C43 Misfire at idle

malcomP

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Feb 16, 2009
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Aberdeen
Your Mercedes
C43 and a C240
My C43 is missing on idle, the diagnostic shows 5,7,8 cylinders are to blame, It doesnt happen above 1000 rpm. A bit confused, fuel, ECU,or something else..... I,m putting it in for brake pipes on the backl and an MOT next week, so any suggestions, injectors, fuel pump etc.....:confused:
 

jibcl500

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Cambridgeshire
Your Mercedes
CL500,ML55,SLK280
Could be as simple as coil packs or leads, didnt the diags give more info, could also be an ECU fault.

jib
 

television

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Daventry
Your Mercedes
2002 SL500, 216 CL500, all fully loaded
As Jez the test are a little bit vague, it should indicate injectors or electrics
 

LYNALL

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Was plugs leads on my e430 3 of them,i changed the lot, may be worth looking at some of the wiring to the coils on top of the rocker covers as they look vunerable, the wiring from where it goes into the plastic trunking along the top of the fuel rail is very well supported and protected.

We tried an experiment and pulled the little plugs of a few of the coils one at a time and the car never registered anything!





Lynall
 

bigasotonuk

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Southampton UK
Your Mercedes
C43/55 AMG 1999 / C230K 1997
Hi,
Was it a proper MB "STAR" machine that was used? as some of the generic testers available are not as specific as the "STAR" tool.
If its electrical, its more likely to be leads, plugs or coils in that order IMO, try swapping the leads from the other cylinders (be careful not to get them muddled up though) also you could try obsverving the leads with the engine running at night as you may see the leads tracking across.
 

German auto clinic

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It'll be leads if it only misses at idle, that said we change loads of coils... Star tester will point to problem cylinder but only after first clearing old faults. It will show misfire but will not show if its lead or coil. Plugs on C43 last around 25k miles if its used properly :) (My plugs are 26k miles old now and I get slight miss at Idle sometimes but it clears with a rev or a clear stretch of road) I quite often find I have to carryout a complete system reset after changing leads or coils, its called bootstrapping and resets all adapted data back to factory settings. This is because the ecu adapts its self the best it can to keep the engine running properly. Trouble is after reset if anything else has been covered up by the ecu's self adaption it will then need replacing (mass sensor) is the normal problem uncovered by this.......
 

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