Misfire on the race car...
- alfaquad
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- Car Make: VW Touareg V6 TDI
- Car Model: Golf 2.0 8v Race Car
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Misfire on the race car...
Hey guys! Just a quick one - running a 2.0 8v on Dicktator, single coil in the race car. What would make the car have an intermittent misfire at high revs only it seems. Car idles fine and drives fine on warm-up lap then as the race starts it starts misfiring and becomes progressively worse as the race progresses. I turned into the pits after 5 laps as the miss got so bad I didn't want to risk breaking engine mounts! Car started with this at my MPC race at Zwartkops, but we sorted it by replacing a dead spark plug. Then at Midvaal it was fine in qualifying but in both race (even though we fiddled with things and replaced a the rotor) it was misfiring badly.
When checking for spark, all four plugs have proper spark - but this is only tested at idle. Think my first option is to get a new distributor cap. Cleaned mine, but think it may be cracked and I can't see it. Seems like plug 4 is wetter than the rest, leading me to believe that it's the cause of the miss. Don't think it's the coil. Will go through all the wiring (which is a bit of a mess) but my first instinct is that dizzy cap/rotor is shot.
Give me your thoughts please!
When checking for spark, all four plugs have proper spark - but this is only tested at idle. Think my first option is to get a new distributor cap. Cleaned mine, but think it may be cracked and I can't see it. Seems like plug 4 is wetter than the rest, leading me to believe that it's the cause of the miss. Don't think it's the coil. Will go through all the wiring (which is a bit of a mess) but my first instinct is that dizzy cap/rotor is shot.
Give me your thoughts please!
2007 Volkswagen Touareg 3.0 V6 TDI
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
- panic-mechanic
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Re: Misfire on the race car...
To check for spark jumping start it at night with no lights on and you'll see if there is a spark loss issue. Also check in the management what the dwell time is, maybe somebody accidentally changed it.
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
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- alfaquad
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Re: Misfire on the race car...
The weird thing is it ran 100s when we changed the rotor and cleaned the dizzy cap between race 1 and 2. Took it out the gate by Midvaal and gunned it to almost redline in 4th down the road - not one hint of a miss and it pulled damn strong. On temp and everything.panic-mechanic wrote:To check for spark jumping start it at night with no lights on and you'll see if there is a spark loss issue. Also check in the management what the dwell time is, maybe somebody accidentally changed it.
I'll check the spark tonight quick.
Think I may have a spare dizzy cap here, but can't really test the thing in the street here at revs. Plus I need to be taking my gearbox out to finally fit an LSD!
2007 Volkswagen Touareg 3.0 V6 TDI
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
- PapaJo
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Re: Misfire on the race car...
Are you using copper wire plugleads or the carbon type?
- Donavan
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Re: Misfire on the race car...
It might be fouling the plugs on cold start.
Might be a good idea just to change the temp sensor and all 4 plugs as an option of narrowing it down.
Might be a good idea just to change the temp sensor and all 4 plugs as an option of narrowing it down.
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Audi A3 8L 2.0T 20V - Race Car - viewtopic.php?f=11&t=205201
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EX: Mk 1 2 Door - 2L 16V Turbo
- panic-mechanic
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Re: Misfire on the race car...
Do not discount somebody having messed with your dickator settings. We have seen it more than once....
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
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'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10
Perfect Power dealer. I do dyno tuning.
- alfaquad
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Re: Misfire on the race car...
Didn't get round to testing the dizzy cap yet.panic-mechanic wrote:Do not discount somebody having messed with your dickator settings. We have seen it more than once....
You say the dwell timing might be off? Hmm. Why would the issue be intermittent though? Fine in quali and when testing on the road, but then acts up in the races?
2007 Volkswagen Touareg 3.0 V6 TDI
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
- panic-mechanic
- Panic's Place
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Re: Misfire on the race car...
More heat. Electrical components have more resistance the hotter they get. This the coil could be breaking up. Too little dwell will mean it can't fully charge and too much dwell will see the coil overheat.
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10
Perfect Power dealer. I do dyno tuning.
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10
Perfect Power dealer. I do dyno tuning.
- alfaquad
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- Registered for: 11 years 7 months
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Re: Misfire on the race car...
It turned out that one of the three wires going into the distributor plug had worked itself out. Luckily I had a spare plug so after wiring that up the car ran without issue again!panic-mechanic wrote:More heat. Electrical components have more resistance the hotter they get. This the coil could be breaking up. Too little dwell will mean it can't fully charge and too much dwell will see the coil overheat.
Ran the full 1-Hour Endurance at Kyalami this last weekend, besides the clutch cable stretching to the point where the clutch still worked, but not 100% about 4 laps into the race and my headlights switch burning out causing me to lose a minute cause of a quick pit repair, the car ran without skipping a beat the whole race. Gavin Ross' Challenge Class A car pipped me on the last lap of the race beating me to 1st in class by 1.8s
2007 Volkswagen Touareg 3.0 V6 TDI
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
1966 Austin Mini 1000 / 1958 Porsche 718 RSK Replica
VW Golf 2.0 8V Race Car
- panic-mechanic
- Panic's Place
- Posts: 26715
- Registered for: 21 years 7 months
- Membership No: 79
- Location: Benoni, putfontein.
Re: Misfire on the race car...
good stuff !
Stephan van Tonder - Jhb - Putfontein Benoni
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10
Perfect Power dealer. I do dyno tuning.
'05 Audi A6 3.0L TDI Avant
'09 Touareg 3l TDI
'13 VW CC 2l tdi (repair project)
'05 Touareg v10
Perfect Power dealer. I do dyno tuning.