bouncing idle
Thread Starter
Member
Joined: Jun 2010
Posts: 210
Likes: 0
2002 C32 AMG
bouncing idle
02 c32 idle's rough and surges/bounces around 1500rpm.
When you first start it, idles normally, then with a tap on the throttle it goes into surge mode.
Throttle ecu reset does not solve.
TB was clean, took it off and cleaned it anyway. No signs of bad tb wires, no change when wiggled anyway. When I unplug the tb it gets a more intense/rapid bounce and idles up.
No vacuum leaks apparent.
Fuel pressure is steady at ~55psi
After I tested the fuel pressure the problem went away, for now. It was a sporadic problem last week.
Any ideas? I can't be the first to experience it.
When you first start it, idles normally, then with a tap on the throttle it goes into surge mode.
Throttle ecu reset does not solve.
TB was clean, took it off and cleaned it anyway. No signs of bad tb wires, no change when wiggled anyway. When I unplug the tb it gets a more intense/rapid bounce and idles up.
No vacuum leaks apparent.
Fuel pressure is steady at ~55psi
After I tested the fuel pressure the problem went away, for now. It was a sporadic problem last week.
Any ideas? I can't be the first to experience it.
MBWorld Fanatic!
Joined: Feb 2006
Posts: 6,213
Likes: 8
LET C32 2002
02 c32 idle's rough and surges/bounces around 1500rpm.
When you first start it, idles normally, then with a tap on the throttle it goes into surge mode.
Throttle ecu reset does not solve.
TB was clean, took it off and cleaned it anyway. No signs of bad tb wires, no change when wiggled anyway. When I unplug the tb it gets a more intense/rapid bounce and idles up.
No vacuum leaks apparent.
Fuel pressure is steady at ~55psi
After I tested the fuel pressure the problem went away, for now. It was a sporadic problem last week.
Any ideas? I can't be the first to experience it.
When you first start it, idles normally, then with a tap on the throttle it goes into surge mode.
Throttle ecu reset does not solve.
TB was clean, took it off and cleaned it anyway. No signs of bad tb wires, no change when wiggled anyway. When I unplug the tb it gets a more intense/rapid bounce and idles up.
No vacuum leaks apparent.
Fuel pressure is steady at ~55psi
After I tested the fuel pressure the problem went away, for now. It was a sporadic problem last week.
Any ideas? I can't be the first to experience it.
Super Member
Joined: Dec 2009
Posts: 826
Likes: 106
From: Sweden
2011 C63 AMG, 589hp
Mine did that when the airmeter went out.
sounded like 'wroom.....wroom.....wroom....wroom' around 1500rpm oscillating in about 0.5s
(hard to write soundeffects on foreign language
)
sounded like 'wroom.....wroom.....wroom....wroom' around 1500rpm oscillating in about 0.5s
(hard to write soundeffects on foreign language
)
Trending Topics
Member
Joined: Jan 2013
Posts: 241
Likes: 1
From: Edmonton
2003 C32 AMG
Any problems with check engine light?
Get it scanned and see if there are any stored codes or events.
Possible its the fuel pressure regulator as stated above, which is an integrated part of the fuel filter on the C32. Easy replacement, give it a shot. Still stumbling afterwards, maybe time to check injector spray patterns... maybe an injector is clogged or malfunctioning?
Also just bouncing it out there, it's a possibility there is an issue with the ECU. Is there oil in your engine wiring harness by chance?
Validity
Engines M112, M113
Power generation / Engine management / Engine running / Stalls/goes out
Power generation / Engine management / Engine running / Surges
Power generation / Engine management / Engine running / Cuts out intermittently
Power generation / Engine management / Engine running / Runs rough/shakes
ME-SFI-Motor electronics (MESE) (CLK (209),C (203),E (211),SLK (171))
Get it scanned and see if there are any stored codes or events.
Possible its the fuel pressure regulator as stated above, which is an integrated part of the fuel filter on the C32. Easy replacement, give it a shot. Still stumbling afterwards, maybe time to check injector spray patterns... maybe an injector is clogged or malfunctioning?
Also just bouncing it out there, it's a possibility there is an issue with the ECU. Is there oil in your engine wiring harness by chance?
Validity
Engines M112, M113
Power generation / Engine management / Engine running / Stalls/goes out
Power generation / Engine management / Engine running / Surges
Power generation / Engine management / Engine running / Cuts out intermittently
Power generation / Engine management / Engine running / Runs rough/shakes
ME-SFI-Motor electronics (MESE) (CLK (209),C (203),E (211),SLK (171))
Last edited by Supgee; Sep 24, 2014 at 09:24 PM.
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Thread Starter
Member
Joined: Jun 2010
Posts: 210
Likes: 0
2002 C32 AMG
Thanks for the detail.
Supercharged engines have a MAP not MAF. Cheap enough part I'll replace that if the fuel filter doesn't solve it.
ECU harness ok.
I've run a can of mb fuel cleaner through about 10k mi ago, I'm at 150k now, plenty of power when I'm not experiencing this. I would imagine a stuck injector would be a constant.
No engine codes but I'll get it scanned for fun. Can I use star to look at throttle pedal output?
It is not a constant problem but has happened a few times in the last few months. Every once and a while it will be noticeable but not extreme, just a little bounce off idle about 50 rpms instead of 500.
Supercharged engines have a MAP not MAF. Cheap enough part I'll replace that if the fuel filter doesn't solve it.
ECU harness ok.
I've run a can of mb fuel cleaner through about 10k mi ago, I'm at 150k now, plenty of power when I'm not experiencing this. I would imagine a stuck injector would be a constant.
No engine codes but I'll get it scanned for fun. Can I use star to look at throttle pedal output?
It is not a constant problem but has happened a few times in the last few months. Every once and a while it will be noticeable but not extreme, just a little bounce off idle about 50 rpms instead of 500.
MBWorld Fanatic!
Joined: Jul 2007
Posts: 2,000
Likes: 20
From: East Bay, Bay Area
2002 C32, 2012 S550
When mine did that, I had to replace my throttle body. Have a mechanic check the hidden codes and see what it points to. My regular OBDII scanner couldn't pinpoint, but my mechanics expensive snap-on pulled a lot more hidden codes that pinpointed the TB.
Senior Member
Joined: Mar 2011
Posts: 359
Likes: 5
From: Kansas City,MO, USA
2015 E350 4 matis, 2003- 911 porsche
Rough idle I had the same issues and this is what I found
1.with car running and idling up and down sprayed carb cleaner around air intake at the rear where the two rubber gators go over the filters to the air intake throttle body. Every now and again idle would even out, this proved that there was some air leaks around the rubber intake boots.
2.After some real close inspection I also found the air breather tubes from the valve covers had a small crack due to hardening on the underside.
3.I purchased a new air intake adaptor with the two rubber boots and at the same the two rubber hose connects to the valve covers.
4.Took all filter off cleaned everything, cleaned the throttle body, it was real dirty. Re fitted the new hoses to valve covers , this is a little awkward, fitted to air intake boot assembly again this was not easy needs some patience DID not have the steel clamp bands so used black wire ties. you can't see them so looks great.
5.Started up and idle is great no hunting or ups and downs.
6. It was very hard to see any leeks so you need to us carb cleaner and spray around air intake area and my engine evened out and then starting to "hunt" again this is how I found the leaks
Hope this helps.
John
1.with car running and idling up and down sprayed carb cleaner around air intake at the rear where the two rubber gators go over the filters to the air intake throttle body. Every now and again idle would even out, this proved that there was some air leaks around the rubber intake boots.
2.After some real close inspection I also found the air breather tubes from the valve covers had a small crack due to hardening on the underside.
3.I purchased a new air intake adaptor with the two rubber boots and at the same the two rubber hose connects to the valve covers.
4.Took all filter off cleaned everything, cleaned the throttle body, it was real dirty. Re fitted the new hoses to valve covers , this is a little awkward, fitted to air intake boot assembly again this was not easy needs some patience DID not have the steel clamp bands so used black wire ties. you can't see them so looks great.
5.Started up and idle is great no hunting or ups and downs.
6. It was very hard to see any leeks so you need to us carb cleaner and spray around air intake area and my engine evened out and then starting to "hunt" again this is how I found the leaks
Hope this helps.
John
Senior Member
Joined: Mar 2011
Posts: 359
Likes: 5
From: Kansas City,MO, USA
2015 E350 4 matis, 2003- 911 porsche
I replaced #4 and the the two hoses on the valve covers that connect to underside of air intake. also look carefully at airline that comes into back side of throttle body , mine was not pushed in properly, it may have got moved when somebody fitted new filters
