Hesitation when cold outside, plugs? O2 sensor? MAS?

[Peterofdevon]

Hi Guys,

The Green 94 hesitates when under 40 degrees out. I noticed it a while back but its way worse in colder weather. Once it runs for 15 minutes its ok but if you shut if off for a while and restart it hesitates again for a while.

Any ideas?

Why is it worse when its cold out?

Peter

[Q45tech]

Fuel volatility is always a major concern until the gasoline in the tank and the fuel rails warm up. Why we have 2 seasonal blends with different vaporization curves.

After partial warm up when the coolant get above 100F but not 174F weird things happen as the ecu tries to guess what the MAF means.

Why OBD2 has a intake air temp sensor to better inform ecu.

Remember the Q ecu use MAF and coolant temp to guess that it is cold air not just heavy air.

One should look for LINEAR changes and no drop outs in data from all sensor whose age may create weird thermal effects as they change temperature [during warm up].

Summer may be 160F under the hood whereas winter may be 60F and lower a 60mph

Remember the radiator only adds 20-40F to outside ambient air without AC heat....the MAF is the one sensor that is not heat connected to the engine