HELP: Bad adaptation values until engine restart along with bad idling at full stop
11-15-2021, 07:15 PM
#1
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Thread Starter
HELP: Bad adaptation values until engine restart along with bad idling at full stop
Hi to all
I've searched all the threads on the forum but I didn't find a solution to my -very weird- problem
I own a 2005 CL203 C180 with 148000kms. The M271 engine is modified with a 62mm pulley and tuned to ~200hp.
The engine was running superfine until the middle of the summer where a vacuum leak appeared along with the known symptoms. It was the $12 hose along with the PCV under the supercharger. They were diagnosed and both replaced by a Merc professional. He also checked the rest of the hoses for leaks and did a leak test. He also replaced the EGR hose because it was old and had some surface cracks. Everything was working fine after that.
A couple of weeks later and almost after 1500kms a really weird issue started making its appearance, becoming worse over time. The engine is idling very roughly (almost stalling) at full stops. It is fluctuating for a couple of seconds then it is almost stabilizing but you can still notice a slight fluctuation like it cannot find an AFR balance. This happens only during the first driving cycle of the day (starting the engine from cold). The STFT at the moment of this slight fluctuation is between +25% and +30%. When I turn the engine off and restart, everything is fine and totally stable like there is no problem at all. No check engine (MIL) light.
What I've done (replaced) during the previous 10000kms, before the issue appeared:
Camshaft Magnets (Pierburg)
Fuel Pressure Regulator (Bosch)
Spark Plugs (Bosch FR6MPP332)
Vacuum Pump (Pierburg)
Fuel Filter (Bosch)
Alternator (Valeo)
$12 Vacuum Hose and PCV (Mercedes original)
EGR Hose (Mercedes original)
What I've done (replaced) after the issue appeared:
Upstream Wideband O2 Sensor (NGK UAR9000EE001)
MAF Sensor (Continental - VDO)
Throttle Body (Bosch)
I always fill the tank with premium (V-Power) 98 or 100 octane petrol from a reputable Shell shop
I also add LiquiMoly Injector Cleaner every 2-3000kms
If anyone has faced something similar and found a solution, I would appreciated their assistance and feedback
Thanks
Costas
I've searched all the threads on the forum but I didn't find a solution to my -very weird- problem
I own a 2005 CL203 C180 with 148000kms. The M271 engine is modified with a 62mm pulley and tuned to ~200hp.
The engine was running superfine until the middle of the summer where a vacuum leak appeared along with the known symptoms. It was the $12 hose along with the PCV under the supercharger. They were diagnosed and both replaced by a Merc professional. He also checked the rest of the hoses for leaks and did a leak test. He also replaced the EGR hose because it was old and had some surface cracks. Everything was working fine after that.
A couple of weeks later and almost after 1500kms a really weird issue started making its appearance, becoming worse over time. The engine is idling very roughly (almost stalling) at full stops. It is fluctuating for a couple of seconds then it is almost stabilizing but you can still notice a slight fluctuation like it cannot find an AFR balance. This happens only during the first driving cycle of the day (starting the engine from cold). The STFT at the moment of this slight fluctuation is between +25% and +30%. When I turn the engine off and restart, everything is fine and totally stable like there is no problem at all. No check engine (MIL) light.
What I've done (replaced) during the previous 10000kms, before the issue appeared:
Camshaft Magnets (Pierburg)
Fuel Pressure Regulator (Bosch)
Spark Plugs (Bosch FR6MPP332)
Vacuum Pump (Pierburg)
Fuel Filter (Bosch)
Alternator (Valeo)
$12 Vacuum Hose and PCV (Mercedes original)
EGR Hose (Mercedes original)
What I've done (replaced) after the issue appeared:
Upstream Wideband O2 Sensor (NGK UAR9000EE001)
MAF Sensor (Continental - VDO)
Throttle Body (Bosch)
I always fill the tank with premium (V-Power) 98 or 100 octane petrol from a reputable Shell shop
I also add LiquiMoly Injector Cleaner every 2-3000kms
If anyone has faced something similar and found a solution, I would appreciated their assistance and feedback
Thanks
Costas
Last edited by kalantz; 04-18-2022 at 04:01 AM.
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biker349 (11-16-2021)
11-17-2021, 02:32 PM
#2
Newbie
Thread Starter
Update:
Unplugged MAP Sensor. Idling superfine. Better than ever. STFT close to 0
Is it a bad MAP sensor or could be something else that is triggered by the MAP Sensor?
Unplugged MAP Sensor. Idling superfine. Better than ever. STFT close to 0
Is it a bad MAP sensor or could be something else that is triggered by the MAP Sensor?
Last edited by kalantz; 11-17-2021 at 05:48 PM.
The following users liked this post:
biker349 (11-17-2021)
The following users liked this post:
biker349 (11-20-2021)
02-21-2022, 04:42 AM
#5
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MY'14 W212 M276 3.5NA @60kMi
You have done a good job at checking almost everything. Hard to find missings bits...
1- Are you sure NGK Lambda are the original OEM... not Bosch?
2- The high STFT screams vacuum leak, right?
1- Are you sure NGK Lambda are the original OEM... not Bosch?
2- The high STFT screams vacuum leak, right?
02-21-2022, 04:57 AM
#6
Newbie
Thread Starter
Hi there
As for the Lambda, my car had indeed an NGK OEM, but I'm sure the problem is neither the Lambda nor a vacuum leak. I've checked every single hose multiple times. How can you explain that after restarting the engine everything works fine?
As for the Lambda, my car had indeed an NGK OEM, but I'm sure the problem is neither the Lambda nor a vacuum leak. I've checked every single hose multiple times. How can you explain that after restarting the engine everything works fine?
Last edited by kalantz; 02-21-2022 at 05:12 AM.
02-21-2022, 05:13 AM
#7
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MY'14 W212 M276 3.5NA @60kMi
> Have you done a compression test to evidence leaky valves?
> You say you've replaced the PCV element, right? (not just the hose).
> Fuel tank EVAP purge solenoid line can leak vacuum...
> You say you've replaced the PCV element, right? (not just the hose).
> Fuel tank EVAP purge solenoid line can leak vacuum...
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02-21-2022, 05:47 AM
#8
Newbie
Thread Starter
Thanks for your immediate reply.
I've only done those things I have described in the first post (yep, PCV has been replaced).
I was thinking to firstly check all parts that are related to car's electronics (solenoids, sensors, etc commanded by or giving feedback to the ECU) before going to strictly mechanical tests. EVAP solenoid is the next thing I was thinking to check. I'm sure it is something that after the engine restart gets reset or is ignored by the ECU; then the engine works as a Swiss watch. What do you think?
I've only done those things I have described in the first post (yep, PCV has been replaced).
I was thinking to firstly check all parts that are related to car's electronics (solenoids, sensors, etc commanded by or giving feedback to the ECU) before going to strictly mechanical tests. EVAP solenoid is the next thing I was thinking to check. I'm sure it is something that after the engine restart gets reset or is ignored by the ECU; then the engine works as a Swiss watch. What do you think?
02-21-2022, 11:18 AM
#9
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MY'14 W212 M276 3.5NA @60kMi
99% good...
Thanks for your immediate reply.
I've only done those things I have described in the first post (yep, PCV has been replaced).
I was thinking to firstly check all parts that are related to car's electronics (solenoids, sensors, etc commanded by or giving feedback to the ECU) before going to strictly mechanical tests.
EVAP solenoid is the next thing I was thinking to check. I'm sure it is something that after the engine restart gets reset or is ignored by the ECU; then the engine works as a Swiss watch.
What do you think?
I've only done those things I have described in the first post (yep, PCV has been replaced).
I was thinking to firstly check all parts that are related to car's electronics (solenoids, sensors, etc commanded by or giving feedback to the ECU) before going to strictly mechanical tests.
EVAP solenoid is the next thing I was thinking to check. I'm sure it is something that after the engine restart gets reset or is ignored by the ECU; then the engine works as a Swiss watch.
What do you think?
Recap: M271-L4 Engine runs perfectly except everytime after start when cold during warming up.
> How is your thermostat? Make sure it stays shut until temperature gets in range to open radiator circuit.
High STFT... FUEL Delivery?:
you've replaced the Bosch regulator already, what about the pump itself?
VVT variable timing :
You have replaced "magnets" but don't say anything about the camshaft timings.
These VVT mechanical gear devices are famous for having issue with worn-out lock pins that allow uncontrolled changes without oil pressure ... your cold start condition.
Robert BOSCH GMBH is the German version of Swiss watchmaker on steroids. They develop the leading automotive designs for the world.
Last edited by CaliBenzDriver; 02-21-2022 at 11:33 AM.
