Engine does not idle
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Engine does not idle
I have a 300SE 2.8l (European Model) being used in India, which has run only 25000 miles and has been immaculately maintained. For the past year I am struggling to fix a simple problem. The engine does not idle, it hunts and stalls. I have carried out extensive and expensive checks and repairs and replaced parts as suggested by two repair shops. This includes possible leakage from the inlet manifold, valve grinding,renewing the sensor, and electrical components of the fuel management system, replacing engine and underdash wiring connected to the EMC, etc.... Yesterday Iwas told that everything seems to be OK as per the Diagnostic readout but, there could be a vacuum leakage which will have to be traced... Any help and suggestions would be greatly appreciated. Thanks in advance. Dipilundefined
Member
Joined: Feb 2004
Posts: 207
Likes: 2
From: Houston, TX
MY2004 E320
Egr/maf????????
Hi,
Suspecting Indian climate and dust levels, I would suggest the MAF and he EGR sensors checked.
Also here is a wild one. Disconnect your battery for 20 minutes. It will loose all data. A friend's S500 had corrupted Data in his computer that was causing unexplainable errors.
Just guessing with your limited explanation, have you had the idle valve checked? Try removing the air filter and start the car to see if airflow restrictions are causing the problem. The hole that sucks air in should have powerful suction.
Just my 2c worth.
Moby Akhtar
1999 S500 Black/Gray
Stock
Suspecting Indian climate and dust levels, I would suggest the MAF and he EGR sensors checked.
Also here is a wild one. Disconnect your battery for 20 minutes. It will loose all data. A friend's S500 had corrupted Data in his computer that was causing unexplainable errors.
Just guessing with your limited explanation, have you had the idle valve checked? Try removing the air filter and start the car to see if airflow restrictions are causing the problem. The hole that sucks air in should have powerful suction.
Just my 2c worth.
Moby Akhtar
1999 S500 Black/Gray
Stock
Thread Starter
Newbie
Joined: Jan 2005
Posts: 4
Likes: 0
Hi Mobin, Many thanks for your response. I have carried out the checks suggested by you but no luck! details of the jobs carried out are as follows. If you could add to this I will appreciate, Best wishes Dipil
Complaint :- 1. Engine Hunting (Idle RPM fluctuates violently)
2. Stalls when accelerator released.
Jobs carried out :-
1. Wiring Harness MAF SENSOR (MASS AIR FLOW):- Wires frayed, hence new wiring harness fitted.
2. HOT FILM - MAF SENSOR :- H.H.T. (HAND HELD TESTER) showed MAF sensor defective - Same replaced.
3. CONTROL UNIT - All wires and the connector checked for loose connection - found all ok.
4. CYLINDER HEAD - Valve grinding job done with new valves and gaskets.
Note:- Inlet manifold rubber rings were leaking - Same was replaced.
5. REGENERATION VALVE - Valve & pipe tested - found ok.
6. ELECTRONIC ACCELERATOR ACTUATOR - wires of actuator frayed - Hence same replaced.
7. AIR PUMP - Valve and hoses replaced.
8. SPARK PLUGS - Replaced with correct plugs.
9. INJECTORS - Serviced (All 6)
This car does not have O2 sensor and there is no provision for fitting it in exhaust pipe.
The CO adjustment potentiometer was disconnected - Same has been connected to Pin No. 23 of control unit.
At present the H.H.T. is not showing any defect but the engine is still hunting.
Complaint :- 1. Engine Hunting (Idle RPM fluctuates violently)
2. Stalls when accelerator released.
Jobs carried out :-
1. Wiring Harness MAF SENSOR (MASS AIR FLOW):- Wires frayed, hence new wiring harness fitted.
2. HOT FILM - MAF SENSOR :- H.H.T. (HAND HELD TESTER) showed MAF sensor defective - Same replaced.
3. CONTROL UNIT - All wires and the connector checked for loose connection - found all ok.
4. CYLINDER HEAD - Valve grinding job done with new valves and gaskets.
Note:- Inlet manifold rubber rings were leaking - Same was replaced.
5. REGENERATION VALVE - Valve & pipe tested - found ok.
6. ELECTRONIC ACCELERATOR ACTUATOR - wires of actuator frayed - Hence same replaced.
7. AIR PUMP - Valve and hoses replaced.
8. SPARK PLUGS - Replaced with correct plugs.
9. INJECTORS - Serviced (All 6)
This car does not have O2 sensor and there is no provision for fitting it in exhaust pipe.
The CO adjustment potentiometer was disconnected - Same has been connected to Pin No. 23 of control unit.
At present the H.H.T. is not showing any defect but the engine is still hunting.
Originally Posted by mobinakhtar
Hi,
Suspecting Indian climate and dust levels, I would suggest the MAF and he EGR sensors checked.
Also here is a wild one. Disconnect your battery for 20 minutes. It will loose all data. A friend's S500 had corrupted Data in his computer that was causing unexplainable errors.
Just guessing with your limited explanation, have you had the idle valve checked? Try removing the air filter and start the car to see if airflow restrictions are causing the problem. The hole that sucks air in should have powerful suction.
Just my 2c worth.
Moby Akhtar
1999 S500 Black/Gray
Stock
Suspecting Indian climate and dust levels, I would suggest the MAF and he EGR sensors checked.
Also here is a wild one. Disconnect your battery for 20 minutes. It will loose all data. A friend's S500 had corrupted Data in his computer that was causing unexplainable errors.
Just guessing with your limited explanation, have you had the idle valve checked? Try removing the air filter and start the car to see if airflow restrictions are causing the problem. The hole that sucks air in should have powerful suction.
Just my 2c worth.
Moby Akhtar
1999 S500 Black/Gray
Stock
Member
Joined: Feb 2004
Posts: 207
Likes: 2
From: Houston, TX
MY2004 E320
Hmmmmm! The O2 sensor is in manifold, not in exhaust like other vehicles. From your description, it feels like an electrical issue to me. I do not know how you would do it in India, but in the US, I would locate another car or a junkyard with same ECU (Computer) and try swapping them to see if that resolves the issue.
The frayed wires on a car with so little miles and such well maintainer owner directs me to electrical gremlins.
Is there a way to have your computer box checked? It should be located physically on left rear corner of the hood if you are facing the car. The black box containing the computer also has the transmission TCU). On older cars, however the same boxes were located under the pass side footwell (yes footwell). Lift up the carpet (originating behind the glovebox) and you will see a cardboard hatch. Lift the hatch, and you will see the stereo amp, ECU, and TCU)
try to get to the box, and wiggle the harnesses to see if that makes any surges in idle. If it does, maybe you need a new box. They are easy to replace, but expensive to replace.
The frayed wires on a car with so little miles and such well maintainer owner directs me to electrical gremlins.
Is there a way to have your computer box checked? It should be located physically on left rear corner of the hood if you are facing the car. The black box containing the computer also has the transmission TCU). On older cars, however the same boxes were located under the pass side footwell (yes footwell). Lift up the carpet (originating behind the glovebox) and you will see a cardboard hatch. Lift the hatch, and you will see the stereo amp, ECU, and TCU)
try to get to the box, and wiggle the harnesses to see if that makes any surges in idle. If it does, maybe you need a new box. They are easy to replace, but expensive to replace.
