I have established through experienced Correct FUEL PRESSURE =/= a properly functioning EHA.

I'll try to keep it short so its not confusing:
BEFORE:
300TE - Poor mpg (13-14 average)....but car accelerates great
260E -- Great mpg (20-22 average), but zero acceleration

Now I SWAPPED EHA them between both cars. NO other changes at all.
300TE -- Now I get 19mpg(wow!!) and car still accelerates great, but a tad tad slower @ bottom end
260E -- Still get 20-22mpg average and complete change in acceleration. Whole different car it feels like.
^ 3 tanks full on both. I wanted to make sure it wasn't just a lucky run.

So now I am trying to figure out the CORRECT way to make sure an EHA is functioning properly. I tested fuel pressure on both cars and it was dead on spec @ 5.6bar in lower chamber and 5.1/5.2 in upper, so how can I test it and make sure the setting is correct?

Thanks

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Strange swap of symptoms. Both cars improved? Weird.

Is it possible that you inadvertently fixed something just by taking them off? Perhaps unclogged or unstuck it? I'm just guessing.

It would be interesting to see if the cars both returned to their original symptoms if you put them back in their original car.

I can't answer your question, I have no idea.

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Well both have been off before as I have tweaked the screw on the back, so no that doesn't sound likely...But yes it would be interesting to switch them back. I probably will out of interest and see what happens...

There has gotta be a way to test them other than just by "feel"...

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I use a wideband a/f ratio meter to see how things are doing...no better way to see where things are @..!

Jonathan

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Better fuel mileage can be a result of O2 sensor control, possibly the EHA change wasn't the only reason for the difference.

Adjusting the fuel mixture so the O2 sensor can work is the key to mileage.

FOR better acceleration having a slight greater difference between system & control pressure is the key.

FROM Bosch the EHA is adjusted to have 0.400Bar differential warmed up with NO lamda control.

Having 0.399Bar means less acceleration. And having 0.401Bar differential and more means better acceleration.

Slight adjustments can allow for better acceleration, but will cause poor mileage IF the O2 sensor can't adjust the mixture in closed loop.

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