325e Running Rich After New MAF

[the_eskimo_wonder]

Hi everyone, my buddy and I just picked up a beat up 85 325e for a six pack of beer and are trying to get it running strong again so we can restore it to its former glory. We're hoping you experts might be able to help us out a little at this point.

When we got the car it was idling at 2500 and was hard to start. Need to bounce the gas pedal a bit while turning over to get it to start. Soaked the ICV in Seafoam and got it back down to normal idle. Bogged out like crazy when driven though. Gas pedal had to be finessed constantly to keep it from just dying when given gas. At idle if you floor it the car just cuts out completely, but comes back if you let off in time.

Did a DIY smoke test with a cigar and fixed one leak we found, seems good now. Coolant temp sensor ohms out perfect. Replaced TPS and spark plugs with no change. MAF was giving some weird readings so replaced it with a used unit that ohms out fine. Suddenly the car started running super rich (smoke out the back, sounding like it has a huge cam at idle) but runs strong if you drive around with your foot in it burning all the gas up.

Snagged another MAF from the junkyard that ohms perfect and it resulted in the same exact thing. At one point we had the original MAF in but the coolant temp sensor unplugged (we didn't realize) and it ran well but idled at 1800 and felt like it was lacking power.

Anyone have any ideas on the next things I should be checking out? I was thinking O2 sensor and checking fuel system pressures but it seems more like a sensor/computer issue than pressure since it wasn't running rich until the new MAF's. All help is appreciated

[wilholl]

make sure you are using an AFM from an "e" not an "i" for your 325e
They are different

[the_eskimo_wonder]

I pulled the junkyard one off what was supposed to be an 85 325e. I did notice that it had the ICV on the driver side of the intake manifold instead of the passenger side like mine. It's possible the junkyard had it mislabeled.

What's the difference in the two? Would I be able to tell by ohming them out?

[wilholl]

I pulled the junkyard one off what was supposed to be an 85 325e. I did notice that it had the ICV on the driver side of the intake manifold instead of the passenger side like mine. It's possible the junkyard had it mislabeled.

What's the difference in the two? Would I be able to tell by ohming them out?

it is probably the correct one.
The part number is the best way to tell.
one is linear the other is not, not sure which is which

o2 sensor will be good to replace and don't forget to check the crank and flywheel trigger sensors, they can cause weird issues.

[the_eskimo_wonder]

Well, update. The part numbers for both of the AFM's I got match and when googled say they're for the M20B25 so I guess I've got the wrong one in there. I might just opt for the reman one off RockAuto so I know it's good since I can't find any info for testing the eta ones online. I'm also trying to find an actual MAF conversion that doesn't require remapping or an arm and a leg in cost but haven't come across one yet.

Also should mention that I tried to replace the O2 sensor today but couldn't get it off. I did fire it up to move it with it disconnected and it ran no differently though. I'm guessing that probably means it's bad so I feel like replacing that isn't a bad idea either

[wilholl]

Check with the guys at Bavarian Restorations

http://www.bavrest.com/index.html

They are a great source for AFM info and reconditioning

[the_eskimo_wonder]

Alright, talked to the BavResto guys, they talked me into a reman AFM, which I just installed as well as a new O2 sensor, and now I'm back to the symptoms of the original one. It starts up fine, idles fine, but drives like trash. As soon as I get it in gear and start accelerating it bogs and bucks and fights me like crazy. Finessing the pedal helps kinda "reset" it when it's bogging, then once I get it up around 3000 rpm it smooths out again.

If it's idling and I just put my foot into it in neutral it spits, sputters, and smokes, but won't really get above 1500ish. You can tell it wants to but something won't let it. The smoke is fairly white and gas smelling though I have a terrible sense of smell.

I'm at a loss here. Was thinking of pulling the spark plugs and seeing if they'd been fouled from running rich but it was doing this before so I don't have high hopes there. Also it had some old gas in it when I got it that we diluted pretty well with fresh 91 and Seafoam but it's not all burned up yet. Could that be it?

[e30davie]

Ignition break down?

How's the cap, leads, plugs and engine grounds?

[the_eskimo_wonder]

Update! Ignition all looks fine. Cap and rotor had some buildup but cleaned it all up nicely and no change.

Fuel pressure is 8psi so I think I found my smoking gun. Especially since the car drives totally fine under 25% throttle, but dies out if pushed harder. It has what looks like a new high pressure fuel pump, though wired a little ghetto-ey. I've replaced fuel pressure regulator and fuel filter with no change.

Is it possible the HP pump is a cheap piece of crap and just not pumping to the right pressure now? I can hear/feel it running and it's getting the full 12V.