SL/R129: idle surge - P1580
Thread Starter
Junior Member
Joined: Aug 2017
Posts: 30
Likes: 1
From: Los Angeles
1997 SL500 AMG
Idle surge - P1580 - Throttle Position Sensor Problem
1. Crack in plastic sleeve where cable attaches to position sensor
2. Half of broken plastic sleeve pulls back with cable when the latter draws back.
3. Cable cover hangs up on plastic sleeve instead if going into mechanism
I am experiencng idle surges upon startup up to 1200 rpms and down and up etc. without touching the accelerator. Fault code P1580. Do I need to clean the throttle actuator?
I just replaced the MAF sensor’s electrical connector yesterday. Idle has been rough lately, but not like this. I have fuel smell at start up. Recently had EVAP and SAI codes which were resolved by replacing vacuum lines.
I have code P1747 as well but that was set a few weeks ago.
As usual, any advice will be much appreciated.
An update to my post: upon inspecting the throttle position sensor, I found the plastic sleeve at the end of the cable cover was broken (see photos). When the cable pulls back half of the sleeve goes with it, while the other half remains inserted in the mechanism. When the cable is released, the covering hangs up on the metal bracket, instead of fitting into it. I do not know if this resolves my idle surge because I am hesitant to run the engine given the violent surges, let alone manipulate the throttle at the same time, but it apoears to be a throttle related failure. I also found a bad crankcase ventilation vacuum line—a Üro Parts hose that split on a Y connector 2 days after it was installed. Will report back. Trying to determine if I have a diagnostic port in the engine compartment.
Thanks in advance.
Last edited by wahnsinn; Apr 28, 2018 at 04:40 PM. Reason: update and photo upload.
Thread Starter
Junior Member
Joined: Aug 2017
Posts: 30
Likes: 1
From: Los Angeles
1997 SL500 AMG
For those who may not know, engine or idle surge, is apparently a common occurrence in all vehicles. Here is a list of possible causes and this is the link to non-MB specific solutions:
• Transmission not locking up (or slipping)
• Vacuum leak
• EGR valve stuck open
• Dirty/sticking IAC (idle air control valve) (P0505)
• Engine temperature sensor
• Knock sensor
• Clogged EGR ports
• Variable valve timing solenoid clogged/sticking
• Air in cooling system
• MAF connector loose/intermittent connection/faulty MAF
• Fuel system pressure issue
• Clogged fuel filter
• Plugged/restricted exhaust
• Crankshaft position sensor (P0336)
• Power steering pressure sensor circuit
• A/C compressor cycling on/off due to low refrigerant
• Faulty TPS
• Clogged/restricted catalytic converter
• Ignition system
• PCV
• High pressure oil system (diesel)
I recently replaced the MAF sensor electrical connector, broke an A/C line which caused the freon to escape, probably have vacuum leaks and have had transmission issues, so I am going to start there.
• Transmission not locking up (or slipping)
• Vacuum leak
• EGR valve stuck open
• Dirty/sticking IAC (idle air control valve) (P0505)
• Engine temperature sensor
• Knock sensor
• Clogged EGR ports
• Variable valve timing solenoid clogged/sticking
• Air in cooling system
• MAF connector loose/intermittent connection/faulty MAF
• Fuel system pressure issue
• Clogged fuel filter
• Plugged/restricted exhaust
• Crankshaft position sensor (P0336)
• Power steering pressure sensor circuit
• A/C compressor cycling on/off due to low refrigerant
• Faulty TPS
• Clogged/restricted catalytic converter
• Ignition system
• PCV
• High pressure oil system (diesel)
I recently replaced the MAF sensor electrical connector, broke an A/C line which caused the freon to escape, probably have vacuum leaks and have had transmission issues, so I am going to start there.
Thread Starter
Junior Member
Joined: Aug 2017
Posts: 30
Likes: 1
From: Los Angeles
1997 SL500 AMG
Resolved.
I replaced several vacuum lines and the air temp sensor and disconnected/reconnected the battery and the idle returned to normal. The P1580 code was cleared. No CEL after 50 miles driving since then.
