A most bizarre problem

[tdgard]

93 M50

I've noticed a very peculiar problem since I bought a new house last June.

From the garage, the driveway slopes downward ever so slightly--call it an inch a foot. When I leave the car out for over several hours (car washings, garage sweepings, woodwork), and I go to restart it, it acts like it's in an enriched state. Long startup, smoke (when it finally starts), and backfiring. Also runs like it's enriched for a moment then settles down. It seems that the longer I leave it out there, the worse it is--almost linear.

What the hell is this?

I back into the garage (when I was young I left my lights on & had to shove a car out to jump it) so the car is in an engine down state.

What in there can get out of whack simply by lowering the front end? It's never happened anywhere else, but as I write this, I realize I don't have these conditions anywhere else.

Car runs great and is well taken care of otherwise.

Ideas?

Here's an edit to address some other questions:

Car does not display these symptoms while driving down a hill.
Full tank of gas.
Hot-cold--dosen't matter.
Rain-shine--dosen't matter.

[mjhanna]

93 M50


I've noticed a very peculiar problem since I bought a new house last June.

From the garage, the driveway slopes downward ever so slightly--call it an inch a foot. When I leave the car out for over several hours (car washings, garage sweepings, woodwork), and I go to restart it, it acts like it's in an enriched state. Long startup, smoke (when it finally starts), and backfiring. Also runs like it's enriched for a moment then settles down. It seems that the longer I leave it out there, the worse it is--almost linear.

What the hell is this?

I back into the garage (when I was young I left my lights on & had to shove a car out to jump it) so the car is in an engine down state.

What in there can get out of whack simply by lowering the front end? It's never happened anywhere else, but as I write this, I realize I don't have these conditions anywhere else.

Car runs great and is well taken care of otherwise.

Ideas?

Here's an edit to address some other questions:

Car does not display these symptoms while driving down a hill.
Full tank of gas.
Hot-cold--dosen't matter.
Rain-shine--dosen't matter.

[Bimmer Nut Ed]

Very strange, don't know what to tell you. Maybe try to open the intake by the AFM to see if it smells like gas.

[tdgard]

my battery will die

[Unregistered]

I kinda have a similar problem. If I back my car into a space, regardless of whether the space is level or not, after I engage reverse gear and have reversed the car, the car sometimes idles about 200rpm higher than usual. If I shut down the car when the car is still idling high, then I have a similar problem to you...the mix seems too "rich" and there is difficulty starting. Not sure whether this is the idle control valve?

Does your idle remain steady when you back into your garage?

Alan Yeung
1990 M5

[Paul in NZ]

neither hot(normal) or cold....i treat it as is its flooded....if it doesnt start first time push the throttle to the floor and hold it there....dont pump and crank it will exhibit the same spluttery start but will catch and clear slowly...
Just make sure that you gas level IS high.prolly less than 1/4 tank on a incline might cause it(And a 1 in 12 incline is quite a good incline!)

[tdgard]

I guess I need to figure out if it's getting too much gas or not enough air. Only this weekend did it really piss me off. Actually this was the first time I really could say "no its not water in the gas or its cold out or its a fluke or..."

Most maddening part is that it does not happen while it's running--then I could shove a probe in an orifice.

Guess the sign over my desk states it best:
DANGER
10,000 OHMS


Very strange, don't know what to tell you. Maybe try to open the intake by the AFM to see if it smells like gas.

[tdgard]

garage is level & idle is fine. I have no problems at all when I'm parked there. It's only when I pull it out--or even just leave it before backing in--that I have this issue.


I kinda have a similar problem. If I back my car into a space, regardless of whether the space is level or not, after I engage reverse gear and have reversed the car, the car sometimes idles about 200rpm higher than usual. If I shut down the car when the car is still idling high, then I have a similar problem to you...the mix seems too "rich" and there is difficulty starting. Not sure whether this is the idle control valve?

Does your idle remain steady when you back into your garage?

Alan Yeung
1990 M5