Engine pulse at idle.

[gort]

So, 2001 1.6 petrol Focus Zetec engine.
Occasionally when warm and idling it pulses, as shown in the video.

No other issues with performance noticed. The actual loud rattle is just the battery cover which is off and resting loose but it helps shows the pulse.
Was going to give the IAC valve a clean or even replace and check hoses, throttle body etc.
This engine doesn't have a MAF, rather a MAP which is a bit more of a faff to clean I think.
Was thinking about fuel pump, coil pack or plugs but it's not a constant problem and only occasional issue at idle (hence thinking the sensor or IAC valve.) Am very much a novice and it's only from things picked up along the way with this engine over the years.
Anything else worth considering that isn't a pig to do?
Cheers

 

[OpenToSuggestions]

Sounds like a logical approach to me.
Perhaps do an error code scan if you can?

 

[DanTheMan]

So, 2001 1.6 petrol Focus Zetec engine.
Occasionally when warm and idling it pulses, as shown in the video.

No other issues with performance noticed. The actual loud rattle is just the battery cover which is off and resting loose but it helps shows the pulse.
Was going to give the IAC valve a clean or even replace and check hoses, throttle body etc.
This engine doesn't have a MAF, rather a MAP which is a bit more of a faff to clean I think.
Was thinking about fuel pump, coil pack or plugs but it's not a constant problem and only occasional issue at idle (hence thinking the sensor or IAC valve.) Am very much a novice and it's only from things picked up along the way with this engine over the years.
Anything else worth considering that isn't a pig to do?
Cheers

This has been a pretty common occurrence on petrol fords since I owned an mk1 focus back in 2007 (I'm sure even earlier too). As you've mentioned, it was mainly put down to the coil pack or o2 / maf sensors.

A lot of people swore that replacing the coil pack / plugs and cleaning the o2 sensor fixed their issues but I had 2 mk1 focuses and they both had that issue. To be fair, the 09 1.25 petrol fiesta I have now has the same issue.

Do you get any flat spots of power in the rev range too? I remember I used to get terrible flat spots between 1800-2300rpm where the engine just had no pull. That did improve with a clean of the sensor and replacement of coil pack and plugs but the pulsing idle seems to be pretty standard.

 

[gort]

No other issues noticed. Just found that that MAP sensor is in a really awkward place, would need the alternator removing to clean or diagnose, although apparently it's not an item that needs servicing. Not quite like the MAF just being on top by the air filter!

I'll pick up a cheap OBD2 scanner, useful thing to have, should have got one years ago, may have helped with other niggles with our cars over the years!
This is more of an annoyance than anything else really but don't want anything to escalate. My Mrs reckons it's being doing it on and off for the past 2 (she drives it the most) but I only noticed more recently.
If yours have done it for a time then it's perhaps something that will remain!

 

[BassHead]

I recently had a similar issue which turned out to be the alternator voltage regulator which was causing the alternator to kick on and off pulsing between 12-14v, with each pulse the alternator would put a small load on the engine and caused the idle to hunt up and down slightly, was unnoticeable while driving. Probably not your issue but worth a shot if you have not already checked what the voltage is reading while idling.

 

[gort]

I recently had a similar issue which turned out to be the alternator voltage regulator which was causing the alternator to kick on and off pulsing between 12-14v, with each pulse the alternator would put a small load on the engine and caused the idle to hunt up and down slightly, was unnoticeable while driving. Probably not your issue but worth a shot if you have not already checked what the voltage is reading while idling.

That's interesting and new to me. Got a volt meter so that should be an easy test.
Was yours a permanent issue at idle or random like mine (occasionally after engine is hot)?
Ta!

 

[BassHead]

That's interesting and new to me. Got a volt meter so that should be an easy test.
Was yours a permanent issue at idle or random like mine (occasionally after engine is hot)?
Ta!

It was intermittent tbh but got worse over a period of time, eventually it was just like it constant.

 

[Gaygle]

That's interesting and new to me. Got a volt meter so that should be an easy test.
Was yours a permanent issue at idle or random like mine (occasionally after engine is hot)?
Ta!

These engines/models were common for earthing problems as well which can cause a multitude of problems like this. A friend of mine had similar when his earthing points were corroded. A garage cleaned them all and it was fine afterwards!