I had a truck come into the shop unable to start, its an 08 mazda scrum. Basically what had happened was the air filter went uncleaned and became so plugged up that eventually the truck just couldnt start at all. Began the diagnosis process with the basics such as Air Filter Replaced, Spark Plugs Replaced (Checked for good compression), Fuel supply working properly, Fuses all checked good...... The truck at this point almost wants to fire up but just cant quite get over the hump.....Removed the vacuum line that attaches to the top of throttle body SEE PIC BELOW and she fired up, So this told me one thing it wasnt getting adequate air, now here is where it got kind of fun because after I got it running initially it would go the rest of the day without failure to start, it wasnt till the next morning that the hard start issue began again, so now I have a bit more information it wasnt getting enough air to start but only on the cold start.....After some research I decided that I would just pull the throttle body completely and clean the entire unit and its sensors do to the fact that the air filter was so clogged I figured it couldnt hurt to clean the rest of it.....Much to my dismay the throttle body and its sensors were thouroughly nasty to say the least.....Gave it a good cleaning and reassembled it and now the trucks wants to fire up much easier but again I only get to test that once every morning because after that initial fire up it runs like brand new the rest of the day.....Long story short keep your air filters clean and in the event you begin having a cold start issue dont just assume it will self correct or that some fuel treatment is going to fix the problem. Do yourself and your truck a favor and figure out what is wrong before you do some real damage. I decided to take a pic of the throttle body and label the parts as I was unable to find such a thing anywhere on the net before this adventure. Hopefully someone else will find this and make some use of it as well. Also if anyone see's that I have something improperly labeled please speak up and I will correct it. Also if I have left out something I should label again let me know and ill fix it. To sum this up it seems to me at this point that it was just a case of dirty parts and the IAC solenoid being ill effected most of all but if something changes and it continues to give morning fits then a new IAC solenoid will likely be in order.
