Cold start good, hot start bad
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Joined: Dec 2006
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From: South River NC
Cold start good, hot start bad
My 86, 300e starts great when cold, just reach in and turn the key. When it's warmed up or hot, I have to grind it few (3-4) seconds before it'll start. I know what the manual says, but has anyone done anything to improve hot starts. I did unplug the sensor on top of the head because the aux. fan continued to run. It was however, slow to start when hot even before I unplugged it.
Any suggestions?
Thanks, Perri
Any suggestions?
Thanks, Perri
Thread Starter
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Joined: Dec 2006
Posts: 60
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From: South River NC
ABS light is not on. Just curious, but what would that have to do with starting? I can't make the connection.
Also, I keep hearing a lot about the Over Voltage Relay, how does that relate to starting?
I suspect it's not getting quite enough gas when attempting a hot start. Pretty sure the cold start valve is making for good cold starts.
Thanks for the reply, Perri
Also, I keep hearing a lot about the Over Voltage Relay, how does that relate to starting?
I suspect it's not getting quite enough gas when attempting a hot start. Pretty sure the cold start valve is making for good cold starts.
Thanks for the reply, Perri
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From: Boston
is a German Tank
ABS light is not on. Just curious, but what would that have to do with starting? I can't make the connection.
Also, I keep hearing a lot about the Over Voltage Relay, how does that relate to starting?
I suspect it's not getting quite enough gas when attempting a hot start. Pretty sure the cold start valve is making for good cold starts.
Thanks for the reply, Perri
Also, I keep hearing a lot about the Over Voltage Relay, how does that relate to starting?
I suspect it's not getting quite enough gas when attempting a hot start. Pretty sure the cold start valve is making for good cold starts.
Thanks for the reply, Perri
The OVP is the Over Voltage Protection Relay. It controls the ABS (even if there is NOTHING WRONG with your ABS) and CISE Fuel Injection Systems, which could be the reason as to why your car is acting up like this.
do a search amigo.
Last edited by shadowgriffen; Dec 20, 2006 at 01:42 PM.
Thread Starter
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Joined: Dec 2006
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From: South River NC
Yea, I always do the searches first, but found nothing really like my symptoms. And let me add, if people would title their posts properly, we could avoid a lot of redundant questions, as this would narrow the searches to the specific topic. Keeps you from having to wade through off topics to find your problem.
I haven't had any trouble with charging, the alt. looks like it was recently replaced.
I'll check the OVP for sure, but I'm leaning toward the accumulator. I've owned Audis and know how the Continuous Injection System works. It would freak-out my co-workers when I would pull the injector from the head while the engine was running, just to show them fuel spraying all the time.
I'll also clean the injectors by adding MEK to the fuel. It's a super trick that really cleans the injectors without having to remove them.
I'm confident it's in the fuel system though.
I haven't had any trouble with charging, the alt. looks like it was recently replaced.
I'll check the OVP for sure, but I'm leaning toward the accumulator. I've owned Audis and know how the Continuous Injection System works. It would freak-out my co-workers when I would pull the injector from the head while the engine was running, just to show them fuel spraying all the time.
I'll also clean the injectors by adding MEK to the fuel. It's a super trick that really cleans the injectors without having to remove them.
I'm confident it's in the fuel system though.
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From: Boston
is a German Tank
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From: Decatur, Georgia
1972 280SE 4.5, 1966 220Seb (under restoration), 1993 300TE (3-kids), 2003 Stella (commuter scooter)
Long start symptoms on these engines are usually caused by loss of fuel pressure. Most likely causes are injectors or fuel distributor. The firing of the cold start injector when the car is cold can sometimes "cover" for the internal fuel pressure loss and hide the problem when the car is cold.. Of course according to Mercedes a 3-4 second start time is perfectly normal, but if it really bugs you get someone to check for fuel system pressure loss when the car is hot. OF course you shouldn't bypass the first steps of checking for good spark and fuel pressure from pump.
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Thread Starter
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From: South River NC
Like Matt said, probably fuel related. It may be normal, but I just can't accept cranking 3-4 sec. to fire the engine. Now, if I could activate the cold start valve when hot I may have something!
Alternator is fine, so is wires, plugs, cap, rotor. I still havn't checked the OVP, but I will and report my findings.
Thanks everyone!
Alternator is fine, so is wires, plugs, cap, rotor. I still havn't checked the OVP, but I will and report my findings.
Thanks everyone!
ON SUSPENSION
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From: Atlanta, GA
Quite a few:)
If giving the car a foot full of gas pedal improves things considerably your injectors are leaking down.
If not, it's most likely your fuel pressure accumulator. Most CISE Hot start issues are the accumulator in my experience.
Jonathan
If not, it's most likely your fuel pressure accumulator. Most CISE Hot start issues are the accumulator in my experience.
Jonathan
Thread Starter
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From: South River NC
Well, I checked the fuse on the OVP relay and it was fine. I guess it's probably the accumulator or injectors leaking down as someone has suggested. I can't hardly believe that these cars had to be cranked 3-4 seconds when hot, when they were new. It's not terribly bad, I suppose one could get used to it, but I don't have to like it! I won't accept it unless forced to.
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From: Boston
is a German Tank
Well, I checked the fuse on the OVP relay and it was fine. I guess it's probably the accumulator or injectors leaking down as someone has suggested. I can't hardly believe that these cars had to be cranked 3-4 seconds when hot, when they were new. It's not terribly bad, I suppose one could get used to it, but I don't have to like it! I won't accept it unless forced to.
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From: Houston, Texas
Dora the Explorer
There is a book that I think should be required reading for all you m103 types:
Here's the link to get it from Amazon.com:
http://www.amazon.com/Modify-Bosch-I...075038-4123878
If you read the section on CIS-E you'll be a freaking expert. When I had my VW Rabbit, I lived in that book.
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From: Boston
is a German Tank
I couldn't agree more.
There is a book that I think should be required reading for all you m103 types:
Here's the link to get it from Amazon.com:
http://www.amazon.com/Modify-Bosch-I...075038-4123878
If you read the section on CIS-E you'll be a freaking expert. When I had my VW Rabbit, I lived in that book.
There is a book that I think should be required reading for all you m103 types:
Here's the link to get it from Amazon.com:
http://www.amazon.com/Modify-Bosch-I...075038-4123878
If you read the section on CIS-E you'll be a freaking expert. When I had my VW Rabbit, I lived in that book.
Thread Starter
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Joined: Dec 2006
Posts: 60
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From: South River NC
Well jhodgkdc got it! A foot full of gas during starting makes it "bust right off". I did add the MEK to the gas as well. That always makes those injectors act as new. I'm happy with the way it is.
When cold, just turn the key, and it starts immediately.
When hot, push the gas to the floor while cranking. It'll start in less than a second.
Thanks guys!
When cold, just turn the key, and it starts immediately.
When hot, push the gas to the floor while cranking. It'll start in less than a second.
Thanks guys!
