briantman

Hello, I am new to the site but have always had good luck picking the brains of mechanics so here goes. I recently bought my 16 yr old daughter a 99 CLK 320 with 96k on it. It had been sitting for 3 years since the last guys couldn't pay the title loan he took out on it. I have replaced plugs, fuel filter, rebuilt alternator, replaced the battery, brakes, and other small things. The problem I am having is that even after running 5 tanks of gas through it there is still a hesitation on acceleration and it will not go into passing gear. I have also noticed that the transmission doesn't shift right when it is running like this. It is worse some times than others but never runs GREAT. If I drive it for a while shut it off and restart it within a couple of hours it loads up and sets a random misfire code. If it sits all night I have to wait 2 to 5 min before I can drive it. It won't take off. I have never owned a MB before always had GM or Toyota. Any Ideas what to do first? From all of the posts on here I have read alot of issues with MAP sensors but that is not a cheap guess. It does set a code for both upper O2 sensors lean mixture. Any ideas appreciated. Thank you, Brian T.

bobbyjo9

Welcome to the forum! MAP sensors are used on the FI cars, you'll be using a MAF. Your right in that they can cause all kinds of weird drivability issues though. Bout the 100k mark seems to be the common range for issues so you are right about there. They dont always set a code when failing also. Try unplugging the sensor and running the car. Does it run different or no change? If no different, I would look to replacing the MAF with a genuine bosch unit. You can try and clean, but for ~150 from AutohauAZ, I wouldnt waste the time.

Your trans issues sound related to the misfire your having. Trans will go into limp mode till you power cycle the key. In other words, A bad MAF could also be the sourse of your trany problems

dlbehrns

autohausaz has the mass air flow element/sensor also and it is not as expensive as the entire unit. all you need is a saftey torques drive socket to remove the element/sensor from the housing. you have to call and ask for it. I could never find it on the website.

briantman

Thank you both, I did remove it and clean it with CRB MAF cleaner. It did seem to help alot but did not completley fix it. I cleared the codes, there were the missfire codes, and codes P0170 and P0173. I ordered a new sensor which should be here tomorrow. I will update how it acts after replacing it. Any thoughts on those two codes or am I on the right track? Thanks again for the replies.

cindyclk

Just replace it! Autohauz is the quickest and cheapest source around. Get the whole unit and it will be in within 15 min...no special tools...just be sure to seat the rear of the air filter securely into the MAF housing before lowering the front.....all your symptoms and codes are symptomatic of a bad MAF....the most common issue with our beloved CLKs...also ..welcome!

betrezra

Agreed with Cindy. The maf runs the entire car it seems...... Poor shifting can result from bad mas. Gl

dlbehrns

Why get the whole unit? The housing for the sensor has nothing to do with the performance. Its just plastic so why pay to replace something that you don't need to replace? I'm just sayin'....

briantman

Thank you everyone for the reply's. I did order a new one through Napa and installed it today. WOW! I had no idea how well this car could run. It is amazing compared to what I though was normal. I'm now wondering if I really want to put my 16 year old daughter in this car (if she drives anything like her mother :-D). There was a noise in the back that I tarced to a broken rear sway bar link and once that is fixed I think she's ready to roll. Thank you again for all of your help and comments. This is why I trust the owners first! Brian T.

dlbehrns

You must be accustomed to some pretty slow cars. I have a 320 with some mods and they are not that fast however, I am glad you are enjoying yourself. That is the most important part.

rsparso

Did NAPA supply a Bosche unit ? Many people have reported very poor lifespans with non OEM maf's, so let us know how this works for you.

briantman

Yes the Napa Echlin was a reman Bosch unit. They offered an ATM line which is a Bosch unit also and is new. As far as the car being "fast" it is just more than I expected. Probably since I was used to how it was running before. I have let my daughter drive it some since we fixed it and she is happy so I am too. Thank you again everyone.