My '06 Tacoma V6 was recently in the shop for some warranty work to replace a bad power steering pump. While it was there, I wanted them to fix 2 other problems. One problem is the TSB concerning the occasional hard start issue, where the engine will crank but not start until the key is switched off and I try to start it again.
The other problem I want them to fix is where carbon, mixed with moisture that is in the atmosphere (I live in Florida where the humidity is high), splatters on the paint and bumper above and behind the outlet of the factory exhaust. It has been doing this for a while, and the carbon is very hard to wash off. It seems I can never get it all off.
I have noticed quite a few Tacomas around, and most of them are clean. Although I have seen some carbon on a few, none are as bad as mine. That tells me it isn't normal.
My guess is that it is running rich, which is causing excess carbon. But the dealer found nothing wrong. The service guy said all pressures, flows, and temperatures seem normal, and that they can't find anything that would cause it.
A while back, I removed the secondary air filter (which made absolutely NO difference in how it runs, power output, or MPG). I took some spray carb cleaner and, after placing a short 2x4 between the seat and accelerator pedal to keep the engine speed up, sprayed down the intake tract.
I saw what looked like a sensor (probably MAF) that was a few inches inside the tract. I sprayed it well, concentrating on the sensor, because I do know a dirty MAF can cause issues. The previous owner had installed a K&N filter (which I replaced with a Purolator, again noticing no change in how it runs, power output or MPG), and I know that K&N filter oil can foul MAF sensors.
After using the whole can, I cleaned the carbon off the paint as good as I could. After driving it several thousand miles, the carbon is back. Not only did using the spray carb cleaner not change how it runs, power output, or MPG, it still puts out too much carbon.
Does anyone here know what could be causing the excess carbon output? I figure that IF running rich is causing it, then my MPG probably is suffering as well. I'm hoping the problem can be resolved, not just so the paint can stay clean, but so my MPG may increase, even if only by a small amount.
Anything you guys know that I can tell the dealer to look for will help.