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I bought an E220 CDi AG back in June and I am very pleased with it, however the idling speed with a warm engine is around 750rpm until I turn on anything electrical, then it increases to about 900rpm; even the radio has this effect.
I accept that the engine management unit will increase revs to take account of electrical usage, but that seems like something is amiss to increase by 150rpm for a radio discharge.
I am wondering if there may be a problem elsewhere, the battery and alternator spring to mind.
I would welcome suggestions.
Thanks
Phil
Last edited by Crustyoldbloke; Nov 21, 2014 at 11:17 AM.
Reason: correction of an error
Thanks Plutoe, it sounds like I need to visit a garage and get it all analysed. I have read bits and pieces about faulty ECU's and when I bought it, I had a fuel temperature sensor renewed.
VIN: WDB211008-2B-299070
Last edited by Crustyoldbloke; Nov 24, 2014 at 06:14 AM.
Reason: added VIN
My theory - breather hose (PCV, diverter valve, heard about a hundred terms for it) goes bad, letting in un-metered air AFTER the MAFs, thus causing a rough idle, possible lean codes and or timing issues to compensate. The breather hose connects from the back of your crank case to the left rear of your intake manifold.
Maybe the techs aren't TSing it properly. My suggestion: Easiest first - replace the breather hose (either with or without the intake manifold removed) part # A1560100170, check this post to install with the manifold left on - sounds and looks like a pain though! https://mbworld.org/forums/w211-amg/...-m156-e63.html
If you can't get to it or want to look around a bit more remove the intake manifold. Be sure to replace your gaskets and 1 time use bolts (A0049905312).
While you have the manifold off, open the belly pan and check the throttle-body plate adapter. I got mine off this weekend and unfortunately found it to be corroded just like Robert AMGs
It wasn't terribly difficult to get to, but successfully troubleshooting it was a bitter sweet experience - happy to find the source of the issue but pissed that MB doesn't sell a replacement plate itself! We have to purchase the entire intake manifold!
It would be awesome if Renntech sold their CNCd throttle-body housing/adapter plate as a replacement (found on their 82mm upgrade). I'd hate to spend the $2500 for an entire intake manifold, and have the issue pop back up later. On the other hand, the plate from Renntech looks robust, but $4k is hard to justify since all I need is the plate.
Quote from E63007:
I thought re-posting this post above from a C63 forum with an M156 NA Engine having idle issues would provide some food for thought!
Myself, I just spent the last month waiting for the title to come through on my purchase of a sweet 2007 E63. With the Owner having agreed once the title came through from his leinholder to take the car to the body shop before our finalizing the transaction, MY 1st Maiden Voyage in the car was blemished by the guys at the auto body shop telling me about their having cleared codes which pointed to a "normal" problem in the transmission! Yikes!! There can be hundreds of potential codes pointing to the Tranny with only 16 or so being able to be "saved" by the ECU for one to view with any Diagnostic! So the Auto Body guys, having done a beautiful job on my hood, front bumper and wheels, sent me tenuously on my way! Upon starting the engine I find the Idle at start up reading 1100-1200 rpm! Think sweaty forehead here! Talk about Bittersweet! It drives so well, with the exception of the slight pull to the right although I'm fully stocked to rebuild the front suspension, but when I brake to stop, the high Idle effects the kick down shifting such that it jumps when reaching 3rd and especially 2nd gear in "C" (Comfort) Mode!!!
I've searched long and hard on these forums to get an inkling of an idea on how to address this issue. Obviously the first would be to have the Original owner own up to his having said "everything works fine" and have his MB Certified Technition take a look, but I remain doubtful of that ever happening! Second would be to get a Star Diagnostic, but I've yet to buy the Asian c4 or C5 etc. PCV/EGR hose leaks or faulty vacuum connections are two others at the top of the list. My car being NA (Non-turbo), I'm not certain how many vacuum hoses may need to be renewed, if any? Trying to find the answer to that question has proved to be a real time draw! Any confirmations along this line would be much appreciated!!
Another possible cause is, of course, covered above in this post. Being that this post is fairly recent, I was wondering if you all have seen this EBay Special for a "New" Aftermarket Intake Manifold Center Plate Gasket Kit??? $200 seems like it would be money well spent without having to pay $2000+ for entirely new Intake Manifold should this issue arise??
The idle speed control on the 646.821 keeps the idle speed CONSTANT even under load requests such as AC or drive position!!
The ECU controls the Idle speed by receiving sensor data from---engine speed(CPS), coolant temp(CTS),accelerator pedal position(APS), and fuel rail pressure(RPS)-------therefore either the ECU or relevant sensors should be diagnosed to determine why the drastic change in idle speed!!-----either live with it or make the investigation a weekend project for the grand kids---they love electronics and can sort out anything!!
This is not a DIY unless you have a copy of DAS Xentry!!
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