99 C280 Surging on idle

[TugaMerc]

Hi, this morning my 99 C280 suddenly started to surge at idle. It feels like the wind is shaking the car. Starts ok, runs ok, no warning lights but the idle varies between 500 and 700 rpm. Any ideas?

[RemoLexi]

Probably a vacuum leak. You'll see some codes for lean mixture.

[TugaMerc]

Idea on where the vacuum leak would be?
Apppreciate the help!

[RemoLexi]

That you would have to look for yourself, near the throttle body is a good start or I use a party fog machine and fog the intake until smoke comes out of a loose line.

[TugaMerc]

it looks like a leak in the intake manifold gasket and a cracked intake manifold. Possible?

[RemoLexi]

Pix ? Never seen a cracked intake manifold.

[TugaMerc]

I have it at the repair shop, the tech is taking it out today to check if the crack runs through the body or is just on the outside.Will report back once reached a verdict. thks!

[TugaMerc]

So, after 2 weeks, 1 throttle body replaced and 3 MAP sensors, the repair shop is trying to find the cause why it works for 20 mins and then the engine becomes lumpy and the sensor is shorted out. Any ideas?

[RemoLexi]

Throwing any codes?

[TugaMerc]

Nope, no codes. The car works fine for 20 mins or so and then the engine is "thrown off balance" Visible symptoms are the engine rocks sideways and the rpm needle fluctuates at idle.

[TugaMerc]

EGR has now been identified as the cause. Factory price of new one is between 275 and 350. Can someone confirm these prices? I'll be calling the dealer to confirm as well.

[TugaMerc]

EGR was the cause, 162 plus tax, case closed