Car difficult to start! Crank Position Sensor?
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Car difficult to start! Crank Position Sensor?
Hi Guys, In the last 2 days my car has been taking ages to start, the car turns over but does not fire, then suddenly it will start about 10 mins later! and then drives fine? I have read many posts and I am thinking to check my Crank position Sensor. I dont have any warning lights on the dash, and the when the car does start it seems to drive fine ,so I am doubtfull its the plugs or fuel pump?
Can you help tell me where the Crank Shaft Sensor is in the engine so I can check it and see if its dirty? Any photos ?
thanks
Can you help tell me where the Crank Shaft Sensor is in the engine so I can check it and see if its dirty? Any photos ?
thanks
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Joined: Aug 2007
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From: Miami, FL
06 CLS55 Renntech stage 5, 04 CL600 ( will miss ),02e55 , 11 R350
I doubt that it is the Crank Position sensor , I am not sure if it is different on the six cylinder engines but on the V8s..M113 it is on the back of the engine toward the fire wall on the driver side ..low half way down from the edge of the firewall ....not very easy to get to but with a small mirror you can see it in there.........have you checked the ignition coils?
Last edited by maxwerks; Dec 1, 2009 at 09:21 AM. Reason: info
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Maswerks
If the ignition coils were bad, would they not effect the normal drive of the car, because once started it drives fine! I will check though tonight, can you advise how I will know if they are good / bad?
If the ignition coils were bad, would they not effect the normal drive of the car, because once started it drives fine! I will check though tonight, can you advise how I will know if they are good / bad?
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Joined: May 2006
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From: San Antonio, Tx
2000 CLK430
If the car starts normally when it is cold and fails to start when the engine is hot then it is more than likely the CPS sensor. Also, it is the cheapest and easiest part to replace and the best place to start.
Greg
Greg
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Joined: Aug 2007
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From: Miami, FL
06 CLS55 Renntech stage 5, 04 CL600 ( will miss ),02e55 , 11 R350
Greg is right, the CPS is a cheap change and it is a good thing to do anyway, specially if you have never changed it . You never mentioned anything about cold starts vs hot starts... it sounded like you re having problems starting regardless.. and mainly you are right.. if the car is running normally after it starts .. the coils could be fine.. but if you have one or two bad coils and pending firing sequence that may also cause that , best and easy way, start the car , open the hood and listen.. is it idling smooth, any hickups .. if it is idling at the right RPM steady with no noise, chances are your coils are fine.
Thread Starter
MBWorld Fanatic!
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
For me it the opposite. The car starts fine when warm. If I leave the car for 15 mins it will start ok.. if I leave about 45mins it takes many turns to start. once it does start though, it drives without any problems, and does not stall or anything.
I have just removed the CPS and thought I had found the problem as it was really dirty, but despite a clean the car still did not start .
I have Denso irridium plugs for about 6 months now, so and I was thinking of putting the old on bosch ones back in to see if it starts better.
I have just removed the CPS and thought I had found the problem as it was really dirty, but despite a clean the car still did not start .
I have Denso irridium plugs for about 6 months now, so and I was thinking of putting the old on bosch ones back in to see if it starts better.
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Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Fixed ! car not starting
CPS - removed checked and cleaned, not likely as my car ran fine when warm but not when cold.
MAF - Checked and cleaned, again not likely as my car ran fine when it did.
Plugs - checked and replaced with spares, not likely coils as there was no probelm once started.
Fuel pump - Could not hear any buzzing sound !? ----> checked relay by openeing it up and cleaning contacts. Put it back and the pump buzzed away ! and now my car started perfect again !
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Joined: May 2006
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From: San Antonio, Tx
2000 CLK430
Damn good troubleshooting!!! Congrats and glad the car is back up and running well. Could you explain the relay that you are talking about. Are you talking about the fuel pump relay that is in the fuse box under the hood? I would like to know for future knowledge.
Greg
Greg
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
Damn good troubleshooting!!! Congrats and glad the car is back up and running well. Could you explain the relay that you are talking about. Are you talking about the fuel pump relay that is in the fuse box under the hood? I would like to know for future knowledge.
Greg
Greg
Thread Starter
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,232
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From: Glasgow, Scotland, UK
SL 350 R230 (3.7L with AMG Speedshift autobox)
MBWorld Fanatic!
Joined: Jul 2002
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From: Hotlanta
AMG
Moot point, I guess...I see your issue is resolved.
However, a weak battery (they normally last an average of 4 years or so) can cause erratic electronic issues, and lead to expensive parts replacement.
Glad you got your issue taken care of.
However, a weak battery (they normally last an average of 4 years or so) can cause erratic electronic issues, and lead to expensive parts replacement.
Glad you got your issue taken care of.
