Typ89 sedan 20v: no spark = bad FP relay!

[PRY4SNO]

Went to go buy a new kitchen at Ikea last weekend, and got stranded in the parking lot when I went to go home. Had to get a flat deck chauffeur home.

Prior to this, the car fired right up basically every time (unless very cold outside... below -20˚C without being plugged in). Gradually over the last few weeks, once in a while, it wouldn't fire up right away. On the way to Ikea the day it failed, the car didn't crank the first time after a while, so I cycled the key and it fired right up.

Initial parking lot diagnosis showed no spark at the spark plugs on the VC/IM. Plugs 1-3 were SOAKED in oil, 4-5 were slightly damp. Not yet sure if that's the VCG leaking or blow by.

Two friends showed up with a spare POS and ignition coil (one of which was mine from my Coupé), but the style was different. On the existing coil there were integrated ground terminals, and both spares had them separate. So I wasn't able to do much that way in the parking lot without more parts.

One of those friends (Lars) popped over today, as it's my first day off on a long weekend. We dug in pretty good. I'd replaced the POS/coil already, with the proper ground terminals attached, and there was no improvement.

Since that didn't yield results, we swapped the distributor rotor & cap and the POS lead, to no avail.

At this point, I'm starting to run out of ideas. Lars suggested following the Bentley procedures to check voltages and ohm values on the electrical connectors on the hall sensor, POS and maybe the one on the flywheel.

Is there something I'm missing? Maybe swap out spark plug wires to rule that out?

Drives me kinda nuts, as nothing changed except one minute the car fires right up... the next it absolutely refuses to cooperate!

[DE80q]

I replied on MG too, but I'll say it here too. Check the FW sensors. Also, pickup and install a new ignition switch. It's strange what things will happen when those are starting to go out.

[PRY4SNO]

I'll keep the ignition switch in mind... hoping to not have to shotgun parts as this car only has to get me thru the winter until the Coupé is driving again.

I have a spare FW sensor (G4?) handy, so I'll try swapping that out next.

Went to pull codes before any of that, and after some digging, found the diagnosis cables. I know I need the Black and Brown terminals, but what wires do I want to bridge?

[All_Euro]

PRY4SNO
...Initial parking lot diagnosis showed no spark at the spark plugs on the VC/IM. Plugs 1-3 were SOAKED in oil, 4-5 were slightly damp. Not yet sure if that's the VCG leaking or blow by...

This could be the valve cover gasket but where were the plugs soaked - connection area or electrode?


Leaky valve seals, for example, can do this sorta thing...

[PRY4SNO]

The front plugs were both ends.

Back two were just on the wire side.

[All_Euro]

Hm, if oil was the issue then the back two cylinders should have fired up... I’m assuming oil didn’t get under the plug wire and was just coating the outside. Aside from the VCG, I’d still want to find out why oil was in the front combustion chambers though.

Are you actually getting fuel and spark to each cylinder?

[PRY4SNO]

Broke out the multimeter today, and had a go at the ignition components.

The only one that wasn't in the middle of the specified range were terminals 1&3 of the ignition coil, which needs ~12V and was getting 10.66 with the ignition switched on. Is 1.34V close enough?

[PRY4SNO]

Are you actually getting fuel and spark to each cylinder?

I didn't want to break the fuel lines at the regulator or rail to verify, as the system doesn't have a simple schrader valve. From my gas mileage I'm fairly certain it's getting plenty of fuel.

All signs point to no spark, anywhere.

[PRY4SNO]

Next up is testing the g4 and g28 sensors; am I looking for 1000 ohm with just the ignition set to on, or while cranking?

[PRY4SNO]

G28 is getting 894 Ω (spec: about 1000Ω)
G4 is getting 926 Ω (spec: about 1000Ω)
Hall sensor is getting 9.83v (spec: at least 9v)

[PRY4SNO]

Bump for longer days, almost have enough light to work on the car outside after work now.

[PRY4SNO]

Bumpity

Could use some ideas.

[DE80q]

Still no spark? Have you figured out why your not getting 12v to the coil? What voltage do you get checking the battery?

Also, were you able to pull codes? I looked back and didn't see you mention it.

[PRY4SNO]

-- Battery is down a bit with all the cranking, reads 10.51v but won't engage my trickle charger yet.

[PRY4SNO]

I've read the guides on 20v.org and SJM a few times, but to be honest wiring diagrams aren't my forte. If someone were to tell me which wires to bridge with spade plugs, I could definitely do so.

[PRY4SNO]

Thanks to scubagli and Obi for the assist on Tapatalk last night...

I never bothered to check fuel since I could tell it was not making any spark whatsoever.

Didn't factor in the fact these cars sometimes won't make spark if there is no fuel delivery.

Once prodded to investigate fuel, I rummaged through my Bentley and step 1 said that if thetre's no prime noise, check the fuel pump relay (208).

Swapped it out with one from my bag of relay spares that seriously weighs 10 lbs, and BOOM!

Fired right up first try.

Thanks guys!

[DE80q]

Glad to hear this finally got sorted out! Are you planning to bring it to Carlisle? Would be nice to have another B3 there.

[PRY4SNO]

Bit of a hike for me, as I'm in Edmonton AB... Canada.

I'd really like to get the Coupé to BBQ but the dollar is really killing my travel plans. Maybe S-Fest West. Maybe.

Sent from my SM-G900W8 using Tapatalk

[DE80q]

Oops, for some reason I thought you were a lot closer than that.