Erratic Idle issues

[keggle]

So I picked up a 97 318ti and decided to do some work on it before I started driving it. It is a manual and has 173k miles. It ran descent, but had holes in the rubber intake boot and CEL. I decided I would replace the coolant pipes under the manifold and behind the head. I got them replaced and replaced all the coolant and vacuum hoses while I was in there. I also replaced the pcv valve and had the injectors cleaned and tested.

Now the issue, I got it all back together and it isn't idling well. The idle is bouncing between 1600-1800rpm. The CEL was the O2 sensor before the cat and I replaced it with a new bosch. Still poor idle, but sometimes it idles ok at first. I found some information on the ICV, so I removed it and checked it out. There was no carbon build up and it seemed to move fine. Only thing was it wouldn't close all the way and I couldn't find info on if it should. So I opened it up and found no problems accept the spring washer was broken inside, but that looked like it should just aid in sealing.

I smoke tested it for leaks and the ICV was the only thing leaking. It was also getting past the PCV valve into the crankcase, not sure if this is normal?

Long story short do you think it is the ICV? It was idling better with the holes in the intake boots. It drives fine, just at low rpm it's a little jerky, probably because the erradtic idle.

Any thoughts? I ordered a new ICV and will wait to see if that fixes it. I am itching to drive it and want to get this working right. I did search, but most of the idle issues were the engine almost dieing and my rpms never get anywhere near that low.

[zoner]

If the ICV was leaking, that could certainly cause rough idle. It might have just been the gasket (unless it was actually leaking from the unit itself- when I replaced mine awhile back, it has a few stress fractures in the plastic).

[xxxJohnBoyxxx]

Is there any exhaust leaks before the upstream O2? a very small exhaust leak will cause a terrible idle but the car will run great above idle. This is caused by the small leak at idle sucking in air which tells the O2 the AFR is lean. When above idle the leak will only leak exhaust out and not allow in fresh air so the car runs normal. just a thought.

Also does the car have a irratic idle (up/down 800-1500) while rolling up to a light or stop sign and then when you come to a complete stop is jumps 3 times then smooths out?

[keggle]

I just replaced the ICV and no luck. It still idles the same. It idles fine for the first 30-60 seconds of starting it up cold. Then the idle starts bouncing between 1600-1800 rpm.

I will look for an exhaust leak, but it doesn't sound like there is one anywhere. It seems to drive fine, when I come to a stop it just goes to the same 1600-1800 rpm bounce. I haven't driven it much yet just around the block a few times.

I'm really starting to think its a control issue more then a vacuum leak. I have blown smoke in the intake and can't find any leaks, I have tried pulling and plugging a few vacuum lines with no change. There is no codes showing. I am at a loss, not sure where to go from here.

[keggle]

OK, I just pulled the connector to the MAF while it was running and the idle went to a rough 800 rpm idle.

There is some sucking noise coming from where the upper and lower manifold come together. It sounds like from the valve that's inside the lower manifold, I don't know what that is. But you can hear air noise from there. I sprayed some contact cleaner around it, but there was no change.

If I remove the oil cap it's like there is a vacuum leak. So I pulled the hose to the valve cover and blocked it, but no change. The PCV valve is brand new. I will keep searching, but I'm tired of throwing parts at it.

I couldn't find any exhaust leaks.

[drummond07]

I cleaned the ICV on my 98 318ti and the rough idle went away. I used carb cleaner and a small (baby sized) toothbrush.

[keggle]

I replaced the ICV, still no luck. I replaced the vacuum line to the fuel regulator as it was the only vacuum line I didnt replace. Had to take the upper manifold off and now it just shoots up to 4000 rpm. Can't find any hoses missed or anything. Found a small leak on the intake divert valve or whatever its called. Waiting on orings for it now, but I don't think that is the problem.

This car is driving me crazy.

[bazar01]

Check the vacuum hoses that are attached to the fuel injectors. They dry rot and crack and becomes a big vacuum leak.

[xxxJohnBoyxxx]

You really need to run INPA or Torque on it if you have android. Computer for INPA and OBD-II bluetooth adapter for torque.

I bet you will find the problem with INPA like a bad outside air temp sender or bad head temp sender.

I had a small vacuum leak on my intake behind the TB and it caused all kinds of ruff idle. If it wasn't shaking my teeth out at 900 rpm it was bouncing between 1,400-1,600. Pluged the leak and idles smooth now. I don't think CCV should have vacuum at idle. It should only start pulling combustion gasses to be reburned while cruising. Also EGR can cause this issue.

INPA will find any issue in the analog screen monitor mode. Also will pull codes that my Actron reader won't show. Torque is second best, easy to use and you can setup a real time gauge for any sensor to ensure it is working correct.

Anyone that wants Torque Pro .apk email me at No1Be4Me@gmail.com and I will hook you up

[reflex88]

Bumpity bump!! Any conclusion here? xxxJohnBoyxxx .. You specifically mentioned and idle that bounces 2 or 3 times when slowing and stopping for lights/stop signs.. I have that exact symptom when my car's cold.. You've gotta explain why you asked that man!! .. Should add, I'm on an M43.

I've cleaned out my ICV..
(tried an eBay one, that was worse)
Changed all suspect hoses.
Replaced the DISA with a know good one and fitted a new CCV valve.
Recent fuel, air, oil filters and plugs.

Once warm, all is well.. always thought it sounded a little too gruff for a little 1800.. do these motors have a nice tone or do i have a tiny hole to find?

Cars done 55k.

[reflex88]

Oh.. one more question... On the M43, would a replacement ICV need adapting to function properly?

[keggle]

It was the vacuum line to the fuel regulator

[reflex88]

Hmmm.. I've already changed that out...

Thanks though...

[ALPINEMTECH98]

My m44 is idleing from like 1k to 400 then stalls...It was running good till I had to take the upper manifold out to change one of the o-rings in my fuel lines to the rail then after I plugged everything back together again, it idles very bad.

I wonder what went wrong? I did replace the intake boots with better ones because the old ones had rips in them hmm...could the gap from the upper intake manifold and lower cause that problem? The guy that i got before me kinda screwed it up and put gasket maker between them and chipped a bit of it and now I cleaned it up with new gaskets and some #2 sealant....but not sure if i made it better or worse.

Let me know, thanks.