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Throttle Position Sensor

21K views 4 replies 3 participants last post by  smackdog 
#1 · (Edited)
Hi guys.

Im totally stumped!

Can anyone help me out with this one?

Ive searched high and low for a TPS and all ive found so far is below.

I think it would fit my car but dates start at 2002.

My car is a 2001 S500.

Anyone know the part number for the TPS.

ERA Throttle Position Sensor Mercedes S-CLASS S 500 10/1998 - 08/2005 | eBay

Thanks very much in advance.

The background to this is I recently posted about my MAF, twice.
The engine management light was on and I had to return a faulty part.

Part replaced and all is kind of ok apart from slowing down where the speedo shows between 5 and 15mph when the car is nearly stationary.

When I eventually replaced my last MAF about 2 months ago, I did an OBD scan and the scanner picked up 4 misfires.
But this soon disapears as its just the ECU picking up the new settings (I think).

Anyway, I had a new code, only once and it hasnt came back, and it was the TPS. Cant remember the actual code but when I looked up it was that.

About a month ago engine management light came on.
Misfires.
I was due a service so replaced all plugs too.

Still it is a bit rugged at idle sometimes.

A few times Ive pulled up at lights or a Give Way.
Stopped the car with my feet firmly on the brake pedal but still in drive, and the car jumps forward as if Ive lifted the clutch like a manual car (stick shift for you guys in the states :p )

Also pulling away, it feels like a faulty MAF but the symptoms Ive added below defo fits into my category.

Anyways, enough of my wiffle waffle, I think changing this will cure all my woes. :thumbsup:

So if you know part number, can you post please? :)

IVE ADDED TPS SYMPTOMS BELOW

Throttle Position Sensor - TechWiki

Common faults

The TPS is sensitive to heat, moisture and vibration leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following: -

Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".

High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.

Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.

Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted acordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.

Engine Misfire: A fault TPS can report values outside the deined acceptable range causing the ECU to incorrectly fuel the engine. This is noticable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.
 
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#2 ·
If you want to be 100% about the appropriate P/N, just pull the TPS out of your car and read it off the part.

It's only a 5 minute job, so in less time that it takes to do a write up here and wait around for a response ... you'l KNOW for sure !

I replaced the TPS on my Euro '01 320 S two years ago and it indeed fixed the hesitation problem .

But now it seems to be doing it again AND the engine light came on yesterday, so now I'm thinking MAF or TPS, again ?
 
#3 ·
Thanks MwC240Sport

After I posted that was what id did.
Pesky Torx Security screws.

The 2 holding in the TPS is between the sizes ive got! :crybaby2:

Ive ordered a new set to include T5 through to T10. £4 from ebay.

Would rather get the OEM Bosch part if it is Bosch rather than the ebay version.

Thanks again. :)
 
#5 ·
Hi guys.

Heres the update.

Could get the correct security torx.
Ive sizes 8 upto 14 and 10 was too big and 9 too small.
I ended up buying a replacement accelerator pedal from ebay with the still TPS attached.

Issue is still the same.

The other night i pressed the pedal to the floor to hear the kick, and the pedal stopped working. With the following codes.

OBD codes
p0221
p0100
p0303 and another 3 cylinder misfires.

Needed to just pull over to the hard shoulder.
I turned engine off and back on and the pedal was working again.

Cant get rid of the p0100 code though.

This is a replacement Bosch MAF that was sent to replace my other faulty MAF that was less than 6 months old.

Seems to me when I use the kickdown, ie when you hear the click, it plays havoc with my MAF.

I do love the kickdown and the power but would to get this fixed but I dont think anything can be done.

My car still drives ok, still a bit hesitant sometimes though. :surrender:

Any thoughts? :thumbsup:

Thanks in advance.
 
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