Hello,

I’m new here, since I have an issue. I hope some of you can help me understand my problems.

3 months ago I got my car tuned stage one,
262hp - 322 nm. After about 500kms when starting the car it cranked longer, and when I’m not touching the gas, it would stall.

Also wen driving, and I’m going in gas, the car starts to stutter, en won’t go forward. More gas more stutters, when I drive very slow, ( kindly touching the gas paddle ) the car goes forward. So when I’m trying to drive normal it’s not always possible.

It’s not always! There are a few moments I can floor it, and it will go kinda smooth. But these moments are rare, and mostly when the engine is colder.

So, what did I try and what did I find out so far.
I did go to bmw dealer, the diagnosed the car and told me I need 6 new injectors. These things where in back order, so 5 weeks later with new injectors, stil no difference. Car starts a little bit better, not the really long cranks I had before. ( but still not, how it’s used to be )

I’m getting no engine lights or any other codes. When the car stutters, and I keep pushing the gas paddle for 10 seconds ( so still while stuttering ) I get misfire codes on random cylinders, 1,3,5 or 2,5,6 as an example. Always different.

I plugged 6 new spark plugs, no fix.

Then I thought I’m checking my fuel pressure.
Low pressure was before starting at 6bars, when starting and reving the car in doesn’t come below 4.9bars seems good to me.

Fuel rail pressure, here comes the weird part.
First try: starting the car at 10bars, When I play with gas, it drops to 5 bars. After 5minutes idling it showed me 50bars? Again playing with gas drops the pressure to 10/15 bars and slowly goes up.

second try, when starting the car 200bars at idle. Playing with gas, slowly goes up and stays between 200/250 bars. Seems better then the first try. So I drove the car a few minutes, and kept checking the pressure. Doing 80km/h in 6th gear downhill with 220bars, when I press the gas paddle it drops very fast to 10bars. And slowly climbing up to 30 bars. Not going higher. Going uphill it doesn’t come above 15bars?

So I tried a new high pressure sensor, installed it plug and play, car shows 14bars, when trying to start it stays between 12/14 bars. And the car of course WONT start. I’ve tried many times, but it won’t start with a new sensor. And pressure always stays between 10/14 bars.

I’m not sure how much pressure I’m supposed to have, but I’m very sure the pressures I’m having are nothing close to what it should be.

I’m thinking it’s the HPFP, but I’m still not sure, after already installing 6 new injectors for almost 2000€, I’m not very sure to buy a new HPFP when I’m not sure this is the problem.

So maybe one of you guys had the same issues, or can tell me where to look else.

Please keep in mind, I get NO engine lights or any fault codes… this makes it even harder to fix..

Thanks for reading!