Question about 1999 Pontiac Sunfire

1 Answer

Car has trouble starting in warm weather

My car starts fine when it is cold outside, but when it is warm it is hard to start.

Posted by on

  • 3 more comments 
  • Johnny
    Johnny Mar 24, 2014

    No codes. It mostly happens when it is warm outside. The engine does not have to be warm for this to happen. I have replaced the gas cap, and plugs and wires. Thank you for your input.

  • Denis Houle
    Denis Houle Mar 25, 2014

    before starting scan data of temp. sensor if it out of range

  • Denis Houle
    Denis Houle Mar 25, 2014

    whatever the outside temp . the temp sensor should match outside temp example if outside is 30 c then the temp sensor should be near 30c

  • Johnny
    Johnny Apr 07, 2014

    I checked the temp, it matched with outside temperature. No fault code.

  • Denis Houle
    Denis Houle Apr 08, 2014

    clean trottle body plate with combustion chamber then change spark plugs and fuel filter see how it goes



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Pontiac Master
  • 1,341 Answers

Scan data if engine temp. is normal if ok see if there is engine faulty code.
hope it helps

Posted on Mar 24, 2014


6 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017

  • 702 Answers

SOURCE: will not start when engine warm

Sounds more like your ignition module is getting hot and not working. I'd go there first before replacing the ECM. You can remove the ignition module and most NAPA stores have the ability to test them for you. Make sure they test it at least 5 times. This way it'll simulate starting and stopping.

Posted on Jul 23, 2008

  • 46 Answers

SOURCE: 95 Pontiac Grand Am Won't Start in Cold old is the battery?? you have 3 options...the battery is bad, the alternator is bad, or the serpentine belt is bad...most auto parts stores will check your battery for free while it is in the car....otherwise take it out and bring it in to have them check it...

Posted on Jan 15, 2009

  • 1 Answer

SOURCE: 97 firebird formula hard to cold start

Check the cold start injector useing a digital multimeter with a bar graph. Unplug the injector wires and insert the probes into the wiring plug, crank the engine and the bar graph should pulse if it does remove the injector and with the wiring reconnected and the injector held over a suitable container crank the engine and observe the spray pattern. If insufficient replace injector. This should be a starting point at least

Posted on Jun 05, 2009

  • 158 Answers

SOURCE: 1997 grand am i replace the power steering hose

Please check the fluid level in the power steering pump. After putting on a new hose the fluid may have traveled through the system and you may need more fluid.

Posted on Oct 02, 2009

  • 1 Answer

SOURCE: i have a 2007 pontiac grand prix gxp with remote

It is a default setting in the vehicles computer. When the remote start is activated it only enables the engine and the accessories are on standby until the key is inserted. As of now I am not sure of a change to this default setting.

Posted on Jan 16, 2010

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

2005 ford focus zx4 won't start in very cold weather

Cold weather makes the engine hard to start for two main reasons. First, oil thickens when it's cold, which increases friction and makes it harder for the staner motor to spin the engine. ... You can ensure that your car will start in the worst weather by keeping the engine or the battery, or both, warm.

Cold-Weather Car Starting Tips - Nature and Community - MOTHER ...

Dec 09, 2016 | Ford Cars & Trucks

1 Answer

My car when using when using my autovox remote starter , starts for 1 second then dies 3 times in a row when cold but works find after warming up .

Cold weather makes the engine hard to start for two main reasons. First, oil thickens when it's cold, which increases friction and makes it harder for the staner motor to spin the engine. ... You can ensure that your car will start in the worst weather by keeping the engine or the battery, or both, warm.

Cold-Weather Car Starting Tips - Nature and Community - MOTHER ...

Dec 09, 2016 | Cars & Trucks

1 Answer

Cool mornings it doesn't want to start ,i have to turn the key to start and let it off several times and it will eventually start after that it starts fine all day and starts fine on warm days

How to Start a Car in Freezing Cold Winter Weather > ... > Cars > Car Maintenance and Repair

wikiHowFreezing cold weather can take a toll on car batteries. ... It's much more difficult to start a cold car with a mostly-empty tank, so do yourself a favor and gas up ...

Why is it so hard to start a car in the winter? - HowStuffWorks
To start a car in winter, your engine has to work extra hard. Learn the top 3 reasons your car is hard to start in cold winter weather.

Debunking 5 Cold-Weather Car Myths - Popular Mechanics

Nov 21, 2015 | Cars & Trucks

1 Answer

Hard starting in cold weather, turns over but does not start easily. Starts fine in warmer weather

check if the car have the thermostat in the cooling system, because in cold weather the thermostat close the water flow in the cooling system (radiator, head of the motor) and the car gets temperature faster to warm the engine to operational temperature.

Nov 20, 2013 | 2004 Jeep Liberty

1 Answer

2006 nissan navara wont start in cold weather

Its cold start issues:----

Go through the list of help links mentioned below:----

Click the link :----

Cold start problem and vehicle shudder around 2500 to 3500 rpms


Low idle when cold out side?


Ford explorer 4.0 will not idle when cold?


Automatic transmission shift lever hard to move on cold mornings?


Car won't start when cold?


These will help.


Dec 06, 2012 | Cars & Trucks

1 Answer

It cranks, but it does not run

Have you check the plugs, cables, cap/rotor ?

One thing you can try since it starts good in warm weather, is to ,on a cold morning, take a hair dryer and warm up the suspect part to warm weather condition. Then try and start the car. If it start ok you have probably found the weak part.

May 31, 2009 | 1991 Mercedes-Benz E-Class

1 Answer

Acura rsx 2002 won't start below -15

you might have water or condensation on your gas lines. put an additive that removes condensation from the gas lines and see how that works for you.

Jan 24, 2009 | 2002 Acura RSX

1 Answer

93 Grand Cherokee 4.0 trouble starting in cold weather

Welcome to the forum. Your question has to many variables. Cold weather out here in Cen Cal this time of year is mid 40s. Is the problem when the vehicle is cold as in ovrernight but starts ok when it is warm? Does it crank OK but seem like it's not getting fuel? If you hold the throttle slightly open, does it start OK?

May 14, 2008 | 1996 Jeep Grand Cherokee

Not finding what you are looking for?
1999 Pontiac Sunfire Logo

125 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pontiac Experts


Level 3 Expert

79024 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8836 Answers

Are you a Pontiac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides