Poor running 350

[bhardy]

Me and my brother both own a 350i and love the cars!! The only problem is that his car doesn't seem to be running on 8 cilinders when cold. The first 10 miles or so, it runs very bad and then at once the engine begins to run as it should. We already tried injector cleaner but this doesn't seem to solve the problem either. If it were to be the sparks it shouldn't run good after a while. Anyone got a clue what could cause this problem??

[bobble350]

Have you servied it lately? Did the problem start by itself? after the car had been stood? after you did something? How old are the plugs? What sort of condition are the HT leads / dizzy cap /rotor arm? Have you identified which pot is missing / swapped plugs / leads injectors around to see if the problem moves?
It's good to try and fix it yourself and I applaud that. Nobody was born with this knowledge and if you don't try you'll never learn.
But this is fairly basic stuff and driving on 7 pots for 10 miles won't do the engine much good.
So if you can't fix it yourself quick, pay someone to do it before you knacker the engine a face a REALLY steep bill.

[danny hoffman]

Try unplugging the throttle pot and see if it improves. Also try unplugging the cold start injector.

Danny

[jmorgan]

Spark plugs? Happened to me once but it was the nipple not screwed on 2 of them .

[HarryW]

Could be one of a couple of dozen things from a dodgy cold start injector to a weak spark that doesn't like the cold enrichment, an oil fouled plug to bad cold compression on a few cylinders, duff temperature sender to dodgy HT leads.
Personally I'd do every thing that costs nothing myself and then if required get it checked out by a specialist. AIMHO and certainly not definitive.

Harry

[skyrocketship]

my '86 350i used to do that - replaced the ECU, cam, heads, airflow meter, and it still does it sometimes!!

edited to say - didn't do all that to solve the problem though - it needed all that stuff anyway!!

>> Edited by skyrocketship on Tuesday 6th May 12:34

[TaSmania]

As said here it could be any of the items listed. The Engine management is banked (fires all one side injectors at once - i.e. not sequential like newer cars!) so it's unlikely to be fuel (but you never know ). Are you sure it's running on 7 or just running badly. Due to the firing order it's often difficult to tell. I had a similar situation on an old SD1 Rally Car. It turned out to be a hairline crack in the dizzy causing condensation which when things warmed up a bit seemed to stop - Bizare. I'd replace the dizzy cap, leads and plugs after just a quick check on the cold start injector (it's a cheap check!!). Good luck - be patient!!
GB

[mhardy]

Just want to thank all of you for your reply, this week i will try out your advise and let you know!
(sorry for my broken english i think my brother is better in it )

thanks
Matthijs