My EHA valve was leaking through the plastic case. I put a new one on and have been trying to get it adjusted right. When I get it to idle very smooth it gets awful MPG. Like 13! I check my Duty cycle it is around 55-60. To get good milage on the highway it idles with a drop and stumbles on light acceleration. I have new plugs cap and rotor are very good timing is on the money. Plugs are factory specs not the Zone specials. It also has a new Idle control vale and hoses. Thanks Alan

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I'm not sure what you are doing, since the EHA does not 'adjust'. If you are adjusting mixture on the airflow meter, then this should not be necessary after replacing the EHA unless someone previously MIS-adjusted it to compensate for an improper mixture due to the failing EHA.

Steve

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'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

Sounds to me it's time for a new fuel distributor

The EHA valve has an adjustment behind the screw that is on the inside of the valve that is next to the distributer. It will make a large difference with litlle change. I have searched the forum under EHA. It fixed most problems except fuel MPG. Alan

__________________
Sold 82 300TD 205K
Sold 85 300SD 310K
85 380 SE 160K Daughters
90 420SEL good Ebay Buy
92 E350 7.3 251K
88 F350 7.3 211K Farm Truck
84 300SD waiting for Engine

How about the oxygen sensor?

I had the same problem. What you need to do is adjust the EHA, but then adjust the mixture in the air intake. They need to be in conjunction with each other. I think to set this properly you need to test the fuel pressure at the injectors?? Ive only ever adjusted the EHA screw and trialed it. I got huge improvements.

Eha's need to be adjusted when new, its a simple fact.

Oxygen sensor can also be tested.

Test the output wire which is under the drivers side carpet and is green. Put the -ve test meter wire to earth. Test for volts and it should be between .1 and .9. .9 being rich and .1 being lean. If you rev the engine slightly it should fluctuate.

If it does not fluctuate then theres problems and further tests need to be done.