Lurching at idle

crawlvo · 2025-02-06T06:46:53+00:00

ah - another 'Rough Idle'..... But, recently I've noticed when coming to a complete stop (braking) the car will lurch around and rev in this weird bouncing...

Major Ledfoot

crawlvo In that diagram, it looks like the ABS booster in that diagram is indeed "thinner" hence why it would need the adapter plate.

Yeah, the 10 inch DBA is thinner, but note also there's different master cylinders too. IIRC the 10 inch was used on 16V cars. The book doesn't distinguish what's used on NAs, turbos, 16Vs, 6-potters, or Dweasels.

crawlvo

shiyeaa, Klamma https://www.gcp.se/products/462996

carnut222

crawlvo Pretty sure I have one of those oil cooler line retaining blocks. Happy to post it to you. Lemme know.

crawlvo

carnut222 that would be fantastic, I’ll PM you

crawlvo

I seem to have fixed the rest of my idling issues (odd surging to 1-2k rpms in park and neutral, threatening to stall on a cold start, minor issues when slowing to a stop) with a new IACV connector. I always knew it was a bit green in there, but I originally cleaned the contacts and thought that would be enough.

I’d thrown in a cheapy IAC valve from aliexpress, to see if any symptoms changed, but no difference. Lopped off the connector and reterminated with a connector kit, now running smooth!

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Wires are under more tension than I’d like.

at 500000ks most of the wiring loom in the engine bay is probably worth replacing, especially things right near the engine. Wires don’t like heat, and most of my connector sealing bits are crumbling away

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I see dave barton has the bits for reterminating connectors (bullet and spade terminals, sealing grommets etc) but thats a pretty big job. one day!

ramrod

A 940 won’t suffer from crumbling wiring insulation. But the metal terminal ends often need cleaning and greasing especially on vehicles that have been exposed to corrosive environments

Brad

Your plugs look just like the ones on my 940. They're all trashed too. I've been looking into options for replacing them and I'd forgotten about Dave Barton.

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ramrod

Brad

There is nothing wrong with that wiring how it is

Now if you go to remove the wires, different outcome as the rubber weather protection grommets will crumble and fall out

It happens on the relays located inside the engine compartment too, the rubber degrades after decades of heat cycles

Major Ledfoot

The recently-acquired (well, most recently-acquired) S90 also has this issue with connector seals and sealant failing.
I removed one of the connectors for the cruise control going to the air pump inside the engine bay, and corrosion had begun.

Seems it's not so much of a case of the wiring insulation failing, but of connector seals failing with Seven and Nines.

I highly recommend Dave Barton's wiring pigtails and complete harnesses - his B6304 plug harness solves many problems, and his LH 2.4 engines harnesses are well made. Both have good documentation too.

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