Lumpy at startup?

Zascar

2008 Cayenne S, 65k miles - when I start she's very lumpy - chugs a lot. I only had the coils done last month I thought that might be it. It's fine when driving and when fully warmed up but when I start at idle its very lumpy and annoying.

On the OBD2 scanner I get P0175 Powertrain system to Rich, and P2181, Cooling system performance.

Any suggestions as to why this is happening?

Mad_Mike

Is it worse at startup?
Normally a lumpy rough start, and then combined with the P0175 code would mean it's running rich and starved of air
If it happens more at startup, it could be an air leak on the inlet manifold and once the engine warms up, the leak is sealing
Lots of other things could be causing it also, such as clogged air filter, bad O2 sensor, coils (which you had done), plugs etc

The 2nd code is probably a faulty thermostat or a temperature sensor.

Zascar

Thanks, yes only at startup for the first few mins, once its warmed up its fine. Air leak sounds likely but yes could easily be any of the others. I just hope my mechanic can find the issue without costing a fortune.

Mad_Mike

Just re-read what I said. I mean a leak on the exhaust side, such as hole in exhaust, cracked manifold, leaking flexi pipe etc
A leak on the inlet would cause it to run lean and not rich! DUH! Sorry

dar_cool

Faulty coolant temperature sensor? If your obd reader can read temperature of coolant perhaps you could check it on startup?