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  #1  
Old 01-28-2002, 09:03 PM
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300E very fast after a cold start....

Hey guys. Here is the deal, whenever I leave the car (92 300E m103) overnight and then start it in the morning, the car seems to go into superfast mode. I tried it out this morning, and floored the cold engine (I know... its not the thing to do... im sorry) and I managed to break lose the rear wheels in a smoky pealout. Now, this is the 300E we are talking about, and ive never dome a pealout before with this car, so I was impressed. Only problem is, after the pealout, my car returned to normal driving mode, which as you all know... is a bit slow. Ive noticed that my car only enters this "mode" in the morning after sitting overnight, it never enters it during the day, even if the car has been left sitting for a while. So here is the question... what is causing this extra performance? Is it the cold start valve? If it is, could anyone expand on what exactly the cold start valve is? I read that its only on 1 cylinder?? Yea... any help would be appreciated, thanks!
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  #2  
Old 01-28-2002, 10:17 PM
Ali Al-Chalabi's Avatar
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The cold start valve on my Bimmer is just an extra injector that adds additional fuel to the engine during the cranking of a cold engine. I believe it serves the same function on the Benz.
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  #3  
Old 01-28-2002, 10:19 PM
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hmmm... so is it possible to get this valve to open on command... ie wire a switch that will activate the valve, so say when an extra boost of speed is required, you just flip the switch... and take off?
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  #4  
Old 01-28-2002, 10:41 PM
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I don't think that will work. It is only enrichining the mixture during the start. The valve will just make the car run rich if it were rigged to do so. There is no extra air going into the engine, so the extra fuel would just pass through unburned.

From what I can remember, this valve only functions while the starter is engaged and then shuts off.
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Old 01-28-2002, 11:06 PM
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hmmm... ok, I understand. But then that still leaves the question as to why my car is so much faster after a cold start... if the cold start valve is disengaged after the engine turns.... what is causing the increased performance. And, do you guys think that the benz under WOT could burn the extra gas? Just a thought...
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  #6  
Old 01-29-2002, 01:44 AM
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My 190e 2.6 does the same exact thing. It will get up and dance and smoke the tires when it's cold. I think the trannie kicks down and hold in first a little longer. I wish it would do it on command.
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Old 01-29-2002, 02:08 AM
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Many more cold engine full throttle burn-outs, and it's won't be a supercharger you need. New engine...

I think it might be a combination of cold dense morning air and enriched mixture.
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Old 01-29-2002, 07:34 AM
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hmm.... I doubt it has anything to do with the air, because like I said, the car goes back into normal mode after you floor it once, the temp of the air didn't change, as it was 30 seconds later. I also doubt its first gear, as my car has first gear start. So, that just leaves enriched fuel mixture. Anyone know how it works? And is it possible to turn it on? Im not looking for a supercharger or anything, just a little tweak to performance. I would equate it to overclocking your computer, It brought a smile to my face when I got my 366 celes to run at 571 mhz instead of 550...
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  #9  
Old 01-29-2002, 08:03 AM
LarryBible
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It is a combination of the added richness AND the cold dense air that the engine is receiving. A gas engine is an air/fuel pump, as the amount of air AND fuel the engine pumps in increases, the power increases proportionally.

You should not drive ANY engine hard when it's cold, you are drastically decreasing engine life. If the engine is cold enough to run like this, the oil is nowhere near warm enough to circulate and do it's job properly at high RPM. I don't care what kind of super oil you use.

In race engines it is not uncommon for an engine to be lost after cooling down during a red flag period and then run hard immediately after restart. Cold oil is incapable of doing it's job properly.

Good luck,
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  #10  
Old 01-29-2002, 09:08 AM
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Ok, I agree with your point about revving a cold engine, and that was the only time I did/am going to do it. But, is it possible to get added fuel richness on demand? Not just for the first 30 seconds of car operation perday?
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  #11  
Old 01-29-2002, 11:03 AM
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are you guys sure you're fully awake during those mornings?
or are you still dreaming of an 8 cylinder car? he he
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  #12  
Old 01-29-2002, 11:22 AM
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I think you might be missing the point. Larry and I are talking about WHY the enriched mixture would work at all, and that is due to the cold dense morning air. Just adding additional fuel through a richer mixture won't add power. You need more O2 molecules to go with the additional fuel.

It is a combination of the two things. If you rich the mix most of the time, it won't make much difference, maybe even make drivability worse. You'll wear plugs out faster, and probably not see any performance increase.

If you activate the cold start enrichment when the intake air is warm and less dense, you'll not make any improvement at all. BTW, your FI system is pretty well designed to optimize the mixture. If you truly monkey with it, you MIGHT be able to get a lttle boost on some occasions, and wreck it for the rest of the time you're driving.
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  #13  
Old 01-29-2002, 02:19 PM
LarryBible
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You possibly could gain a slight power increase by cheating the system to make it rich. The downside is all those that blackmercedes pointed out PLUS the worst one. That is that the rich condition will dillute the oil on the cylinder walls and lead to premature engine wear.

Have a great day,
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  #14  
Old 01-29-2002, 02:41 PM
Indy300CE
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This doesn't have anything to do with something as simple as 1st gear acceleration when cold and 2nd gear after the first shift through, would it?
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  #15  
Old 01-29-2002, 02:57 PM
moedip
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Crazy thought - could it be the viscosity of the oil when cold maybe giving slightly higher compression - then as the engine heats -the oil thins and compression goes to normal?? Just wondering
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