Dead-ish Battery + Tough Start + Rough Idle

Dec 28, 2015 | 05:44 PM

DC Ross

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Joined: Dec 2015

Posts: 2

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2009 CLK 350

Dead-ish Battery + Tough Start + Rough Idle

Hey all,
I have a 2009 CLK 350. It's been running fine (even yesterday). Went to start it today, it turned over but didn't catch. I tried jumping it from one of those portable jump things. After the 5th or 6th try, it finally did start, but idled really, really roughly and the Check Engine light was on.

Any ideas???

Thanks much

Dec 29, 2015 | 03:19 AM

Glyn M Ruck

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Joined: Jun 2008

Posts: 19,942

Likes: 192

From: Llandudno, Cape Town, South Africa

late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires

Get the battery properly load tested & if not OK replace with a good 100Ah battery. OE are excellent and last a very long time. These cars are very voltage dependent. If nothing improves then get hold of an OBDII scanner & scan for stored codes. Plug under cover in lower dash below steering wheel/column. Their must be stored codes or you would not get a CEL light. Alternatively get the car scanned with a Star at a dealer. It takes a lot of guessing out of things. It could be a CPS, low fuel pressure, MAF, on plug coil, Temp sensor etc. etc. etc.

Just one thing on the M272 engine. Make quite sure that the airbox is clipped down firmly over the MAF at the rear of the V of the engine. If it leaks air there it can cause strange running & is frequently a really dumb cause of issues.

Good luck!

Last edited by Glyn M Ruck; Dec 29, 2015 at 03:22 AM.

Dec 29, 2015 | 08:06 PM