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  #1  
Old 06-01-2005, 10:11 PM
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New problem arises with the 450SEL

I keep on stalling. I have researched around here and yeppers it seems to be the idle control valve. Slight issue tho. I cant find it. I tried searching manuals and manuals, parts sites after parts sites and none have it. Could someone point me out a how to on this item. Its a 78 450SEL with the m117.

Thanks everyone
Peter

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  #2  
Old 06-02-2005, 01:18 AM
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I think it sets at the front of the engine. It will have 2 (I think) very large vacuum hoses running to it and will have an electrical connector. Go to the top of the page and open Fastlane. Look through the parts and there will probably be a picture of one.

Thanks
David
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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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  #3  
Old 06-02-2005, 01:20 AM
WANT '71 280SEL's Avatar
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I don't think your car has one. The stalling upon stopping is cured by the idle control valve on the newer engines. (m103/m116/m117) I know yours is a 117 but you have the different fuel injection.

Thanks
David
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  #4  
Old 06-02-2005, 08:20 AM
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Fuel pump relay?

Same thing happed to a buddy of mine and it turned out to be the fuel pump relay.
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Al
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  #5  
Old 06-02-2005, 08:56 AM
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A '78 would have the older-style idle valve. I am not sure where it is on the V8's - probably the top front of the engine. It is identifiable by the very large screw that is used to set the idle speed. It is mechanical and does not do very much. Try backing the screw out a bit to speed up the idle and see if that helps.

When does it stall? Hot or cold? Run OK otherwise? Hard to start hot or cold?
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Chuck Taylor
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'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #6  
Old 06-02-2005, 11:55 PM
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The car starts up perfect. BUT it runs slightly rich at start and then slowly leans out. When the car warms up to 180 exactly, after about 30 seconds it starts misfiring and jumping and shaking a little. That starts out slow at first and slowly increases to a complete stall. If reved above 2000rpm it stays there but sometimes it still feels a slight misfire. Then when it goes back to idle it completely stalls. After about 3 minutes or so of cooling down it starts right back up. Until then it will only crank and nothing else.

The car has been doing this for quite some time especially in warmer weather thats what I noticed. But while assembling the car after the paint job, I put some music on and accidentally left the key in the ON position and after about 15 minutes or so I started smelling a burning smell and that probably fried something in the passenger side of the engine bay.

The fuel pump relay sounds like the right part to me from all angles but I will go and try it out tomorrow.

Thanks,
Peter
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  #7  
Old 06-03-2005, 12:09 AM
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Keep us posted

Sounds like you have a good car, do you have any pictures of it?
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Al
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  #8  
Old 06-03-2005, 12:14 AM
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Car is for sale!!!

I just finished painting it last week and its all back together as well but its dirty. I got it out of the body shop and on the way home the problem started so I need to fix it, go detail it at work and then take as many pics as I can. It looks really sharp, its also for sale right now in the classified on this forum. I wish I could keep it but im moving to california and it would cost way too much in gas and time getting it there.

Peter
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  #9  
Old 06-03-2005, 12:16 AM
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Understand

Good luck in your move, there are plenty o 450's in California.
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  #10  
Old 06-03-2005, 09:00 AM
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Yeah I know, but first I would like to make a 190 really fast. Im still in the search for a wrecked c36 to put into a 190. But once I find the right w116, I will jump on it. I was thinking of a w126 for a while but it doesnt feel the same. Even the 560SEL has too much of a boats handling so Im just gonna put a 560s engine and tranny into a w116.

Those are my 2 cars that im on the lookout for in the near future.
Peter
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  #11  
Old 06-03-2005, 09:31 AM
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It would be really odd for the FP relay to die almost predictably like this.

Does this car have the lambda setup with an O2 sensor, computer, and frequency valve? If so, it may be going into closed loop when it hits 180. If you have a lean mixture to begin with, the lambda may be switching on, malfunctioning, and leaning it out enough to kill the engine.

Look for a 6" long valve with a two-wire connector and a fuel connection to the FD, somewhere close to the FD.

You can also look at the diagnostic socket and see if Pin 3 is wired.
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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #12  
Old 06-03-2005, 09:41 AM
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There isnt an oxygen sensor on the car. The engine starts out rich when cold and slowly goes leaner and leaner. By the time it hits 175, its noticeably lean.

Could the problem be the cold start valve as shown in the picture or the mixture regulator that has i believe 2 sunken in screws. Or the warm up regulator.
Or I just found, could this be the frequency valve thats faulty?
Peter
Attached Thumbnails
New problem arises with the 450SEL-cold-start-valve.jpg   New problem arises with the 450SEL-warmup-regulator.jpg   New problem arises with the 450SEL-frequency-valve.jpg  
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  #13  
Old 06-03-2005, 10:02 AM
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If you have a frequency valve, then you need an O2 sensor and a computer to control it. Do you in fact have one?

Another possibility. There is an auxiliary air valve controlled by a thermostat in the block that supplies extra air during warm-up. It may be that you are not getting air through the idle air valve. When the AAV shuts off at 180, no more air and the engine dies. Try turning the big screw on the idle air valve ccw and see if that helps.

Maybe your initial diagnosis was right.
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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #14  
Old 06-03-2005, 10:09 AM
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I do have a oxygen sensor and a computer because I have a frequency valve.

If I turn the screw on the idle air valve it just makes the idle go up I believe. Although is the idle air valve the one with the big plastic screw on it with a spring under it?
Peter
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  #15  
Old 06-03-2005, 11:22 AM
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Quote:
Originally Posted by alabbasi
Good luck in your move, there are plenty o 450's in California.
There are currently a lot of 450sel's popping up on CL in the LA area if you're moving into this area. Most seem nice but nobody can afford the gas and the people that can afford it want something newer.

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