Rough idle especially when cold

Also, there's no bubbles in the radiator from what I can tell.

Hi,

This could be a few things. First, is the coolant level dropping? It doesn't have to mix in the engine oil. It can enter the combustion chamber and burn.

As far as the knocking, that is usually the result of timing or can be cause by coolant in the combustion chamber. That's why I asked about usage.

The temp sensor can cause the fuel mixture to be off, which can cause the idle issue. However, I don't see how it would cause a knocking.

Have you scanned the computer for trouble codes?

Let me know.

Joe

Here is a guide to help scan for codes and check for a blown head gasket:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

and

https://www.2carpros.com/articles/head-gasket-blown-test

Can you please shoot a quick video with your phone so we can see what's going on? that would be great. You can upload it here with your response. Please run down these guides and report back.

Thank you both so much!
I ordered an OBDII Scanner a month and a half ago but it's been stuck in international transit due to covid-19. Thanks for the guide and I'll definitely scan codes first thing when I get the scanner.
I think the coolant level has been dropping slowly but I'll run the car a bit more to see if it drops further.
I'll also take a video of what's going on when I know more.
Thanks again.

Please let us know what you find. We are interested to see what it is.

Will do! I'm very keenly waiting my scanner.

CYBAFORGE:

You did not mention if the "check engine" light is on. I can think of two things off the top of my head: EGR (Exhaust Gas Recirculation) or IAC (Idle Air Control). I believe your vehicle has an IAC valve. The IAC valve is responsible for controlling idle. It's possible for a bad IAC not to set a code. EGR is another possibility. At WOT (Wide Open Throttle) there isn't enough vacuum to open the EGR valve,

Right now, I can't help much more than that. Disconnect the vacuum hose on the EGR valve and plug it and see if it idles better. An open EGR valve supports the more water at the tail pipe too.

Lets hope you checked the PCV valve and for vacuum leaks.

AutoZone does free scans,

I've seen no codes and a bad IAC. See if the idle increases when you turn on the air conditioning. The IAC should be responsible for doing that.

An EGR problem that I trouble-shot drove me nuts, This particular vehicle I was working on was designed to open the port to EGR valve when the ignition was on, When the ignition was off, the EGR got full vacuum. By design this prevented engine run-on. The exhaust and intake manifolds were connected together and the engine could not run in that state so it stopped.

That solenoid was installed in a bad place, The car had rough idle if you started it 20 minutes after the car cooled down from operating temperature. It had a very short time window where it would stick.

It may not be the EGR valve, but it could be whatever is controlling it. I don't yet have the ability to assess my confidence level for your particular vehicle.

I hope something here helps.

Thank you so much for your reply!
The check engine light isn't on but it's running so poorly that I have to believe the light is broken (or since I bought it from a mechanic he cleared it? Not sure how that works exactly)
Unfortunately it's not registered so I can't legally drive it right now.
I'll definitely check how it respond to the A/C, thank you!
I really thought it was the EGR valve for ages until I became convinced that the petrol e46 don't have them. They do have secondary intake valves/pumps but mine seems to be missing (but apparently you can do that).
I'm quite out of my depth so if I say anything that doesn't make sense please let me know but thank so you much for your time!

From what I can tell "they" call it an air diverter/bypass valve and the p/n changed sometime during the year so the replacement will be VIN specific.

Definition:
The diverter valve, also called the air diverter valve, are part of your vehicle's emission system. Air diverter valves recycle exhaust and engine gases to lower the amount of emissions into the air by taking pressurized air from the air pump and diverting it to the exhaust manifold. If you notice that your fuel economy is reduced or your engine runs rough while idling, you may need to check your diverter

That sounds like an EGR valve to me except it's using high pressure air. Hopefully one of the other experts can post a nice picture for you.

Can you please shoot a quick video with your phone so we can see what's going on? that would be great. You can upload it here with your response.

Thanks for all the help!
I've attached some stuff:
Some photos of what I think are disconnected (temperature?) sensors on top of my engine?
One photo of some attached sensors on the side of my engine
A video of me starting the car a few hours ago:

0:00 - Car starts and immediately stalls.
0:11 - I press the accelerator so car doesn't stall and keep my foot there.
0:17 - The revs drop even when the pedal is constant.
0:19 - I press the pedal more to keep the revs up.
0:30 - I press it some more to test the high revs.
0:38 - I try to see if it will idle without the pedal but it stalls.
1:16 - Ignore me pressing the radio.
2:10 - It finally stalls by itself!
2:30 - I move the car around a bit (reverse first).
2:47 - I go forwards.
2:56 - It stalls going up a tiny slope.
3:20 - Back to where I started, back in park (such a low idle :c).
3:45 - More testing the high revs.

And finally a video of me playing with the A/C while it idles (it started up perfectly somehow and got a bit worse over time)
If it's relevant it's about 15°C (or 60°F) and I'm not that far above sea level.
Thank you so much!

Try disconnecting the MAF sensor.

IAC: You can also try disconnecting this electrically. The idle might stabilize at a higher RPM. Disconnect and re-connect with the car off.

The MAF sensor sometimes does not set a code. With it disconnected, the car generally is driveable, but not quite right.

Disconnected the MAF sensor and it runs much better! High idle but much less of a problem. Should I be getting a can of MAF cleaner?
Should I still try and disconnect the IAC valve? (do you mean just unplug it and plug it back in immediately while the car is off or actually trying to run the car with it unplugged?)
Thanks!

Update:
Bought some MAF cleaner and cleaned my sensor, let it dry then put it back in and was a bit better than before (didn't immediately stall) but still a rough, low idle.
Unplugged the sensor again and back to ¬900 rpm idle.
I think I'll try and clean it again with more cleaner and let it dry for even longer too.
Also will try and reset idle rpm's if I can do that and drive it around a bit to see if it gets needed some time to get used to the clean sensor.
If not I guess I'll buy a new MAF sensor.
Thanks again for all you guy's help and please let me know if you have any suggestions!

Once the sensor is too far gone cleaning will not help. did you check for a vacuum leak that will cause it as well. here is a guide to help:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please run down this guide and report back.

When I remove the MAF sensor, it doesn't have any of the problems - could it still be a vacuum leak?
Thanks

It sounds more like the sensor is bad, I would try a new one. You get that scanner yet? it might have a code for a bad sensor. Here is how to replace the MAF. Check out the diagrams (below). Please let us know what happens.

Thank you!
Unfortunately the scanner hasn't come yet.
I'm going see if I can get a second hand a scanner for cheap.

Sounds good, let me know.

cybaforge:

I actually think your getting somewhere and I think the MAF is bad. It doesn't always set codes. Sometimes, like you, you can't even keep the engine running.

I don't think you've been "throwing money at it".

I would go ahead and replace the sensor.

There are still lots of things that can cause eratic idle. Let me ask a question. Were the plugs or wires replaced that you remember? Bad wires or bad routing of the wires is another cause. You can "inspect" the wires. e.g. look for burn marks, are they close to the engine block, are they separated, do adjacent firing cylinders or waste spark cylinders run next to one another, covered with oil etc.

A disconnected MAF will perform better than an bad MAF sensor, The engine doesn't necessarily run smooth. Like I said...it's "not quite right".

Your also now in a situation where you don't know if the "check engine" light is on or burned out. if you have an Autozone nearby, lay down a deposit and borrow the tool. Autozone has a lend-a-tool program. A deposit gets you a tool to use. There's no excuse not to borrow a scanner.

Another reminder is that with all of the stuff you have been doing, the car is likely in a state where it has fine tuned itself. Once you replace something after the check engine light has come on, you need a "drive cycle" for the ECM to say, I think the car is okay.

Even though the check engine light is not on, it can prevent you from passing emission inspections, Example...You replaced the battery. There is no check engine light, but it may fail emissions.

A drive cycle varies by manufacture, but usually the car has to have reached operating temperature and you have had to cruise at constant speed for a while.

Example, from this site, but not for your vehicle: https://www.2carpros.com/questions/2006-chevrolet-equinox-drive-cycle

I'm really glad you think so!
My OBDII scanner isn't coming anytime soon and I had no idea that there were AutoZone's nearby. I'll definitely do that next time or if a new MAF sensor doesn't work. I tested my MAF sensor and it had infinite resistance between all the pins (only tested it when off) so I'm guessing something burned out. I just ordered an aftermarket MAF sensor that had good reviews for about $50.00 and I'll hope it don't have to buy a $200.00+ from a store.
Thank you so much for all your help, I'll let you know how the new MAF sensor works.

Word of warning - Never use an ohmmeter on an Oxygen sensor.

I'll keep that in mind.

Just received my aftermarket MAF sensor and after driving for 20 something km's it works almost perfectly! I couldn't have done it without everyone here's help. thank you so much!

That's good news. Let us know if you have questions in the future.

Take care,
Joe

Cybaforge,

Nice to hear success stories.