FAO Seriously Knowledgeable People - E85 Electrical Problem

R

RJS-Z4

Senior member
 SE London/Kent
Hi all, been away for a while but I see some of the same faces are still around...

Some of you may remember some time ago I posted about my z4 cutting out, well the garage traced the problem back to the DME, and I found a like for like perfect replacement, I assumed it was fixed and posted as such... but unfortunately this didn't solve the problem. Since then I've been able to find another like for like replacement and my z4 has been a driveway ornament for some 5 months now.

I'd love some expert opinions if I may, I've tried to outline as shortly as possible below the series of events:

  • On a summer evening drive, flying along quite happy with the roof down the car just cut out. Thankfully it restarted and I thought no more of it, but in the coming weeks it began to do it more and more and be more and more difficult to restart.
  • Upon some local recommendations I took the car to Scotts Performance Cars (Biddenden Motorsport) in Dartford.
  • They did all manner of checks, I cleared ECU before I gave it to them so it was clean, they test drove it and eventually it cut out etc.
  • They diagnosed it as DME (which is ECU) fault. In order to replace this with a second hand unit there are a number of things that need to be replaced, not just the DME.
  • It needs to have the DME (with exact matching numbers from a 3.0 manual) and the associated EWS (key ECU box), the key, and the ignition barrel off of the car. After a few weeks of searching I managed to find one and they fitted it. Solved I thought.
  • The car fired and didn’t cut out, however it would only run on 5 cylinders, cylinder 3 wasn’t firing at all.
  • They tried swapping coils, plugs and whatnot, and it always remained on cylinder 3. So they concluded that the second hand DME I had sourced must have had an inherent fault and I either needed a new DME or to find a different one.
  • I returned the one I’d bought for a refund thankfully and I’ve had it recovered home as they didn’t have much space there and I need to transfer insurance etc to the mini.

So now, I’m considering sending it to another specialist for a second look (Crago's in Dartford), and if they conclude the same thing, breaking it.

All opinions are more than welcome, and I salute you if you've read it all. If some good does come out of the helpful wonderfulness of this forum, then I'll be donating some spare parts to members by way of give aways as a thank you.
 
Blimey. Tough break and sorry to hear of your troubles.
I'd be keen to determine if this is a power issue - battery/power loom etc or a control/logic issue -DME/Ecu.
When you say the car cut out did all systems cut out? Lights, heater, stereo etc. The it would be fairly safe to assume that its a power supply issue and not an ecu issue as i believe some systems operate on different power supply buses. Then i'd be tracing back to the battery header....
Have you also scanned for any obd fault codes?
 
Chris_D said:
Blimey. Tough break and sorry to hear of your troubles.
I'd be keen to determine if this is a power issue - battery/power loom etc or a control/logic issue -DME/Ecu.
When you say the car cut out did all systems cut out? Lights, heater, stereo etc. The it would be fairly safe to assume that its a power supply issue and not an ecu issue as i believe some systems operate on different power supply buses. Then i'd be tracing back to the battery header....
Have you also scanned for any obd fault codes?
Click to expand...

So it's definitely not power related, everything else is fine, when it goes, it cranks over like mad just won't fire.

And at the time I did indeed scan, the two codes that brought me pain were:

2869: DME self diagnosis: RAM-check failed

28B2: rpm limiting: reset


Smartbear said:
I'd send your suspect ecu away for testing/repair, how old is the battery?
Rob
Click to expand...

Anyone you'd suggest? I've found some chap in Hayes that seems good, but he either wants the car (which will be a pain), or to supply a refurbished unit at a higher cost and obvs I have no idea if that'll work perfectly.
 
Bbremain were used by some members of the smart roadster club with successful results, don't think they charged £600 either :thumbsup:
Rob
 
Smartbear said:
Bbremain were used by some members of the smart roadster club with successful results, don't think they charged £600 either :thumbsup:
Rob
Click to expand...

Without meaning to sound daft... who??
 
RJS-Z4 said:
Smartbear said:
Bbremain were used by some members of the smart roadster club with successful results, don't think they charged £600 either :thumbsup:
Rob
Click to expand...

Without meaning to sound daft... who??
Click to expand...

Oops, these are the guys :oops: http://www.bba-reman.com/gb/index.aspx
Rob
 
Smartbear said:
RJS-Z4 said:
Smartbear said:
Bbremain were used by some members of the smart roadster club with successful results, don't think they charged £600 either :thumbsup:
Rob
Click to expand...

Without meaning to sound daft... who??
Click to expand...

Oops, these are the guys :oops: http://www.bba-reman.com/gb/index.aspx
Rob
Click to expand...

Thanks I'll call them monday, and I'm also going to call around recovery guys to get me a cost to get to west london. I'm gonna fix this damn thing before the end of Feb. Utterly determined.
 
Rob, I had the issue of cranking and not firing. It was a £10 fix, bring the ignition switch. If this is you problem it will be easy to check as the ignition lights probably won't come on. But for a tenner might be worth getting a used one and swapping anyway. Only 10 minutes to swap as well.
 
Sorry cant help with the electrical gremlins but if you drop your motor to Hayes then give me a shout I can
drop you home im only 10 mins away from hayes.
 
Just in case it turns out to be your ECU, I was looking on the Fiat forum [don't tell anyone] as we have a Punto in the family & there's a company called 'ECU Doctor' that seems to do a very good repair/postage service using your own ECU which is tested then repaired then guaranteed [always prefer to use my old unit whatever it is] maybe worth looking into or at least for another occasion?
Hope all goes well, keep us informed.
Don't lose faith in the big Z, I took my 3.0 out for a 200 mile jaunt last week, first time out in 6 weeks, boy what a fantastic girl these cars are!!!!
 
I've seen things similar to this before.
A coil shorts out, on primary or secondary side. Coil then takes 20+ amps and burns transistor driver out in ECU. Technician comes along, correctly diagnoses faulty ecu and swaps it over. Problem is....the faulty coil is still there and damages the new ECU immediately.

Fix in this case is to change coils first then change/repair ECU.

Its a VERY difficult decision to call an ECU faulty. All powers, grounds and inputs have to be checked to be sure.

Not saying that this is your problem, but why would a garage swap coils etc when 3 minutes with an oscilloscope will prove faulty coils or not.

Will the car start now?

Can you get any live data out of it? Fuel trim etc?

Good luck with it.
Andy.
 
I've been involved in fixing 4 cars with similar problems in the last couple of years, my new Mini, my old C-max, an RS and a Volvo. All started an ran fine but would cut out randomly, usually at speed and after miles, then start, or not randomly. The Mini was the first and gave me the heads-up as BMW replaced the main ECU(DME) and the fault was still there. It turned out to be water in the connector/loom. An upgraded fix from BMW sorted it. The C-max had a cracked wire in the connector that couldn't be seen, the RS was water/corrosion in the connector, ditto the Volvo but you couldn't see the issue until the connector shrouding was stripped.

If it looks tastes and smells like DME related than it probably is but they are pretty much the strong point in the chain, connector, looms and grounds are far more likely as mentioned by andyfanshawe.

Good luck and keep us updated :thumbsup:
 
I had a similar problem couple of years ago with a Fiat Punto, same cause as mentioned by Andy above, the coil pack broke down and spiked the ECU so needed the coil pack replaced first before changing the ECU.
After reading all sorts on the web about having to change the locks and ignition switch if using a second hand ecu, I used a company called cartech electronics to supply a second hand ecu, which they 'virginised' so that it would code up to my car. The swap out worked perfectly and the ecu coded up ok.
Just been on to the cartech site and it seems that they offer ecus for BMW, but didnt go through the list to see which models they do - check out http://www.cartechelectronics.com/BMW-petrol-ecus/?sort=featured&page=1
hope this may help.
 
You have my sympathies, had a similar electrical nightmare with my Audi S5 as PVR likes to remind me.
I didn't have the patience to follow through and fix it though once my Indy turned round and said we no longer know the cause! :headbang:
Hopefully you get to the bottom of it! :thumbsup:
 
My 1987 Shelby would just die when driving sometimes it will start again right away other times it wouldn't it was a bad fuel pump. just thought i would throw that in. :evil:
 
That is what my Audi did!
Except I had both fuel pumps and the fuelling ECU replaced and it still did it :headbang:
 
Ok so the chap in Hayes appears to have fixed it. Supposed to be collecting Monday...

I'll update in good time I guess...
 
RJS-Z4 said:
Ok so the chap in Hayes appears to have fixed it. Supposed to be collecting Monday...

I'll update in good time I guess...
Click to expand...
full diagnosis, remedial actions and critique required...... :thumbsup:
 
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