PCV valve cause rough idle?

BlakeS94

My girlfriends Suzuki Alto 2010 has had a rough idle problem for quite a long time now. Haven't had the time to check it out but plugged a basic OBD2 into the car yesterday and monitored the live data, I had thought coolant temp sensor but it's reading within range when car was warmed up and climbed gradually as it should.

Ignition system is fine, tested primary and secondary windings of ignition coils with a multimeter, also pulled each one with engine running, and car ran even worse and died after a few seconds. Spark plugs were changed recently by myself with the plugs recommended in owners handbook, removed and double checked the gap on the plugs, all good. Petrol car so presumed fuel filter is fine as there's 60k miles on it.

Serviced recently , oil changed and oil,pollen and air filter replaced.

Throttle position is correct going by live data on cars computer. Issue is when car is idling it idles badly and sometimes stalls, especially when slowing to a stop.

So anyway, I'll get to my point. I removed the PCV valve from the valve cover today. And it is completely seized. Not a single sound out of it when I shake it. You can hear a rumbling in in video, it's from the wind or something I can assure you there's not a single sound coming from the PCV valve.

I'll attach a video below. Surely replacing this will solve the issue?

https://youtu.be/B6S1fyxca0M

BlakeS94

A bit stumped, the valve is pulling vacuum, a lot of it, when I disconnect it from the valve cover at idle and place my finger over it, but it doesn't make any sound when I shake it. Cleaned the valve a bit, there's a slight rattle if I shake the **** out of it, no difference though. I'll just have to replace it and see how it's goes, hoses look fine

Dirty Nails

Wasting your time & money,I'd imagine.

Try IACV

BlakeS94

There's no IAC valve its an electronic throttle body

listermint

Looks broken per your video. Attach to the throttle side to see if vacuum is pulled it should suck closed if your finger is put over the end.

Change it anyway they're only a few euro.

Also check all the hoses to it and the breather hose too cracks can mess the system up. Might even remove them to check bend the hoses in case there's is hairline crack you can't see normally.

BlakeS94

It's pulling vacuum, whistles like mad when I remove it from the valve cover with the hose still attached, its only the hose from the valve to the intake and the breather hose that are part of that system, incase I'm missing anything.

There is some very slight oil residue around the grommet when I removed the valve

BlakeS94

Got this sorted the other day. Replaced the PCV valve with a genuine part. Removed the PCV hose and the breather hose and inspected, they look good no damage or any splits or cracks.

I removed and cleaned the MAF/IAT and MAP sensors with MAF cleaner, while they were drying I removed what I needed to get access to the throttle body, it was fairly gummed up where the plate closes and meets the body itself. Got the missus to sit in the car with the key in position 2 and press the accelerator pedal to open the throttle plate, sprayed throttle cleaner onto a toothbrush and scrubbed anywhere I could get access to in and around the area, without touching the plate (wasn't easy as the Alto has quite a small throttle body positioned low down at the back of the engine)

Everything back together and the car sounded different straight away, already much smoother. (As much as a 3 cylinder can be anyway)

Took it for a long spin to blow out any of the throttle cleaner leftover. Topped up the lost coolant from removing the pipes coming off the throttle body. Car idles great now, couldn't be any more steady. Don't know how long it will last but at least I know where to look if it starts acting up again.

No issues regarding the electronic throttle body, no lights on the dash and the car started up straight away idled a bit higher and came down to a steady RPM.

Typically it need relearning idle after throttle body cleaning. No big deal if you can not to do it by computer, after X kilometers car learn itself. Mostly you do not need to clean the plate but plate edges can be dirty.

BlakeS94

It doesn't need to relearn the idle because I never touched the throttle plate as I said in my initial post, I was very careful about that. The idle was perfect afterwards which proves the electronic throttle system was undisturbed

https://www.boards.ie/discussion/comment/118494833#Comment_118494833

You said you cleaned everywhere, where was access. I know you missed the plate edge but you cleaned the body. It still need to relearning by diagnostic tool or over the time it can learn itself. Reason is simple, you changed the airflow by cleaning the throttle body. Do not understand me wrong, cleaning is good. The cleaning restored the original airflow