Hesitation on cold start

[gcarch]

Hi people. I noticed that if I were to drive off immediately after I have a cold startup in the morning, the throttle seems to surge and hesitate. Depression of throttle results in hesitation. But if I were to wait for the engine to warm up for about 3 mins, everything seems fine. Idling is smooth and stable, no hesitation evident when its at normal operating temperature. Anyone else experienced this?

 

[planta]

bro, this is normal.
the engine will be at its std condition when it is at std operational temperature.
My E46 N42 also sounds loud for a few minutes till it warmed up in a few minutes.

planta

 

[viewfinder]

I've noticed an idling of approx 1min is sufficient, may vary from car to car. You can probably learn to tell the difference in engine sound by which time the surge/hesitation effect will be much subdue.


Some people also say old transmission oil contributes to it... no idea.

 

[gcarch]

I also read that the vanos control unit actually contributes to the 'racket' during cold starts...gets worst when the vanos unit konks off.

Viewfinder...am looking at bilsteins for my Z.... u know any suppliers/fitters in Pg?

 

[gcarch]

Thx guys for the feedback.... feel better now... phew!

 

[viewfinder]

I got mine from Marco of Motorsport Divisions in KL. Waited ~3 months for delivery from Germany because aint that many e34 demands nowadays. Remember to order to the bump stop for the front shocks also because the normal stock cannot fit in the giant size front.

 

[gcarch]

Thx viewfinder. Appreciate that.

 

[viewfinder]

Actually you can also try Goh Swee Hin. They can source for you and it would be a one stop solution. I installed mine over... much thanks to Zoggee for the special delivery.

 

[pion]

Hi people. I noticed that if I were to drive off immediately after I have a cold startup in the morning, the throttle seems to surge and hesitate. Depression of throttle results in hesitation. But if I were to wait for the engine to warm up for about 3 mins, everything seems fine. Idling is smooth and stable, no hesitation evident when its at normal operating temperature. Anyone else experienced this?

Hmmm... Perhaps we are having the same cold start thingy.. But if i let the engine warm for say 30 seconds or more ...its ok..
I posted on the cold start thingy here
Was told by the SA that it happens to some E90s too.

 

[gcarch]

Hey, thx for sharin this PION... appreciate it. :rock::rock::rock:

 

[gcarch]

BTW...do I need to clean my throttle body after like a certain service interval?

 

[pion]

the question now is.... is the cold start hesitation thingy normal / acceptable? Is BMW aware of it and doing anything about it?

 

[KT_wolves]

You may well want to read the operation manuals.

Allow the engine to run...but not more than 20 seconds idle time.

Do not allow the engine to warm up at stand still
Drive off ASAP, using moderate speeds

 

[gcarch]

You may well want to read the operation manuals.

Allow the engine to run...but not more than 20 seconds idle time.

Do not allow the engine to warm up at stand still
Drive off ASAP, using moderate speeds

I think it didnt state that one should switch to Sports mode after 20 secs warm up time before driving off...cos if its in economy mode, the engine hesitates and surges. Mine takes about a minute for the temp gauge to reach normal operating temperature, after which the hesitation and surging doesnt happen at all.

 

[pion]

... the hesitation disappears when u tap the accelarator..right?

 

[gcarch]

ermm.... more like....continuous hard tapping. lols.
I recently changed my plugs twice... :stupid::stupid::stupid:
From the original OEM NGK's to OWS super plugs (cost a bomb) and then to Bosch Ytriums.

I feel the original OEMs give the best feel. Or maybe the OWS irridiums were not gapped properly...hmmmm

 

[viewfinder]

Within a minute and your temp gauge has reached the middle point? That seems really fast. Mine are definitely near the far left, boundary of the blue indicator bar.

...Mine takes about a minute for the temp gauge to reach normal operating temperature, after which the hesitation and surging doesnt happen at all.

Not sure about OWS, but the multiple-point platinum plugs from Bosch and Beru stated (on the box) no gapping should be done. Perhaps your Z3 ECU has not gotten to know your cost-a-bomb plug characteristic yet?

 

[gcarch]

whoops...let me clarify again... Temp gauge was slightly above the blue bar, not yet at mid point within a minute. Since flushing my radiator with distille water and filling up with 2 bottles of redline coolant, normal operating temperature while doing some civilised driving (no excessive speeding) with constant high speeds of up to 100kph, temp gauge needle was clearly below the mid point. Only when I really push the limits of the car does it reach the midpoint. Before using redline, temp gauge needle was always at midpoint and slightly above midpoint when driven hard.

 

[gcarch]

Yup...no gapping necessary on the multi grounded plugs (NGK and Bosch) but on the single grounded NGK irridium IX plugs, gap was stated as 0.762mm whereas my OWS twin irridium plugs are factory gapped at 0.8mm

I think I'll get them regapped and try them out on my trip to KL.

 

[gcarch]

Guys, I think I may have found out the reason for the cold start problem.
And I think it affects only earlier engine models with dual vanos (especially the M52TU engines) Not 100% sure but it all points to worn gaskets in the vanos unit- all 4 pieces of em)