HELP po300 and po175

[svoteam]

i have a problem, about 2 weeks ago on thanksgiving i went out to my car to start it up to go to jersey to my sisters house and with in 1 minute of it running it started running really rough and the check engine light came on, i shut her off went into my house got my scanner and pulled po300 and po175 so just left the truck there and took my other one, the next day i cleared the codes started up and drove fine, but then it came back again now what i noticed is that when ever i start the car from sitting over night or for a couple of hours it will run rough and spit out po300 random misfire i dont see the po175 anymore only po300, this is the funny part if i start her up and rev the engine up to 1500 to 2000for a couple of minutes it with run fine no codes just alittle rough for about 20 sec. i dont get it while driving only on cold startups
any help thaks walt

[AROD]

Hope this helps !

http://www.obd-codes.com/p0175
http://www.obd-codes.com/p0300

A code P0175 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled
There could be a vacuum leak.
There could be a fuel pressure or delivery problem

Possible solutions include:

Inspect all vacuum and PCV hoses, replace if necessary
Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect fuel lines for cracks, leaks, or pinches
Check the fuel pressure at the fuel rail
Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.
Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)

[svoteam]

i under stand the causes but my problem is that it only happens during a cold start and if i rev the engine to 2000 for a couple mins its fine

[svoteam]

egr valve??

[Knuckles]

Originally Posted by svoteam

i under stand the causes but my problem is that it only happens during a cold start and if i rev the engine to 2000 for a couple mins its fine

Mine did something similar and I got a P0174 and it happened when I installed my 90 mm... It went away after my tuner adjusted the tune.... Have you done any work on the Rig lately? Also our rigs don't have a MAF sensor......

[AROD]

If you are only getting the misfire code then I usually start with the following checks:
-check spark plugs for damage and gap
-check coil packs ( make sure they are grounding correctly through the plug and not arcing )
-clean O2 sensors
-Clean cam position sensor

Those would be the "easy" fix's - if you still get the code I would look into
-cleaning injectors
-fuel supply ( pressure and cleanlyness )
-exhaust valve ( stuck open ? )




I dont have much experience on these engines but I have done 3 engine swaps/rebuilds on my STi .. needless to say, misfires are a crap shoot to track down.

[svoteam]

yo jose thanks again for the tcm, just got it today, not gona install till i figure this out, i will call you when im ready, only happens from a cold start and if i rev it doesnt do anything only from a normal startup it will spit po300

[svoteam]

thanks arod i will check that stuff

[Knuckles]

Originally Posted by svoteam

yo jose thanks again for the tcm, just got it today, not gona install till i figure this out, i will call you when im ready, only happens from a cold start and if i rev it doesnt do anything only from a normal startup it will spit po300

Anytime bro! Yeah same thing was happening to my Rig when it was cold..... Hopefully to find the issue....

[AROD]

Do you have an A/F Guage ?

Sounds like you are running lean on cold start up...

For what its worth, p0300 means its a random misfire.. if it was cyl. specific it would end with a 1-6