Recreating 1979-81 528i emissions controls?

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tlake
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Recreating 1979-81 528i emissions controls?

Post by tlake » Sat Aug 17, 2019 11:47 am

From my understanding you have the lambda sond oxygen sensor going into the exhaust, feeding a corrective signal back to the ECU to hold the air fuel mixture at 14.7:1, while the three way cat does its filtering job. I assume these cars had an engine wiring harness with a wire going to the oxygen sensor :?:

I also assume that pre 1979 US spec cars, and Euro 528is, did not have this wiring harness provision for the oxygen sensor :?: So, if you want to follow this method it needs an aftermarket cat, and what would you do concerning getting the oxygen sensor set up so it can talk to the L-jet ECU :?: Thanks.

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Mike W.
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Re: Recreating 1979-81 528i emissions controls?

Post by Mike W. » Sat Aug 17, 2019 12:04 pm

Running a signal wire shouldn't be that difficult, but pre 79 ECUs don't have the capability of reading it or doing anything with it. So you would need a later ECU also. The distributor was different also and that was a big deal, electronic ignition for a hotter, more reliable spark, instead of vacuum retard only it was dual diaphragm advance/retard in 79 and advance only in 80-81, plus the wiring harness in 80-81 was a little different to accommodate the electric AAV on top of the valve cover instead of the water Technically there was also a thermo valve in the 'stat housing that prevented vacuum advance before it warmed up.

Injectors were different also although they had nearly the same flow rate and impedance, but didn't have the external resistors on the 528i. There were really quite a few changes not to mention what they didn't have which is all the vacuum lines, valves and switching valves plus the obvious EGR and air injection.

I think I've got any and all of that if need be including a harness.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

tlake
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Re: Recreating 1979-81 528i emissions controls?

Post by tlake » Sat Aug 17, 2019 2:01 pm

Thanks Mike, in some ways it isn't so bad because the car has Euro 1980 528i injection and no pollution controls, plus the transistorized igniton that came with the Euro car. The Euro 1980 ECU may be different to its US 1980 counterpart, and also wouldn't have the wiring harness provision for the oxygen sensor. By the time BMW was offering the Katalyser option on German market e28s they were on Bosch DME. That made it easy to have the cat, or not. Apparently the take up rate for the cat in Germany was less than BMW expected.

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Mike W.
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Re: Recreating 1979-81 528i emissions controls?

Post by Mike W. » Sat Aug 17, 2019 8:06 pm

I think you're good then, especially with electronic ignition as long as you don't have to pass smog. The old points and condenser didn't last long before needing replacement, on the m30 in my Bav I would barely make 5K miles. Same with plugs too. BMW went from madness, although it did have good power output in a diminished age, but madness with the 530i to genius on the 528i. Virtually nothing at the time when most cars were a maze of vacuum tubing, EGR and smog pumps.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

tlake
Posts: 144
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Re: Recreating 1979-81 528i emissions controls?

Post by tlake » Sun Aug 18, 2019 11:58 am

Mike W. wrote:
Sat Aug 17, 2019 8:06 pm
I think you're good then, especially with electronic ignition as long as you don't have to pass smog. The old points and condenser didn't last long before needing replacement, on the m30 in my Bav I would barely make 5K miles. Same with plugs too. BMW went from madness, although it did have good power output in a diminished age, but madness with the 530i to genius on the 528i. Virtually nothing at the time when most cars were a maze of vacuum tubing, EGR and smog pumps.
I was surprised to see that Willy Martini's old track e12 535i, a Group 2 racer, had points to go with the M90 engine and triple Weber carbs. Now owned by Walloth & Nesch.

BMW had no choice with the thermal reactors, and of course they used them through the 1979 model year on the 320i, 633CSi and 733i. Most cars in 1975 used a 2 way cat (pellet type) and a carb, this resulted in poor performance and cats that burnt out fast because of the imprecise fuel mixture. The funny thing was BMW didn't use fuel injection on the M30 in America until 1975. One of the few benefits of thermal reactors was that you could use cheap leaded regular, and avoid expensive unleaded, which was sometimes hard to find.

The M30 was such a clean burning engine it didn't have any pollution controls, even including the 1974 model year. The only change in 1972-74 was a lower compression ratio versus Euros, and leaner carburetion, retarded timing. That said, because BMW stayed with carbs the drivability wasn't that great. If they had applied D jetronic in 1972-74 to North American e3s and e9s, those cars would have run much better.

It's proof that the M30 was a very clean engine because after going with a 3 way cat it could dump the EGR and smog pump. Many fuel injected cars had to keep the EGR into the 1990s, like the Cadillac 4.9 V8. :mrgreen:

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Lock
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Re: Recreating 1979-81 528i emissions controls?

Post by Lock » Wed Aug 21, 2019 1:56 am

I got lucky with the '79 528i. I have only two vacuum lines in the engine bay - one from manifold to fuel pressure regulator, and one from manifold to vacuum advance (I bypassed the vacuum thermo valve). And it runs fine with the vacuum retard disconnected, and the throttle body vacuum ports plugged. That plus cat and oxygen sensor and it runs great. The exhaust smells a little "1970s" at idle though so the cat might be on its way out.
I get lost looking at all the lines and wires in a 530i.
1979 528i 5-speed conversion G260/6
1980 Honda CX-500

tlake
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Re: Recreating 1979-81 528i emissions controls?

Post by tlake » Wed Aug 21, 2019 12:39 pm

Lock wrote:
Wed Aug 21, 2019 1:56 am
I got lucky with the '79 528i. I have only two vacuum lines in the engine bay - one from manifold to fuel pressure regulator, and one from manifold to vacuum advance (I bypassed the vacuum thermo valve). And it runs fine with the vacuum retard disconnected, and the throttle body vacuum ports plugged. That plus cat and oxygen sensor and it runs great. The exhaust smells a little "1970s" at idle though so the cat might be on its way out.
I get lost looking at all the lines and wires in a 530i.
Yes, I guess however sophisticated a cat is, it's a filter and like any filter it gets clogged with use and will need replacement at some point. That also implies maximum performance when the cat is brand new.
As a side note I don't think the 528i's slightly lower power was due to pollution controls 169 hp SAE versus Euro 177 hp DIN. That difference was probably mostly from the respective compression ratios of 8.2:1 and 9.0:1

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Mike W.
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Re: Recreating 1979-81 528i emissions controls?

Post by Mike W. » Thu Aug 22, 2019 12:40 pm

Good cats, under good conditions will last pretty much indefinitely. The one on my E28 was still working when I sold it with 330K on it and performance was good.

Compression is huge in determining HP. Even E28 528i's were up to 183HP with 9.3 instead of 9.0 CR.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

tlake
Posts: 144
Joined: Wed Feb 03, 2010 6:33 pm
Location: WA

Re: Recreating 1979-81 528i emissions controls?

Post by tlake » Sat Aug 24, 2019 11:25 am

Mike W. wrote:
Thu Aug 22, 2019 12:40 pm
Good cats, under good conditions will last pretty much indefinitely. The one on my E28 was still working when I sold it with 330K on it and performance was good.

Compression is huge in determining HP. Even E28 528i's were up to 183HP with 9.3 instead of 9.0 CR.
The 1980 Euro e12 528i had that 9.3:1 motor too. It was introduced at the same time as the revised Euro e23 range, which included the new 728i, joined by a 628CSi.

The two factory cats on a brand new 1997 Audi A6 failed at 35,000 miles. Had to replace, and the car was transformed, more power, quieter. It was obvious they had been deteriorating for some time.

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