mplsCLK

...using the boards to fix problems I have been having without needing to post..
(The footwell wetness and fuel filter guides were helpful.)
But I been having this rough idle issue. First after reading I concluded it was motor/tranny mounts and I still believe that's amplifying my MAIN issue. I saw a post on here where someone in the w208 forms said basically if you're experiencing vibration you have a problem that motor mounts alone wont fix. (Also, when I'm idling sometimes the needle will fluctuate a few hundred RPMs [so sit at five and go alittle bit halfway to 10 and back down] It happens more so when I'm coasting down from a high speed as if I was slightly pressing on the gas so often) Seeing all of that I was sure that I had a deeper idle issue So I went down and hooked it up to the obd.. I got some codes back,

0400 Exhaust Gas Recirculation Flow
0173 Fuel Trim Bank 2
0156 Oxygen Sensor Bank 2 (I got 2272 and 2273 which I guess means its running too lean and too rich[must just mean the sensor needs replacing])
0161 Oxygen Sensor Heater Circuit Bank 2

I see that I need my gaskets replaced on the valve covers [I'm not sure if they are just the breathers but I'm assuming the breather is on one side only?] because both sides have oil crud on them.

Given the information that I have, I'm assuming to clean out my egr valve, check for vacuum leaks and put new gaskets on my valve covers (or clean breathers??) and possibly replace the oxygen sensor at bank 2

I'm wondering if there is any advice that could be given as to what I should do first and if cleaning the oil crud and working on the breathers would fix my oxygen sensor. If possible any reliable mechanics in the twin cities metro area of minnesota also.

Btw, the rough idle is making my muffle rattle pretty hard as it makes more noise during the idle than the motor itself. Would the work on the egr valve clear that up?

Any input?

Thanks in advance.

jonUF02

Sounds like you are on the right track. I would replace the O2 sensor Bank 2 and clear the codes, possible reset the ECU to re-learn. All the codes are related to emissions control. The whole system could be thrown off by a bad sensor. The Fuel Trim code might be triggerd by the system trying to compensate for the bad readings from the sensor. This is all just logical thinking, but I'm not a mechanic.

MarcusF

At this age, I'd change both primary O2 sensors and if it's a V8 (sorry I'm on my cell and can't tell), make sure the rubber seal between the MAF and air cleaner isn't dried out (the dealer regularly lubes the seal with $100 grease). If that seal lets air seep through, the idle will be odd.

Also, how old are the plugs and wires (miles and years ).

jazzmammal

It's a 320 Marcus. There's one guy who posted about a 320 with about 200K miles on it with a very gunked up EGR valve and hose. Just cleaning those out solved a similar problem. He posted pics that showed exactly how to do it. The housing for the EGR tube is tricky to get to but doable.

The other thing that worries me in your post is the exahust rattle. You're saying the rough idle is causing the rattle? Unfortunately that may not be it, it could be bad cats and if that's the case they need replacing. Hitting the cats with a rubber mallet and listening for rattles is the test for that. Rattling means the cat elements inside are broken.

Bob

mplsCLK

Well... Some idiot hit my rear driver side wheel well, and dented it in, after that I had rattle. I thought about that being possible but when I reach underneath and grab the muffler shielding the rattle stops. I forgot to deal with it when I was under there with the fuel filter. I also don't have any odd smells. Maybe you're right though, I really don't know much about exhaust.

Edit: Considering my girl took it for a drive and now it doesn't want to start (5+ seconds of crank) sputters and misfires, won't rev past 3k I think I will clean the egr and the maf again(actually take it out of the housing this time) and see if I can get some function first. Then possibly try smoking the vacuum lines?

I have a reasonable amount of cash to play with I just don't like throwing money at cars as last time I did that I spent a lot of money and never fixed my initial problem. (e32 v12 bmw with a slow power draw)