Misfiring, high IAT Please help!
09-11-2012, 02:13 PM
#1
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Misfiring, high IAT Please help! This one is alittle beyond me, I need some help from the LS pros...
I have an '03 Silverado SS with the 6.0. 106k miles
A couple of weeks ago, when starting cold the truck would misfire until it warmed up alittle, or I mashed the gas at low speed (pulling out of the neighborhood). I finally decided to investigate once it finally threw a blinking check engine light a few times this light would extinguish once the truck started running ok) BTW the truck runs perfectly once its warmed up, even if it is shut off and started warm after this.
I have HP Tuners so I hooked it up to get the code, P0300 misfire as I suspected. I also noticed that my IAT was way high, 144 *F when the truck was cold and not running. Once started it would creep down to the mid 120's. I've ran scans a half of a dozen times and its consistent. Also, after starting cold, and it starts to misfire, my LTB1's go nuts while its misfiring, so I guess something it making it think its running lean and dumping fuel into the drivers side bank? Once it warms up, everything smooths out and returns to normal, except for the IAT's (02's stay rock solid through all of this).
Hoping there was a problem with the MAF I replaced it, which seemed to help alittle but still getting a misfire and IAT's are exactly the same as before.
What do you all think? Did I possibly get a new bad MAF from the autoparts store (I got a reman). All help much appreciated, want to try to fix this and not have to take it to the shop, they will probably be stumped too and charge me a bunch for nothing.
Nate
I have an '03 Silverado SS with the 6.0. 106k miles
A couple of weeks ago, when starting cold the truck would misfire until it warmed up alittle, or I mashed the gas at low speed (pulling out of the neighborhood). I finally decided to investigate once it finally threw a blinking check engine light a few times this light would extinguish once the truck started running ok) BTW the truck runs perfectly once its warmed up, even if it is shut off and started warm after this.
I have HP Tuners so I hooked it up to get the code, P0300 misfire as I suspected. I also noticed that my IAT was way high, 144 *F when the truck was cold and not running. Once started it would creep down to the mid 120's. I've ran scans a half of a dozen times and its consistent. Also, after starting cold, and it starts to misfire, my LTB1's go nuts while its misfiring, so I guess something it making it think its running lean and dumping fuel into the drivers side bank? Once it warms up, everything smooths out and returns to normal, except for the IAT's (02's stay rock solid through all of this).
Hoping there was a problem with the MAF I replaced it, which seemed to help alittle but still getting a misfire and IAT's are exactly the same as before.
What do you all think? Did I possibly get a new bad MAF from the autoparts store (I got a reman). All help much appreciated, want to try to fix this and not have to take it to the shop, they will probably be stumped too and charge me a bunch for nothing.
Nate
09-14-2012, 06:53 AM
#4
don't know about misfire but of cours pull the valve covers and check every spring. then take time checking every coil pack and wire. Lastly , my iat's are high because my cats are clogged.
