Rough idle solely at start up?

[BustedBoat]

Good Morning everyone, sorry once again for my long absence. I've been having this problem for a couple of months now and I've finally decided to buckle down and figure it out. I have a very rough idle at start up. During this time the exhaust starts to smell like gas. Sometimes the smell is strong enough to smell it around the car. The problem always stops when i give the engine a quick rev. I thought it was my fuel filter so I replaced it. But still no good. Any thiughts?

[danewilson77]

....and no codes.

I would start with basic maintenance. Inspect the intake boots, disa, clean your icv and MAF sensor.

If a sensor had failed, you should see a code so you can probably rule out O2, CPS, etc....

If that all checks out...we'll keep working on it.

Sent from Williamsburg, VA USA

[BustedBoat]

I'll try to find someone with a reader. The maf sensor was clean.

[danewilson77]

I'll try to find someone with a reader. The maf sensor was clean.

No SES light then?

Sent from Williamsburg, VA USA

[BustedBoat]

No unusual lights, no.

[danewilson77]

Ok. Plugs, and oil done as required?

I mean...you said you did your fuel filter. Maybe pump is going out on you. See if you can pull stored code (if any are present)

Sent from Williamsburg, VA USA

[BustedBoat]

Isn't the fuel filter and pump one piece? Plugs and oil was done.

[danewilson77]

No. The pump is located under the backseat. The filter and regulator are one unit.

http://www.zhpmafia.com/forums/showthread.php?4521-BMW-330i-ZHP-fuel-pump-DIY&highlight=fuel+pump

[BustedBoat]

A more experienced friend of mine corrected me and said that rough idle can be misleading and that the problem should be better titled as rough start up. He also reminded me that the problem is also solved if I turn off the car and then start it up again. I don't know if that helps narrow down the problem, but I figured it wouldn't hurt to mention it.

[Johnmadd]

A more experienced friend of mine corrected me and said that rough idle can be misleading and that the problem should be better titled as rough start up. He also reminded me that the problem is also solved if I turn off the car and then start it up again. I don't know if that helps narrow down the problem, but I figured it wouldn't hurt to mention it.

Sounds like a fuel system issue, check pressure at fuel rail. More than likely its the fuel pump on its way out in my opinion. Id buy a new one with assembly and seal and keep it in the trunk with a big hammer and big flathead screwdriver, its an easy diy, maybe even print out a diy and stick it in the glovebox.

[BustedBoat]

I hate being the noob but how do i check the pressure? Is that where i listen for a noise under my passenger seat at key position 2?

[danewilson77]

You check it at the fuel rail in the engine bay. You have to pull the cap off of the Schraeder valve. You could listen o it......key in pos 2....but that would only tell you the pump is energizing, not necessarily pumping.

[llll1l1ll]

I did the fuel pump in my E30 and it took me about 30 minutes. Don't forget the o-ring on the bottom of the pump seal like I did!

If you're smelling gas everywhere, I would consider the idea that maybe an injector is stuck open? My E30 had a similar problem. It would idle super rough, as if a cylinder was dead, but would perk up if I gave it some gas. I would shut it off and you could see the fuel pouring out of a cylinder.

[BustedBoat]

Months and Months later, problem solved. I took it to a shop, they said the intake runner valve was leaking. Is that the DISA valve? Either way all is solved and better. Thanks for your help everyone!

[danewilson77]

I hope that's what it is. I have never heard of that, but most likely they were referring to DISA.

[LivesNearCostco]

I've had a similar problem for the last year, but my car only has rough idle if started warm idling in neutral with the clutch out. Does not happen with cold start. The idle smooths out if I push in the clutch pedal or give it a little gas, and once I start driving it doesn't come back until I shut the car off and restart it. My indie shop did a smoke test a while back but didn't find any leaks. One of the mechanics at the shop, upon hearing my description, said he fixed a similar problem in another BMW by replacing the DISA.

I put the electrical tape around the DISA gasket and verified that the flap still springs back, but didn't do the vacuum pot test as described in the G.A.S. kit DIY. I wonder if my DISA flap could be stuck in one position? I still have the 4K dip on the dyno chart (don't notice it when driving), but maybe the DISA could have failed in some way but still flips at 4000 RPM to trigger the dip?

Edit: Not sure if my DISA is original. Last owner didn't replace it, but one before that might have. If I pull it again, will it have the build date imprinted somewhere?

[Sockethead]

I can tell you that on my car, the DISA appeared to be working fine but I still had the dip... I check it severl times over the course of a year or more. Then I just went ahead and did the G.A.S. repair on it... the dip went away and the car ran much better...

[sketchyd]

Months and Months later, problem solved. I took it to a shop, they said the intake runner valve was leaking. Is that the DISA valve? Either way all is solved and better. Thanks for your help everyone!

correct, the intake runner valve is the DISA. the flap actually changes intake runner length (long and short runners) for better high and low end power, which is supposed to result in better mileage. they're a common e46 problem, the pin in the flap works loose and in worst case scenarios can come all the way out, and can grenade the motor if it makes it through an intake valve. also, rarely throws a code, except maybe a misfire.

[BustedBoat]

Hey Guys, so turns out the problem is back. The Disa valve seemed to fix it momentarily before it little by little crept back. No codes are being thrown. Fuel pump has been replaced, battery was replaced albeit it with a duralast (odd circumstances). Fuel Filter was replaced about a year ago, with Kayser. Spark plugs have been replaced as well. Any thoughts as to what it can be?

On a side note, I'm having qualms about asking this question...even though I'm only stating this after I ask the question...But honestly I feel like I am not exactly the most valuable member of the famiglia. I lurk a lot but I don't have the knowledge to really help out my fellow members. In a sense I feel like I'm all take and no give. IF you guys could recommend a way I could be of better use for the forums I would appreciate it.

Edit:I should also add a more in depth explanation on what's going on. Not dependent on hot or cold start. I experience this regardless. It is not an all the time problem but it does happen often. I turn the key and the car cranks for a long time. Once the car eventually starts the rpms fluctuate a lot, engine makes "clanking" noises. Once I give it gas, problem is solved. Rpms drop to the stable range.

[echo46]

I have three suggestions. 1. Check all the intake boots and CCV hoses for cracks. Let's first rule out a vacuum leak. 2. Check your fuel injectors for leaks. Sometimes one or more of the injectors leak a little after the car is turned off which causes a rough start up until the extra fuel burns off. Sometimes you can smell the gas at the fuel rail. On my leak you couldn't smell it because it was only a slight drip after shut off. I had one leaky fuel injector and after I replaced it the car started perfectly. Let me know if you are going to check yourself and I will walk you through the steps to pull the fuel rail. 3. Is your starter good?

[BustedBoat]

As far as my own novice eyes saw there are no tears. Thanks for reminding me, there are times dependent on just how rough the start up was, there can be a rather strong smell of fuel. I honestly cannot say where it is coming from. But I can smell it from inside the car. 2. I would very much appreciate being walked through this. 3. Honestly not sure how I can tell if my starter is going bad? Like I mentioned earlier it is not always like that, there are times where it starts perfect. Also I should note, that if it starts bad...I can turn off the car and turn it back on normally.

[echo46]

After you shut the car off, wait five minutes then open the hood and smell around the fuel rail. Let me know what the results.

[BustedBoat]

I didn't smell anything out of the ordinary. I did have the engine cover on. Not sure if thay will make too much of a difference but all I smelled was hot engine :D

[echo46]

I think DW mentioned this above but you may have a fuel delivery issue. You need to check the fuel pressure at the rail. Maybe clogged filter or a clog in the gas line?

[wertyu78]

Are you experiencing any coolant loss?

[BustedBoat]

Okay I will hunt down a fuel pressure gauge. A friend had lent me one but it wasn't working right. I did at one point but it was because of a stupid mistake I had made, and it was fixed within a day. Definitely not related to the problem.

[BustedBoat]

Hey everyone back at it again. I've been juggling school among other things, but I have once again attempted to attack the problem that's been eluding me since I first got the car. Let me first start by going over what the problem is in more detail; start up takes very long, it cranks and cranks. After start up car makes a "clunking" uneven noise. After delivering some gas, car idles normally. There is a very powerful and pungent smell of gasoline, so I am starting up incredibly rich.

Now things I have replaced to tackle this issue. Firstly no codes of value came up when I last checked in the fall/winter. Fuel pump has been replaced as of last summer, fuel filter was replaced about 20k ago. Spark plugs about 15k, battery last summer. I swapped my Icv with a friends and the problem didn't improve at all. No sight of boot tears either. Any help would be awesome!