Cold Start Hesitation

[ken729]

I have a 2000 Impala LS with a 3.8l engine. Can anyone tell me what causes cold start hesitation? Here is what happens. When I start the car in the morning it fires right up no problem and idles fine. Unless I wait for a minute or two, it will hesitate briefly when I first start out on the road. After this happens it runs fine for the rest of the day with no hesitation at all. Any idea what this could be?

[richtazz]

how many miles? how long since you tuned it up? Any Check engine light?

[ken729]

93k miles on the car - air filter and PCV are new in the last 10k miles, fuel fllter was done 25k miles ago. I haven't changed plugs yet.
This hesistation has been a long time problem going back prior to the GM recall on the fuel pressure regulator. The engine won't hesitate if I rev it a little after I start it - but it will as soon as I put it in to reverse or drive and step on the gas. It will only do that once until it is re-started cold. The car runs real good otherwise - very smooth and good power. Getting about 22/28 mpg.

[kidamaro]

I have exactly the same problem. Have a 135,000 miles on it and it started at about 40,000. Mostly I have ignored it, but it is getting a little worse. let me know if you find out what it is.

[ken729]

I changed the park plugs yesterday - that didn't fix it. I suspect it's either intake or fuel related. I'll let you know if I find something.

[kidamaro]

I am actually having some service done on the blower resistor and asked the dealer about it. They said there diagnostics revealed 11 different codes, all related to communication as if the battery had died. They said something about having to reprogram everthing when you change the battery, which I did a couple of years ago. Maybe that's what it is.

[tractorboy]

did you change the spark plug wires too ?
do you have a check engine light on ?
could be the fuel regulator.
I would try some top engine cleaner ( no carb cleaner )
I would also try some injector cleaner that you pour into the gas tank.

could also be the IAC pintle having carbon and not seating.

[ken729]

Never got a check engine light when it hesitated. I did clean the IAC pintle last year which was gunked up a bit but that didn't really help. The fuel pressure regulator is brand new along with the fuel filter in the last 12 months. One new development since I put in the new plugs last week is that I have not experienced the cold start hesistation in the past 3 days now -which is very unusual. (The plugs I took out (OEM) had 97k on them - were at about .080 gap and generally looked beat). Hopefully the good performance will continue -if I get the cold start hesitation again I'll try the fuel injector cleaner.

[tractorboy]

Whoa .080 ? that is way to much, even for used plugs, should be .060
what was the gap on the ones you put in. ?
you should also replace the spark plug wires with DELCO ONLY..
it might also be a good idea to reset your PCM ( computer)
ONE CAUTION, IF YOU HAVE THEFT LOCK SET ON YOUR RADIO AND YOU DO NOT HAVE THE PASSWORD , YOU WILL HAVE TO GO TO THE DEALER.
Remove the negative bat cable, then the pos, wait for 5 minutes
conect the pos then the neg. For the next few days drive moderately while the PCM is in learn mode, NO WOTs
I have a 2003 Impala and i do not have theft lock, the radio uses the vin, so i think maybe all 2003 or newer it is the same.

[ken729]

I put in double platinum plugs gapped at .060 and its running great. I think the .080 gap I measured on the ones I took out was partially a result of being incorrectly set when they were first installed by the factory. I didn't reset the PCM with the new plugs installed but since I am on day 4 with no hesitation problems I'm going to hold off on that ( unless I can reset the BCM that way at the same time -which would be a big help). Thanks for the input.