Hey Guys, just experienced this twice recently (1/10 starts). Both times I had run some errands around town & the car had sat for 20-30 mins. Idle was rough, dash lights would dim... 10 seconds later or so it vanished and idled okay. No idling problems once driving.

Any other symptoms I should be noticing or looking for?

check your batteries
did the EML light come on?

Hmmm... can't say I noticed the EML light. Dying batteries known to cause this @ startup then?

I've only noticed it when driving around the city. Long drives afterwards, I can't say I've noticed it.

do a stomp test, and see if it throws any codes...

Intake Gaskets? Leaking around the intakes?

Never done a Stomp test before.

Key on, Engine off, Stomp brake pedal X amount of times?

Something to that effect?

Thanks 8eights. I will try this when I get out for some lunch...

Already saved. Is the procedure a Trade secret or what?

stomp 5 times for the left bank and 6 times for the right.

stomp 5 times for the left bank and 6 times for the right.

if nothing comes up is that a good thing or am I dong it wrong.

My car is fine btw

if nothing comes up is that a good thing or am I dong it wrong.

My car is fine btw

Same here, my cars does nothing when I do this procedure.. (91' 850i)

Rough running at start up WHEN the engine is cold, and cldears when the engine is hot is usually intakes manifolds.

A lot of people have reported start up rough running for a few seconds to a minute after the engine is hot, this is generally a fuel system issue.

1. Check valve(s) in the fuel tank after the pumps are shot and the fuel pressure leaks down quickly after the engine is shut down. Take a bit of time to rebuild the operating pressure after the engine is again started.

2. The connecting hose(s) between the check valves and the nipples to the outside world are degraded and will let the fuel pressure leak down and similar to the previous the pressure needs to be built up again for normal engine requirements.

3. Fuel filters are not at fault, unless there is a fuel leak at the connections. A dirty or plugged fuel filter will result in poor operation at high power demands not at idle conditions.

4. Any hose in the fuel system from the tank to the fuel rails could be leaking and thereby causing a loss of fuel pressure. Fuel smell should be present if that is the case.

5. FPR (fuel pressure regulators) could be faulty, leaking and causing the fuel pressure in the fuel system to drop, many people have reported that changing these fixed the problem, still, others have had this issue and changed the FPR with no positive results.

6. Injectors could be leaking, again causing the fuel pressure in the fuel system to leak down.

7. If it gets extremely hot outside, any leaking condition could also set up a vapor lock in the fuel system that will take the fuel pumps working at full pressure to force the bubbles thru the injectors. If it si really bad, the engine will not start at all.

8. If fuel in the tank is quite low, (NO, it will not burn out the pumps!!!!) the fuel temperature will rise higher because the unused fuel that circulates up to the injectors is fed back to the tank, it ill pick up engine heat on this loop and heat the tank fuel, increasing the likely hood of vapor lock.

IF the symptom continues, the first thing i would do is to measure the fuel system pressure and watch it carefully after shutdown, It should be at ~3.0 bar (~45 PSI) and it should stay there, slight drop on shutdown but then remain for at least 20-30 minutes. If the pressure drops quickly this is a sign of a leak in the system and you can expect issues at start-up.

Hope this helps

first are they really $450 a set.second,why?i havent done mine yet but suspect them.im going to do a torque check on the hardware to see if anything is loose first.thanks

first are they really $450 a set.second,why?i havent done mine yet but suspect them.im going to do a torque check on the hardware to see if anything is loose first.thanks

2X (part 11 61 1 736 656 + part 11 61 1 736 657) = $ 630

But only if you have good connections in Germany! Why???


But you don´t need them new when they are not broken! A good gasket sealing compound will work! Hylomar is my favorite.