Idle Surge Help Needed!

[ruffbunch]

I have a 1995 525i. I have taken much advice from this forum but still have the problem. When I start my car in the morning (engine cold) the idle surges and will not stop until the car warms up to just the top of the blue on the temp guage. While surging it will occasionally die when I stop. It also has smoke coming out the tailpipe at it surges up. Once warm the car runs smoothly and fine.
I have done the following-
1. repaced the PCV at front of crankcase along with both hoses
2. new intake manifold gaskets
3. new throttle body gasket
4. new idle hose/elbow tube (under manifold) along with a new connector it has into the manifold
5. new rubber boot from MAF to throttle body along with both hoses that connect to it. This includes the one that runs over to the PCV valve.
My car still has this horrible idle surge from a cold start. Until is warms up it runs crappy, too rich, smokes as it surges up and is almost undrivable.
I took my car yesterday to a BMW mechanic and he hooked it up to a diagnostic machine and it shows not error codes. It says my car is fine. He was puzzled and said he does not know why the idle surges but gives a 50/50 chance it might be the PCV valve.
Can anyone advise me on what you would do at this point? I have spent hours searching threads and cannot find any answers. Thanks!

[ruffbunch]

Sorry- the mechanic said it is 50/50 to be the ICV NOT the PCV. Is it worth spending the money to replace it or is there other advice to consider? Thanks!

[Bill R.]

engine temp sensor and the connection at the temp sensor. Typically its one of these two things.




I have a 1995 525i. I have taken much advice from this forum but still have the problem. When I start my car in the morning (engine cold) the idle surges and will not stop until the car warms up to just the top of the blue on the temp guage. While surging it will occasionally die when I stop. It also has smoke coming out the tailpipe at it surges up. Once warm the car runs smoothly and fine.
I have done the following-
1. repaced the PCV at front of crankcase along with both hoses
2. new intake manifold gaskets
3. new throttle body gasket
4. new idle hose/elbow tube (under manifold) along with a new connector it has into the manifold
5. new rubber boot from MAF to throttle body along with both hoses that connect to it. This includes the one that runs over to the PCV valve.
My car still has this horrible idle surge from a cold start. Until is warms up it runs crappy, too rich, smokes as it surges up and is almost undrivable.
I took my car yesterday to a BMW mechanic and he hooked it up to a diagnostic machine and it shows not error codes. It says my car is fine. He was puzzled and said he does not know why the idle surges but gives a 50/50 chance it might be the PCV valve.
Can anyone advise me on what you would do at this point? I have spent hours searching threads and cannot find any answers. Thanks!

[31Hertz]

Try cleaning the ICV with contact cleaner or throttle body spray. Then test the resistance values as below.
4011

[Bill R.]

values, it will be the movement is impeded or slowed down by gunk buildup in the valve.



Try cleaning the ICV with contact cleaner or throttle body spray. Then test the resistance values as below.
4011

[ruffbunch]

A lot of this is new to me so have patience as I learn. I actually took off the ICV to clean it when changing the manifold gaskets. I was not sure how to do it so I just put it back on. Can you tell me exactly what you do to clean it properly?

[billb]

...where my engine would run fine until it went closed loop, then would not idle, poured out black smoke, etc. Everything else checked out okay. Turned out to be the MAF that ScottyWM let me borrow his to troubleshoot. $85 later for a used one and we were back in business.

[Bill R.]

spray it into the one of the large hose openings in the icv until it comes out clean. Don't use any sharp objects or tools to scrape the inside clean , just keep flushing it out with spray until its visually clean.




A lot of this is new to me so have patience as I learn. I actually took off the ICV to clean it when changing the manifold gaskets. I was not sure how to do it so I just put it back on. Can you tell me exactly what you do to clean it properly?

[ruffbunch]

okay- I'll give that a try and keep you updated on how it turns out. Thanks for the advice.

[31Hertz]

values, it will be the movement is impeded or slowed down by gunk buildup in the valve.

Ach, Ja. I just figure if he is cleaning it; he might as well test it.;)

[ruffbunch]

I had to take the manifold off again to get the idle control valve out. If you can get it off another way then you 'da man! I have cleaned it thoroughly with throttle body cleaner. It appears to me to be clean. I am ready to reassemble but before I do- can anyone advise anything else to check on while it is easy to do so???? You might check the list of what has already been done- thanks!

[BillionPa]

if that doesnt fix it, clamp off the vacuum line to the charcoal canister purge valve.

[ruffbunch]

help me here- I'm not exactly sure where that is.

[ruffbunch]

Okay- here is the latest update. I am still going to need some help! I cleaned the ICV thouroughly and put everything back together. It started on the second try amazingly and ran okay but the idle surged a bit. I drove it out and once warm the engine ran great. Strarted it this morning and it ran smooth for about 5 seconds and then the idle began to surge and at the surge peak their is a rich mix of black smoke from the tailpipe. It will do this until it warms to about the top of the blue on the temp guage.
What should I try at this point?
I can put a new ICV on. I could try a used MAF to see if that helps. I'm just hoping to get this problem behind me!!!

[BillionPa]

hmm, the ICV sounds fine at this point, but it sounds like the closed loop operation is shot.

my 3 suspects are coolant temp sensor, air temp sensor, O2 sensor heater relay.

[ruffbunch]

which one would you start with? I'm learning as I go here in terms of doing my own work so I'll have to investigate all three of those repairs to do them. Any tips?

[Bill R.]

the car and o2 sensor warms up. Your fine there from your description. You problem is during the open loop operation. The first and most likely thing i would check is the coolant temp sensor. I would inspect it, check it with an ohmeter and clean the terminals and connector end on it. The terminals are frequently where i find a problem, not the sensor itself.




which one would you start with? I'm learning as I go here in terms of doing my own work so I'll have to investigate all three of those repairs to do them. Any tips?

[ruffbunch]

Is it #13 in this picture? Seems pretty easy. I've never replaced before so just seeing if I'm on the right track. Thanks.
http://www.realoem.com/bmw/showparts.do?model=HD63&mospid=47404&btnr=11_1282&hg=11&fg=15

[632 Regal]

yes! thats a good start.

Is it #13 in this picture? Seems pretty easy. I've never replaced before so just seeing if I'm on the right track. Thanks.
http://www.realoem.com/bmw/showparts.do?model=HD63&mospid=47404&btnr=11_1282&hg=11&fg=15

[BillionPa]

got my loops mixed up, oops.

but my thoughts were in the right direction.

go at them in sequence.

[ruffbunch]

Thanks for the help. I'll have to order what I need and will provide an update accordingly. You guys are life savers!

[ruffbunch]

I just put on a new engine temp sensor and engine coolant sensor as well as replacing the Idle Control Valve (ICV). I did not know if the old one was bad so I just replaced it to be sure. I unhooked the battery cable during the process to reset the computer.
I fire up the engine on the second try and it runs out smooth for about 15 seconds and then begins to surge again. I back it out of the garage and let it sit and idle and it continues to surge although not quite as badly as before the repairs.
I shut the engine off and then go back out to drive it. It surges up and down as before but just not as severely until the engine heats up to just the top of the blue area. It is a fairly warm day today (60'ish) so the engine was not that cold to start with.
I need help on what to do next. Can anyone offer additional advice on how to stop the engine idle from surging while running cold? (I might be away from the computer till Sunday afternoon as we are leaving on a trip. I hope to have some great advice when I return. Thanks for your help!)

[BillionPa]

well, if those didnt do it, then its probably a vacuum leak. intake manifold gasket perhaps?

[SnakeyesTx]

Man! I've been following this thread for a while now. I've got a similar issue to yours except I don't get the smoke out the tailpipe issue. Mine does the exact same thing with everything else you described. Aweful idle when its cold, surges badly, even leaps into traffic when I stop at a light in Drive. I've taken my car back to the shop 4 times since my engine was replaced about 2 weeks ago and they can't find the problem either. Its really annoying since the old motor never did this. I totally feel your pain here. In my case it feels unsafe to drive on cold days because of the leaping action I get. Even after mine warms up, I can feel the slightest miss in the idle when its not bucking and giving everyone around me the impression that I have a bimmer with hydraulics. :(

Can't wait to hear a working solution so I can crawl under mine and end this nightmare. Oh yeah... wait till you see what it did to my guibo (the bucking in gear part). I'll take pictures in the morning when its light out.

[ruffbunch]

Intake gaskets replaced as an original attempt to fix this issue. I have taken the manifold off twice since then but the gaskets are practically new and show absolutely no wear at all so I did not replace them. When I replaced them, it did not help at all with the surging idle
The only redeeming value of what I've done so far is that it does run out smoother- especially when it warms up and the surging stops.
I'm open to and welcoming advice. What say you?????

[ruffbunch]

yeah, mine really surges pretty strong too. I usually put it in neutral when I stop or it does look like I have hydraulics. The problem is that too often it just goes dead when the idle goes low after the surge and I have to restart the car.
I'll gladly post the resolution when I find it. Believe me, I can't wait!!!

[Bruce Kennett]

yeah, mine really surges pretty strong too.

hi ruffbunch and snakeeyes,

mine did the same thing -- first time, i was sitting in D in front of a crosswalk and a mother with two young children was walking right in front of the car! car surged and luckily i just STOMPED on the brake and the car only went ahead a few inches. but it scared the @#$%^&* out of me.

a few days later it did the same thing.

my indie replaced the whole valve and it's been fine ever sincve. i know that cleaning is what most people recommend but if you haven't yet replaced the control with a new one it might be worth doing, just for the chance that it'll be what gives you the peace of mind you are seeking.


bruce

[ruffbunch]

actually, I just replaced the ICV as well as the engine temp sensor and the coolant temp sensor. Those are the last three things I did. Prior to that I list what I did in my intro at the top of the thread.
I don't know what else to check as far as a vacuum leak goes. I sure would like to know what is causing that surge!

[ruffbunch]

I did more research and found a thread that suggested replacing the fuel pressure regulator and it seemed to help. I think I will try that although it will be after T'giving as we travel all week. I also saw suggestions about the ECU being part of the problem. Does anyone think that might be part of this surging idle problem? How would you determine if it is ECU related?

[SnakeyesTx]

I'd like to rule out the ECU only because I replaced my motor. The original engine ran fine with its original ECU. The replacement motor is the shaking nightmare with my original ECU. Strangely enough, it didn't buck at all today, but it I noticed that the bucking/crap idle issue is usually when its really cold outside and the engine isn't warmed up.

I like the idea of it being an open-loop issue. This makes me think this is strictly an electrical gremlin. I haven't actually seen the ICV before so I'm unsure if its electrical AND vacuum or not. All I know so far is if I put my thumb into the hose coming out of the ICV, the vacuum will suck my thumb into the hose tight, the idle raises a little bit, smooths out wonderfully, then stalls out a few seconds later. Take a picture of the one you took out so I know what we're looking at here! Realoem's picture only goes so far. Hell, that diagram on realoem made it look like the ICV was near the firewall.. which we all know it clearly is not :D

[ruffbunch]

I am leaving in about an hour to be gone for the week of Thanksgiving. When I return I will post the pic. It is frustrating to have to wait but such is life. Thanks!

[halogen25]

I've had similar idle problems and would like to add my recent problems to this thread.

My '94 525iT also had idle/surge/stalling issues. I changed the ECM, which seemed to fix the problem, until it came back about 1 month later!

Just for the hell of it, I took out the battery to check its charge, and after putting it back, the idle problem was fixed.

So now I disconnect my battery about once a month to "reset" the idle. Can someone suggest why this works? I would prefer not to yank out the back seat all the time...