Start up problems

[[email protected]]

Dear Z4 users.
Recently I have got problems starting my Z4 35is 2012 with MHD stage 1. The egine cranks sometimes up to 10 sec before it starts. And I can hear the egine make small missfires during idle.
When running normally I cant notice anything. Runs smooth and no missfire as can be noticed. Somtimes during heavy acceleration there seems to be a lag before the power kicks in. I now there are som common issues like the high pressure gas pump and the coils.
Have any of you other users have similar problems, if so what was your solution?
If not, what to start with?
New start plugs are ordered. Hopfully this is what I need.
Sorry for bad language, all answeras are appriciated.

[ph001]

Unfortunately I don’t think new spark plugs will cure your problem, but new injectors will.

[kinger]

#2.... for injector problems
Mike

[Chippie]

Isn’t long cranking a symptom of a failing high pressure fuel pump

[Smartbear]

Get the car scanned for codes or it’s guesswork
Rob

[R.E92]

Probably the high pressure fuel pump. A car will fire up with dodgy injectors and run rough but they don't usually cause long cranks.

Are there any codes if you scan with MHD?

Have any components already been changed by previous owners?

[ph001]

Isn’t long cranking a symptom of a failing high pressure fuel pump

....not when it runs normally once warmed up.

Probably the high pressure fuel pump. A car will fire up with dodgy injectors and run rough but they don't usually cause long cranks.

Are there any codes if you scan with MHD?

Have any components already been changed by previous owners?

It causes long cranks because the cylinder bores get washed by the unburned fuel which results in low compression when you first crank it.

[Player 1]

Long crank was the first warning I had of the fuel pump failing. Error codes would be handy but long cranking didn't throw any for me, it wasn't until developing a misfire past 60-70% throttle that any fuel pump related code appeared.

[Chippie]

Isn’t long cranking a symptom of a failing high pressure fuel pump

....not when it runs normally once warmed up.

Probably the high pressure fuel pump. A car will fire up with dodgy injectors and run rough but they don't usually cause long cranks.

Are there any codes if you scan with MHD?

Have any components already been changed by previous owners?

It causes long cranks because the cylinder bores get washed by the unburned fuel which results in low compression when you first crank it.

Misfire from cold is a sign of leaking fuel injectors, fuel dripping onto the spark plug directly below the injector wetting the electrode and causing the misfire

[[email protected]]

Thanks for all answers.

Reading all answers and between the lines I assume that it is the injectors that are my problem. I will give it a go with replacing them.
So next question. What type of injectors will do its work. If the original injectors last for 25000 km I think and upgrade of those is at least some thing to think about. Are there any injectors of better quality than the OEM on the market? What are you guys using?

Next question about analyzing the problem with MHD monitor app. What should I be looking for? Is it the timing the different cylinders or what? I will for sure change all injectors, but it would be nice to know witch one is bad.

Once again, thanks and drive tastfully.

[tintoverano]

this could get you closer

there my be different INPA function keys you have to use, but same captions

[tintoverano]

this could get you closer

there my be different INPA function keys you have to use, but same captions

also https://bimmerprofs.com/diagnostics-inpa-part-4/

[ph001]

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.

[Chippie]

Thanks for all answers.

Reading all answers and between the lines I assume that it is the injectors that are my problem. I will give it a go with replacing them.
So next question. What type of injectors will do its work. If the original injectors last for 25000 km I think and upgrade of those is at least some thing to think about. Are there any injectors of better quality than the OEM on the market? What are you guys using?

Next question about analyzing the problem with MHD monitor app. What should I be looking for? Is it the timing the different cylinders or what? I will for sure change all injectors, but it would be nice to know witch one is bad.

Once again, thanks and drive tastfully.

25000km doesn't seem a lot for injector/s to fail, although I have seen posts where fuel pumps have failed early, most of the problems tend to start at around 500000 miles plus

[Pbondar]

Thanks for all answers.

Reading all answers and between the lines I assume that it is the injectors that are my problem. I will give it a go with replacing them.
So next question. What type of injectors will do its work. If the original injectors last for 25000 km I think and upgrade of those is at least some thing to think about. Are there any injectors of better quality than the OEM on the market? What are you guys using?

Next question about analyzing the problem with MHD monitor app. What should I be looking for? Is it the timing the different cylinders or what? I will for sure change all injectors, but it would be nice to know witch one is bad.

Once again, thanks and drive tastfully.

25000km doesn't seem a lot for injector/s to fail, although I have seen posts where fuel pumps have failed early, most of the problems tend to start at around 500000 miles plus

How many miles / km has the car done..seems implausible that a 10 year old car has done 25k Km..