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'91 190E 2.6 5-spd
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Discussion Starter #1
Have a '91 2.6/5 spd. New plugs, wires, distributor, rotor, fuel filter within the last 2,000 miles. Good fuel pressure

I'm having issues with erratic idle and hesitation when accelerating until the it's over 2,200 rpm.

I pulled off the air cleaner when I was going to clean the throttle body. What is the vacuum line off the end of the fuel pressure regulator supposed to connect to?

I was told that the vacuum off the breather hose between the air cleaner and the valve cover doesn't connect to anything, but I'm assuming the one of the FPR should go somewhere.
 

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'91 190E 2.6 5-spd
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18 Posts
Discussion Starter #2
Remembered to look at the emissions diagram under the hood. Looks like the line off the end of the FPR is supposed to go to the breather tube between the air cleaner and valve cover.

Looks like it the tube was just open-ended under the air cleaner and the connection on the breather tube was open-ended, too.

One other question - Does the ICV need to come off to clean it?
 

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1992 Mercedes 190E 2.6
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25 Posts
Yes, the vacuum line from the FPR goes to the breather hose from valve cover to the air cleaner.

As for your second question... I do not know.

Also, I do not think there is actually vacuum going through the vacuum line from the FPR to the breather hose since the breather hose is exposed to atmospheric pressure. I recently broke that vacuum line on mine and since then Im running the car without that vacuum line, and there seem to be no difference.
 

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'91 190E 2.6 5-spd
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18 Posts
Discussion Starter #4
Any advice for getting the hoses off the IAC so I can pull it out and clean. Don't want to trash the hoses trying to get it out. There's a lot of crap in the way.
 

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The vacuum line going to the FRP is there in case the FPR diaphragm ruptures. You could cap that vacuum line, it wont make a difference. Also I HIGHLY recommend getting brand new IAC hoses. They will crack most likely. Don't be cheap and try to fix them, it they have a any leak they'll cause problems. Buy new IAC hoses from the dealer!
 

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W-1-2-3 Go!
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The vacuum line going to the FRP is there in case the FPR diaphragm ruptures. You could cap that vacuum line, it wont make a difference. Also I HIGHLY recommend getting brand new IAC hoses. They will crack most likely. Don't be cheap and try to fix them, it they have a any leak they'll cause problems. Buy new IAC hoses from the dealer!
Agreed. Air Mass Sensor must be removed to access the two vacuum hoses. One goes to engine head, one goes under AMS.

Perfect time to also clean up throttle body while AMS assembly is out.
 
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