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Old 03-30-2013, 06:10 PM   #1
josenne
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Join Date: Mar 2010
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RPM Issues

Hello Everyone,

I am reaching out for some help with an RPM issue. I have searched around and tried a few solutions, but to no avail.

Symptoms:
-Upon starting, the car will idle somewhere in the 400-1000 RPM range, but will not settle properly, feels very rough (shaking), and "clunks". See the linked youtube video (), and listen towards the end for the clunking.
-If I push the accelerator (not to the floor, just some) the engine will rev-up after a bit of a lag, and the problem die off. After about 30s-1min I can usually let it come back to idle and it will not be as bad. This occurs on most starts, cold or not
-While driving on a relatively level road I set the cruise control at ~40 mph and the tach searched from 1400-2500 RPM, all the while maintaining the correct speed.
-It has stalled out on me a few times when I let off the accelerator prior to making a turn.
-Autozone trip for a code reading gives P0171 and P0174 as well as their counterparts with the strange % symbol.

Steps I have taken so far:
-The first thing I did was remove and inspect the air intake boots, and clean the idle control valve. I also cleaned the MAF sensor at this time. The air filter is a k&n type (with small amount of oil), so I clean the MAF sensor every few thousand miles anyways.
-In getting to the ICV I noticed that the DISA valve was malfunctioning (no tension on the flapper), so I repaired it with the kit from germanautosolutions.
-Though the associated codes were not being thrown, I replaced the camshaft position sensors, since that seemed to be a common item that would lead to these sorts of issues
-Replaced spark plugs
-I also ran seafoam through the secondary air intake
-Though not part of this round of repairs, I replaced the fuel filter ~20k miles ago.

Things I have not done but have come up on other threads:
-MAF replace
-CCV
-VANOS
-take to professional (BMW is an hour+ away; I have not yet found a local indy shop, but I am currently leaning towards trying this route)

I would appreciate any suggestions on things to try and diagnose next. I would like to avoid throwing parts at the problem, but at the same time the local place I called charged $75 just for me to come in the door, and would not even waive that it if I left it there for repair

Last edited by josenne; 03-31-2013 at 04:20 PM. Reason: updating latest repair attempts
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Old 03-30-2013, 06:24 PM   #2
Br0k3nLiNk
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I know it sounds a little stupid and minor, but I had this on my old E36 and had to clean all my spark plugs. Although it turned out one was slightly lose so not sure if it was that.

Shakey idle and then fine when revved.

Edit: almost seemed like running on 5 cylinders until revved..

Last edited by Br0k3nLiNk; 03-30-2013 at 06:27 PM.
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Old 03-31-2013, 04:20 PM   #3
josenne
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Quote:
Originally Posted by Br0k3nLiNk View Post
I know it sounds a little stupid and minor, but I had this on my old E36 and had to clean all my spark plugs. Although it turned out one was slightly lose so not sure if it was that.

Shakey idle and then fine when revved.

Edit: almost seemed like running on 5 cylinders until revved..
Thanks for the suggestion. I checked the spark plugs (went ahead and replaced them while I had them out), but the problem persists...
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Old 03-31-2013, 04:56 PM   #4
Dave1027
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Those codes you posted mean the mixture is too lean and that's usually caused by a vacuum leak. Go through the intake with a fine tooth comb.
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Old 04-01-2013, 05:07 AM   #5
Br0k3nLiNk
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Quote:
Originally Posted by Dave1027 View Post
Those codes you posted mean the mixture is too lean and that's usually caused by a vacuum leak. Go through the intake with a fine tooth comb.
I didn't notice the codes in his post lol, mine does those warning lights every time I do a long journey but never stays lit. Need to hunt my issue too.

From when I looked up people say what Dave has suggested. I cant remember the forum that i saw it but a lot of the time it can be components in the fuel system restricting petrol flow. Could be the pump or a dodgy injector(s)?
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Old 04-01-2013, 05:25 AM   #6
jfoj
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Suggest you read the first link below in my signature.

Very common problem areas are intake boots being cracked, fuel pressure regulator vacuum line cracked/broken, SAP vacuum lines cracked/broken around the valve cover, SAP hoses cracked/broken.

One very simple but overlooked problem is the CCV lower oil return line that connects to the base of the dipstick tube.

Also pay careful attention to the DISA section.

If it is rubber or plastic and under the hood, it needs to be replaced!
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Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616

Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temps, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose fan switch O-ring - BMW #13621743299

Last edited by jfoj; 04-01-2013 at 05:28 AM.
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Old 04-01-2013, 08:39 AM   #7
josenne
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Thanks for the links jfoj.

I have already replaced the flapper in the DISA valve (which I know goes against your suggestion) and put in the associated o-ring, and I have previously needed to replace my rubber intake boots, so I know exactly the types of problems you are talking about there. This afternoon I will remove the CCV oil drain hose and inspect it, which is something I have not yet done. For prudence I will also re-check my intake boots and spray some brake cleaner around the DISA, throttle body, and ICV mating points just to make certain they are not the sources. If those don't yield anything I will go over the "other areas to look" section you pointed out.

Last edited by josenne; 04-01-2013 at 09:13 AM.
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Old 04-05-2013, 05:22 PM   #8
josenne
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Hello everyone. I wanted to post an update on my findings. It turns out that I did not inspect my lower intake boot quite carefully enough, and I have a pretty sizable hole (or 3) in the rubber. I had concentrated on the lower boot when checking things before, as that is where I previously ran into issues. Additionally, it appears that the lower oil drain hose from the CCV is broken (I have only felt it, as I am going to wait for the new part to arrive before removing the old). Nobody near me seems to have these parts, so it is more of the hurry up and wait game. Thanks again to jfoj for pointing out the common problems to check (of which I had 2).
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Last edited by josenne; 04-05-2013 at 09:44 PM.
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Old 04-05-2013, 05:25 PM   #9
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Jfoj it. I just jfoj'd it this weekend after my car started misfiring and it has given me a buttery smooth idle. Also, if you replace the DISA, go ahead and get the upgraded flurosilicone o-ring. Scrape off the dinky molded o-ring. It got flatter already and I just installed the DISA a week ago. It still seals nice, but I noticed a difference.

You'll also notice better response from a stop, and MUCH better MPG.
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