1996 850 R Strange cutout with all newish ignition parts Topic is solved

Post by **Clemens** » 12 Mar 2020, 05:18

crap, problem persists. it seems that it only happens once the car has warmed up. it misses under full throttle above 4000 rpm and at idle. for the first few miles als seems fine and dandy. are we still thinking cap and rotor? need to switch them with the 94 to see if that helps.

Post by **abscate** » 12 Mar 2020, 05:33

Definitely. Make sure you push the connectors in.

Post by **Clemens** » 12 Mar 2020, 08:29

I just stopped by my local indie and he suggested that it could be fuel starvation. Does that soubd plausible?
The fuel filter is 4 years old, fuel pump and fuel pump relay are probably original.
When fuel pumps were dying on my 854 I always had no start issues but all was fine as soon as it was running.
I am toggling between being motivated to find the source and throwing the towel...

Post by **abscate** » 12 Mar 2020, 08:39

you can monitor fuel pressure either in VIDA or with a gauge.

A 'diagnosis' of fuel starvation just invites a parts dart solution of lots of high margin, labor intensive parts swapping.

Post by **Clemens** » 12 Mar 2020, 11:10

okay, where could I get Vida from?

also, could brick diag read the fuel pressure?

Post by **misha** » 12 Mar 2020, 12:03

VIDA on pre '99?

Post by **abscate** » 12 Mar 2020, 15:27

misha wrote: 12 Mar 2020, 12:03 VIDA on pre '99?

Corrected above.

Serbia 99 - US 2

Post by **misha** » 12 Mar 2020, 16:34

@clemens
Swap cap & rotor from '94 T5 so we can rule out ignition parts.

If problem persists....remove fuel pump relay,open it up and take a close look for cold or cracked solders.
Since the problem appears when car is warmed up and electrical parts like relays shows their weakness when they are warmed up...it could be a fuel pump relay...or main fuel injection relay(grey one) on fan shroud.

Post by **Clemens** » 12 Mar 2020, 17:35

Thanks Misha. Will try tomorrow.

Post by **amblerman** » 13 Mar 2020, 09:14

Clemens wrote: 18 Feb 2020, 12:11 One of them was a tad brownish around the shaft, maybe oil that got down the upper part of the plug when refilling oil?

That brownish stain is called a corona stain.. No that wasn't a lame attempt at a joke based on our current global crisis.

See here:

http://www.ngk-sparkplugs.jp/english/te ... index.html

Good description here from the folks at NGK.
-A <edited to fix link>