My midlife crisis purchase; E86 BMW Z4 Coupe
Discussion
Sounds like you're taking a methodical approach to finding the short. Don't rule out one of the lambda sensors, there are four of them and it's entirely possible that the heating circuit has failed in a way that causes a short. I don't know how easy they are to disconnect, and you'll certainly get an engine management light while it's disconnected, but you should at least be able to eliminate those as a cause of the short.
Worst case it might be that the short is in the wiring loom itself, if it's been rubbing and worn through, which would be tricky to trace. An easier option may be to remove the fuse and probe the "cold" side of the fuse (ie the side that is connected to the lambdas). It should be open circuit or at least high resistance through whatever's connected to it. If you're getting low resistance to ground, start disconnecting the circuits running from that fuse to see if the resistance suddenly jumps, which would indicate that you've found the fault circuit.
Worst case it might be that the short is in the wiring loom itself, if it's been rubbing and worn through, which would be tricky to trace. An easier option may be to remove the fuse and probe the "cold" side of the fuse (ie the side that is connected to the lambdas). It should be open circuit or at least high resistance through whatever's connected to it. If you're getting low resistance to ground, start disconnecting the circuits running from that fuse to see if the resistance suddenly jumps, which would indicate that you've found the fault circuit.
pmorg4 said:
Sounds like you're taking a methodical approach to finding the short. Don't rule out one of the lambda sensors, there are four of them and it's entirely possible that the heating circuit has failed in a way that causes a short. I don't know how easy they are to disconnect, and you'll certainly get an engine management light while it's disconnected, but you should at least be able to eliminate those as a cause of the short.
Worst case it might be that the short is in the wiring loom itself, if it's been rubbing and worn through, which would be tricky to trace. An easier option may be to remove the fuse and probe the "cold" side of the fuse (ie the side that is connected to the lambdas). It should be open circuit or at least high resistance through whatever's connected to it. If you're getting low resistance to ground, start disconnecting the circuits running from that fuse to see if the resistance suddenly jumps, which would indicate that you've found the fault circuit.
I'm doing my best to be methodical.Worst case it might be that the short is in the wiring loom itself, if it's been rubbing and worn through, which would be tricky to trace. An easier option may be to remove the fuse and probe the "cold" side of the fuse (ie the side that is connected to the lambdas). It should be open circuit or at least high resistance through whatever's connected to it. If you're getting low resistance to ground, start disconnecting the circuits running from that fuse to see if the resistance suddenly jumps, which would indicate that you've found the fault circuit.
I've been focusing on the CCV side of the circuit because that is what I've changed / fiddled with.
Re the lamda sensors, the pre cat ones are easy to unplug because they're under the engine cover on top of the engine. The post cat ones can be got at easily but I'd need to jack the car up. I had no issues before replacing the CCV.
If there is a break in the loom, I'm guessing that it'll be the cable that supplies power to the heating elements and runs under the manifold. There are only two cales in a plastic sheath that run to the cable block that is connected to the side of the manifold.
Court_S said:
My Z4 was in useful mode tonight.
I still find it amusing seeing a silly car doing practical things.
More Z4 + SeaSucker adventures.I still find it amusing seeing a silly car doing practical things.
650 miles, mainly rainy motorway driving, to St Simon near Aurillac, France from the Ashdown Forest.
Dropped my mate (pictured) so he could cycle back to Blighty for fun....
Wasn't sure if would work with the 'double bubble' creases on the roof, but absolutely fine.
Hope you resolve the electrical gremlins !
S
ess said:
More Z4 + SeaSucker adventures.
650 miles, mainly rainy motorway driving, to St Simon near Aurillac, France from the Ashdown Forest.
Dropped my mate (pictured) so he could cycle back to Blighty for fun....
Wasn't sure if would work with the 'double bubble' creases on the roof, but absolutely fine.
Hope you resolve the electrical gremlins !
S
Good effort that. I’ve not used mine on a motorway or for any long trips yet…I’m still learning to trust it. 650 miles, mainly rainy motorway driving, to St Simon near Aurillac, France from the Ashdown Forest.
Dropped my mate (pictured) so he could cycle back to Blighty for fun....
Wasn't sure if would work with the 'double bubble' creases on the roof, but absolutely fine.
Hope you resolve the electrical gremlins !
S
So, if done some more fiddling tonight….
One of the throttle body bolts was a tad loose which was probably leading to a slight vacuum leak. The idle still flutters a wee bit initially but less than it was.
I am however still going through fuses at a rate of knots. I’ve tried unplugging each of the four power connectors on the CCV individually and all together. I also tried unplugging the pre-cat O2 sensors since they were so easy to get at, but nope. The fuse still blows as soon as the engine is started but the management light doesn’t come on until it’s next started.
I’m guessing it’s looking more and more like a wiring fault somewhere on that circuit.
One of the throttle body bolts was a tad loose which was probably leading to a slight vacuum leak. The idle still flutters a wee bit initially but less than it was.
I am however still going through fuses at a rate of knots. I’ve tried unplugging each of the four power connectors on the CCV individually and all together. I also tried unplugging the pre-cat O2 sensors since they were so easy to get at, but nope. The fuse still blows as soon as the engine is started but the management light doesn’t come on until it’s next started.
I’m guessing it’s looking more and more like a wiring fault somewhere on that circuit.
cerb4.5lee said:
I'm sorry to hear how much of a headache it is giving you currently Sam. I hope that you get to the bottom of it as soon as you can.
Cheers Lee. There are no obvious side effects other than the amber check engine light. Topping up the oil regularly is starting look like the better option; the joys of hindsight.
cerb4.5lee said:
I'm going back years now, but I remember my XR4x4 being a pig at blowing fuses as well. Everytime I touched the electric window switch it blew a fuse, and it used to drive me mad everytime I went to grab a ticket in multi storey car parks for example!
Fecking cars eh?!
Indeed. Fecking cars eh?!
Just to top it off, the near side headlight washer has given up the ghost and emptied the contents of my washer bottle on my drive.
Used ones are super expensive, like almost the same as a new one which is £115. Mine are disabled so I don’t really want to pay that for a new one. I’ve ordered a water bottle for a car without headlight washers for now (£14 from eBay). That’ll stop the leak.
I was then further rewarded by not putting the cap on properly which has been lost today. The Z4 is definitely fighting me a bit at the mo.
Court_S said:
Cheers Lee.
There are no obvious side effects other than the amber check engine light. Topping up the oil regularly is starting look like the better option; the joys of hindsight.
Yes and I properly feel for you regarding that for sure. There are no obvious side effects other than the amber check engine light. Topping up the oil regularly is starting look like the better option; the joys of hindsight.
My mechanical skills are virtually non existent, so I was happy to stick my head in the sand with the E90 330i's oil usage, and I just continued to throw a litre of oil in that every 2k miles.
You've just fell a bit unlucky with this though I reckon. However you were trying to do the right thing though, and I can't fault you for that at all.
Court_S said:
cerb4.5lee said:
I'm going back years now, but I remember my XR4x4 being a pig at blowing fuses as well. Everytime I touched the electric window switch it blew a fuse, and it used to drive me mad everytime I went to grab a ticket in multi storey car parks for example!
Fecking cars eh?!
Indeed. Fecking cars eh?!
Just to top it off, the near side headlight washer has given up the ghost and emptied the contents of my washer bottle on my drive.
Used ones are super expensive, like almost the same as a new one which is £115. Mine are disabled so I don’t really want to pay that for a new one. I’ve ordered a water bottle for a car without headlight washers for now (£14 from eBay). That’ll stop the leak.
I was then further rewarded by not putting the cap on properly which has been lost today. The Z4 is definitely fighting me a bit at the mo.
I remember the windscreen washer bottle used to leak on my Z4M too, and I believe that it is a pretty common fault.
It is definitely testing you at the moment as you say frustratingly.
Forking grim. As a last ditch before pulling the inlet I’d see if you can remove the positive and negative wires from the fuse box snd see if that solves your issue. I suppose it’s not out of the realms of possibility that you’ve pinched the wires, caused a dead short and it blows the fuse as soon as you put the ignition on.
JakeT said:
Forking grim. As a last ditch before pulling the inlet I’d see if you can remove the positive and negative wires from the fuse box snd see if that solves your issue. I suppose it’s not out of the realms of possibility that you’ve pinched the wires, caused a dead short and it blows the fuse as soon as you put the ignition on.
That’s what I was thinking of doing. The two wires that provide power to the CCV are colour coded and I’ve kind of been able to figure out twice route. There’s a really good auto electrician (well they get great reviews) so I’m tempted to give them a shout tomorrow. I’m starting to think that a wire has got damaged somewhere along the line and after 18 years and numerous heat cycles it wouldn’t really be a surprise.
Whilst I’m still no further forward with the flutter at idle in cold start or with apparent electrical fault I went back to my happy place of cosmetic stuff. 
The brace behind the grilles was in a really bad state and it bothered me. It’s apparently quite a common issue on Z4’s.
It’s held in with four T30 screws and I attempted to get them undone with the grilles removed however BMW used the s
ttest bolts with a very shallow head. Joy. Os it was off with the front bumper
Removing some of the many screws and fixings.
Bumper off revealing the manky brace.
With better access and my dagga dagga gun, the four bolts holding the brace in place were soon out. Old and new brace.
Because I’m a bit weird, I took the opportunity to clean behind the bumper because no matter how much I get in the gaps with detailing brushes, there’s always a layer of green filth that’s visible.
And cleaned.
After my headlight washer crapped themselves yesterday, I swapped the water bottle for one from a car without washers because it was st loads cheaper than replacing the washers which are turned off.
The used part absolutely stunk and was full of sludge and alga which was nuked with lots of Milton.
The redundant washer line was removed from the front bumper.
I’ve also removed the side reflectors and am painting them body colour. They were in horrible condition and like many Z4 parts are bloody expensive for what they are. Plus I think the reflectors look cack.
The brace behind the grilles was in a really bad state and it bothered me. It’s apparently quite a common issue on Z4’s.
It’s held in with four T30 screws and I attempted to get them undone with the grilles removed however BMW used the s
ttest bolts with a very shallow head. Joy. Os it was off with the front bumperRemoving some of the many screws and fixings.
Bumper off revealing the manky brace.
With better access and my dagga dagga gun, the four bolts holding the brace in place were soon out. Old and new brace.
Because I’m a bit weird, I took the opportunity to clean behind the bumper because no matter how much I get in the gaps with detailing brushes, there’s always a layer of green filth that’s visible.
And cleaned.
After my headlight washer crapped themselves yesterday, I swapped the water bottle for one from a car without washers because it was s
t loads cheaper than replacing the washers which are turned off. The used part absolutely stunk and was full of sludge and alga which was nuked with lots of Milton.
The redundant washer line was removed from the front bumper.
I’ve also removed the side reflectors and am painting them body colour. They were in horrible condition and like many Z4 parts are bloody expensive for what they are. Plus I think the reflectors look cack.
Court_S said:
After my headlight washer crapped themselves yesterday, I swapped the water bottle for one from a car without washers because it was st loads cheaper than replacing the washers which are turned off.
The used part absolutely stunk and was full of sludge and alga which was nuked with lots of Milton.
The redundant washer line was removed from the front bumper.
I’ve also removed the side reflectors and am painting them body colour. They were in horrible condition and like many Z4 parts are bloody expensive for what they are. Plus I think the reflectors look cack.
The washer reservoirs and filters often seem to grow amazing amounts of algae. Getting rid of the pointless headlamp washers is definitely the way to go! t loads cheaper than replacing the washers which are turned off. The used part absolutely stunk and was full of sludge and alga which was nuked with lots of Milton.
The redundant washer line was removed from the front bumper.
I’ve also removed the side reflectors and am painting them body colour. They were in horrible condition and like many Z4 parts are bloody expensive for what they are. Plus I think the reflectors look cack.
I never understood the side reflectors either - they look terrible. Thankfully Ms don't have them, so why do 3.0Sis?
Anyway good luck with the idle problem.
Mr Tidy said:
The washer reservoirs and filters often seem to grow amazing amounts of algae. Getting rid of the pointless headlamp washers is definitely the way to go!
I never understood the side reflectors either - they look terrible. Thankfully Ms don't have them, so why do 3.0Sis?
Anyway good luck with the idle problem.
It was an impressive amount of crack in there but to be honest the one on my car wasn’t much better. Both filters were covered in black sludge too. I never understood the side reflectors either - they look terrible. Thankfully Ms don't have them, so why do 3.0Sis?
Anyway good luck with the idle problem.
I have no idea why the EU cars got the side reflectors. The US needs them by law I think. They’d look so much better without them. Mine will blend in soon enough.
No luck on the idle flutter on the electrical issue so far. I think I’m going to pull the manifold once more just to check. It’s booked in with an Indy on the 9th and an auto electrician on 11th.
I also need to decide what to do about my fog lights. Up close they’re absolutely gone; the reflectors are nothing but rust and there is a cream cheese like substance behind the lenses. I think I’ll for blanking plates because I don’t really use them, new ones are bloody expensive and used ones will probably be shagged.
Court_S said:
Jhonno said:
No headlight washers with xenons is an MOT failure is it not?
Dunno. My 335i and 130i both passed MOT’s with them turned off.However, doesn't look like your tester is concerned about it, so all good.
Gassing Station | Readers' Cars | Top of Page | What's New | My Stuff