VCat

Tried starting car this evening. Weird click and spin sound but not 'engaging'. Started second time but accompanied by nasty burnt electic smell and lumpy idle.
Drove for a half a mile, came to a corner and NO BRAKES! Power assistance had failed so needed a very heavy shove. Not fun with my 3 month old daughter next to me. Very scary.

So I need to fix car hopefully tomorrow morning before I have to get to a friend's funeral in the afternoon.

What's happened to my 928?!

Mrmerlin

need more info what year is this?
what was the last thing you fixed?

It sounds like you have different issues a bad starter connection and broken vacuum line to the booster

VCat

1990 928 GT.

Had a big service 4 months ago but nothing related. Been running great though have had occasional mis-starting where it would click and spin with instrument panel reset (defaults to MPG after digital display goes blank for a second). But always would start fine second time. And never with this burnt electrics smell.

VCat

Or unassisted brakes. Could be unrelated unless there is some shared curcuit. But no warning lights came up surprisingly.

Mrmerlin

time to check the elex grounds at the battery and the starter and hot post and the CE panel.
Also after cleaning you need to check the charging system at idle and at 1500rpm it should be over 13.5 V if not then you may have a failing alternator with a bad diode, the elex smell sounds like an arcing connection this will cause a low battery output and possibly the battery not reaching full charge
look for a broken vacuum line at or near the booster

VCat

Thanks Mrmerlin: will check these tomorrow morning (it is nightie here in the UK) first thing.

Dan

John Speake

Are you sure the "No brakes" was not because the engine had stopped and there was no servo assistance ? Lumpy idle could be car running on 4 cylinders due to igntion protection relay being triggered.

nowlings

Plus 1 to john, im thinking starter solenoid and maybe a side of voltage drop because of dirty connections, so bigger resistance causing the burn smell

VCat

John: the non-servo assisted brakes problem continued after I had pulled over, turned off ignition then started car again, though idle was still rough after this.

Can the ignition protection allow engine to still run while not providing servo-assisted brakes?

Mike Simard

A ground or bad connection does sound like a possibility. On these kinds of threads where MMerlin chimes in, the answer is usually what he said and we all just reword it
Also check the battery itself and main ground strap from it.

VCat

Got a new powerful battery about half a year ago (Bosch S5?). At same time, cleaned terminal connectors to battery and ground strap to body point near battery, but not ground points in engine bay.

Ignition relay protection: had a search on here and I should mention that when revving car slightly then letting revs drop, there was a significant pop from exhaust before it resumed the lumpy idle.

Mike Simard

Going out on a limb here but do you have shot motor and trans mounts causing your drivetrain unit to move around? Do you hear things clunking when driving?

VCat

Mike: don't hear any clunks while driving and think people what did service would have spotted that (hopefully!).

The car has had a good run from London to Isle of Wight, then a good drive about the island during the day until the last journey which fortunately was just a mile. So lucky the the loss of servo-assistance brakes happened as I tried to slow for parking, as opposed to zooming into a bend...

Mrmerlin

look at the coil wires and see if they are rubbing on any metal if so then they might need to be replaced
Then pull the coil wires look at the ends for corrosion

VCat

So, started car this morning- engine fine, no lumpiness on idle and revved and accelerated fine.

But still no brake assistance! Surprised there is no warning light/digital display about servo-assistance failure.

So my uneducated theory is that upon trying to start the last night, the intermittent starting problem that the car has always had has triggered the brakes problem by some voltage knocking out the fuse when something arced, causing the burnt electrics smell.

Going to check the fuse/relay board now...