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#1
06-28-2016, 09:37 PM
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70' 280SE Rough idle...
Hey Guys, just picked up a 70' 280SE and am going through some routine maintenance. It runs quite well, but is a bit stumbly at idle (and worse with the AC on) and when driving down the interstate if I give it 3/4 throttle or more it starts missing. I just replaced the cap, rotor, and plugs with NGK(correct non-resistor type) gapped to .028" and all of this helped everything except the slightly irregular idle. It has a Pertronix ignition, good Beru wires, fresh ethanol free gas, etc. Any ideas? Timing issue? I have a fresh fuel filter on the way but not counting on that fixing the issue. Car runs and drives beautifully under every other condition. Any advice would be great. Thanks
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#2
06-30-2016, 03:37 PM
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You might try some fuel injection cleaner. I don't know if this is the main source of your problem but it would be cheap and very likely needs doing.
A compression check would also be a good thing to run. Neither of these are a sure thing, but with problems like this you need an old time ignition analyzer to spot the problem or you need to start trying all the cheap stuff first.
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#4
06-30-2016, 05:12 PM
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When the AC is turned on it signals the idle relay to increase the RPM at idle. So you may have an injector or port in the FD that isn't quite cutting it at normal idle
__________________
BENZ THERE DONE THAThttp://www.peachparts.com/shopforum/...c/progress.gif 15 VW Passat TDI 00 E420 98 E300 DT 97 E420 Donor Car - NEED PARTS? PM ME! 97 S500 97 E300D 86 Holden Jackaroo Turbo D 86 300SDL (o\|/o)
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#5
06-30-2016, 07:13 PM
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With this being a 1970 I am going out on a limb here and thinking it is a mechanical fuel injected six.
I missed the part about the A/C. There is a relay on this car that sends power to what is called the 'lifting motor'. It is a simple device, an electromagnet, that kicks out a plunger when it is energized. This plunger pushes against the fuel linkage on the intake side of the engine. It is located to the rear of the intake manifold and above it. It is not much to look at, just a round little thing bolted to a small plate with two wires coming out of it. It is easy to test. Just put 12v to it and see if it pops out. Or you can test the wires going to it with a voltmeter to see if it is getting voltage. It has been some time since I worked on one of these and I cannot remember if it has two wires or one. If only one then it grounds through the body. Check out Ebay for one of these. You might not need one but you might be able to see some good photos so you would know what you are looking for.
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#6
06-30-2016, 08:29 PM
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Quote:
__________________
Graham 85 300D  ,72 350SL, 98 E320, Outback 2.5
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#7
07-01-2016, 12:21 PM
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I agree. But I was hoping it might be of some help to know what I posted.
I called a friend of mine that has a bunch of FI parts and asked if he has a spare lifting motor. He said no but another term for this part is the lifting magnet which I have to admit is more to the point. After all, all this is is a big electromagnet. He suggested another cause for a rough idle with the A/C is running is the York compressor is worn out. I can see this although I have never run across this myself. If the pistons in the compressor are worn out and dragging on the cylinder walls it would put a drag on the engine. (duh) I think the original poster might be fighting several small items that add up to a rough idle. That's usually the case when I run into something like this. And this could be nothing more than a vacuum leak.
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#8
07-04-2016, 06:35 PM
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Thanks for all the input guys. Yes, kit's the M130 FI 2.8 I6 motor. I will test the lifting magnet and take a close look at all vacuum lines. Also, the AC was not used for some time, so I wouldn't be surprised if the compressor is due for a replacement, but the idle is still a touch off at idle even with the AC off
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