My Car dont like Cold Wind !

[haffeel]

Dear forumers,

My car E30 325i has peculiar problem. The engine starts fine in the morning, but the car hesitates and gets in to a jerking motion back and forth when travelling at a speed of 20 to 40Kms speed, Any thing above that speed there is no such problem. Any speed below 20Kms also no any problem.

So now I am forced to drive fast in the morning avoiding the speed band 20 to 40Kms speed, or else not just jerking some time, I even hear a big DANG sound from the engine bay .. real scary ..


Once the engine has well heated in 30 minutes of ride , the problem totally disappears.

Next strange observation, suddenly when it starts to rain even at noon time, when all around it becomes the wind outside becomes cold, the sickness appears immediately.

So it looks like the engine does not like cold air .. I thought engines simply love cold wind.

My mechanic says, may the AFM needs adjustments with correct CO measured from the exhaust.

what is happening?

Your valuable feed back appreciate.

cheers

[johnono]

Haffeel, have a carefull look at the hose work around the I.C.V , throttle body and airbox area, if u have loose hoses or ill fitting pipe work it may contribute to bad idle speeds or inacurate fueling

give the pipes a wiggle, while the engines running from when u just start up.. if it gets more "choppy" as u moove certain pipes then its a good chance u have an air leak ( being sucked in rather than blown out) and bad readings to uԚ´re icv / afm

i the "Dang" whilst the car hops or has it happened independantly?

could the dang be a burst pipe of some kind? hows the temperature read generaly? got any more details on general running also, to eliminate possibles mate ;)

[Sanchez]

i have similar problem, when cold it jurks, and when floored nothing happens.

[hogweed]

If it's temperature-related, the temp sensor sounds like a good place to start!

[gcorky]

maybe dizzy cap leads,especially the rain thing.

[haffeel]

johnono, the big DANG sound came few times during the jerking movement when it wants to move forward. I never heard this sound other times.

yes, I will check the pipes for leaks as you informed me. Next week I am changing my air inlet manifold to 325i and the throttle body with a BIG BORE JOB and bigger butterfly.

Hope I solve this problem soon.

My car works so beautiful, except for this silly problem

TQ

[haffeel]

hogweed, where is this temp sensor? Any way I can test it ?

TQ

[johnono]

i know how u mean fella, its the small things that really bug!

get under the hood fella and have a look, let us know what u find ;)

[hogweed]

hogweed, where is this temp sensor? Any way I can test it ?

TQ

Sorry I have no camera at the moment - at the front (ish) end of the cylinder head, there's a load of water hoses and thigns, and a couple of wires go into electirical plug thigns which disappear into the metal junction of some of these. These are the sensors - one is brown, and one is blue - I * THINK * the brown one activates your temperature gauge, and the blue one is the ECU's temp sensor, which is the one you want.

But Simon will correct me if I'm wrong...

Soeone can tell you the resistance it;s supposed to be too - but if it was me I'd just fit a new one - they're not dear, and half of them are knackered.

[elliot]

blue one on the otherside of this

[haffeel]

Let us suppose, the blue sensor is faulty, then what type of action will the ECU take?

How that action will effect the jerking movement?


TQ

[hogweed]

Let us suppose, the blue sensor is faulty, then what type of action will the ECU take?

How that action will effect the jerking movement?


TQ

Don't know about the jerking exactly mate, but the water temp sensor is a MAJOR determinant of how the ECU meters fuel Ԛ—a if (like mine did) it thinks the engine is at operating temp when in fact itÔš's stone cold, it will be seriously underfuelling, which leads to pretty ropey running.

If (like mine was) the carbon track on the AFM is a bit worn out just at the throttle opening you cruise at most of the time (quite possibly 20-40km/h), youÔš'll find it becomes very sensitive to underfuelling, giving the jerkiness youÔš're talking about. Mine did, anyway.

Although this jerkiness isn't CAUSED by the weak mixture, it can be made seriously worse by it.

The first thing you must do before anything else is remove the wiring from the AFM, ICV and TPS, and get the terminals nice and clean with some sandpaper Ԛ—a that alone cleared up 50% of the problems my car had 5 years ago, and no recurrence since!

Then look at a new temp sensor, as theyÔš're cheap from motor factorsԚ…

Your AFM may well need adjusted to bring the CO to the right level but that only affects your idle fuelling, NO EFFECT on the car when your foot is on the throttle, even gently.

Finally, if by Ԛ“dangԚâ€a you mean the car gives a big bang and a jerk when you floor the throttle suddenly, thatԚ's likely to be the connectors on the TPS (as above) or possibly a faulty TPS.

None of the above is guaranteed to cure your car, but they all should be done, and very possibly one of them will.

Good luck, Meester BondԚ…

[haffeel]

hogweed, thanks for the detailed explaination. Preeetty goooood advice and makes lots of sense. I shall do all what you said,

I will be all DIM (Doing It Myself) come this weekend

thanks

[haffeel]

Guys, I solved the problem. Simply changed the BLUE sensor and Bingo all the jerking problem gone.

and i changed the sensor all by myself too .. Waaow, made my mechanic friend jealous ..

thanks for you guys here for all the help and suggestion