The “cold start” issue

A relatively minor irritation with both GBMINI#2 & #3 at various times of year:
The car is reluctant to start first thing in the morning when the engine is cold – nothing to do with the weather.
GBMINI#2 used to sometimes stall and require a second start; curiously the second start was always quick and perfectly reliable!
GBMINI#3 is improved – it just runs rough for a few seconds after taking a little longer than expected to start.

The issue has been attributed to gas formulation changes (the problem normally appears suddenly either in the spring or fall), but of course the ultimate cause is something wrong with the engine programming – even if there was something wrong with the gas, it should take the engine computer only a couple of cylinder firings to notice and take corrective action, yet GBMINI#2 occasionally would struggle for a few seconds before finally stalling!

I have read before to try a lower octane gas (lower octane is more likely to ignite so there is some logic to this). So last month I filled with Sunoco 91 instead of Sunoco 93 – the effect was instant & dramatic; next morning the car started immediately and ran smoothly. This continued through the use of the tank, and a second tank of Sunoco 91 also let the engine run well.

For a proper “scientific” test, I then switched back to Sunoco 93; after a short stop 10 minutes later it was already noticeable that the car did not re-start quite as easily, and next morning the normal cold start problem returned.

So now I am back with Sunoco 91, and the car is starting fine each morning. I have not noticed any significant difference in MPG, or available power – in fact if anything the car felt less smooth with the 93.

It will be interesting to see if the cold start issue is banished forever, or if it returns eventually …

PS: GBMINI#3 maintains a calculated MPG between 25 & 30, the higher averages being the result of longer runs – just about the same as GBMINI#2 after the JCW upgrade.

21 thoughts on “The “cold start” issue

  1. Innteresting thoughts Ian. I may have to give it a try as well. My new MCS has had the cold start stutter since new. While it has never actually stalled it’s still annoying!

  2. Did you have the shudder while parked with the A/C on, like at a stop light? If so, did the lower octane fuel correct that as well?

  3. I have not noticed any “shudder” while stopped, but I rarely use A/C anyway – when I get warm weather here, I want to enjoy it!

  4. Interesting findings Ian. I have not found 91 octane where I live so I can’t try this. But I seem to of developed a habit when starting my MCSa. I turn the key to position 2 for a few seconds then turn the car over. Seems to do the trick regardless of where or when I got the gas.

    Maybe in my car is more of the argument that the fuel pump needs to run to move fuel to the engine.

    I will be putting several hundred miles on my car in the next week or so and hope to not see the darn SES and EML lights to much.

    They seem to happen mostly when its super hot and I go over a speed bump or down a off ramp.

    Sorry to go off topic but figured it was relavant.

  5. I have the same cold start problem, and like Ian’s, its starts in the spring and fall. I have also waited a few seconds like MDSBrain and it seems to make the start a little more reliable. While I was in for my last service, MoP suggested it was the gas formulation and said to down the octane about every ½ dozen fill-ups, so as to force the computer to reset the octane calibration. 89 worked like a charm with no noticeable side effects, apart from my wallet wasn’t as light as normal after leaving the gas station 😉

  6. I did try the waiting a few seconds trick on GBMINI#2, but it never helped me – curious why it works for some cars and not for others.

  7. No cold start issues with the ’04 but the ’02 had it until MINI re-programed it.

    When I 1st got my ’04 MCS it didn’t have the stumble or any other problems but it was a cooler time of the year. I think it’s the heat out here in LA LA Land but I have been getting a slight 1st gear stumble the hotter it gets out here. My ’02 MCS never did get rid of it’s stumble.

    I have what we used to call a loading up condition while at a long signal, the car wants to stall. Only happens with A/C on and in 90Ëš+ heat and after idling for a long time.

    Can’t find any 91 in LA but if I do will try it out.

  8. Now in my second summer, mine has had cold-start issues in the summer that disappear in the winter. This summer, however, I taught myself to turn the engine on, but wait a few seconds (till some lights start going out) before I crank the starter. This allows the fuel pump to bring the lines up to proper pressure. Since I’ve been doing this I haven’t had a single cold start issue since. Not even a sputter. Within a week or two it became second nature.

  9. I am happy to see others with the cold start problem and stutter with the air on at idle in hot weather. My running stumble at idle with the air on just started this year after the emmissions recall. I have always run 93. I will try 91 next tank. Is this an issue for warantee fix? 03 MCS with SC pulley mod.

  10. My April ’05-build MCS does the cold start stumble thing. It catches quickly, but after 5 seconds will run rough and try to die, but it never does. This has happened a couple of times at a stop light, but the engine has never quit. I had it into the shop yesterday to have a couple of minor issues taken care of, and also to have this issue and generally poor performance (sluggish, feels like it’s loading up) between 2500 and 3500 RPM, especially after shifting, say from 2nd to 3rd. They put the latest firmware (v42.something) on and reset all of the “adaptations” that the computer’d learned. I still had the stumble/rough idle this morning, so that hasn’t changed. The car does feel a little smoother and slightly more powerful at low speeds, now, but that could be my imagination. The loading-up feeling still happens… I’d tried using a mid-grade of gas at one point, but I’ll give it another go after this tank.

  11. I’ve only had my MCS about three weeks, but also notice the rough running when starting in the morning. I haven’t noticed it leaving work, but then it hasn’t been exactly cool during the days here (Boston area). The gas stations I usually stop at have 89 or 93, not 91, but it may be worth a diversion.

    On my previous car (94 Ford Taurus SHO), many people had to use the trick of moving the key to on but not start and wait a bit. Or even move the key back to off and on again before starting. That usually meant your fuel filter was clogged or your fuel pump was failing (or both).

  12. I have also noticed the rough at idle. I called MoP and they told me to run 91. So, I have the UNIchip and switched it to race mode… running good now. If anyone has a UNIchip and this issue run race mode. It’s like running on a cold fall day. 🙂

  13. Yeah, RB, Indy. It has been humid, and my car doesn’t seem to like the humidity much. Unfortunately, it’s only been *not* warm and humid for like a couple of days since I’ve had the car. 😛

  14. Yesterday I was parked in 95+ heat for about 2 minutes with no rough idle and haven’t had one for about a week and LA has been running in the +90s all week. Go figure. My rough idle doesn’t seem to have any rhyme or reason.

  15. Isn’t UK gasoline 91 octane..? Maybe that explains the preference for 91..!! 😉
    I don’t have the cold start issue (at the moment) but I do have the ‘lumpy’ idle. Maybe I’ll look for 91 and see if it fixes that too.

  16. I had too had cold start problem with my 03 MCS.
    I changed the gas to octane level 87 yesterday after reading this post.
    The lowest level I could get around here.
    Thanks to you guys, this morning, it started on first try!

    I bought my MCS a month ago and now I remember this cold start problem started after I refill the gas with 92 octane level gas.

    I see some people on this post saying 91 will work, too. So, next time when my MCS needs a gas, I will fill up with 91 and see.

    My question is … is it okay keep using lower octane level of gas for a long time?

    Does anyone know?

  17. Kio,
    I would *not* recommend sticking with 87 – that is lower than the specified minimum for the car.
    If you cannot find 91, you could try filling at half a tank instead of letting it run lower, and alternating between 87 & 93; the resulting mix should be OK.

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