I have temp misfire that won't set a code. In the first 5 seconds of a cold start only it stumbles and sounds like an exhaust leak (maybe the turbo wastegate lever) then clears up and is fine. Has anyone heard of this. Hard to bring to dealer because it has to be a total cold start. Could it be a coil or ??

 

replace the Crank position sensor - they die and are cheap - then see where you are - if it didn't help it will have saved a breakdown further down the road anyway

 

Possible CPS but a little hard to tell for sure. Another symptom of a bad CPS is start it, drive it, stop for fuel, won't restart until cold again. But it isn't expensive and you will need it one day. Keep us posted.

 

What diagnostic tool are you using?

 

Any and all misfires create pollution/emissions and should set a code.

Well, I suppose if there is no injection of fuel, there is no pollution. Does the detection monitor the electricity or the sound?

Or perhaps not enough fuel ... which can mean too much air ... which suggests vacuum leak. It requires a rich mixture to get a cold motor running.

Perhaps the ecu doesn't get the message the engine is cold.

 

I think that's true in closed loop mode. In open loop (cold start) it does not always set a code.

 

I had an issue once where the car (M273) would not start cold. Towed it to dealer and they said the engine was flooded. Said it needed software update, which they did.

Also told me that if I had floored the gas pedal when starting it would have worked.

So, a simple test for you would be at the cold start floor the gas pedal and see if it gets going smoother. You naturally let pedal up right after it fires up.

If this test shows better engine start perhaps you have the “too much fuel” issue like I did…?

 

she had a Pug that would flood if you started and didn't run it for more than 30 seconds - and refused to restart rest of that day
she also managed the same on a VW golf Mk2 - but this had fly by wire and if you ask for full throttle the computer says no - so it has zero effect - I took the plugs out and span it up with a screw drive holding on full chat and buckets of flue flew out the plug hole - it was Ok ever after

Bosch injection crap !

 

OP as has been mentioned above... Crank position sensor gets replaced first.

With direct fuel injectors one of then could well be dripping fuel into a cylinder overnight. If you replace one replace all eight. Being direct injection it won’t get ‘flooded’ as in the bad old days of carburetors so it would feel as a thud-thud-thud when first started with one cylinder not running until it clears up. Pull all spark plugs and look for one that stands out. That is the dead hole. Give it fresh spark plugs. Coils are also old enough to be suspect.