I have a 2008 bmw 528i, stft is negative and ltft is runn...

Hi. I'm Daniel, I'll be the mechanic assisting you today. I'm sorry to hear about the issue you have with your 528i. Let's see if we can figure this out and get you back on the road quickly. Are there any fault codes stored in the DME (engine control computer) or is the CEL (check engine light currently coming on?

multiple misfires and evap leaki changed my o2 sensor but it's still running weird

Can you share the fault code list with me. From your description we are looking at a mixture issue. Are there any relevant faults about this as well?

p0300p1515p0456the car wasn't maintained before i bought it so now i have all the problemswhen i accelerate it stutters and sometimes the car stalls but it turns right back on

Apart from the misfire code (P0300) we don't have a relevant fault that could cause this. If the mixture would be out it should set a relevant code for this. Possible that we have a issue with the ignition system. Did you check the spark plugs and ignition coils yet?

i replaced them 2 months ago the coils and spark plugs

Did you use OEM or aftermarket parts? Was the issue already present before the replacement? What scan tool did you use on the car? Is the issue permanently present?

all OEM parts. no it just recently came up. i use hp tuners n gauge to read all my codes

Is the issue permanently present? I don't know this scanner. Is the tester able to display all codes, generic and BMW relevant?

it's preset and yes it displays all codes

Ok, thanks. At this point we only have the misfire codes and the fuel trim numbers you mentioned to go on. If there is a actual mixture issue we should have a relevant fault code for it as well and your scanner should display it. Possible causes I can think at this point are: - AIrflow restriction due to a blocked exhaust or catalytic converter or a restriction in the intake system - Fuel pressure issue (fuel pressure is not monitored on the N52 engine) - Mechanical issue on the engine If possible check the exhaust and intake system for any possible restriction next. A blocked catalytic converter for example could cause the issue we experience. In addition monitor fuel pressure with a gauge while driving. If no faults are found so far inspect the engine mechanically and perform a compression& leak down test next. I'm sorry that you have to deal with this, I know it can be frustrating. Let me know how it goes and if you have any questions at this point. Thanks.

thank you so much for your helpi really appreciate it

You are welcome. Glad to help. Please keep me posted on the result. You can follow up with me here anytime. If I'm not online then I get back to you as soon as possible.