E28 525E - Where Does This Go? + Some Other Advice Needed

[M M 250]

I'm slowly tidying up my 1985 E28 525E Auto and could use some advice on a couple of things from people more familiar with these cars.

Firstly, where does this go?

It looks like there is meant to be a vacuum hose on that end that goes somewhere but I don't see anything missing anywhere else and haven't been able to find any pictures to help here. Could anyone help me here?

Secondly, the car has been using a very large amount of fuel. Since I bought it, it would do about 90kms to 13Liters of 95 suburb driving (I don't sit in traffic much but do drive in suburb areas with stop/start often) and if I was lucky, 10L per 100kms on the motorway. Recently it has become worse and now it does about 75kms to 13liters of 95. I realise it's a big motor but this seems very excessive to me, especially because my Mk2 Golf with a 2L with bike carbs that is running rich at the moment gets better mileage than that, and this is supposed to be an "efficient" motor. In an attempt to fix this, I have replaced the fuel filter, fuel pressure regulator, coolant temp sensor, spark plugs, intake boot (which has a rip and was taped up), checked for vacuum leaks/split hoses etc and have looked at the AFM adjustment screw today which was 13 (yes, 13) turns out. I looked for the o2 sensor however it appears that it never had one (which seems unlikely), or it was removed, and there is no connector or wires for it anywhere that I can see, nor a bung in the exhaust.

Also, when shifting from reverse to first or the other way round(remember it's automatic), sometimes the revs drop and occasionally it stalls. It then restarts perfectly. I'm not sure if this is connected yet but I guess it may be.

Can anyone advise me on what I should be looking at next to try and fix this excessive fuel consumption? I've read that valve adjustment can help, which is where I'll be looking at next. Any help is appriciated.

[C-130 Hercules 571]

I don't have that on mine (525ee). The setup is a little different altogether. Maybe Brent can give advice. The low revs and stalling is a common issue on these. You probably have to adjust he AFM a little to compensate.

[scottbeattie 63]

Same here, '87 525ee and I don't have it either. Mine also stalls occasionally, but only when I haven't warmed it up.

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[M M 250]

Thanks for the responses. It could be an early car thing as mine was built in 84. Who knows. I've blocked it off for now.

I'm not too concerned with the stalling thing, it's easy to live with but would be interesting to find the cause. I'm more concerned with fixing the excessive fuel usage.

Out of curiosity, what are you guys getting in terms of fuel economy?

Edited November 8, 2014 by M M

[tcbaurpower 5]

Have a look under the intake manifold as there can be a few pipes down there. Might be hard to see them from above.

[C-130 Hercules 571]

Out of curiosity, what are you guys getting in terms of fuel economy?

About 10L/100k in town. More like 8L on open road.

[scottbeattie 63]

About 10L/100k in town. More like 8L on open road.

Mine's about the same

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[M M 250]

Ok then there's definitely something wrong. Thanks.

Have a look under the intake manifold as there can be a few pipes down there. Might be hard to see them from above.

Will do, thanks.

[polley 916]

check throttle position switch

[M M 250]

check throttle position switch

Thanks, just did a check now. Apparently it has no continuity on any throttle position across any of the pins. Maybe I was doing it wrong, but I'm not new to this and was following instructions in the Bentley manual.

I did find where that vacuum part goes in my pictures though. Noticed a loose, half hanging off vacuum hose on the throttle housing, pulled it out to find it was just tucked under the intake manifold and a bolt was in the end to block it off. I have now fitted a new hose and while I was there I cleaned the air fuel meter. I took the car for a spin and it seems to be going better, doesn't stumble between drive and reverse and idles nicely. But will wait a few days to see for sure and see how the fuel economy is. If there is no difference I'll be looking into the throttle position switch more.

Thanks for all the replies so far.

[M M 250]

I'm going to bump this thread as I still have this problem. I bought a new TPS and installed it, adjusted it correctly and it operates perfectly. The old one was way off and filled with oil. I also replaced the thermostat just in case, but it hasn't fixed it. It is still using 15L per 100kms. Anyone have any other ideas? I'm starting to run out of things to fix.

Also, I've checked for vacuum leaks all around the intake manifold and all intake parts, can't find anything. There are also no fuel leaks anywhere (unless the injectors are not closing properly or something, is this possible?).

Edited January 6, 2015 by M M