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| Flat Spot... https://www.ausmini.com/forums/viewtopic.php?f=5&t=1536 |
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| Author: | Lillee [ Sun Aug 15, 2004 1:13 am ] |
| Post subject: | Flat Spot... |
Hey guys, When I first baught the car, she would accelerate happily without fluttering and flat spots. Lately however I have noticed that I get a really bad "fluttering" (like a hesitation) during acceleration and a flat spot on nearly every gear at around 3000rpm? (not sure as I dun have a tacho). I am pretty sure it's not my carby, as no matter which way I tune it (rich or lean) it does this. Could it be my dissy? I am not sure if it ever worked but the vaccum advance no longer works on the dissy and I was told that this could lead to a flat spot on acceleration? Also it's noticeably noisier than usual too... Tell me what to look for and check. What does the vaccum advance actually do and why don't cooper dissys have them? Cheers! |
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| Author: | drmini in aust [ Sun Aug 15, 2004 6:41 am ] |
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When your foot is down, the vac advance does SFA. It's a part throttle economy device, nothing more, gets you maybe 5mpg better economy.. You should not have a flat spot, with or without it connected. I'd suspect the dashpot in the carb, or maybe wrong needle, or it's just adjusted too lean. When Chong brought his car up here it was like this- I made it one full turn richer and it was sweet. 
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| Author: | 68matic [ Sun Aug 15, 2004 3:53 pm ] |
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yeh after my fiasco with my pcv the dissy on my mino was tapped to try improve it. and sometimes now when you put your foot down it kinda flutters so my thing ive gotta do to him is redo the timing |
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| Author: | Lillee [ Mon Aug 16, 2004 8:09 am ] |
| Post subject: | |
I think i found out what it is! Fuel!!! I put in Mobile Synergy 8000 anf flashlube last tank (cause I couldn't find a BP) and it started to act up then. Yesterday morning I topped up on Ultimate and the problem seems to have dissapeared!  it's still not 100% but it's much much better than before... I thought Synergy 8000 was 98ron as well? so what's the difference?
I admit that I haven't tested her thoroughly but I can tell you that it was a different car on the way back from BP than it was on the way to BP... 
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| Author: | Anto [ Mon Aug 16, 2004 11:42 am ] |
| Post subject: | |
Yeah sometimes you can get a dud batch of fuel. At least I can't think of any other explanation. I always fill up with Shell Optimax, usually from the same place. However I do recall one day where the car ran like an absolute dog over about 3,500rpm which meant I had to keep it at 80km/h or below or it didn't thank me for it. Only did it for a day and then was fine, and I never figured out why. Usually I'd put it down to carb icing on the SUs part, but it wasn't that cold in the afternoon, was it? He he Dell'ortos don't ice up except that once, but that was the exception that proves the rule....
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| Author: | Lillee [ Mon Aug 16, 2004 2:05 pm ] |
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hrmm i was told not to use Optimax as it is too dense of a fuel for 4 cylinder cars. All the WRX guys use Ultimate because of that... There is a shell practically next door to me that I never make use of because of that... I still want to do the pulsar conversion 
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| Author: | Morris 1100 [ Mon Aug 16, 2004 3:20 pm ] |
| Post subject: | |
In Sydney there are only two oil refineries one is owned by Shell and the other is owned by Caltex. All the fuel comes from those two except for the imported fuel. As far as I know Mobil and BP buy their fuel from Shell. So I would not go out of my way to avoid one company over another because it all comes out of the same tank! Iwas having a problem with my Falcon about two years back, it was getting an orange coloured build up on the spark plugs. It was the additive that is used in LRP The problem was ...... I was not running LRP! I was runnning unleaded!!!! The servo was just filling his tanks with whatever he could get! I was lucky it wasn't diesel. |
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| Author: | Anto [ Mon Aug 16, 2004 3:26 pm ] |
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The only reason I use Optimax is because it is my local petrol station, and also because back when LRP was introduced apparently they were the only ones to state which VSR additive they used. I've since switched to Flashlube and Optimax, so it doesn't matter anymore. I'm sure BP and Mobil etc are fine, especially in a not so interesting A series motor, but I've paid my money and made my choice
Anto. |
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| Author: | Lillee [ Mon Aug 16, 2004 5:02 pm ] |
| Post subject: | |
Heck I will try Optimax for the next tank and see how she goes eh? 
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| Author: | drmini in aust [ Mon Aug 16, 2004 7:26 pm ] |
| Post subject: | |
BP 98 Ultimate comes from BP's Kwinana WA refinery. According to their website. They even ship from there to NZ. Mobil Synergy 8000 comes up from Melbourne. That's why distribution of these 2 fuels is a bit patchy- not all servos have it. I agree, sounds like a bad fill of fuel. It can happen but should be less likely with 98 than the other grades. |
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| Author: | drmini in aust [ Mon Aug 16, 2004 7:28 pm ] |
| Post subject: | |
68Delux wrote: Heck I will try Optimax for the next tank and see how she goes eh?
If your 1100 is stocko, you may as well use common 91 unleaded and save yer money.. compression ratio is too low for premium to really make a difference.
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| Author: | Gareth_1330 [ Mon Aug 16, 2004 7:53 pm ] |
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when i used to use LRP my plugs would be buggered in just a few hundred K's, they were covered in so much crap it was like i wasn't getting consistant spark... Sometimes i would get a batch of LRP and the car wouldn't rev past 5, it would miss from then on (motors over 100 horsies and is makes max power about 7,000 rpm, and sees it regularly)... Graham Russell who is a top engine builder reckoned BP or i think Mobil, he didn't like Optimax to much either.. I run flashlube as my additive, although the Doring fuel catalysts are quite good, Ive seen the seats of heads of motors running unleaded and one of these catalysts and there fine... They break down the long strain hydrocarbons which damage the seats to shorther strain ones which dont, at no cost to fuel quality... Flashlubes just as good but these are fit and forget, just pipe it in your fuel line after your filter and cable tie it to the bracing near the radiator
Apparently though new fuels have enzymes in them that grow and block everything up, kills the fuel of and has the side effect of making it very murky... Apparently this can happen very quickly in some cases, ie within a few weeks, our fuel situation is crap  could be worse though, could be paying at least twice as much for the same crap fuel in europe ..............I was lucky enough to have a chat with a petrochemical engineer about this the other week who happened to be in the shop (ie Minispares and Repairs, where i work). Only way i know to remedy this, and im sure theres more products and ways, but Doring also has another product, its a ball with some **** metal wrapped around it, you drop it in your tank, forget about it, and over time the metal wrapped around the ball very slowly dissolves, killing these enzymes, as far as i know flashlube doesn't solve this problem, incidentally we stock both the catalysts and "funky balls" at work
I hate sounding like a salesman.... but i do know the doring products work cos we have tested them and use them.... otherwise we wouldn't sell em
Gareth |
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| Author: | Lillee [ Mon Aug 16, 2004 11:33 pm ] |
| Post subject: | |
Yeah I heard about those inline catayst thingies might have to look into one of those. Doc: Geez man I dun mind paying $0.50 extra per tank to get 98ron into the mini! I average $12 a tank right now as I never seem to let it get too low in my tank cause my fuel gauge sender plays up
Hey Gareth might have to give you a buzz some time and talk about some work i need done to my pride and joy
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| Author: | Wombat [ Tue Aug 17, 2004 10:46 am ] |
| Post subject: | |
Sometimes condensation can build up in the tank and/ or supply tanks putting water into the fuel. I regularly (usually when prompted by rough running) add a cup of methylated spirits to a tank to clean it out - water dissolves in the metho - metho in the petrol - flushes it though the system. |
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| Author: | Anto [ Tue Aug 17, 2004 11:14 am ] |
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That's a good idea. I think previously I have had problems with condensation in the fuel system, when sometimes the car seems to run a bit rough in the morning. Condensation in the fuel tank wouldn't surpise me considering the huge condensation problem that exists in my garage (it could do with insulation!) |
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