So, the MPV is getting a tad old. 2005. 163k miles. I have driven this vehicle nearly everyday for 13 years. I am familiar with it's nature.
Recent observations: Cooling fan stayed on after turning off the engine on a morning that wasn't particularly hot. A/C was on. Temperature gauge has been running where it always has, at just under halfway on the gauge.
Vehicle stalled at a stoplight when something "kicked in" but the idle control did not catch it in time. It has never, ever, done that before. Restart was normal, i.e. immediate.
I've been paying more attention to the idle speed. Right around 700 RPM in Drive. Yesterday, I swear it didn't move when I shifted to Neutral. Today it seemed like it went up a tick, to 800. Idle might be fluctuating a bit, where it used to be rock steady.
No miss at idle or under acceleration. Gas mileage may have dropped a bit last tankful. Might just be warmer weather and more A/C.
No CEL, no codes when I hooked up the code reader.
Engine is Mazda variant of Ford Duratec 3.0, built in Lima, OH.
So, what say ye? Vacuum leak? Idle control thingamajig? Or could it be a bad fan motor or A/C clutch drawing too much current?
Thank you for any wisdom you might impart.
*Edit: Ooops! I left the "L" out of "PUZZLER!"
For a 2005, a vacuum leak should be easily detected. If you have a scan tool, you can look at the trims to see what's going on.
But my guess is the AC system/charge. When the compressor is engaged, the fan will be on, no matter what. So i'm guessing that a low charge, and it constantly trying to do something is the source of the problem. You can get a cheap can of R134 with a gauge to see what's going on there.
IAC valve? Searching “Mazda MPV idle control valve” yields a bunch of youtube videos, so maybe it’s a common issue? Wouldn’t hurt to pull it & clean it.
Is it closely related to the duratec 3.0 in that era Ford Ranger? If so I'd guess IAC valve. Many many many miles in a ranger as a delivery driver running the AC 10 months out of the year and they would exhibit similar symptoms. Sometimes cleaning works. A vacuum leak would cause the IAC to appear to act up too, but we never had issues that way... YMMV
Good answers guys! I will pull and clean the IAC. Might even buy a new one, since 50 clams gets me the Hitachi unit that was OEM.
I do suspect the a/c may need a charge since it definitely doesn't seem to be cutting it on these hot days. Haven't noticed it cutting out though, just not blowing AS cold as it once did.
Update!
I pulled the IAC and cleaned it up with Throttle Body cleaner. It was not particularly dirty, but it's quite clean now. No change in idle quality.
It has not stalled again, but the problem persists. Idle seems to fluctuate between about 650 and 750.
Cooling fan operation is erratic. Fan will come on with the A/C, but then cut out for a time. It will also sometimes continue to run on after I shut off the engine, which it never used to do. Temperature gauge reads just below halfway, which is where it always runs.
Coolant temperature sensor? Fan relay? Suggestions?
Thanks!
Just watched a couple youtube vids on the cooling fan control module. Seems like a common failure. Pretty sure that's it. It's an easy enough fix, so I'm going to throw the part at it and see what happens.
