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1998 ML320 (W163)
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Discussion Starter #1
So, I replaced my intake manifold on Sunday and when disconnecting the Engine Coolant Temperature Sensor, it broke at the connector, the pins were still intact so I went ahead with the replacement and just tried to slide the connector back over the pins to start it (I have purchased a new sensor and will replace it). However I cannot get it to start, it doesn't even try to turn over, no click, no nothing. With the sensor not "connected" the Secondary Air Pump will turn on when the key is turned to start, but that's about all. Will this sensor stop the engine from even trying to crank/start or should I start looking elsewhere for the problem? I don't know if this is normal or not but it only lets me turn the key to the start position once, and I do have two keys and have tried both and they both do the same thing.
 

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2003 ml500, 2004 ml350
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Let’s take a step back why did you decided to replace the manifold? Usually not much goes wrong with one to start, servere over heating could cause one to warp but beyond that.

If the crack is just the lock tab and the plug is still connected and making contact all should be good. I would think the sensor would be a measurement that is needed for part of start fuel air mixture. But not sure Witek or some others may have that answer.

Did you disconnect and reconnect the battery with the key in the ignition?
 

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1998 ML320 (W163)
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100 Posts
Discussion Starter #3
I bought a used intake from eBay because it had good, properly spraying, fuel injectors in it and I was hoping that changing those would help to fix the major lean condition I was experiencing (~35% LTFT on both banks) which was causing misfires and massive losses of power, so I just changed the entire intake since I had one I knew had no issues. The crack is in the actual sensor itself and not the connector, when trying to disconnect the connector from the sensor it basically broke in half with the pins still in the sensor (I'm assuming old and brittle plastic). And no I did not disconnect or reconnect the battery with either key anywhere near the vehicle, I've heard the stories. I've had key issues before, entirely my fault and me not paying enough attention to put the transponder back in the key itself when changing the case, but even then it would crank, start for a second, then immediately die so I don't suspect a key issue.
 

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Dallas, Texas
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Coolant temp sensor will not keep engine from cranking. Examine your work something got broken or pinched in the process.
 

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1998 ML320 (W163)
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100 Posts
Discussion Starter #5
I've looked at it multiple times already and didn't see anything out of the ordinary, I will check again when I get home tonight though. Any reason the Secondary Air Pump would be the only thing coming on when trying to start?
 

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1998 ML320 (W163)
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100 Posts
Discussion Starter #6
I did notice, the ABS and ESP lights hang around for about a second longer than usual and the warning triangle light goes out earlier than usual when trying to start. Maybe I'm just over-examining and it's normal but I'm not sure. I had no starting problems before though.
 

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2003 ml500, 2004 ml350
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573 Posts
Take a look at cable connections, fuses. and relays if no crank your problem seems to be on the electrical side of things.

Since you did not disconnect the battery something could of cause a fuse to blow.
 

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1998 ML320 (W163)
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100 Posts
Discussion Starter #8
Take a look at cable connections, fuses. and relays if no crank your problem seems to be on the electrical side of things.

Since you did not disconnect the battery something could of cause a fuse to blow.
I did disconnect the battery before I touched any of the wires/sensors. The battery was disconnected for maybe 2 days if that may have anything to do with it. I will check the fuses and connections when I get home.
 

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And no I did not disconnect or reconnect the battery with either key anywhere near the vehicle,

Sorry took the above to mean you did not touch the battery at all. You just meant you did just not with the key around the ignition.

If disconnected that long did you try resynicing the keys?

And if you disconnected you lessened the chance of a blown fuse unless it happened during disconnecting -reconnecting.
 

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1998 ML320 (W163)
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Discussion Starter #10
Sorry took the above to mean you did not touch the battery at all. You just meant you did just not with the key around the ignition.

If disconnected that long did you try resynicing the keys?

And if you disconnected you lessened the chance of a blown fuse unless it happened during connecting reconnecting.
No I didn't, one of the keys I can't do that with because it doesn't have lock/unlock buttons (dealer said they don't make them anymore). I can try it with the other key but I've heard some people having bad experiences with doing that. Is it normal for it to only let me turn the key to the start position once without turn the key all the way back and trying again?
 

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2003 ml500, 2004 ml350
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Correct a valet key does not require syncing at all and should work regardless.

Does your lock unlock features work with the one remote. The only reason I bought up resynicing is heard some folks say they had a no start then resyniced and all was well.

Sorry not getting your key position question.
 

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1998 ML320 (W163)
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Discussion Starter #12
Lock and unlock is working.

Okay, when I try to start the car, it lets you turn the key into the start position, you let the key go to the "on" position (in my case still no start), but it locks me out from turning it straight from "on" to "start" again unless I turn the key to "off" and then try again. Is that normal behavior? I wouldn't really know because my car has always started so I've never had to try to restart it.
 

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Lock and unlock is working.

Okay, when I try to start the car, it lets you turn the key into the start position, you let the key go to the "on" position (in my case still no start), but it locks me out from turning it straight from "on" to "start" again unless I turn the key to "off" and then try again. Is that normal behavior? I wouldn't really know because my car has always started so I've never had to try to restart it.
This is normal mechanical "non repeat" feature of ignition switch. Should keep you from engaging starter with engine running.
 

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2003 ml500, 2004 ml350
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That sounds correct our 350 has an occasional no start, need to change fuel filter just have not gotten to it.

So when it happens after a no start it seem we need to go to off then to start again, but a start error flash’s at the odometer.
 

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1998 ML320 (W163)
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Discussion Starter #19
Hold it gents. I thought we are looking at "no starter action" condition.
We are, I'm willing to eliminate all variables that will prevent starting though. But yes, as of now I can't even get it to turn over, no click like a dead/dying battery or anything. The only thing that works when I try to start it is the secondary air pump.
 

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We are, I'm willing to eliminate all variables that will prevent starting though. But yes, as of now I can't even get it to turn over, no click like a dead/dying battery or anything. The only thing that works when I try to start it is the secondary air pump.
SAI pump should not run until engine starts and runs for few seconds.
 
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