Author Topic: Warm start issues (Read 3427 times)

Intense · « **on:** August 22, 2007, 08:51:27 AM »

Hey all,
Hoping you can help my diagnose a problem.

On warm starts, my engine takes a couple cranks before it catches and then it runs like crap for a minute or so. After that, whatever issue I have clears up and she runs fine. In that first minute, the engine will stumble and hesitate and occasionally die unless I give it some gas.

Cold starts (sitting overnight), do not seem to exhibit the same behavior.

When I bought the car a couple months ago, she didn't exhibit the same behavior. Initially, I thought it was the fuel pump. But after reading a couple threads, I'm re-thinking that. I need to put a fuel pressure gauge on the fuel line to see if it's dropping off when I let her sit.

Beyond a fuel system problem, what else could it be?

thanks

bmwpower · « **Reply #1 on:** August 22, 2007, 09:04:51 AM »

Could be plugs. Crappy plugs/non factory platinum type can cause that, too.

Leaky injector.

Intense · « **Reply #2 on:** August 22, 2007, 09:13:54 AM »

Quote from: bmwpower;32205

Could be plugs. Crappy plugs/non factory platinum type can cause that, too.

Leaky injector.

Interesting, what are the brand/style of plugs are recommended? gap?

I haven't smelled any fuel after I turn off the engine and let it sit. So, I ruled out injectors

bmwpower · « **Reply #3 on:** August 22, 2007, 02:58:53 PM »

Quote from: Intense;32206

Interesting, what are the brand/style of plugs are recommended? gap?

I haven't smelled any fuel after I turn off the engine and let it sit. So, I ruled out injectors

I don't have the correct part number with me, but it should be in your manual.

I meant an injector might be leaking INSIDE, essentially flooding the cylinder with gas.

Vladi · « **Reply #4 on:** August 22, 2007, 05:12:08 PM »

NGK BKR6EQUP or NGK BKR6EK are recommended by BMW.

ABuseO · « **Reply #5 on:** August 28, 2007, 10:58:10 AM »

I am having this exact same problem. It starts fine over night, but when you start it up after you've driven it somewhere the engine seems to be lacking, but after about 2 minutes it seems to run fine.

I assumed it was the fuel pump too, but i havent had time to experiment with it.
Let me know if you find out whats going on.

Austin

johna · « **Reply #6 on:** August 28, 2007, 04:51:49 PM »

It may be worth cleaning your throttle body and air flow meter as I had a similar problem and much to my suprise it was cured by doing this.

P. Kennedy · « **Reply #7 on:** August 28, 2007, 05:26:44 PM »

What did you use to clean with?

johna · « **Reply #8 on:** August 28, 2007, 08:41:28 PM »

Throttle body cleaner (carb cleaner that is suitable for EFI throttle bodies would be fine too).

badboypolar · « **Reply #9 on:** August 29, 2007, 10:46:19 AM »

I had that problem and I did two things that fixed it. First I replaced my injectors as I had a leaky injector. This by itself is a problem that will cause it. After I replaced the injectors I still had some hesitation when warm.

So I replaced my AFM, which fully cured the problem.

Don't under-estimate what replacing the AFM can do.