throttle issues
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2002 c240
throttle issues
was wondering if anyone has wiring diagrams for the accelorator pedal positon, and throttle position sensor. i have a 2002 c240 after about a 1/4 throtle it falls on its face. no codes set. i would like to measure resistance on both sensors i belive there is a large dead spot on one of them causeing the issue just want to verify which is failing i dont want to just throw parts at it
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Joined: Jun 2011
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From: Cape town
not a merc
First check fault memory. You won't figure out much the way you want to test it, pedal has output is from hall sensors and both outputs needs to be in tolerance if each other and the outputs work in reverse of each other,
Maf could be faulty. Best is to look at maf values while you accelerate
Maf could be faulty. Best is to look at maf values while you accelerate
Thread Starter
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2002 c240
sorry for delayed response finally got some time to to work on the car. i retrived code p0104 grabbed a new sensor from the parts store car ran well for about 20 minutes with new sensor then issue came right back when it warmed up. while it was running my short term fuel trims were pegged at 25 i checked for a vacuum leak and was unable to find one. the map pressure seemed a litttle out of spec. the second you open the throttle past 1500-2k it istantly dies falls on its face
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2002 c240
i changed the mass air flow sensor. same issue. i put the orignal back in and same issue. randomly it will run properly. the scanner i have at home isnt the best and the data reads slow so its tough to watch and track. swhen its running well all data looks normal. mass voltagw at idle is about .7. when you open the throttle the voltage jumps over 6volts and it stalls. im starting to think there is a circuit concern not a sensor
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MBWorld Fanatic!
Joined: May 2017
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C320
was wondering if anyone has wiring diagrams for the accelorator pedal positon, and throttle position sensor. i have a 2002 c240 after about a 1/4 throtle it falls on its face. no codes set. i would like to measure resistance on both sensors i belive there is a large dead spot on one of them causeing the issue just want to verify which is failing i dont want to just throw parts at it
Last edited by tjts1; Dec 18, 2017 at 02:34 AM.
Thread Starter
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2002 c240
thanks ill check those. the maf data i dont like but i dont think the chances of my maf and a replacement putting out the same data. at idle the fuel trims are right around zero the second you start adding throtle the trims spike.
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2002 c240
i mean at idle my short term fuel trims are between 0 and 1-1.5 as soon as you apply throttle they jump to 25 which is max fuel added. so its either running really lean like bad pump or clogged filter bad pressure regulator
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C320
https://imgur.com/UDJrcIQ
Another symptom was more fuel on the left side than the right side of the tank.
https://imgur.com/a/J9xCb
That's because the system uses the fuel return from the FPR to siphon gas from the left to the right. Low pressure = no excess fuel return = no siphoning from left to right.
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From: Cape town
not a merc
If you say it falls on its face at 2000rpm, it must be very lean, keep the fuel gauge connected when you rev it to see what happens to the pressure. Does actual value of coolant temp look normal? Airmass should be around 12 -13 kg/h at idle engine at operating temp and AC off
