PM

:roll: Would my 1987 528i have the temperature time swich :?: I havealready replaced the cold start injector, no luck
Posted Image
87' E28 M5 (Nr172), 87' E28 528i, 87' E28 525e

#14 Sir Anthony Regents-Park

Sir Anthony Regents-Park
  • LocationSheffieldshire

Posted 25 October 2008 - 04:20 PM

I got it wrong again.

According to Real OEM, they all do - even late ones like yours. I could have sworn they got rid of them around 1985 - M20 engined cars got rid of the cold start injector in '85 and had a different ECU.

Oh well.....

I guess the thing to do is make sure the temp switch is doing its job. Test resistance above 40 degrees C.

1.) Between terminal G and earth, 50-80 ohms.

2.) Between terminal W and earth 100-160 ohms

3.) Between terminals G and W. Below 30 degrees C, 25-30 ohms. Above 40 degrees, 40-80 ohms.

W and G are marked on the switch where the plug fits in.

Classic BMW Service and repairs.


#15 JAM172

JAM172
  • LocationEast Sussex.
  • Occupation:Projects manager
  • Current Car:E28 528i & E28 M5 (Track car) & E39 530d

Posted 25 October 2008 - 04:48 PM

:? ok, i have just been out to try to work out which of these sensors is the time switch, there are three, the small one i am guessing is for the temp guage :?: There are two others side by side, the one closest the rocker cover is white and to it's right is the same size but brown, any ideas :?:
Posted Image
87' E28 M5 (Nr172), 87' E28 528i, 87' E28 525e

#16 JAM172

JAM172
  • LocationEast Sussex.
  • Occupation:Projects manager
  • Current Car:E28 528i & E28 M5 (Track car) & E39 530d

Posted 29 October 2008 - 01:39 PM

Ok, I have located the part needed and cost from the main dealer. an expensive gamble:

Temperature time switch p/n :13621274630
Sealing washer p/n: 07119963200

Cost inc: vat £60.71.

How sure are we that this is the problem :roll: :?:
Posted Image
87' E28 M5 (Nr172), 87' E28 528i, 87' E28 525e

#17 Sir Anthony Regents-Park

Sir Anthony Regents-Park
  • LocationSheffieldshire

Posted 29 October 2008 - 04:18 PM

You need to test the old one with a scope/multimeter. No point in changing it if it's working!

Classic BMW Service and repairs.


#18 Ka-50

Ka-50
  • LocationLondon

Posted 29 October 2008 - 05:18 PM

I have a thermo-time switch on my '87 528i!
I've just managed to find an old Testing Schedule for the L jetronic system this is a schedule for some kind of crypton tune system or similar which refers to certain test leads so I'll try to give you the lowdown of it which you can check with a multimeter.
The thermo-time switch has letters G and W or K marked on the terminal housing to indicate the heater winding and switch terminals respectively. G is the connection to the winding and K/W is the connection to the switch.

Procedure:

1. Ensure that the engine is cold, i.e below 30C
2. Pull the connector off and measure between G and K/W (this should measure through the switch and heater winding) this should measure between 3-5 ohms.
3. Measure between vehicle earth and K/W terminal this should measure zero which indicates the switch is closed.
4. Push the connector back on and run the engine for a while. When the temp exceeds 35c measure between K/W and earth again you should get 100 ohms - infinity (the switch should open)

Posted Image

Hope this helps
Remember, speed doesn't kill it's the rapid deceleration on impact

#19 JAM172

JAM172
  • LocationEast Sussex.
  • Occupation:Projects manager
  • Current Car:E28 528i & E28 M5 (Track car) & E39 530d

Posted 29 October 2008 - 05:57 PM

I have a thermo-time switch on my '87 528i!
I've just managed to find an old Testing Schedule for the L jetronic system this is a schedule for some kind of crypton tune system or similar which refers to certain test leads so I'll try to give you the lowdown of it which you can check with a multimeter.
The thermo-time switch has letters G and W or K marked on the terminal housing to indicate the heater winding and switch terminals respectively. G is the connection to the winding and K/W is the connection to the switch.

Procedure:

1. Ensure that the engine is cold, i.e below 30C
2. Pull the connector off and measure between G and K/W (this should measure through the switch and heater winding) this should measure between 3-5 ohms.
3. Measure between vehicle earth and K/W terminal this should measure zero which indicates the switch is closed.
4. Push the connector back on and run the engine for a while. When the temp exceeds 35c measure between K/W and earth again you should get 100 ohms - infinity (the switch should open)

Posted Image

Hope this helps


Excellent, thanks very much.

Thanks to you too Andy.
Posted Image
87' E28 M5 (Nr172), 87' E28 528i, 87' E28 525e

#20 JohnH

JohnH
  • LocationJ6 M25
  • Current Car:E28 527i

Posted 29 October 2008 - 06:31 PM

So far i've replaced the coolant temp sensor and thermotime switch with no avail.

The car only has 42000 miles so it should not have any major wear problems

Thanks

JAM172, based upon e34525isports original description of the problem, it would appear that the thermotime switch may not be the problem.

From reading the VIII/86 handbook, it says 'If the engine does not start at the first attempt, e.g. in very cold or hot conditions, press the accelerator pedal half-down when trying again.' Presumably to allow more air through to weaken the mixture. It then goes on to say 'Run the starter long enough to for the engine to start, no longer than 20 seconds without a break'. Reading between the lines it sounds as BMW also had problems, and this was nothing out of the ordinary!

I think seventhirtyeye's point about the ignition/starter system needing to be up to scratch may be the solution. to quote from 'Bosch LE Jetronic (BMW) Copyright Equiptech',

'Basic ECU operation

When the ignition is switched on, voltage is applied to the fuel injection relay. Once the engine is cranked upon the starter,
cranking voltage is applied to ECU pin 4 and relay terminal 50. The relay windings are energised, the relay contacts close and
voltage is output at relay terminal 87 and either 87a or 87b (depending on vehicle). Voltage is thus applied to the ECU at terminal
9, AFS, TS, AAV (electrical type) and the fuel pump.

Once the engine speed rises above 400 rpm, a speed signal from the ignition coil terminal 1 to terminal 1 of the relay and
terminal 1 of the ECU holds the relay contacts energised. If the engine speed falls below 400 rpm, the relay will be de-energised
and the relay voltage output will cease. The engine will stop.
'

So it would seem that you need to get up to 400 rpm before things start to happen when the key is in the start position.

I also read somewhere that the ignition earth circuit takes different paths depending upon whether the ignition key is in the start or run positions. With my car if it doesn't start at the first turn of the key it often struggles into life after I release the key from start to run. Prehaps its a bad earth.

I dont known whether that helps any. Maybe its just that, the starter motor isnt up to the job, or the battery is down on power.

#21 Sir Anthony Regents-Park

Sir Anthony Regents-Park
  • LocationSheffieldshire

Posted 30 October 2008 - 10:52 AM

Good point - I had a 525e that was a bastard to start. I replaced the starter and it was fine after that - it really span it over good and fast.

Classic BMW Service and repairs.


#22 e34525isport

e34525isport

Posted 30 October 2008 - 10:16 PM

Wow thanks for the replies and info. A litte update, so far i've replaced the thermotime switch, cold start sensor,
dizzy cap, rotor arm, fuel pump relay and tomorrow i'll be replacing the fuel pressure regulator.
I've also replaced all the small 4mm rubber hoses on the engine and the rocker cover breather pipe as they were
a little perished too. Hopefully the fuel pressure regulator will sort it out but if not its down the route of the
injectors next :roll:

My E30 is a pre-facelift model with the fuel pump under the car instead of in the tank like the face-lift models.
I believe Hartge left the fuel system alone in the E30 so it should be a standard pre-facelift setup which does not
have a pre-fuel pump. I'll keep you updated as i will get to the bottom of this! :twisted:

#23 e34525isport

e34525isport

Posted 31 October 2008 - 10:11 PM

Right i've replaced the fuel pressure regulator, i'll test it tomorrow morning to see how it starts or if anything has changed. Its an interesting point about the starter motor, even though mine sounds like it turns over correctly and fast enough, the second the engine is fired up i hear a metallic kind of 'ping' sound. I've never thought anything of it and thought it must just be an M30 trait. Does anybody else get that noise and would this also indicate a tired starter motor? Cheers

#24 JohnH

JohnH
  • LocationJ6 M25
  • Current Car:E28 527i

Posted 01 November 2008 - 07:28 AM

Cant say I remember any funny noises with my old 528i. I now have its starter motor fitted to my M10 engined '02 which cured its bad starting behaviour.

We await your test in the morning with baited breath, though you would really need to go through several cold start cycles to be sure. Keep us informed.

#25 umquat

umquat
  • LocationSouth Notts
  • Occupation:Software Engineer

Posted 07 February 2010 - 11:13 AM

Be interested to know how things turned out with this one? Its been over a year since the last post
83 Saab 99 with Saab minilites Azure Blue

71 Beetle, 1300, Orange

Former owner of 86 E28 520i Auto, Zinnoberrott

#26 e21Jason

e21Jason
  • LocationEdinburgh
  • Occupation:Consulant Enginner

Posted 07 February 2010 - 10:54 PM

I have the full jetronic bosch manual (from a dastun but it is very detailed) for such a rare car drop me a PM with your address and I will send a cd over

Jason
E36 328 touring
E36 M3 Compact
s50'd e21 race car

#27 e34525isport

e34525isport

Posted 09 June 2010 - 04:52 PM

Hi guys just a little update, after replacing everything all that is left to do is the injectors. They are removed and are being sent off for a full refurb so will report back soon. After thinking about it all it could be is faulty/leaky injectors because when fuse 11 for the fuel pump is removed till the fuel lines are empty and the engine dies on cold start up, if the fuse is put back in and the engine is restarted it fires straight up on the button where as if the fuel lines are left pressurized the cranking takes a good 3-5 seconds. This would explain ...

If left for a few days (the longer the better) the car starts on the button. I left it over winter for 4 months untouched and it started better than ever, like new.

If run and left over night the car is fairly difficult to start on the morning, throttle helps if pumped/held wide open and the car splutters for a brief moment before it fires into life (approx 5 seconds of cranking)

Once warm if car is started again within say 10 mins the engine fires up fine on the button (the sooner it is started the better).

If left anymore than 30 mins the car gets more difficult to start and even more so the longer it is left.

Engine idle is not 100% steady, once warm and put into drive the car idles at approx 500 rpm, sometimes slightly lower but if the throttle is blipped in neutral the idle speed will increase to say 750rpm (but it always differs) and when put back in drive with my foot on the brake the idle speed will lower itself again to 400/500rpm but the car runs smoothly and never wants to stall. Driving is normal it's just a low idle issue when the engine is put in gear.

Anyway after 25 years i'm sure an injector refurb would be beneficial even if it ain't the cure but i'm pretty optimistic it is.

#28 abdoosh00

abdoosh00
  • LocationLeeds

Posted 09 June 2010 - 06:48 PM

I had the same issue on my 520, I replaced the cold start injector and all went fine from there. not sure if yours has one anyway. its worth checking if it does!!!

#29 Alex

Alex
  • LocationBradford
  • Current Car:BMW E28 528i

Posted 09 June 2010 - 06:53 PM

My cold start injector made the world of difference for me too!
1983 528i se (in bits)
Posted Image

#30 JAM172

JAM172
  • LocationEast Sussex.
  • Occupation:Projects manager
  • Current Car:E28 528i & E28 M5 (Track car) & E39 530d

Posted 20 October 2011 - 02:56 PM

Thought I would update this thread as I still have cold starting issues with my 528i. I have found this link and there are some interesting items with, with particlar reference to the auxilary air valve. Although the L-jetronic relates to an Alfa GTV, the principles are the same, see what you think.

http://www.hiperform...m/Ljetronic.htm

Edited by JAM172, 20 October 2011 - 02:56 PM.

Posted Image
87' E28 M5 (Nr172), 87' E28 528i, 87' E28 525e




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