Fuel Cut/Engine Stutter During Road Trip

[fostersafb]

So My wife and I took the MS3 from California out to our family in Colorado. One way so far, about 1400 miles. Towards the end of the trip the car started doing some weird things. I first noticed it while using cruise control, which we used for as much of the drive as possible. During normal cruising, 70mph, the car would sort of hiccup and stutter very abruptly then would be fine. It felt like fuel cut or when you start to run out of gas. So I turned off the CC and still did it. Then I thought, maybe the auto climate control could be the culprit since it cycles the A/C off and on constantly and I thought maybe there was a problem with the compressor. Also, the temperature varied from about 9 to 25 degrees while it was happening. In addition the altitude varied between 4k to 7k feet. Turning the A/C off didnt make a difference. Next I tried some different RPMs to find a possible pattern. It only seemed to happen in 4th-6th gears from low rpms. As soon as the I hit the gas it would do the fuel cut stutter then after continuing to accelerate it would just stutter and not really pull at all. To me it felt like it was running extremely rich but I'm no expert.

Is it just the ECU trying to adjust for the varying temps and altitude? If thats the case it would seem that it should be able to compensate a little more smoothly than it is.

I'm out in Colorado untill the weekend, and want to find out if I should take to a dealer out here before driving the 1400 miles back home.

TIA

 

[Moonpie.Express]

Is this the first time she has seen cold weather? I have found that as soon as the temp drop occurs, I will get that dead spot. Boost kicks in anywhere from 5 -10 psi, then it goes flat. I have downshifted then it kicks in again.

 

[fostersafb]

Is this the first time she has seen cold weather? I have found that as soon as the temp drop occurs, I will get that dead spot. Boost kicks in anywhere from 5 -10 psi, then it goes flat. I have downshifted then it kicks in again.

Pretty much, the coldest its seen prior is somewhere around 34 degress. I just got back from running to the store and a dead spot is a good way to describe it. It happened again in 4th from about 2500-4000 rpms. It just stutters then sort of vibrates and continues to stutter without seeming to make any power as the rpms increase.

Oddly enough the little town we are in just so happens to have a Mazdaspeed dealer that can check it out on friday before the drive home.

 

[fostersafb]

Ok, so I just got back from the dealership here in Pueblo, CO and still no exact diagnosis. I took one of the techs on a drive to duplicate the issue, luckily it happened a few times and even threw a CEL. Before getting back to the dealership the tech said it was definitley a missfire and may have been a bad tank of gas. The CEL was a random missfire which could be one of about 30+ possible causes. The tech ran through the list (quickly) and the only possible cause on the list he liked for it was "poor quality fuel". He suggested getting a bottle of water eater and then topping off the tank. Other than that they didnt have anything else for me.

I went ahead and grabbed a bottle of the reccomended additive and topped off the tank. I'm not sure how long it supposed to take to run through the whole system but on the way home it missfired like it had before. Hopefully it does the trick. I doubt it will work out this way but I'm hoping to be able to run the tank almost dry before refilling on the trip home.