96 e320 running rough and smell of fuel

[STGold72]

Hello everyone, my name is Shawn and I am new to the forum. I was wondering if anyone might have an idea why when my 96 e320 is at operating temperature she really idles and runs rough. There is also a smell of gas on occasion. I have already replaced the MAF sensor and am getting ready to replace the CPS. Would anyone else have any ideas what else it may be. Thank you very much and it is nice to be here.

[Ferdman]

STGold72, the smell of gas may be due to a hairline crack in the EHA valve atop the intake manifold. To confirm that the EHA valve is leaking remove the air cleaner assembly when the engine is cold, start the engine and inspect the EHA valve for wetness caused by leaking gasoline. Typically when the engine is hot any leaking gas will evaporate so you will not be able to observe the EHA valve leaking/weeping. If the EHA valve is leaking you may get lucky and replacing the two green O-rings may resolve the problem; however, more than likely you will need to replace the EHA valve.

[97 SL320]

96 uses EFI not CIS so post 2 won't help.

Pull the vacuum hose off the fuel pressure regulator ( at the front of the injector rail ), if you have liquid fuel coming out, you have a bad pressure regulator.

Past that, check fuel pressure.

[Ferdman]

97 SL320, you are correct. I should have realized that because I own a 1995 E320 with the same engine. When I wrote my first response I was recalling my experience with our 1991 300CE and its EHA valve which was leaking and I needed to replace.

[97 SL320]

Yep, if the car was older I'd have to research what fuel system it had. I think the change occurred when the 3.0 went away and the 3.2 came on line in the early 90's

[duxthe1]

I'd start by pulling the plugs and see which ones are carbon tracked.