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  #1  
Old 10-15-2002, 11:12 AM
jmdunn
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Did I distroy my catalytic converter by running too rich?

I Just recieved a new fuel distributor and control pressure regulator for my 77 450Sl. I did the basic adjustment of turning the mixture screw until fuel neither rose or fell in the injector ports. I was able to get the car to start but and it idles ok in P but in D it idles terribly and coughs or dies. DO I need to adjust sytem pressure? I have a CIS pressure guage but don't know the correct system pressure or how to adjust it. Can anyone help please?

Thanks in advance,
jmdunn

Last edited by jmdunn; 11-14-2002 at 04:05 PM.
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  #2  
Old 10-15-2002, 11:49 AM
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Not sure if this will help. Give it a try.

1973 450sl Fuel Pressure Problem
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  #3  
Old 10-16-2002, 11:02 AM
jmdunn
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Maybe the salvage yard sent me the wrong fuel distributor? I plugged off the hole(> on the pic)that goes to what I think should be the Lambda control. I finally found the system pressure settings on my CD of 5.6 bar sytem pressure and set that by adding shims from my old distributor to the valve. Should I send this back and request a distributor from one without lambda. It idles fine in Park but with a load on the engine same story. I can't even drive it. Gas analyzer was also set to 1.5% CO. Help please.

thanks,
jmdunn
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How do I adjust system pressure on my new fuel distributor-picture-002.jpg  
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  #4  
Old 10-16-2002, 06:43 PM
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Absolutely, you must get the right distributor. The lambda control distributor expects and needs lower chamber regulation via a electronically controlled frequency valve (controlled leak). By shutting off the circuit you bring differential pressure to zero and are only getting it started by in effect over enriching it. Problem is that without control the only way for proper running would be to reset the mixture to every airflow quantity; not very practical.
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Continental Imports
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  #5  
Old 10-19-2002, 10:21 PM
jmdunn
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O.K. I'm beginning to get frustrated now. I got the correct fuel distributor back on the 450 and set the system pressure to 5.6 bar again. I took all the lines off and checked for good flow to all cylinders from the distributor. All that checked out, reset the mixture to 1.5% CO and the thing won't even start. I bump the CO up to 3.5% and it runs in P at 1000 rpms with the air screw out almost all the way. If I go any leaner than 3% it dies. Next I take each injector out 1 at a time and hook them to a spare line attached to one port on the fuel injector with the fuel pump jumpered. All the injectors seem to have a good pattern when I push the air flap down more than 1/3 of the way. At light pressure( < 1/3 the way down)I get very poor fuel pattern more of a modified stream. Do I need to replace the injectors or just have them cleaned. Is it normal for poor pattern at what would be low rpm if the engine was running? At about
4-5% CO the thing will idle rough in D (~550rpm)but not die and run if you can put up with the hesitation when you first hit the gas up to 25mph, hard starts and 5-8 mpg, which I can't. Could it be something else. I've replaced the vac. advance, control pressure regulator, cold start valve checks out fine, replaced additional air valve, cleaned the throttle body. Checked all vacuum lines against diagrams and replaced them all.

thank you for any help,
JMdunn
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  #6  
Old 10-21-2002, 10:34 AM
jmdunn
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I really need some help here....Anyone? I would be very grateful.
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  #7  
Old 10-28-2002, 12:54 PM
jmdunn
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I replaced my injectors, holders and seals. Still the same problem I need help. Could my catalytic converter be plugged from running so rich before. It has 173,000 miles on it.

thanks again
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  #8  
Old 11-14-2002, 04:03 PM
jmdunn
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This car has been sitting for weeks, I really need some help.
Could I have ruined my catalytic converter by running too rich with the incorrect fuel distributor? If so how can I check it?

thanks again
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  #9  
Old 11-14-2002, 04:33 PM
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A basic way of testing for plugged cats is to measure the manifold vacuum at 800rpms and then raise the rpms to say 2000 the manifold vacuum should be greater at 2000. If it isn't the cat could be the problem.

Measuring the ackpressure at the O2 sensor hole is another way. Shouldn't have more than 2psi at normal loading.

Another way is to just leave the O2 sensor out and see if the reduction in pressure forward of the cat makes a difference in manifold vacuum.
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Steve Brotherton
Continental Imports
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Bosch Master, ASE Master, L1
33 years MB technician
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  #10  
Old 11-15-2002, 10:40 AM
jmdunn
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Steve,

I have no 02 sensor so, do I jus connect my vac. guage up to the vac. port for ignition advance or charcoal cannister? Also, I plugged off the EGR valve because it failed the test on the CD and wont hold vac and the check valve for the Afterburn air intake doesn't seem to be sucking. Could these be causing my described symptoms.

Thanks again for your quick replies and efforts.
jmdunn
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