I have a low idle issue that I have been dealing with for a while. It idles around 500 and then when the efan kicks it drops to about 300 and almost stalls. I have an Optimum Red Top battery and I have already replaced my Idle Air Control valve and no luck. Any ideas guys? I am also throwing a code about a small evap leak and I have already replaced my gas cap and not sure where to look next. Anyone run into that before?

Im doing shocks, plugs, brakes and a fan blower resistor tomorrow.... anyone have any suggestions for any of these? Thanks for the help guys!

 

plugs should be copper core champion ONLY
brakes take your pick, fan blower resistor (for the cabin fan) is a 15 min job, takes longer to buy the part than change it, shocks are up to you(and everybody will have their own favorite type that they recommend) i like monroe reflex lineup for daily driving. the EVAP leak could be cracked hoses on the charcoal canister (under drivers side seat, there is a nice write up on it in the FAQ thread near the top of the forum index page)

the other possibility for the low idle issue is a bad battery (yes this can and DOES cause it) or, if it does it while driving replace the TPS

 

Thank you! I will check that canister under the seat and I will run my battery up to Auto Zone and have them check it, do you think the Optima is putting out enough juice?

 

how old is the battery? its more of an age thing than a brand thing, and just FYI batteries can PASS the load test and still not have enough juice for the computer in these things

 

Cheack to make sure tjat the vacuum hose on the back side if the throttle body is not craked that was my problem

 

OK, I dont think the battery is TOO old, maybe three years? I checked the vacum lines on the throttle body and they look good, I need to find out whats causing this low idle and evap leak!! Sometimes this crap can be annoying!! Anyone think that my CAI is causing the weird idle RPM's?

 

for the evap leak it is either a gas cap or a cracked hose, follow the hoses from the charcoal canister into the engine bay and see if any of those are cracked too.

the AVERAGE life span of a battery is 4 years, if you do alot of short trips, or sit w/ the engine off listening to the radio (draining the battery) the lifespan will be less. Lead acid batteries are happiest to be kept fully charged and not allowed to cycle too deeply a deep (to a low charge point before recharging) charge will be bad for the lifespan of the battery. so 3 years it is possible that your battery is weak and needs to be replaced.

also keep in mind these trucks (and most modern v8 engines) tend to idle around 500-600rpms, that is NOT low, it is normal, however the drop on increased electrical load definitely points to the battery, either that or the alternator (have that tested too)