[Mathman]

OK, I posted a while back with a cold weather starting problem; the car would start and then die. After 2-3 starts, it would remain running, but for the first 2-3 minutes the engine would miss under acceleration. It continued through several tanks of gas, so I quickly ruled out fuel contamination.

I took it to the dealer for an inspection. They checked plugs, plug wires, ignition coils, fuel pressure, and the IMRC. None of that turned out to be the culprit. Anyone else experience this, or have any other good ideas? Here is what Mazda came up with: use 87 octane. Their theory is that the higher octane fuel isn’t being burned well enough due to the combination of altitude and temperature, and that a more volatile fuel might burn better. FYI, in the mountains 87 octane is mid-grade; the cheap stuff here is 85 octane.

Even if it works (and it’s too early to tell), I believe something is wrong. We’ve got a great fuel injection setup and the compression ratio is reasonably high, so something else must be going on… I should be able to start the car at 30 degrees F at 5,300 feet elevation with no problems.

 

[Frosty]

:dunno:

Thats the first i hear of such a problem. Down here its not as cold as in colorado, but i have had no problems with cold weather starts. Not even the canadian owners have reported problems.

I think your dealer might be on crack or something b/c it clearly says in the manual to use premium grade gasoline. So 91+ octane would be required. Since you cycled through the 87 octane tank, I would assume that you are back to 91+ octane. Otherwise, this might the cause of your problems. Stick to what it says in the manual, some dealers don't know their head from their a$$.

As for the elevation, i'm not too sure about how this will affect the engines combustion. Perhaps someone else will chime in.

 

[drzoidberg]

I am not sure about the theory but, I will share my experience. ~4900 ft elevation, temperatures ~30 F highs and ~10 F lows and none of the problems you describe. I have always run 91 octane as well. Good Luck!

 

[Mathman]

[quote author=Frosty link=topic=66401.msg1138764#msg1138764 date=1168276635]
I think your dealer might be on crack or something b/c it clearly says in the manual to use premium grade gasoline. So 91+ octane would be required. Since you cycled through the 87 octane tank, I would assume that you are back to 91+ octane. Otherwise, this might the cause of your problems. Stick to what it says in the manual, some dealers don't know their head from their a$$.
[/quote]

According to the mechanic, he was pretty much stumped. He called Mazda, and *they* recommended the 87 octane.

I just put the 87 octane in there, and I’m not sure if it’s working yet. It was 45 degrees this morning.

 

[Mathman]

[quote author=drzoidberg link=topic=66401.msg1138858#msg1138858 date=1168280188]
I am not sure about the theory but, I will share my experience. ~4900 ft elevation, temperatures ~30 F highs and ~10 F lows and none of the problems you describe. I have always run 91 octane as well. Good Luck!

[/quote]

Thanks for the info – those are very similar conditions. I think I may wait another few weeks to take it back to the dealer… maybe others will have this problem and it’ll be resolved.

So, anyone else have an idea? Should I try to get my ECU reflashed or something? It really seems like they tried the usual suspects…

 

[Boother]

I live in Calgary, which is about 3800 ft elevation and I have never had any issues with cold starts at well below 30F and I always use 91 octane.

 

[Judd]

Could it be EGR related? Rough idle at startup is often a symptom of a sticky EGR valve.

 

[GT1]

[quote author=Mathman link=topic=66401.msg1138724#msg1138724 date=1168274883]
OK, I posted a while back with a cold weather starting problem; the car would start and then die. After 2-3 starts, it would remain running, but for the first 2-3 minutes the engine would miss under acceleration. It continued through several tanks of gas, so I quickly ruled out fuel contamination.


[/quote]
When you experienced this problem, how did your car run after warming up?

Using 87 octane to fix your problem is total nonsense.

 

[Mathman]

Boother – thanks. It’s nice to know that other cars under similar conditions are working just fine.

Judd – they didn’t check the EGR valve. I plan to take it back to them in a little while, and I’ll mention that.

GT1 – until the car’s warm, it runs poorly. The engine will miss when accelerating for several minutes after startup. Once it gets near operating temp, it starts running just fine.

 

[Boother]

87 octane is not total nonsense because the higher elevation lowers the octane requirements for the engine. The higher altitude reduces the overall cylinder pressures.

It is not an EGR valve problem. If the valve was sticking, it would throw a code.

 

[GT1]

[quote author=Boother link=topic=66401.msg1139268#msg1139268 date=1168295494]
87 octane is not total nonsense because the higher elevation lowers the octane requirements for the engine. The higher altitude reduces the overall cylinder pressures.

[/quote]
If all MS3's and MS6's exhibit that problem, then Mazda needs to fix the ECU code.

If the problem is unique to his car, then the real source of the problem needs to be properly identified and corrected.

Either way, "fixing" the problem with 87 octane fuel is nonsense.

 

[dutchie3]

[quote author=Mathman link=topic=66401.msg1139252#msg1139252 date=1168295042]
Boother – thanks. It’s nice to know that other cars under similar conditions are working just fine.

Judd – they didn’t check the EGR valve. I plan to take it back to them in a little while, and I’ll mention that.

GT1 – until the car’s warm, it runs poorly. The engine will miss when accelerating for several minutes after startup. Once it gets near operating temp, it starts running just fine.

[/quote]

sounds like an ignition issue...or maybe a fuel pump