My 300E developed a problem early last summer where sometimes it would misfire at lower RPMs and stall out. It idles fine, but the moment you put the engine under load (i.e. going from park to drive), the RPMs drop, it begins to misfire, and eventually stalls if you don't put your foot down. Then, after starting it back up again it will misfire on the startup and immediately stop the rotation of the engine (like a preignition or something, not quite sure). I think I've tackled all the usual culprits. So far:

- replaced ovp with new unit
- replaced cap and rotor, just inspected them again today to see if there was anything wacky there...cap had some usual corrosion on contact points but nothing out of the ordinary
- replaced wires, checked again for arcing today and nothing
- replaced EHA (was leaking wildly, had to be done anyways)
- checked engine temp sensor, appears to be fine
- checked the flywheel crank sensor (which goes to EZL), came out to 880 ohms, which is well within spec
- replaced O2 sensor
- fuel pump is always on during this so that rules out FPR
- replaced spark plugs (proper style - ordered from here)
- checked vacuum connections, seems fine

Today before I started it (it had been a week or so), I replaced the EHA and in doing so I checked the MAF plate. It did not spring back to the top but stayed wherever I pressed it to (and I had to pull it back to the top). However after starting the engine and having it run like crap, I checked it again and it sprang back up to the top--so I don't think that is the culprit.

Also this is completely intermittent. After it ran like crap today, I shut it off, let it cool down a bit while I checked the cap, rotor, CPS, and wires. Started it back up again with its temp roughly 40*C and continued to run fine as if nothing ever happened. Shut it down and started a few times and it was still good. I hadn't replaced anything in between these two times I had it running, just disconnected/connected the aforementioned things.

Emissions test for this bad boy is er....tomorrow. I need to get it so I know it will not stall out on me on the way over to the testing facility or worse run like crap on the wires.

Any thoughts? I checked the duty cycle not too long ago and it looked fine...I am going to check it again now but I don't suspect anything to be wrong since it was ok before.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Do you feel low on power? When was the last time you replaced the fuel filter?

I had (still have) a power issue, along with poor mpg. dropping a bottle of redline fuel additive helped a lot.

Intermittent problems suck.. They get expensive too.

My last guess would be to change injectors.

__________________
Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

I replaced the fuel filter about a year and a half ago, the old one appeared to be the original. When its working, it runs fine and gets good mpg, its got to be something electrical somewhere in the system since its intermittent but I feel like I've checked all the boxes. BTW that EHA valve worked out great - got it on this afternoon and it doesn't leak a drop, turns out the smaller O rings were right. Thanks!!

Edit: also, duty cycle today (while running ok) was fluctuating between 48-51% which is very good. Hmmm

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I would check vacuum, however I doubt it is an issue.

What is the idle difference normal vs bad, park and in drive?

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Eugene

10 E63 AMG
93 300te 4matic
07 BMW X3
14 Ford F-150 Fx2

sounds like a vacum leak check the hoses that go to the Idle control valve! Mine were shot! as soon as I put it in gear it would want to die,even worse the warmer the eng was. replaced the hoses and all is well

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88 W124 3.0
96 R129 119eng
06 ML350
98 ML320 sold
02 CLK55 amg

In park, it now misfires when idling (didn't do that at the time of my first post). Giving it some gas makes it misfire but the RPMs still rise up, about 2500-3000rpm there's no more misfire and its as happy as could be. Putting it in gear causes it to misfire and stall.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I know your fuel pump is working, but is it making pressure?

I replaced mine, and lots of little intermittent things like stumbling instantly went away.

It was a good investment to replace the OEM pump. It was only 25 years old, and submerged in some of the worst gasoline ever refined... It amazes me just how skanky modern fuel really is!

__________________
My first Mercedes Benz. 4/6/07.

1984 190E (201 024) 2.3L four.

check if fuel pump ground is clean

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

The two hoses to the idle valve get loose, crack, etc. I have a new pair on the counter that I will install this weekend hopefully. Another place to find leaks are the injector seals and the rubber boot that makes up the underside of the air flow metering chamber.

-CTH

__________________
- cth350@gmail.com
http://www.111lakeside.com/

Possible ignition coil going bad when hot, removed coil wire and check spark while sombody cranks , hold about a3/8 inch gap , spark should be blue, if its orange = weak, should jump a 1/4 gap with no problem, and be cafefull dont shock yourself , use insulated plyers or wooden clothing clip to hold wire

Thanks guys - I guess I will double check the vacuum lines again, the intermittent state of it is what really throws me for a loop but it can't hurt to eliminate one more variable.

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

Just passed emissions, and it was well within the boundaries in every field. Not surprising since its AFR/duty cycle was pretty much perfect when it was running okay. Thankfully it didn't stall out on the rollers!

__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I recently had similar problems that I had a hard time finding. It turned out to be a bad idle control valve and badly cracked hoses connected to it. The idle control valve has a shutter that moves to control air. It would stick at one position. I bought a used one on eBay and replaced the hoses. It runs perfectly now.

Brent Smith
Atlanta, GA
1986 300E 274,000 miles

Idle control valve, hoses, and possibly the fuel pressure regulator could be bad.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Had a similar problem with an '87 300E. Turned out it was the coil. I'd try as replacement to make sure.
Anziani