Hi there!

I fixed my leaking intake manifold gasket on my 91' 740 and changed the oil that was gassy from running rich, but now I still have a little bit of gas in my oil. I'm thinking I either have a leaking injector, or a stuck FPR. I pulled the vacuum hose off of the FPR and pulled a solid vacuum on it and it seemed to hold pretty well, but that doesn't mean that it isn't stuck closed. I'm guessing I'm going to have to yank the return hose off of the line and see if it's returning fuel or trickling.

If it does end up being the FPR not working would I be able to mount up one of the universal FPRs with a gauge built in or would it be best to go with what it calls for? I'd love to have an inline fuel pressure gauge!

I also found, when I was underneath the car changing the diff fluid and trans fluid, that the return line where it goes into the top of the sending unit is leaking. I thought it was the hose at first, but it is the 90 degree elbow that is friction-fit into the top of the sending unit/fuel pump assy. Is there any way to replace that fitting without replacing the whole pump/sending unit assembly? My fuel pump works great right now and I don't feel like spending hundreds of dollars on an occasional dribble of gas.

 

I'm still getting an SES light at start-up for about 2 minutes. My codes are a 132 (batt voltage), a 221 (O2/Lambda), and a 233 (Idle valve). I've cleared the codes several times, but they keep coming back on immediately. When I entered KOEO self-test with my dia port all of the sensors/switches/valves click or open/close, my IAC is opening and closing AND my idle speed is very stable (600-700 rpm) through all ranges cold and hot and at start-up I get a slightly higher idle that comes down quickly but gradually. However, I am getting a little fuel in my oil. I checked for blow-by with the cap off and I have a slight vacuum with the cap off, which signals to me no internal problems. My FPR isn't leaking and I can pull a consistent vacuum on it and it holds very well. The line going to the FPR is good and if I pull it and put my finger over the hole I get decent vacuum as well off of the intake; I haven't gauged the vacuum yet, but I'm sure it's acceptable.

SO, where do I go from here? With the OBD system being so primitive I can usually get things right by using old-school mechanical intuition, BUT being that there is an OBD system, albeit a primitive and finicky European one, and not being able to communicate with it except for with blips on an LED I'm kind of stumped.

 

Ok. I just figured out that I don’t actually have an ses light...my SERVICE light is on, but I just figured out that it is really a "maintenance" (oil change) light. I'll reset that, so now I really won't have any hard codes set, BUT I still do have a rich condition, which is resulting in me getting fuel in my oil...and as far as I can tell my fpr is good, NO amm (regina). No idea how old the O2 sensor is. I also have a small exhaust leak between the head pipe and the cat at the flange and the also the extra O2 bung.

ANY IDEAS? Why is my car running rich/internally leaking gas past injectors?

 

Any exhaust leak upstream of the O2 sensor will result in an over-rich condition. The leak lets in oxygen which causes to the O2 sensor to read a lean condition. This the computer picks this up and enriches the mixture.

 

Save yourself some headaches...replace the O2 sensor. Think about it....prior to combustion, the ecu gets input from the AMM, CPS, ECS, knock sensor and something else I'm forgetting. After combustion, the lone sentinel to advise the ecu as to how it is doing is...the O2 sensor. Without a well functioning O2 sensor, all sorts of symptoms appear. As mentioned, exhaust leaks play havoc on the ecu too...but the O2 needs to work well to avoid your symptoms.

 

Makes perfect sense to me. The seemingly innocent exhaust leak is large enough to make the O2 sensor significantly richen up the mixture, but small enough that it doesn't throw a hard O2 sensor code for out of range. I was thinking about doing a cat-delete, but my second O2 sensor bung has no threads left in it. I guess I'll have to just fix the leak for now and try that out later...

Thanks again everyone!