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Old 10-09-2011, 09:48 AM
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Graham Graham is offline
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Join Date: Nov 2004
Location: Ontario, Canada
Posts: 4,393
Good News - Great that you haveher running well! Checking bthe trigger point connector is a good tip! Mileage is amazingly good. I don't bother checking mine!

Quote:
Originally Posted by Jay Gibbs View Post
A little news on my 75 450SL...

I've been tinkering with it for nearly the last 3 years working out some issues familiar to anyone who owns one of these...have replaced every single rubber bushing underneath, steering box resealed, and all new shocks and it now rides and handles like a dream. The difficult issues have been related to the engine and performance...ie: rough idle, poor gas mileage, hot start problems and asthmatic, labored, lethargic performance. I had replaced a bunch of engine sensors, trigger points, fuel filters, etc all with limited success...that is...until today...

After slowly acquiring all the replacement parts needed, I have finally removed ALL the emissions controls...the combined exhaust manifolds/cats, the EGR system, the air injection pump and ALL the associated plumbing- 58 pounds worth of junk! Replacing it all with 18 pounds of exhaust manifolds from a '74 450SL, and I'm happy to report that the results are nothing short of spectacular! The rough, hunting idle is for all practical purposes gone...nice and smooth...wow. Acceleration now happens with an astonishing urgency and a free breathing rush that makes it feel like it just cannot possibly be the same car! Best of all, I just got back from a couple trips- one 135 miles, the other 170 miles- filled up the tank after each one (mostly highway driving 65-70 mph, a little stop and go, toll booths, and with several 60 to 100 mph blasts thrown in for the sheer fun!) the result was 16.5 miles per gallon!! Holy S..T!!! I'm pretty sure with a little more judicious throttle useage, I could break 18 mpg! This car hasn't EVER shown me more than 12 since I owned it, and the average has been closer to 9...

Had a local shop do the manifold change and adjust the fuel injection for proper mixture- the exhaust gas results were- CO: 0.43; CO2: 14.13; HC PPM: 46; O2: 1.2

Nice part is that in PA, (and other states too I'm told) that when your car is older than a certain model year, emissions controls are not required to be maintained, so this was a perfectly legal transformation! The ultimate win-win!

It is also amazing how much the underhood temps have dropped, and how much more room there is now between the frame rails and the manifolds without those lousy cats crammed in there...alot cleaner looking setup.

A little note on those trigger points too...the car had been running great, and then I did a little cleaning up under the hood. Afterward I started the car and it stumbled badly like the trigger points were gone again. Figured I must have moved something while I was cleaning. I moved and jiggled the big rubber plug connector from the trigger points with the car running and the engine instantly came back to life...turns out the female side of the socket has some loose connectors, and just a little movement made it lose electrical contact. I'm going to try to get a new replacement female side connector.

Hope this provides some hope and ideas for you other guys who have had similar issues with your D-jet equipped rides...this car is really a blast to drive now!

J.G.
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Graham
85 300D,72 350SL, 98 E320, Outback 2.5
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