35is Cold Start Rough?

S

sunnydays

Active member
Hey guys,

When starting my car, the idle feels a little rough. It almost feels like I can feel it misfiring. This only occurs on cold starts, warm starts etc are fine.

Apart from the rough cold start, the car runs perfectly fine at WOT. The car starts and cranks fine as well. There is no check engine light, or any other light showing on the dash, and there are no codes showing via code reader either.

Now I have googled this and seen people with similar issues on the N54. I have seen a suggestion that it could be an injector leaking, causing built up fuel in to the cylinder to combust on cold start. How ever I can also see people suggesting walnut blasts, coils, sparks, HPFP etc...

Any one had anything similar?
 
My 35i idles ever so slightly irregular, and at 95K miles and never having had the intake valves cleaned, my money is on the carbon buildup. Will do that/have it done in September, so until then can't be sure. Mind you, it does this with a warm engine, so not limited to cold start-ups, and your issue could very well be the injectors.
 
Thanks for the info guys, I will pull the spark plugs in a couple of days and see if there is any sign of fuel on them. Will report back
 
Really you should change the injectors in 3's

1-3 or 4-6.

Indexing can be an issue,but many people have fitted one and got away with it,some have caused fuel trim issues.

The MSD 81 DME is also starting to fault as time goes on,the MOSFET drivers for the injectors are now starting to fail

Pay your money and takes your choice.
 
Z4M-2006 said:
Really you should change the injectors in 3's

1-3 or 4-6.

Indexing can be an issue,but many people have fitted one and got away with it,some have caused fuel trim issues.

The MSD 81 DME is also starting to fault as time goes on,the MOSFET drivers for the injectors are now starting to fail

Pay your money and takes your choice.
Click to expand...

Yes the injectors will be changed in banks of 3.
Also read about the MOSFET issue on the DME too. That seems to be a cheap fix from what I have read.
 
sunnydays said:
Z4M-2006 said:
Really you should change the injectors in 3's

1-3 or 4-6.

Indexing can be an issue,but many people have fitted one and got away with it,some have caused fuel trim issues.

The MSD 81 DME is also starting to fault as time goes on,the MOSFET drivers for the injectors are now starting to fail

Pay your money and takes your choice.
Click to expand...

Yes the injectors will be changed in banks of 3.
Also read about the MOSFET issue on the DME too. That seems to be a cheap fix from what I have read.
Click to expand...

Yea if your handy enough you can change the MOSFETS yourself.. I think they are surface mounted so could be a bit trickier.
 
Yea if your handy enough you can change the MOSFETS yourself.. I think they are surface mounted so could be a bit trickier.
Click to expand...

Am I in the company of gods? I know we have rocket scientists on the forum...what limits do you know?

Un soldering surface mounted devices for mere mortals usually results in the destruction of said circuit board..respect..
 
1353 8648937-12 is the latest index 12 injector and seem reliable. They were £102 ech from a main dealer as of Jan 2018, but typically these were only used for warranty work and BMW will want to retail part number 1353 8616079-12 which is exactly the same but with a £240 price tag.

As for the MOSFETS, my company can replace those for you no probs.
 
ph001 said:
1353 8648937-12 is the latest index 12 injector and seem reliable. They were £102 ech from a main dealer as of Jan 2018, but typically these were only used for warranty work and BMW will want to retail part number 1353 8616079-12 which is exactly the same but with a £240 price tag.

As for the MOSFETS, my company can replace those for you no probs.
Click to expand...

Thanks for the info!
Is 1353 8648937-12 still available at £102?
I can see ML Performance retail the version 12 injectors at £150, but £102 would be a bargain!

Thank you, I will get back to you regarding the MOSFETS :)
 
Update to this:

The car has been sat in the garage all week., I finally got round to pulling the coils and spark plugs.

Spark plug 1: Stank of fuel, I am guessing this is where my injector leak is coming from :(
Spark Plug 2: Looks fine
Spark Plug 3: Very wet, How ever there was no smell of fuel. Perhaps oil?
Spark Plug 4: Also wet, but no smell of fuel
Spark Plug 5: Also wet but no smell of fuel
Spark Plug 6: Also wet but no smell of fuel

So I can see Spark plug 1's injector is leaking.

What do you guys think about the other sparks being wet? A quick google suggests a leaking valve cover gasket, or even spillage from when the oil was poured in (although I would find it hard to believe that it spilled across 4 spark wells.).

Images below

Spark plug 1 -> 6 (Left to right)
S9sA5jR.gif


Pictures of the spark wells (labeled)
VDBPpUZ.gif
 
I would be putting injectors 1-3 in as well as a cam cover gasket set.

Probably a set of ;lugs too depending on how long they have been in.
 
sunnydays said:
Hey guys,

When starting my car, the idle feels a little rough. It almost feels like I can feel it misfiring. This only occurs on cold starts, warm starts etc are fine.

Apart from the rough cold start, the car runs perfectly fine at WOT. The car starts and cranks fine as well. There is no check engine light, or any other light showing on the dash, and there are no codes showing via code reader either.

Now I have googled this and seen people with similar issues on the N54. I have seen a suggestion that it could be an injector leaking, causing built up fuel in to the cylinder to combust on cold start. How ever I can also see people suggesting walnut blasts, coils, sparks, HPFP etc...

Any one had anything similar?
Click to expand...

:(

Sorry you’re having this Sunny, I’m surprised it’s started as it was fine with me but I guess there’s got to be a start point sometime....
 
Z4M-2006 said:
I would be putting injectors 1-3 in as well as a cam cover gasket set.

Probably a set of ;lugs too depending on how long they have been in.
Click to expand...
Hi mate, thanks for the response

I have ordered 3 new Index 12 injectors, as well as 6 new spark plugs.
I am thinking of proceeding in the following order:

Clean spark plug wells
Replace spark plugs
Install new injectors
Run the car for a week or so, after which I will inspect the spark plugs again. I will do the valve cover sometime shortly in the future

Sound sensible?
 
john-e89 said:
Sorry you’re having this Sunny, I’m surprised it’s started as it was fine with me but I guess there’s got to be a start point sometime....
Click to expand...

Hi John, hope you are well
Don't worry about it, these things happen. The car is almost 10 years old, and it is a N54 after all :)
 
sunnydays said:
Z4M-2006 said:
I would be putting injectors 1-3 in as well as a cam cover gasket set.

Probably a set of ;lugs too depending on how long they have been in.
Click to expand...
Hi mate, thanks for the response

I have ordered 3 new Index 12 injectors, as well as 6 new spark plugs.
I am thinking of proceeding in the following order:

Clean spark plug wells
Replace spark plugs
Install new injectors
Run the car for a week or so, after which I will inspect the spark plugs again. I will do the valve cover sometime shortly in the future

Sound sensible?
Click to expand...

Yea,

Im sure thats the only way that oil can get into the plug holes though,so im thinking your delaying the inevitable.There about £65 for a gasket set.
 
You must log in or register to reply here.
Back
Top Bottom