Pilgrim

Got back from a 1,600 mile round trip to Park City, Utah last week. Spent most of the way down cruising at 75 - 80mph on I-84.

Going up a long hill in Utah the engine sputtered and bucked, so I pulled over on the shoulder cursing; it had happened here locally a year or so ago. Ambient temp was about 85 and the engine temp was centered on the gauge both times. Fuel state was about 1/2 tank of Shell premium from a high-volume station in Mountain Home, ID.

Finally, it died completely (which it had not done a year ago). Sat ten minutes, intermittently trying to start it, but looking up AAA number in cell phone list. Then it started, and ran about 1/10th of a mile and died again. Sat some more since I had lost my cellular signal and didn't feel like walking back to get it.

Then it started again after a few minutes. It was a little short of power at first, but got better every second, and after I crested the top of the hill it ran normally for the rest of the trip. I stopped in Tremonton, filled up, and dumped in some Techron, just in case. There was no apparent loss of power, and mileage at cruise speed was 19 - 20, completely normal.

Got back home just fine, actually cruising closer to 85 than to 80, with no problems at all.

What it felt like was just exactly what running out of gas, or a clogged fuel filter, or (in the old days) vapor lock feels like. I wonder if being on a medium long, steep (for the Interstate) hill has anything to do with it, like somehow unporting the fuel pickup.

Then, on Monday, I took it into the local Mazda dealer (Bob Hall, and I like 'em a lot). They kept it, saying I'd probably get it back Tuesday. Uh-uh. Their first intention (since done) was to clean the intake runners. After having read what I have here, I said "Hell, yes" when they asked. Then, at Mazda's expense, they went on to decarbon the engine. Diagnostics fail to reveal anything, so far.

They've called me twice a day to keep me up to date. The last two calls advised they've been on the horn to Mazda NA, who will report back tomorrow, and while it is not definite, they are talking about replacing the engine.

Hmmm . . . I think I like a company that will replace an engine when something is wrong and they can't find out what, but on the other hand, I'm not sure I want to have a car where the engine is, more or less, a disposable item.

Anyway, I await Mazda's pleasure on the issue.

Pilgrim

DOMINION

So your car passed the Diagnostics? and they still dont know whats wrong?
I say take it the another dealer cuz that dont sound right.

Nubo

Vapor lock/fuel starvation was what came to mind here as well. Weak pump?, clogged filter?

What was your speed and altitude up the long hill?

I'd agree with Dominion -- if they are replacing I'd sure want to know what diagnostics it's based on.

The only problem in my mind with replacement is that it will likely be a remanufactured engine. How many miles currently?

Razz1

Going up hill, is a sympton of a bad CAT.

Check it out, by removing the pipe and looking in.

Pilgrim

21,000 miles on the engine.

Got the car back with the same engine. They cleaned the intake runners and did a full de-carbon process on the mill. Said they couldn't find anything at all wrong, but that it's on record now as having had the problem (twice). Having pursued intermittent problems on Harleys and BMWs, I'm sympathetic when a shop can't find a problem that is so intermittent and throws no codes.

They had it three days and I could have had a free loaner, but I declined it. The only thing they charged me for was the oil change I asked for, so I was pleased with that.

However. . . I asked the tech how the fuel filter looked. He told me that he'd checked the fuel pressure several times and it was fine each time, so he hadn't pulled the pump to check the filter sock. I'm surprised that's all the filter there is, but apparently so. Anyway, if it happens again I'm going to hammer on them to check that first. Apropos of nothing in particular other than frustrations, one of the most maddening intermittents I ever chased was a fuel starvation on a Harley caused by a paint chip in the tank shifting around and blocking the fuel outlet from the tank on the right through a hose to the tank on the left, where the petcock was located. If the chip was in the wrong spot the left tank would run dry for a while, until, while the bike was sitting on its sidestand with me cursing by the roadside, the chip shifted and let gas flow once more.

As to the cat - I've never seen one completely strangle an engine to death, then be all right after the passage of a few minutes with no change to anything but temperature. And that would be on two occasions a year apart. But I'm sure willing to listen to a reasoned explanation for how it could be.

Pilgrim