M40 316i FPR replacement?

[Foe]

Having read some similar issues, whilst searching, but no outcome if successful.

My problem is, starting the car up this morning, it was rough, revs were up and down, tried to pull away, stalled. Started her back up, it tried to cut out, so I had to keep the revs up.
Now this only happened for literally 5 minutes.

So drove 30 odd miles, in which everything fine. No stalling at lights, drove okay, a bit down on power. However when I got home I let it idle, and noticed the rev needle pulsating withe the engine, only a little pulse, but there.

I don't want this happening again, as it's a pain!! So want to try and resolve this as soon as I can, either before it gets worse.

On checking wiki page, it states could be a vacuum leak, so checked the hoses, fine and my air intake boot and there seems to be a lot of cracks, and flaky rubber in the folds.
I'll order a new hose and see how this goes.

In the meantime is there anything else I should check?
I'm thinking the Fuel Pressure Regulator next, as this seems to be the source of similar issues to mine. Not sure how easy this is to replace?

Thank you

[Brianmoooore]

FPR is a long way down the list of suspects, but as with most things, testing is the way to go, not random replacement.
Buy yourself a £15 fuel pressure testing kit (with a tee piece), plumb it in and check.
Also, temporarily add a bit of clear tube to the small rubber hose from the FPR to the inlet manifold, so that you can check that there's no fuel flowing through this tube when the engine is idling.

[Foe]

FPR is a long way down the list of suspects, but as with most things, testing is the way to go, not random replacement.
Buy yourself a £15 fuel pressure testing kit (with a tee piece), plumb it in and check.
Also, temporarily add a bit of clear tube to the small rubber hose from the FPR to the inlet manifold, so that you can check that there's no fuel flowing through this tube when the engine is idling.

Thanks for the reply and sitting down with a cuppa, you're right, one thing at a time.
I'll start with the intake hose, as it's in a bad way and I'll order a fuel pressure test kit. Good to have in the tool box.
A good idea about the clear hose.
I'll report back.

[Contours]

While you have the intake boot off, you could clean the throttle body out with carb cleaner--this can also add to idle problems.

[Foe]

While you have the intake boot off, you could clean the throttle body out with carb cleaner--this can also add to idle problems.

Good Idea, thanks.

[Foe]

Something like this £15 kit?

[Brianmoooore]

There's a bit more than you need in that kit, but other than that, it's very similar to mine.

[Foe]

Hopefully can't go wrong for £15.... ordered.

[Foe]

There's a bit more than you need in that kit, but other than that, it's very similar to mine.

Whilst I'm waiting for the new intake boot and pressure kit.
How do you go about setting up to test the fuel pressure? What pipe goes where?
Thanks

[Brianmoooore]

Start the engine and pull out fuse 11 in the fusebox. This will stop the fuel pump, and a few seconds later the engine will start to hunt and then stall. Turn off the ignition and replace the fuse. This will have relieved most of the pressure in the fuel system, and you won't get sprayed with fuel when you take things apart. This needs to be done again when you finish testing and remove the gauge.
Disconnect the fuel feed hose from the fuel rail (NOT the FPR), connect the hose to the tee piece in the kit, connect the short piece of hose in the kit between the other end of the tee piece and the fuel rail, then connect the gauge to the branch of the tee piece.

[Foe]

Thank you

[Foe]

Thought I'd check in to give quick update.

I replaced the intake rubber boot and it was heavily corroded between the ribs. Not only that, the is a breather pipe, at the bottom of the intake, which was loosely connected.
Now starts up fine with no pulsating at idle.

I'll keep an eye on this for now and report back as not had enough time to really give it a few starts.

[Foe]

Working today so took the car out, just to see how things are going/working.....
The high idle on start up seems to have gone, however, when driving, heading towards a crossing, I'll take my foot off the accelerator, rather than brake, when I put my foot down, there's a lag, then the car will jump to where the pedal should be.
I can only describe it as, if I put my foot half way down on the accelerator, the throttle arm moves nothing, then the car will realise I've put my foot down then go straight to the half way point. Like a delayed response.
This happend prior to the accelerator cable replacement.
I need to complete a fuel pressure check as Brian mentioned, but anything to clean out or try in the meantime? Working until 5pm so will be dark when I'm home. But could try on Monday.
Thanks

[Foe]

All done! The throttle cable was not sat it the plastic housing on the throttle cable properly. Tightened up the cable adjuster and hey presto none of the above!!