Buy Now | Log In | ALLDATA Corporate Site | AutoZone.com
Back To Home Page
Log In To Your Subscription
Go To ALLDATA Back Home
Buy A Subscription! Back Home About ALLDATA Information View Sample Vehicles Read Testimonials Frequently Asked Questions Contact Us
Dowload Our Navigation Chart

Sign Up To Receive ALLDATAdiy.com Alerts

Click Here to receive regular product updates, special offers, and automotive news.

2012 Subaru Now Available May 2013: More 2012 Vehicles Added including Fiat!
• View New Vehicles
2012 Subaru Now Available December 2012: More 2012 Vehicles Added including Chevy & GMC!
• View New Vehicles
View All News and Updates:
• Go To News
Tech Tips
  Read All Tech Tips

ALLDATA Tech Articles Are Updated Weekly
• View All Tech Articles

  Dodge Durango: Brake Pulsation Problems In Paul's Durango
• Read Dodge Article
 
Fixing A Smelly Audi Audi Tech Tip: A4 begins to Smell caused by a Faulty Hose Composition
• Read Audi Article
Why Do You Need To Change Your Timing Belt? Why Replace Your Timing Belt
• Read Belt Article
Jim Grant Tech Tips Jim Grant Tech Tips
A collection of helpful articles based on reader submissions
Home >> Featured Tech Articles >> Go Back
   
  Jim Grant's Tech TipsJim Grant's Tech Tips
Below is a collection of Jim Grant's Tech Tips sorted by Vehicle Make. These Tech Tips were answers to questions submitted to Jim by ALLDATAdiy.com users over the course of many years.
If you have any questions, please feel free to email us.
 
 

Miscellaneous
Acura
Audi
Buick
Cadillac
Chevy
Chrysler

Dodge/Plymouth
Ford
GMC
Geo
Hyundai
Honda
Isuzu

Jeep
Lexus
Lincoln - Mercury
Mazda
Mercedes
Mitsubishi
Nissan
Oldsmobile
Pontiac
Saturn
Subaru
Toyota
Volkswagen
 
   
  Jim Grant's Tech Tips

'95 Toyota 4-Runner, Rough Cold Weather Idle

Q: My ‘95 Toyota 4-Runner runs rough when it's cold. As soon as it is warmed up, it runs great, but it does take some time to warm up. It also seemed to have some roughness when it wasn't being pushed (accelerated) above 50 mph or so. I had it in to Toyota and had the fuel injection serviced. The problem wasn't as severe for some time, but with the cooler weather coming, the problem when cold seems to be increasing. What do you suggest, or what do you think might be the problem?

...Paul W.

A: I would suggest inspection of two items. First, the coolant thermostat. The thermostat is designed to maintain coolant temperature to a specified temperature. If a thermostat is failing to bring and engine up to the correct operating temperature the vehicle’s computer will make incorrect fuel adjustments. In simple terms, the engine would get too much gas for too long of a time. This could result in spark plug fouling and poor performance. So a properly operating thermostat is critical. Second, the spark plugs. The wrong heat range spark plug can cause rough idle and misfire problems, when the engine is cold, that will be much more noticeable in colder weather. There is a lot that goes on in engineering a spark plug. A spark plugs tip temperature must remain between 500C-850°C. If the tip temperature is lower than 500°C, it will not be hot enough to burn off carbon and combustion chamber deposits. The result is a fouled spark plug causing an engine skip or misfire. As the weather gets colder the spark plug tip temperature is more critical. The difference from one heat range to the next is approximately 70°C to 100°C. With that in mind you can see that a cooler heat range spark plug can result in cold driveability problems. Also not all spark plugs are created equal. Some manufacturers try to get one part number to fit a broad range of engines. The problem with this? What works in one application may be too hot or too cold for another, which results in a performance/driveability complaint.

 
     
Have any Questions About ALLDATAdiy.com? Please Email Us
Buy Now | Log In | About | Sample Vehicles | Testimonials | Join Affiliate Program