Cold start issues

[flmont]

with it being 32 deg's in Tucson this morning I started the 02' Stk 2.7 up and it Popped and Burbled then stalled I restarted and it did much better...But it took 3 times before it would Idle correctly,..02 sensor's, and MAF and Vacuum tubing and reservoir all replaced last year ,..gotta be a vacuum leak correct ?? But in warm weather NO issues,..It starts up just fine ?? Thanks, Frank

[blue62]

How many miles??
Any codes??
Any pending codes??
Any mods?? or is it stock????

You had a similar problem in January of this year under similar temp and moisture conditions.
What was the fix then???
What shape are the plugs and coils in???
What grade of gas are you using????

[flmont]

Hey Blue62,..

No codes,89.500 miles,no mods all stk,I replaced the usuall parts 02,MAF,the plugs, the power packs Etc,. Oddly, it only happens when its cold,.45-50 Deg's it dos'nt do it I think a bad 02 sensor,.I could not use the Durametric yet,.It had a dead battery which I picked up a replacement today,..hope to check it out over the weekend ..Thanks Frank

[blue62]

Originally Posted by flmont

Hey Blue62,..

No codes,89.500 miles,no mods all stk,I replaced the usuall parts 02,MAF,the plugs, the power packs Etc,. Oddly, it only happens when its cold,.45-50 Deg's it dos'nt do it I think a bad 02 sensor,.I could not use the Durametric yet,.It had a dead battery which I picked up a replacement today,..hope to check it out over the weekend ..Thanks Frank

The problem may be due to a bad battery.
As temp. drops so does battery voltage.
These cars do weird things when battery voltage drops just a little.

O2 sensors are not active during cold start events.
So O2 sensors have nothing to do with cold starting issues.

If the problem persists after changing out the battery:

Hook up your Durametric and record your coolant temp. and your intake air temp.
Before you start it. While it is still cold.
They should be near ambient temp.
Then start it and watch to see if coolant temp. rises as it should.

Coolant temp is one of the things the DME/ECU looks at on cold start.
If the coolant temp. sensor is working properly, then at lower temp. the DME pulses the fuel injectors longer to create a rich fuel air mixture. Takes the place of a choke.

If the coolant temp. sensor is going bad and is reading high when your doing a cold start then the DME doesn't pulse the injectors long enough to create a rich fuel air mixture and thus can create cold starting issues.

Coolant temp. sensors are very often overlooked when one is having cold start issues.

Hope that makes sense.
Let us know what happens.

[flmont]

WOW,..That sure is interesting I will attempt that 1st thing tomorrow morning, I know it sure smells rich as its popping off..THANKS !!

[flmont]

I did the new temp sensor and sadley no change,.still popping off and no codes only when cold,..anything above 50 deg's starts fine..Hmm