RAFFIE55

Hello; I am triing to narrow down the problem on my wife 1999 ML430. The
CEL is on. A while back I installed a Cold air intake with a K & N filter. Now If hammer it from a stop; the car Bogs and if I let up on the accelerator it seems it picks up better. When you are crusing and step on it hard it Bogs. But if I ease into it, it seem like it performs better. I had it scanned and they are comming up with fuel trim errors. Does that mean O2 sensors are bad or MAF? Please advise! Or should I put it back to stock?

lkchris

K&N is a great way to ruin your MAF Sensor.

Plus, they don't filter anything and are a total joke.

PaulX608

It's your MAF. Get some electrical parts cleaner and hose it out. Then remove the oil source(that would be the wet filter). If you insist on using your CAI, which I'm guessing is NOT drawing cold air like the stock setup but is instead open to the hot air under hood, then replace the wet filter with a dry one. IMHO, you should replace the stock air box. It's well designed and is not likely to be improved upon by an eBay tube and oily paper. If you're lucky, your MAF will work again once cleaned. The CEL may go out after a couple cycles with the MAF working again, but more than likely you'll have to erase the code. If you don't have a OBD code reader, maybe you could sell your aftermarket HOAI(hot oily air intake) and get one.

RAFFIE55

Thanks I'll try it out. So you are pretty sure it's not O2 sensors. You are right about the ebay special, that exactly what I bought. I thought I could squeeze out a little more power. I guess not.

lkchris

The notion that ANY engine is "strangled" by the OE air filter is patently ridiculous.

Your engine will continue to demand the same amount of air and get it regardless.

unlukky

+1

Electrical cleaner on the MAF is definitely a good start.
-John

xvvvz

FWIW, CRC makes a specific fluid for cleaning MAFs. It is about $6 a can at Pep Boys.

RAFFIE55

Well guys I tried the cleaning the MAF and the disconnected the neg bat. terminal for a bout 30 mins. Turned it over and no CEL and it seems like it runs better. Still debating if I should put back stock air box. Not sure how long the light will stay off. Maybe, I am use to driving my E55 and every time I drive the wife's ML; it just seems sluggish. I know the cleaning definitly helps. Is it just me or when you get on it from a stop and about 3000 rpm it almost feels like the secondarys open up. Is that how MB designed the throttle to work.

RAFFIE55

After a few hundred mile the CEL came back on. Didn't check the code yet. But I am putting back the stock air box. Maybe I'll get the drop in K & N. So is it possible the MAF needs replacing? It did run better after I cleaned it. So I am not sure?

ruBENZ

It's your MAF sensor. Replace it. A fairly simple DIY. http://cgi.ebay.com/ebaymotors/Meter...spagenameZWDVW