BMW p0170 LTFT +19.5 Does not move?

Hi There Folks, Just looking for some direction if anybody can please help me?
I have acquired a 1999 BMW 318i 1.9 petrol e46
1 owner from new, full service history, in lovely condition.

However the car was sold to me as the engine light had come on,
they had it checked at a garage and had a print out of the codes plus
the freeze frame data,the codes where then deleted.

So this is what I have,

Freezse frame Data as follows,

1) Cause of freeze frame P0170
2) Fuel status

---

CL
3) Engine temp

---

105c
4) Load

---

26
5) Engine speed

---

1944
6) STFT

---

MINUS 1.6
7) LTFT

---

POSITIVE 19.5
Thats all I have...

The car drives very well, and has good idle when Hot or Cold, not lumpy.
Starts first time, does NOT hesitate on acceleration and has good power.
No signs of anything wrong.

I don't seem to be able to reproduce the engine light or code at all?

But on checking the fuel trims the long term is solid at +19.5 and will not move either way
regardless to where throttle position is held?

STFT seem to be doing it's job +/- 3

O2 sensor voltage switches between 0.05/8.8

Maf at idle 3.0 g/s and climbs the scale without hesition.

So first off I'm thinking it can't be a vacuum leak? OR could it be?

Any help or advice would be great to get me started. Many Thanks.

Have you checked your fuel pressure? Also need a little more info, year, engine.....

and yes... a vacuum leak is my first thought. You could add propane and watch your fuel trims improve, but what I have always done...(old school) is have the car running, and spray a little brake clean around the intake, any vacuum lines, etc. At idle, spraying brake clean, if you have a leak, you will hear the engine idle increase a bit. If this happens, you have found your vacuum leak. Just make sure you use all of the safety precautions at your disposal before you attempt this. I have never had an issue doing it like this but I have heard of negative effects. :whistle:

Dave101 wrote: Have you checked your fuel pressure? Also need a little more info, year, engine.....

Sorry, didn't read the full post. :blush:

With a vacuum leak toal fuel trim (stf+ltf) would normally improve with increased throttle opening and RPM.
Fuel pressure was my first reaction also, it could also be the O2 sensor has drifted out of spec --- propane enrichment test would be a good move, comparing upstream and downstream O2 outputs when forcing rich-lean might give clue.
I would also check the MAP sensor is giving a sensible reading at key on engine off and at idle,

Thank you, fuel pressure was down, new filter fixed, saved me both time and money:)