M42 won't hold idle UPDATE: New problem. Need help

[shameson]

Really? Hmm I've heard soaking it is the trick. I'll just spray it then

Did get a spare fuel pump so will do that after doing the fuel filter this weekend

[jdt10768]

I would not soak the entire ICV. Just spray a bunch through it both ways. Tap it a few times all around and spray again. Install and test.

[shameson]

clean shit from ICV with carb cleaner, reinstall. test.

Ya I need to try that. Im going to soak in carb cleaner an see what happens

Can you hear any air leaks? Sounds like what mine was doing.
Do all the mess under the intake. Replace all the hoses and simplify the whole thing.

Ya I've already looked at the hoses/ vacuum lines and replaced just about all of them. Had a few that were bad but replacing them didn't change anything

Eventually I'll go through and simplify the whole deal

[econti]

Can you hear any air leaks? Sounds like what mine was doing.
Do all the mess under the intake. Replace all the hoses and simplify the whole thing.

[roguetoaster]

You can just unplug and remove. It's between the valve cover and firewall. Held on by a 10 or 13 mm bolt I think, and a couple small hoses.

Elec plug has a small wire retaining clip that will fall into the engine or onto ground. Use needlenose

It's an 11mm nut that is the far right hand side of lower intake manifold.

The plug on most of the ICVs I have seen is the push down on the metal spring to release type, don't use pliers unless necessary.

If you have yet to do the mess under the intake work the ICV will be a bit fiddly to reinstall due to the shape of the lower hose going to it. This hose is also prone to cracking, be sure to look at it if the above applies.

[jdt10768]

You can just unplug and remove. It's between the valve cover and firewall. Held on by a 10 or 13 mm bolt I think, and a couple small hoses.

Elec plug has a small wire retaining clip that will fall into the engine or onto ground. Use needlenose

[FCBmw]

Is it possible to pull it with the manifold on?

[jdt10768]

clean shit from ICV with carb cleaner, reinstall. test.

[FCBmw]

I seem to be having a similar issue. My car seemed to be running ok with the revs up but every so often it would really run like crap. Especially when starting up in the morning. The car would barely idle almost like running out of gas. When I could get it going with the revs up at normal driving speeds it would be ok. When I came to a stop it would stall out or stumble. After it would start up every time. I unplugged the ICV and besides a high idle it has yet to have any of the mentioned issues. It also threw a code of c9 (lamda control). So I am just wondering if this tells me that the ICV is bad? Also is it ok to drive around with it unplugged?

TIA

[roguetoaster]

If I just unplug the ICV, how should I tell whether it's the issue or not?

Unplug, adjust the throttle stop until you are 900+/-50 RPM. See if the idle stays steady.

[shameson]

Technically it's a throttle stop on the TB as it does nothing more than adjust how far open the butterfly valve opens. You may be thinking of the idle adjustment screw on M20 ICVs (I forget if the M42 has one).

My thinking is that if the engine can hold an idle that way you should be good to go. A first step if you don't want to try that might be to just unplug the ICV.

If I just unplug the ICV, how should I tell whether it's the issue or not?

[roguetoaster]

Technically it's a throttle stop on the TB as it does nothing more than adjust how far open the butterfly valve opens. You may be thinking of the idle adjustment screw on M20 ICVs (I forget if the M42 has one).

My thinking is that if the engine can hold an idle that way you should be good to go. A first step if you don't want to try that might be to just unplug the ICV.

[shameson]

When I arrive at a mystery such as you have I try to eliminate parts from the equation. In your case I suggest removing the ICV from the system and setting idle at the throttle body. That should tell you what you need to know.

Thought you're not supposed to mess with the idle screw?

I'm going to try cleaning my ICV and see if it makes any difference

[roguetoaster]

When I arrive at a mystery such as you have I try to eliminate parts from the equation. In your case I suggest removing the ICV from the system and setting idle at the throttle body. That should tell you what you need to know.

[shameson]

First lesson: quit throwing parts at a car until you know what the problem is! Cause now you don't know if any of the new parts might be bad or you installed them incorrectly.

Lecture over. Now some questions: Did the engine run ok prior to the alternator problem? Next: are you sure you didn't kill your battery? Check it. If less than 12.3 volts with a multimeter, you may have a bad battery.

I didn't put in all the parts at one time, I've been doing all this over the course of the last month trying to do it in steps: tried just the AFM first, then tried just the cam, crank sensor and tps, then just the fuel relay next, etc. That's just a list of what I've done so far. Sort of throwing parts at you could say, but methodically to see if anything changes it. It's all stuff I'm glad to know is new lol

And yes battery was replaced at the beginning of this year. I have a multimeter and the battery was between 13-14 volts when I started the car after replacing the alternator, when the problem first occurred