theeddie

i have a buddy whos car idles very rough. the car will drive fine, but it feel like a cammed mustang at a light.
i think i checked all the hoses. i ran the smooth idle log in star and it shows all the cylinders as rough

any ideas

02S430

how many miles? have you checked you engine and tranny mounts? if you have high miles did you change your plugs and wires? have you changed your air filters regularly? might have a dirty MAF sensor

cahiil55k

Mine does the same thing, though very rarely. It usually happens on a 70* day, moderate humidity, and after a 20 mile highway cruise with no traffic. There is no CEL. I haven't datalogged it yet and am waiting to have my wideband o2 sensor installed but will let you know if I find anything. It's not the transmission or engine mounts for me - the car actually feels like it is going to shut off while stopped at traffic lights. It always goes away after I park and shut her off for 10 minutes or so.

theeddie

100000 miles never did plugs and wires was my next move but kind of pricey for him
tranny mount is brand new
ill check the filters

and im pretty sure the e55 doesnt have a maf

02S430

ever change your fuel filter? your injectors might be dirty

02S430

sorry forgot it has no MAF, autohaus az has the wires for $170, not sure about the plugs but that might be the problem if its not the mounts

cahiil55k

Good advice. I almost changed my fuel filter last year but since it required replacing more than the filter itself (have to change the entire fuel sender if I recall correctly) I opted to not do it yet because it wasn't showing any signs of wear or damage. I'll have my tech research if becomes more frequent.

02S430

no prob, lets us know what happens

berti_00

spark plugs and wires and your back to like new

majid3

I was told stalling at lights could be Idle Control Valve, Over £1000 from UK MB dealer but removal and clean may resolve the issue.

Anyway service was due and I had already ordered all the parts Oil filter from MB and all other filters from Euro Car Parts (UK Indy Company). So maybe try the service and ICV clean.

BTW i had P0-301, P0-302 to P0-308 fault codes too. These are cylinder misfiring codes and the end number relates to the cylinder number i.e. P0-301 cyl no1. But they all dissapeared after the Launch diagnosis reset the fault codes.

Really I need to diagnose with Star machine then service and clean ICV.

Critter

Clean the throttle body, throttle plate and inner barrel.
To check , remove intake hose going into throttle body, turn on key, have someone depress the throttle which should open up the throttle, use finger to wipe the back side of the throttle plate which is actually the top side. Look at finger should be covered in black sludge. Using a clean rag and a tooth brush soaked in intake and choke cleaner clean the inside of the throttle barrel and the backside of the plate. For those more adventurous people, remove the throttle body all together and clean it completely.
You will be amazed at the grime that accumulates on the throttle plate which greatly affects idle quality.

bstudey01

This sounds like the dreaded 82mm TB swap issue. Mine does the same thing, I have tripped a code though but not always. The issue has to happen 3 times in a certain time frame before it will actually trip a cel. Have you noticed a very slight hiccup while driving on the highway usually upon light acceleration up a hill at about 70mph? Once you get the wideband watch your STFT's while driving on the highway. My car will hiccup, then stft's max out to +25%. A simple restart always fixes it too. I think there are many others with this issue, I wonder if the OP is modded???

Bandit

Check the intake manifold gaskets. Easy fix and a common problem on this generation E63.