Hello fellow Mercedes enthusiastss. Quick background of myself I bought my first 1998 slk 230 in July. I love it and joined this site which has been extremely helpful
on pointing me in the right direction and avoiding those expensive dealerships. The following is my situation and my thoughts. A lot of the info I have taken from other
posts on the site and compiled it together. If some of you could confirm my thoughts or point me in a different direction it would be greatly appreciated. Wanted a little
feedback before I purchase the part and make the fix.
Symptoms and Error Codes
First my check engine light came on but car was running yet. I didn't notice any performance issues however that could also be from being a new owner. However one cold morning
the car would not start. It just kept turning over but not taking off. Like it was being denied fuel.
I pulled the codes P0170 Fuel Trim Malfunction, (Bank 1) which many posts point to the dreaded MAF (Mass Airflow Sensor) sensor failure.
Also code PO410 Secondary Air Injection System came up which I did not find any posts for.
What I have researched is that problems with Mass Air Flow sensors are common.
Bad or contaminated Mass Air Flow sensor can possibly cause a wide range of various vehicle drivability problems such as
- stalling, especially when the engine is cold,
- poor acceleration, etc
Function of MAF Sensor
A MAF uses a measured temperature difference between two heated wires in the intake system to judge the speed of the incoming air.
(more airflow cools the wires more and signals the need for for fuel). In the Case of a bad MAF (which I think I have) it signals that less air is flowing past the wires
(perhaps they cool more slowly when they develop a film on them) then the volume of fuel injected for each combustion event will be less. So in general it is used to control
the rate of fuel flow at the injectors needed to burn at the correct fuel-air ratio with the mass of the air being passed through the MAF.
With error codes P0170 Fuel Trim (Bank 1) and PO410 Secondary Air Injection System coupled with it being a cold morning I believe the MAF (Mass Airflow Sensor) sensor failure
is at fault. P0170 Fuel Trim meaning that the MAF is telling the ECU to enrichen the engine and it's reached it's limit.
What happens at that point is other stuff starts acting weird too. I think that is why the PO410 Secodnary Air Injection System code was thrown.
Solutions - Clean or Replace
Sometimes cleaning the MAF may provide a temporary solution to the issue. However this is probably a better solution when noticing performance issues and a temporary solution for that.
If the MAF gets dirty a Can of CRC Mass Airflow sensor cleaner may do the trick.
- Remove the MAF, removed the sensor insert from the MAF (requires security torx) and spray the entire thing and the gold colored wire near the end until it is shiny new.
Recommended cleaners from posts to this site.
- CRC QD Electronic Cleaner
- CRC MAF cleaner
In my case since the car will not start I believe the best route is to replace the MAF. As we all know this is not a cheap part and it is highly recommended going with Bosch.
People have had issues when trying to go the cheap route here with another brand. What I found is in my case with 1998 SLK 203 I have the following engine.
- SLK230 Chassis 170.447 Liters 2.3 Cyl L4 Fuel Gas Eng. Num 111.973
All SLK320's and '98 and '99 SLK 230's have the Bosch removable insert. BOSCH Air Mass Meter B3130-70629 F 00C 2G2 025
The following site Auto Parts at AutohausAZ - OEM Auto Parts - Discount Replacement Parts, Resources and Car Care Tips
is recommended on posts from this site and has a very good price on a Bosch MAF for $178 which it returned as a part for my make and model of car.
Your Parts Search Returned 1 Part(s)
I have not found any detailed docs on how to replace. So I would imagine it is not to bad of job. The MAF is always located in the intake stream between the manifold and the air filter.
What I have seen is to disconnect the battery while installing. Make sure it remains disconnected for 30 minutes. This will reset all of the computers.
It is also important to ensure there is no air leak, the seal has to be perfect, or else you will have problem. If someone could point me to some more detailed instructions or give me some
pointers that would be great.
Thanks for reading through my post and giving any feedback on my situation even if it is just to say I'm on the right track. I'm hoping when I'm done solving this problem it will be
a good post for future people to look at on how to solve this issue. I will also record my steps on how I resolved the issue when I get to that point.
In conclusion as I become more knowledgeable about my car I can help others like those of you who replied to my post.