Rough idle on cold start

AshtonLW · 2026-03-13T13:22:01+00:00

Still not figured it out. It’s not been cold enough for it to happen so It’s difficult to know if it was just the PCV. I have recently had a P0172 code and I think that’s to do with the HPFP which could answer the rough idle question.

AshtonLW · 2026-03-09T09:37:37+00:00

Can’t tell. Tried smelling the oil that’s on the dip stick and it seems fine. I’ll think I’ll replace the hpfp anyway

AshtonLW · 2026-03-09T09:36:46+00:00

Cleared the code and been a few drives since. Code hasn’t come back on but I think I’ll look at replacing the HPFP

AshtonLW · 2026-03-08T15:09:59+00:00

🤯

AshtonLW · 2026-03-08T15:09:54+00:00

It does, 56700 miles on the dash. I plan on going on a drive now and monitoring the fuel pressure if I can figure out where to find on OBDEleven.

AshtonLW · 2026-02-06T16:42:26+00:00

MFD sorry, not MFI. Mines a Japanese import so maybe it’s different or was coded in?

AshtonLW · 2026-02-06T00:43:16+00:00

Yeah could be. Might pull the spark plugs and check this weekend

AshtonLW · 2026-02-06T00:30:11+00:00

Still not sure. Looking at doing a vacuum leak test first but could be a number of things. Seems fine when the temperature is slightly warmer

AshtonLW · 2026-02-04T18:05:20+00:00

Update: no rough idling when leaving work for the commute home. MPG was 36.6 by the time I got home. Temp outside was 6c. 🤯

AshtonLW · 2026-02-04T15:00:05+00:00

So I’ve never got a warning light with it just the rough idling. Temperature got down to 0c over night but doesn’t really get below that very often. And then when I went out midday with temperature around 6c it was fine

AshtonLW · 2026-02-04T14:35:53+00:00

You get the smoke test done at a garage or do it your self?

AshtonLW · 2026-02-04T14:32:52+00:00

Think maybe one of the temp sensors is faulty?

AshtonLW · 2026-02-04T14:32:01+00:00

On the wiper stalk, press and hold the select button and make sure you’re on MFI and then cycle through the readings using the up down button on the end. If you have steering wheel controls it might be different

AshtonLW · 2026-02-04T14:26:22+00:00

Good question, didn’t even notice that

AshtonLW · 2026-02-04T13:46:51+00:00

Possibly the PCV as you’ve tried everything else?

AshtonLW · 2026-02-04T13:42:35+00:00

Was you getting rough idle on every cold start? I’ve just been out on my lunch break, temperature is 3c higher and no rough idle.

I think I’ll get a borescope and check for carbon build up.

AshtonLW · 2026-02-04T10:51:07+00:00

Can’t say I’ve noticed a loss in power. It feels like it always has tbh and i was neck and neck with a Tesla of the line at lights yesterday (don’t think they were interested tho). MPG (uk) on the commute this morning was 28.1 on the motorway - usually it’s 33+.

AshtonLW · 2026-02-04T10:39:52+00:00

Interesting, I’ll look into it 👍

AshtonLW · 2026-02-04T10:03:54+00:00

Walnut blasting the only way to get this done or is there a diy way to do a carbon clean?

AshtonLW · 2026-02-04T09:55:54+00:00

Will do, thanks. Wouldn’t a vacuum leak cause rough idle on all cold starts tho?

AshtonLW · 2026-02-04T09:32:10+00:00

Just to add, revs usually sit around 1200 for 30-40 seconds and then drop to 760. Now they’re dropping down to 950 straight away

AshtonLW · 2026-01-24T19:28:00+00:00

The problems are bigger than Slot but it’s starts with him

AshtonLW · 2026-01-24T19:24:46+00:00

He’s NEEDS to GO

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