1992 300e acceleration issues
 

Hi all... first off just want to say I'm new to peachparts.com, but I've been reading some threads and it seems to be a very reliable place to get some help with my first car.


Ok its a 1992 300e 3.0L w124 160k miles on it..... automatic

When I start the car everything is fine, drive around for awhile and at stop signs and red lights I notice the car starts 2 pull forward.... if I put it in neutral the rpms jump from idle (in drive 700) to around 1500... and if I put it back in gear they go back down but the car still pulls forward.


Ok some history of the car
I took it 2 some "experienced mechanics" my uncle suggested 2 me.... they said the heads needed 2 be machined... after about a week of no returned calls I went and they had it all put back, (I had gone and they had the engine out and other frightening things)... but it was heating up... fixed that and I ended up paying $2000 USD

Just installed new iridium spark plugs (do they even make a difference??)
New k&n filter

I'm in college so don't really have a fortune 2 spend on her... but she is my daily driver so I want 2 keep her in good shape

Any help would be greatly appreciated

See the Owner's Manual for the correct spark plug. Instead of a K&N air filter use a stock filter specified for your engine. Buy both online or at your local MB dealer. It's best to have MB-trained techs work on your 300E.

Do not use iridium spark plugs in that engine. Obtain the proper ones from your local Mercedes Dealer or from on Fastlane (this web site)....Roy can get you the right ones. They are a non-resistor "standard" plug.

As for the high idle, that would likely be caused by a significant vacuum leak somewhere. Where does the "economy" gauge sit while in park and while in drive? It should be in the black all the way to the left in park, and maybe a needle width or two to the right when in drive. It might also be a binding throttle cable, but that isn't very likely. Check all hoses and vacuum connections. Vac leaks = high idle on a gas engine.

As mentioned above, use the proper German paper air filter. K&N stuff is junk and let too many particles through, causing engine wear.

If it ends up that you can't figure out the issue I'd highly recommend going to a MB dealer, instead of an independent shop. The dealer has the knowledge and equipment/info to properly diagnose and repair the car.

Ok so no iridium spark plugs check, old filter was in pretty good shape, spend $50 on K&N filter so i put the old filter back on.

it doesn't have an economy gauge, should it????

where could i find the vacuum diagram (dont have orignal manual), they seem kind of brittle and would like to replace them correctly, like i said i had some "expericence mechanics" work on her and i have a feeling they just pluged the vacuum hoses anywhere, but this problem has been happening since before then, so i'll do my best if i can't do it, i'll take it to the MB dealership when i can get the $$$ to do so....

Also this problem doesn't always happen, just when she feels like it :mad:, and sometimes will go away while driving the car, could that change the problem??

<if I put it in neutral the rpms jump from idle (in drive 700) to around 1500... and if I put it back in gear they go back down but the car still pulls forward.


>

Do a search on OVP relay.

If it doesn't have an economy gauge someone may have swapped out that gauge pod for a diesel one. Or perhaps the whole cluster from a diesel....does the tachometer go to 7000rpm with a redline area marking? The diesels don't have that.

I had a similar problem with my 89 300e. the problem ended up being the idle control valve. still idles a little high, (850) but not 1500 like it used too

here goes a picture of my instrument cluster.... the picture is with the car on and in park (the random acceleration is not happening, just a picture of the instrument cluster) I'll see if i can post a video of the problem soon.

would it be the idle control valve if it just does this sometimes, at random moments and lasts well untill i get home (5+ miles)

would the OVP relay, that deals with electronics have something 2 do with acceleration?? i mean cuz in gear it feels like im accelerating, and when i shift to neutral it jumps RPM's as if i were accelerating, but i'm not???

The gasser W124s didn't have an economy gauge (can't say for sure about the diesel versions)...Our former R129 did however.

OVP is power feed, so with an intermiitant OVP feed , the electronic controls cut out.
Very common for OVP to be the cause of high idle , and sometimes coupled with the ABS lamp.

When it does it, give the OVP a few good taps ....and check the fuse on top.

hate to admit to such, but i'ma newbie working oh german cars, i'll get my hands dirty with no problem, but could some1 direct me to the ovp relay and the idle control valve?? where are they located?

See the SEARCH BOX feature on the top of the page?

All that info is right there in depth...pages on pages of stuff.

Every gas MB I have ever seen that is pre-95 has an economy gauge, including my 1990 W124 300E, and my friend's former 1985 280te W123.....

Weird that this one does not have it, first I've ever seen.


Anyways....I got to thinking, and right before the Crank position sensor on my 300E went bad (and caused stalling issues) it would hunt for the idle and do the surging thing while driving and a high idle in park. I replaced the sensor and both of those issues went away. Just a possibility. The idle control valve could very easily be a culprit too, or the rubber lines going to/from it could be hardened and leaking.

My 1992 190E doesn't have an economy gauge either, and the part number on the instrument cluster is correct for my vehicle. I don't believe it was an option, so maybe it just varies by year. All of the 190E models from the 80's that I have seen had the economy gauge, but none of the 90's models I've seen have had them.

Weird....maybe they got rid of it in '91? I could swear I've seen a '92 4Matic at the junk yard that had one.