Low idle 99 gmc sierra

Bruce Bracey

• 1000 Answers
• Posted on Apr 30, 2009

SOURCE: 99 GMC Sierra Pickup: Crank but no start. starts

The theft light issue is a good observation. Have you replaced the key tumbler or an ignition component lately? Has there been a lightning storm close very recently?

What the flashing security light is indicating is an attempt to relearn the key you are using.
Turn the key to run position, allow light to flash for 10 minutes, when light stops flashing turn ignition to OFF position for 5 seconds, turn ignition to run position and start over. Do this for 3 consecutive cycles, the the theft system will relearn the key cylinder code and store it once again.
Try that first before you go any further.
Let me know what you find.
Regards,

SOURCE: 06 f-150 5.4L low idle code and warm ac at idle.

should idle around 700

SOURCE: Rough/Low idle then dies.

is your check engine light on any longer ? also has your throttle plate ever been cleaned that can cause this symptom it will get build up on it and not allow correct idle ,you can clean it yourself ,rmove the big hose that goes up that goes up to your throttle body and get a can of deep creep sold at any parts house ,then spray the deep creep on a shop rag and by hand wipe out as much of the flap areas as you can ,its hard to get your fingers in there but be patient . but dont spray any thing down in the throttle throat it may cause more problems ,try the wipout of the throtlle area and see if it help your idle !

SOURCE: 2000 gmc starts but then idles rough then dies

I had to replace the mass air flow sensor. $ 150. the engine would shut off when driving too.changed fuel filter only worked for a day. The sensor is just after air filter.

SOURCE: LOW OIL PRESSURE ON 2007 GMC SIERRA 1500. CHANGED

have it tested using a manual gage if still low then main baring ore most likely bad that would mean a over hall if is really low and bearings bad should be making rattle noise when started up first few seconds

Testimonial: "thanks alot.truck is not making a rattling noise.we did check it with a manual gauge.it read about 10 at idol. press. gets better as you incr speed"