Vehicle: 1990 Mercedes 300CE, Black/Black - H&R, Bilstein, etc.
Location: Los Angeles, CA
Posts: 78
Hard start (esp. when Cold), low idle-- Idle Control Valve?
Okay, I've replaced the air filter, leaned the mixture a bit (trying to find the "sweet spot" without a sniffer is a lot like a dog chasing it's tail--I know...), replaced the breather hose, but now the car is very difficult to start (especially in the morning), and idles very rough until warm. Once warm, it idles a bit better (just a tick over 500 RPM), but still a bit rough. I suspect the Idle Control Valve, and am even contemplating the "plumbing valve" fix, but want to hear some opinions. The car seems to run fine otherwise (especially ont he freeway). In the morning, I turn the key (no gas pedal) and the car will fire right up, then die. I'll turn the key again, hold it for a bit, then it starts idling very low.... once a bit warm,it starts idling a little higher, then I can feed in a bit of throttle to take her past 1000 RPM, and get her truly warmed up.... This can't be good for the cams (with such low RPM and oil pressure). Any thoughts or ideas? I could take her into the local Merc indy, but I promised myself I would be "hands on" with this car... TIA!
You can inspect the idle control valve quite easily. Just disconnect it from the hose and see if it works freely. These are quite simple parts and rarely go bad. You can spray a little carb cleaner on it, but it is just a simple mechanism spring loaded.
__________________
1984 300D 225,000 miles (hit and totaled by bad driver)
1987 300E 209,000 miles (donated to worthy cause, still going)
1988 300E 205,000 miles (still a daily driver)
1998 E320 70,000 miles (Obsidian, 17' E500 rims)
1990 300CE 88,000 miles (Silver/ black int)
I had a similar problem after I had the gaskets done. The problem totally unrelated...it was the fuel filter. A seven dollar part and quite easy to replace.
__________________
_______________________________________
"It's not a matter of picking your nose; it's a question of where you put the booger"
Currently Own:
2000 E55 AMG (Black Widow)
Previously Owned:
1987 300E (Ministry of Sound)
1983 280SE (Big Papa)
1984 190D (Little Red Devil)
Vehicle: 1990 Mercedes 300CE, Black/Black - H&R, Bilstein, etc.
Location: Los Angeles, CA
Posts: 78
Quote:
Originally Posted by elchivo21
I had a similar problem after I had the gaskets done. The problem totally unrelated...it was the fuel filter. A seven dollar part and quite easy to replace.
The fuel filter... Hadn't considered that... Where is it located? I'm thinking about diving in today again... Am learning a few things quickly (like, the parts guy at Downtown LA motors doesn't really understand the difference between the M103 and the M104 and keeps giving me M103 parts: air filter, oil filter, air intake--all different!! LOL!).
Vehicle: 1990 Mercedes 300CE, Black/Black - H&R, Bilstein, etc.
Location: Los Angeles, CA
Posts: 78
Update
Quote:
Originally Posted by 247hoopsfan
You can inspect the idle control valve quite easily. Just disconnect it from the hose and see if it works freely. These are quite simple parts and rarely go bad. You can spray a little carb cleaner on it, but it is just a simple mechanism spring loaded.
Update: Well, finally had time to yank the Idle control air valve thing, check to make sure the little spring-loaded door worked freely, and sprayed carb cleaner into it, followed by a bit of WD40... Well, that didn't help. The car fired right up when I first tried, but that was probably due to the shot of WD40 (acts like a "starter" fluid). I suppose that my next step will be to replace the fuel filters. Pardon the question, but can someone point me in the right direction as to their location? I need a manual bad--anyone know where to source a good one?
The fuel filter rest right next to the fuel pump under the car in front of the rear passenger side wheel. Change it but I don't think its your problem. I would test the coolant sensor.
How are you adjusting the mixture? Are you using a multimeter or are you just trying to do this by "feel"?
Vehicle: 1990 Mercedes 300CE, Black/Black - H&R, Bilstein, etc.
Location: Los Angeles, CA
Posts: 78
Quote:
Originally Posted by Yal
The fuel filter rest right next to the fuel pump under the car in front of the rear passenger side wheel. Change it but I don't think its your problem. I would test the coolant sensor.
How are you adjusting the mixture? Are you using a multimeter or are you just trying to do this by "feel"?
Yal--hi, thanks for the response. I actually just bought a multi-meter and wil try to determince the fuel/air ratio mixture taht way. Do you know where I need to set the multimeter at? I read something about "%", but of course, multimeters allow for amp/ohm/v/mv settings and DC, AC, check, etc... Please advise.
Also, with respect to the coolant temp sensor, the gauge in the dash seems to work just fine--are they related, or am I looking at two different sensors?
Two different sensors. The one for the guage is a sender unit usually single pin. The coolant sensor (or temperature switch as it is sometimes called) is different and sits on top of the engine somewhere. Its usually black, maybe round, multi pin.
The % thing, you'll see that on a mutimeter that has a setting for duty cycle. You then use pin 3 on the x11 connector to figure out the mixture which should be at or near 50% duty cycle. http://www.landiss.com/mixture.htm has a good description of it, I hope it applies to the M104 also. If not you can read the voltage instead at the EHA using SteveB's description here...http://www.continentalimports.com/ser_ic20134.html
Okay, I've replaced the air filter, leaned the mixture a bit (trying to find the "sweet spot" without a sniffer is a lot like a dog chasing it's tail--I know...), replaced the breather hose, but now the car is very difficult to start (especially in the morning), and idles very rough until warm. Once warm, it idles a bit better (just a tick over 500 RPM), but still a bit rough. I suspect the Idle Control Valve, and am even contemplating the "plumbing valve" fix, but want to hear some opinions. The car seems to run fine otherwise (especially ont he freeway). In the morning, I turn the key (no gas pedal) and the car will fire right up, then die. I'll turn the key again, hold it for a bit, then it starts idling very low.... once a bit warm,it starts idling a little higher, then I can feed in a bit of throttle to take her past 1000 RPM, and get her truly warmed up.... This can't be good for the cams (with such low RPM and oil pressure). Any thoughts or ideas? I could take her into the local Merc indy, but I promised myself I would be "hands on" with this car... TIA!
You don't adjust the mixture on that car with a "sniffer". So lets play with adjustments without a clue, throw parts at it at will, anyone with a suggestion is a better choice to follow than a qualified mercedes guy. Any guess will do to continue on wasting money and probably doing damage to the engine, cats, and god knows what else.
The mixture adjustment should have been tamper poof for this reason. Take the car to a Mercedes mechanic and have it adjusted before you have to spend real money.
Sorry for the real advice, but other than swapping a couple parts you should not have played with the mixture. If the mixture is adjusted improperly it will cause hard starting, especially cold starts.
You can check the fuse in the overvoltage relay located behind the battery beside the engine control and abs control units.
Good luck, but still have the mixture corrected.
Rich
Linear Mode
