Help. BT stalling - The Unofficial BMW M5 Messageboard (m5board.com)

apbails · 9th September 2007, 17:04

Took the BT on a 500km drive this week. It ran great on the highway but when I got into town it began to stall at stoplights. It does restart but belches carbon from tail pipes. It is intermittent, the next stop it will idle fine. Other times I have to keep on the throttle lest it stall. It had a couple spirited runs on the track at Watkins Glen

, and performed beautifully. Also ran fine on the trip home. Any thoughts? Vacuum leak?

Sebring NL · 9th September 2007, 17:29

Start with the simple cheap things.

Take out and examine sparkplugs

search for vacuum failure if plugs look odd

Change ignition parts

puppypilgrim · 10th September 2007, 07:44

Before anything else, check and trace ALL VACCUM LINES. See recent posts on this topic.

You can test for vaccum leaks by spraying carburetor cleaner in and around areas of suspected leaks one at a time. If the engine revs up and smooth out (basically changes sounds immediately after the spray), then you have a vaccum leak in that area. Be aware that in some very rare cases, some people have experienced fires from this procedure. However, this is a well known test used by automotive community. Google for more info.

You can "T" into the vaccum hose of the fuel pressure regulator and take a reading using a vaccum meter.

Check your AIR BOX and air filter to see you didn't suck it out of position during your wide open throttle runs at the track.

Check your entire intake manifold system for loose hoses and loose hose clamps. Chances are something came loose or the vertical hose that is hard to find or something split and cracked under stress of tracking (due to age of the hoses).

1. Change rotor, cap and distributor if they were not replaced when you got your car.

2. Pull and check spark plugs. You can get these plugs from a VW dealer or supplier. Its the same one for the Corrado G60 (supercharged)

3. Check and replace fuel filter

4. Remove Mass Air Filter (MAF) and spray thoroughly with electrical contact cleaner. Take care not to touch or break the wires inside the MAF. They are delicate.

cdnalpina · 10th September 2007, 17:02

I would also check the resistance in your plug wires while you are checking the plugs. I have a bum wire in one of my cars and it caused the car to stumble and come close to stalling at lights.

Take a volt meter, put it on the 100 ohm setting I think it is and put the leads to each end of the wire. I think the magic number is around 5. Basically, check all of them and if any are different then you have a bad wire, or wires, in your set.

m5 killer · 10th September 2007, 19:34

check rubber pipes coming from the hardpipes going to the throttle body

apbails · 13th September 2007, 01:37

Thanks Gents for the input. Have her at the shop and of course she's running like a dream. She won't misbehave for my mechanic. As yet have found no vacuum leaks. Plugs, rotor, cap, wires, etc. have been changed in the past year. Every Alpina turbo hose/sleeve is in like new condition. Now looking into ignition items. Have a weekend road trip planned, we'll see how she goes..........

apbails · 18th September 2007, 04:29

A follow up.........The one thing we did find... the bolts for the fuse bracket that serve the "hot" leads from the battery were VERY loose. The car is performing beautifully.

cdnalpina · 18th September 2007, 06:23

Good to hear!