Mazda MPV: running rough @ idle

I was hoping you could help me out with an issue I'm having with my 2001 Mazda MPV.

About 4 weeks ago, it was missing badly. I took it to my mechanic and we determined that it may needed a 'tuneup'. It was on original plugs, so he changed those ($300 bucks, the labor on that is a nightmare). Anyway, got the truck back and it was running fine.

About two weeks latter I notice it missing at idle in the morning. When it warms up, it gets better, though never completely goes away. It feels like a fuel issue, maybe an injector (it reminds me a lot of how my Mazda pickup used to run before the carb rebuild)? I tried running premium and putting a tank of fuel treatment in, which makes it run better, but it still misses. I've run several tankfuls of good gas through (Phillips or Shell 91 oct) but it has stayed about the same. I did go back to a tank of 85 and it seemed to be a little worse.

Any ideas? Do you think fuel is the right track or could it be spark? I'll admit, I've become more of an armchair mechanic that last few years. But I'm not all that excited about spending more money to not fix the problem so I willing to do some digging.

Thanks!

how many miles?

I work at mazda and mpvs come in on a regular with problems like this and luckily most of all mpvs have the same parts failures so they are fairly easy to maintain.

I would need a little more description of the problem though to figure it out.

First and foremost check the pcv hose those things are notorious failures on these cars the rip and tear and cause lean conditions and usually dont even set a code.

Next i would do a power brake test and see the severity of the miss, if you can make it miss everytime no problem doing this it usually ends up being coils or spark related. Coil on plug and coil packs on these mpvs fail fairly often. This too rarely sets a code even though it happens very often.

Next check the idle air control. This is less likely to cause a miss but more likely to just cause crappy drivability. I only mention cause it is very common for the motor to fail and easy to diagnose. Just rev then car and listen for a boatlike foghorn noise coming from the intake. If it does you could use a new one of those.

The egr passages can also become blocked on these cars and need to be cleaned, this causes misses but more then likely set the MIL so keep an eye out.

Now those are just the most common failures and pretty much all MPVS ever come in here for. Great cars. But these do not take into acount your mileage and past service history, if your car has 500,000 and carbon buildup out the whazoo then none of those are gonna be your problem. So keep in mind these are just some places to look NOT the solution to your woes (or maybe they are). And yes check your fuel pressure and hold pressure. Harbor frieght sells fuel pressure gauges for like 10 bucks.

And last but not least if all else fails and you decide YOU dont want to do it, take it to the dealer for a diag. The IDS or MDS mazda specific scan tool we use has a MISFIRE check specifically for the v6 model Mpvs and 6's. Plus a whole bunch of other cool stuff that if the tech knows what hes doin he will have you in and out. Sorry to go on and on just tryin to help.

If you provide more info i MIGHT be able to help further.

Thanks for the suggestions!

Truck has 110,000. When the problem first showed up, it was throwing a code, but I don't remember exactly. I just spent the morning driving it. It was a very slight miss at idle. Once under power, it's fine.

What else can I tell you?

We had a similar issue with our '04 a couple of months back. Rough idle, patchy/twitchy acceleration... but fine, once up to speed. Did some google searches and came up with just one possibility... coils. Don't know about the '01's, but the '03 and '04 models have a tendancy to go through coils. Verified this at the local Mazda dealership. Because of the design of the engine and the lack of air circulation and poor heat evacuation, the back coil tends to go bad.

That's exactly what it was. Pita to get to, so had the dealership do the work, plus replace the rest of the coils while it was open.

Again, don't know if this is a same problem for the '01... but it might be.

Mark

the 01 model year has a coil pack not individual coil on plugs like 02 and up. But a coil pack can still fail just the same and have been known too. As far as your mileage and assuming your car is fairly well maintained, just definately look into those four ideas i gave you. could very well be the coils or maybe not. Make sure the batt and alt are good too. lemme know how that goes.