unplugging icv '91 325i

[davem]

Is the engine supposed to run different when you unplug the ICV while the car is running? I seem to remember reading something like that here. I have a constant but rougher idle and when I unplug the ICV nothing changes at all.

[Jesse30]

IIRC it'll stumble a little.


try just pulling your ICV out cleaning it. its likely a little dirty and not working properly.

[jlevie]

If everything is working correctly, the idle should rise slightly when you unplug the ICV. A rough idle could be due to any of an number of things. But at the top of list would be intake leaks. Find a shop that can run a smoke test on the intake.

[ak-]

Prophet jlevie has given the same advice over and over again that I feel like he just now has his answers on Copy and Paste.

SEARCH man..

Ask when you are genuinely out of luck.

[davem]

Prophet jlevie has given the same advice over and over again that I feel like he just now has his answers on Copy and Paste.

SEARCH man..

Ask when you are genuinely out of luck.

I have: cleaned the ICV, replaced intake boot, breather hose, spark plugs, adjusted valves, new valve cover gasket, cap & rotor, fuel filter, O2 sensor, air filter, have tested the resistance of the ICV switch, checked the throttle position switch, also had some bmw mechanics to troubleshoot it, they said no intake leaks and put some injector cleaner in the gas tank.

I think I've done enough to ask a simple question.

I'm still considering new plug wires, rebuilt injectors, new fuel pump (hope not).

[lateracer]

I'm still considering new plug wires, rebuilt injectors, new fuel pump (hope not).

Rebuilt injectors did more than I thought they would for improving my idle. Noticeable doesn't begin to describe it.

Plugs 'n wires don't usually make a difference you can feel but it's hard to tell if they're not working right. Best to just bite the bullet and replace 'em if they're looking old (or you know they're old).

This may be more opinion than fact, but I think replacing the fuel pump is easier than replacing the injectors from a mechanical standpoint. I just always seem to cut the back of my hand on something when pulling those things off the intake. It's really not that bad...unless you smoke while you do the job.

[davem]

Rebuilt injectors did more than I thought they would for improving my idle. Noticeable doesn't begin to describe it.

Plugs 'n wires don't usually make a difference you can feel but it's hard to tell if they're not working right. Best to just bite the bullet and replace 'em if they're looking old (or you know they're old).

This may be more opinion than fact, but I think replacing the fuel pump is easier than replacing the injectors from a mechanical standpoint. I just always seem to cut the back of my hand on something when pulling those things off the intake. It's really not that bad...unless you smoke while you do the job.

I am hesitating because fuel pump, wires, and getting injectors is expensive. The wires look okay but I don't have any service history of them being replaced.

I picked up some used injectors that I can have rebuilt, so they will cost me about 50% of new ones. I also have a line on a deal for a new fuel pump. I've already put quite a bit of cash into this car so I need to proceed cautiously as I still need to change the coolant, do subframe bushings, engine mounts, tranny filter & fluid etc etc.

Thanks for the reply, I may as well go ahead with the injectors.

[Sagaris]

By checking the resistance of the ICV switch I assume you mean the idle switch on the bottom of the throttle body?

EDIT: you re-worded your post so it makes sense now.

[ak-]

I have: cleaned the ICV, replaced intake boot, breather hose, spark plugs, adjusted valves, new valve cover gasket, cap & rotor, fuel filter, O2 sensor, air filter, have tested the resistance of the ICV switch, checked the throttle position switch, also had some bmw mechanics to troubleshoot it, they said no intake leaks and put some injector cleaner in the gas tank.

I think I've done enough to ask a simple question.

I'm still considering new plug wires, rebuilt injectors, new fuel pump (hope not).

Then obviously mention all this in the beginning so we can all have an idea where you are at dude.

[lateracer]

I am hesitating because fuel pump, wires, and getting injectors is expensive. The wires look okay but I don't have any service history of them being replaced.

I picked up some used injectors that I can have rebuilt, so they will cost me about 50% of new ones. I also have a line on a deal for a new fuel pump. I've already put quite a bit of cash into this car so I need to proceed cautiously as I still need to change the coolant, do subframe bushings, engine mounts, tranny filter & fluid etc etc.

Thanks for the reply, I may as well go ahead with the injectors.

Yeah, plug wires and some other choice items for these things are ridiculously pricey. Getting these things back up to 100% is a long and slow (and expensive) process.

I also did the second injector set you're doing for my rebuilds so I was able to remove and replace all at once. Good call on that one.

An inline fuel pressure gauge - which is cheap - can be installed to where you can read it while the car is moving. Along with being good to have, it can also tell you how your fuel pump is doing. Possibly buy you some time.

The other stuff you mentioned like mounts/bushings will make a big difference as well. Before you go too far in chasing down a funky idle, you may want to get your intake system checked for leaks professionally (smoke test). As I'm sure you've noticed, you can get help here from people who know what they're talking about, but it's often dished out in less than friendly terms.

You get what you pay for:-D