weak starting
 

I was wondering if any could tell me what causes the engine to rev up higher when starting, and then drop down to idle speed.

my 1985 190E 2.3 8vlv has a really rough time doing this when I start it and I would like to cure this problem, sometimes on a start, even though it starts up right every time, it will die, on second start it will be just fine, but it never starts up propperly when cold.

This is what I would expect, from 0 rpm to 1500rpm, and then hold it there for a second or two, and drop down to 1000rpm for warm up and then after it warms up to 650rpm all in idle of course. my car does 0 to 650 very slowly as if it's struggling with something, if it does not die here, it will go to a 1000rpm and stay there until it is warm, then back to 650rpm.

Can anyone explain the theory behind this? would love to fix this, maybe something is leaking in my car that I should take a look at, injectors are clean, but it's as if it lost pressur right after you start it up, but I know it does not lose pressur, I tested it.

xp

Sorry I can't really help you except to say that this is typical of 190s. Mine is the same way. It's more difficult to start when it's cold and especially if it's also wet.

There is some kind of valve in the engine that controls the ratio of air to fuel which sometimes can go bad. From my understanding, it's a very labor intensive job to fix which will run more than a$1,000. Hope that's not what's wrong with your car.

Here is how our '91 190E 2.3 behaves, since I fixed the idle. Note that the idle circuit of yours is a different design (I believe). When the engine is first started cold, idle goes to about 1200 rpm - not racing, idling smoothly - then drops to 750 rpm in 5 - 20 sec. Idle may go a bit higher, maybe 850, for awhile if it is pretty cold out.

If you have an idle control valve, it may be gummy and need cleaning. Injector cleaner in the fuel tank will NOT do this, it must be removed. If the connecting hoses are hardened with age, they should all be replaced, and I found the OVP relay apparently had bad contacts. Also check for proper operation of thermostatic elements and check for vacuum hoses loose.

Steve

Circuits circuts circuits....
 

Thanx a lot for the advice, so far, I have done most of those things, but I'm not sure to what valve you are referring to sflori, to control the air/fuel mixture I only know of the EHA, and idle control valve, one takes care of it at idle, the other while driving, if there is another one I'd love to know where I can find it, I'm sure it needs a good cleaning, temperature sensors might have something to do with it I completely agree, I will look into replacing mine soon, the parts list goes on he he he :)

Actually, I noticed that this started happening after I cleand the idle control valve, it's almost like it needs the second try to catch on propperly because it's reaction is delayed by something, go figure...

come summer time I'll be taking the entire car apart, maybe I'll find what's causing this.

xp

XP,

I'll give my mechanic a call to see what valve it is. I really don't remkember if it's a valve or something else. The "idle control valve" that sborg mentioned sounds familiar, but I'm not sure.

I won't be able to call him until Friday, though, as I'll be in CA directing a promotional film for the USMC until Thursday night.

great :)
 

That would be great sflori, I would really appreciate it, I'm sure a lot of people on this forum would be able to answer this too.

directing sounds great, hope it all goes well.

xp