need help with a scan tool

[Number_35]

Originally Posted By: Chester11

2007 Mazda 6i (2.3).

Yep - understand, it's an older car that I kinda like messing with. No leaks, but I did find out that the in line check valve seems slightly restricted (it sounds a bit like a trumpet and not an easy flow). It appears that I have to replace the entire hose, which is $94! Mazda parts are somewhat challenging to find, but that is crazy. I also posted on a Mazda specific forum to see if they had ideas. I would hate to make a junkyard run for a hose.

Our late great 2001 Protege was running very roughly a few years ago, and generated lots of codes. I finally found that the underside of the corrugated air intake hose (which is after the MAF sensor and before the throttle body) had cracks in it, on the underside only. The result was that air was entering and not being detected by the MAF. Duct tape was a good temporary fix, and I did replace the hose a couple of days later. This is now one of the first things I look for when faced with a rough idle. This was the Mazda 2.0, not the Duratec 2.3, but the same principle will hold.

 

[Chester11]

appreciate all the comments guys. It's not kicking out codes - even when I completely disconnect the brake boost line - which struck me as odd.

I have a tool coming to look at the fuel trims, and ordered the mount. After watching the mount in action last night, it is flexing pretty significantly - you can see it vibrate in gear.

Looking at a vacuum diagram from the shop manual, it looks like there is a small line near the intake box which runs some type of variable air damper. I've never seen the line when removing the box, so I need to run that down. (The shop manual is also for right hand drive, so who knows if the line is really there).

Good point also about the snorkel. I have taken that off several times (cleaning the throttle body, replacing the mounts) so I could have torn it slightly.

 

[Chester11]

so update time. the fuel trim data is pretty steady. Mostly single digits, with a couple blips here and there. When the vibration is felt, it shows about -0.8 to 0 on short. a small positive on long (2-3%).

in gear, if you touch the brake at idle it short does go positive on short for a few seconds, and them recovers. pumping the brake a few times can raise it to over 12 for few seconds. this could be normal, I don't know.

the O2 data is all over the place (long arching highs and lows with noise in between - not the quick up and down I expected) - even the post cat is all over.

sitting in the car for a bit - I did notice an exhaust smell - so I'm leaning toward an exhaust leak before the pre-cat sensor that the computer is adjusting for, or a blown cat. either way - beyond my skills so I'm probably going to throw in the towel.