Hi guys, my 1.6 16v has developed a poor running issue when cold.

 

Through the winter on particularly cold mornings the car wouldn't start as quickly as you would expect and on a couple of occasions I had to turn the key back to 'zero' and try again. I'm not sure if this is related to what I'm continuing to experience but thought I'd mention it in case it's relevant.

 

Now that the weather is warmer the car will run a bit rough at first and has a noticeable lack of power low down but the symptoms clear up fairly quickly. When pulling away from the junction at the end of my street the car will really drag it's heels below 2,500RPM(ish) in second. After work today I sat in the car using my phone while it idled and noticed that as soon as it dropped down from the cold idle RPM to the warm idle RPM (thermostat opening up?) it smoothed right out and the power was normal when driving off. The symptoms aren't always as severe after every cold start however, some days are worse than others.

 

Typically I'd assume a rough idle was an ignition coil problem, or a faltering fuel pump with the low power but with the symptoms going away once the engine has a bit of heat in it has me a bit lost on how to further diagnose the problem.

Really need to get the fault codes read first but it sounds like the coolant temp sensor could be the problem 

16 hours ago, nige8021 said:

Really need to get the fault codes read first but it sounds like the coolant temp sensor could be the problem 

 

Forgot to mention that there is no EML but will check for codes. Now that you mention it the cluster did beep and engine coolant warning light would flash on the coldest of mornings through last winter. This problem is mentioned a couple of times in the cars service history going back to 2009 or so. Coolant level was OK every time.

Edited 9 June, 20224 yr by Matt1.4

1 hour ago, Matt1.4 said:

 

Forgot to mention that there is no EML but will check for codes. .

 

Not all codes will put the EML on, mainly those concerning the emission system will, there might not even be anything relating to the CTS you might need look at the live data when the engine is cold and see what temperature it is sending to the ECU