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Inluvwithmy1602

Intermittent Starting Woes

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Hey chaps

 

I've been having some issues with my '86 Eta.

 

The car runs and drives extremely well when it goes - the problem is that it has an intermittent and rather annoying non-start issue. The non-start events are completely erratic with the car running fine one minute, then failing to start the next. For example I can pull in to a filling station, turn off the ignition and fill up with fuel and when I go to start the car it just turns over with no attempt to fire. I can drive the car for two weeks (it's my daily driver) without the problem presenting itself at all. Then all of a sudden the problem comes back.

 

Now I have read the fantastic Motronic non-start guide by Duncan and have since changed the DME and Fuel Pump relays for brand new ones from BMW, and changed all the fuses in the fuse box and squeezed the terminals to ensure a decent grip. I'm sure that the battery is good as it turns over just fine. I'm finding it difficult to diagnose the problem with a multi-meter as sod's law dictates that the car behaves itself impeccably when i get the tools out!

 

With the relays and fuses changed I'm thinking that the culprit may be the speed and crank position sensors. Do I just bite the bullet and buy new ones anyway and hope that solves the problem? Any attempt at testing anything with the multimeter has been futile thus far because the non-start issue always seems to occur when I'm in a hurry (i.e. on the way out to work in which case I jump into my trusty '02 and get to work that way) and when I subsequently have time to investigate the problem's not evident!

 

One thing I have tried when the car won't start is rocking the car a few feet back and then forth with the gearbox in Drive in an effort to help the crank and speed sensors 'find their mark'. Doing this a couple of times seems to result in the car starting - but then again in the past just sitting patiently for 5 minutes and then trying to start has also yielded success.

 

I'm at a loss as to what to do as I feel like I'm just chucking money at the problem blindly. In an effort to save a bit of cash I have been looking at getting the crank and speed sensor replacements from GSF when they next publish a 50% off code which will make them around £30 each. Anyone had any experience of non-genuine sensors?

 

As ever, any advice gratefully received.  

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Its pretty simple set up and you've changed the obvious - have you been through the earth points?

 

I had one that made enough contact sometimes but not others causing lots of head scratching - the one that stumped me was on the back of the head which grounds the injectors among other things.

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A broken wire at the plug end of the crank sensor caused the exact symptoms described on my 535i I managed to resolder it until I got a new one. 

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I had an intermittent engine issue with the Bronzitbeige Eta that took over 18 months to resolve.  The biggest problem is that you cannot diagnose it because it is intermittent.  It would never stay broken for long enough to diagnose and never at the garage with all the tools and manuals :x

 

After using the Bentley manual and steadily working my way through all of the engine management sensors, AFM, ICV, engine management loom all that was left was the engine management control module.  Replaced the module and the engine has been sweet now since 2008.  It should be as by then it was running a completely new engine management system.  That fixed it.

 

Might be worth running the car with a known good spare control module and see if the issue resolves / persists. 

 

Over on my28.com some of our American brothers carry spare relays, sensors, control modules on longer road trips just in case...

 

Regards,

 

Mick

 

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9 hours ago, Ordnator said:

I had an intermittent engine issue with the Bronzitbeige Eta that took over 18 months to resolve.  The biggest problem is that you cannot diagnose it because it is intermittent.  It would never stay broken for long enough to diagnose and never at the garage with all the tools and manuals :x

 

After using the Bentley manual and steadily working my way through all of the engine management sensors, AFM, ICV, engine management loom all that was left was the engine management control module.  Replaced the module and the engine has been sweet now since 2008.  It should be as by then it was running a completely new engine management system.  That fixed it.

 

Might be worth running the car with a known good spare control module and see if the issue resolves / persists. 

 

Over on my28.com some of our American brothers carry spare relays, sensors, control modules on longer road trips just in case...

 

Regards,

 

Mick

 

 

Thanks for the advice Mick - I will be on the look out for a control module. Maybe someone coming to Fort Nelson might have one for loan or sale?

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15 hours ago, Sam535i said:

A broken wire at the plug end of the crank sensor caused the exact symptoms described on my 535i I managed to resolder it until I got a new one. 

Thanks Sam

It's good that you managed to track down the problem and temporarily repair your sensor. I'll take a closer look at the sensor cables this weekend weather permitting. 

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17 hours ago, duncan-uk said:

Its pretty simple set up and you've changed the obvious - have you been through the earth points?

 

I had one that made enough contact sometimes but not others causing lots of head scratching - the one that stumped me was on the back of the head which grounds the injectors among other things.

Thanks Duncan

I'll take a look at the ground points this weekend. Any ground points that are not obvious that I should be aware of? 

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1 hour ago, FIVE-OH said:

A dry solder joint within the ecu is not that uncommon. If your handy with a soldering iron, it may be worth a look.

Thanks five-oh. Will investigate the ECU in turn. Cheers

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I take it that it was a broken wire that you had to replace rather than a corroded terminal?

No just not quite nipped up.

 

I'd replaced the head and obviously didn't tighten it. It was fine but movement of the engine would sometimes break connection. Engine rocks back and it was fine.

 

Of course when static everything checked out

 

 

Sent from my iPhone using Tapatalk

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My pain lead to the no start guide. I had a box in the boot with a set of spares. Afm, coil, relays, Ecu, plug leads, dizzy cap, rotor arm and pulse sensors. Figured that if it broke down I could get it going if I had the parts. Never needed them but have peace of mind especially when I went to France in it.

 

 

Sent from my iPhone using Tapatalk

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My money would be on the crank sensor. If the ECU can't read the flywheel rotating from the crank sensor then it won't fire up. Its one of the cheaper parts to replace and they do wear out with time. When the crank sensor stops sending the signal, the engine will just crank over and will do nothing else as the ECU will stay inactive.

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15 hours ago, Goldsoul said:

My money would be on the crank sensor. If the ECU can't read the flywheel rotating from the crank sensor then it won't fire up. Its one of the cheaper parts to replace and they do wear out with time. When the crank sensor stops sending the signal, the engine will just crank over and will do nothing else as the ECU will stay inactive.

 

Hi Goldsoul

 

Well I replaced the crank position and speed sensors last Tuesday night and I have not had any starting problems thus far. Because the problem was intermittent I'm reluctant to state that the problem has been cured but it looks promising so far.

 

Oh, and if anyone's interested I got the sensors for £15 each from Paddock Spares a land rover parts supplier. The sensors from the 525e are the same as those used in the land rover discovery 300 TDi and are pretty cheap compared to other places. 

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Nice find,  ;) how did you work out that the sensors were the same. I did know that Landrover use a similar gearbox model though.

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1 hour ago, garym535i said:

Nice find,  ;) how did you work out that the sensors were the same. I did know that Landrover use a similar gearbox model though.

I saw parts listed on eBay for the 525e cross-referenced with a land rover part number and did a bit of digging around. Land rover part no. ERR2079 is the same part and even has the same length cable as the original sensors - I am told some sensors for the E28 sold through the big after market parts suppliers have cables that are a little longer which means you have to tie or tuck up the excess cable. These land rover ones have been working perfectly since I fitted them a week ago - I use my eta as a daily driver btw. The cost of the sensors from the stealers is £130 each, so £15 is a bit of a steal.

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Good find that, I work for the BMW group and get staff discount on genuine parts and and paid £65 for mine and thought that I was doing well at that price. :unsure:

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