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Location:
Adelaide
Registered:
May 2003
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 weird dyno readings (help)
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Tue, 17 June 2003 14:25
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Heya all
As the first thread which im starting in this forum i thought i would pose a little problem.
I had this dyno done yesterday
Now what im wondering is what the little flatspots on the graph are. They are too small to be gear changes, so thats ruled out.
There was also a note on my reciept which said: "NOTE: Number 1 lead is open circuit" which has stumped me. Ive tried disconnecting the number one lead and the idle definately changes.
I dont think im getting pre-detonation on Cyl1 because i cant hear anything abnormal. I hope im not anyway.
Help?
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Location:
Gold Coast
Registered:
January 2003
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Re: weird dyno readings (help)
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Tue, 17 June 2003 21:09
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leads can appear fine under no load but breakdown under load.
As for that dyno chart. There should be no gear changes in that.
It should be done in 4th gear(or which ever gear is 1:1). I have never seen a dyno chart that does not have some sort of dip or low in it before. I would not be concerned about this.
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Location:
Carlingford, Sydney
Registered:
May 2002
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Re: weird dyno readings (help)
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Wed, 18 June 2003 00:04
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that wasnt done in 4th
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Location:
Cabramatta, NSW
Registered:
May 2002
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 Re: weird dyno readings (help)
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Wed, 18 June 2003 00:10
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Topping out at 120km/h suggests it was done in 3rd gear.
Try borrowing a set of leads and sticking them on. See if you notice a difference.
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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Re: weird dyno readings (help)
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Wed, 18 June 2003 00:18
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That's a third gear run. The clues are the 2000 Nm of torque ( ) suggesting rather a lot of multiplication and the peak speed of ~120 kph. Other than that, the curve looks otherwise normal.
Why should the note on your receipt have you stumped? Didn't you pay good money to have the dyno done? Why not have a chat to the dyno guy and ask him to explain to you what he meant by that.
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Location:
Adelaide
Registered:
May 2003
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Re: weird dyno readings (help)
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Wed, 18 June 2003 00:26
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I should have made the note that that run was only to 6400rpm. But from the little test i did today it seems to be a 3rd gear run.
Probably because i dont think this gearbox has a 1:1 ratio gear.
The guy who did the test is currently sick and not at work unfortunately. Otherwise i would probably have a better understanding. Also none of the rest of the guys there can figure it out because they agree that there is still spark going to the number one cylinder.
Also i have seen graphs which have no dips or notches in them, and the possible ignition issue is worrying me slightly. The issue was pointed out by someone on another forums without them seeing the note on the reciept, which suggests to me that maybe there might be something in it.
Anyone else got a clue for me?
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: weird dyno readings (help)
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Wed, 18 June 2003 01:28
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only an engine brand new from the factory will have no flatspots, and even then it may have some.
basically, the smoother the graph, the smoother your power delivery.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Re: weird dyno readings (help)
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Wed, 18 June 2003 02:11
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I am no expert but a curve like that would indicate to me your power delivery is deffinatly less than Ideal. Bad spark caused by a dodgy lead could be a part of it and the dyno tunner would not have writen it if it were not an issue.
You may simply have some spark escaping or earthing out under load. This will result in a less than ideal burn when that cylinder fires. Lead s are not necessarily dead or alive. There is alot of in between
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I supported Toymods
Location:
I renounced punctuation
Registered:
May 2002
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I supported Toymods
Location:
Berowra-Sydney
Registered:
July 2002
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Re: Don't read too much into dynos - what does the car actually feel like?
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Wed, 18 June 2003 08:11
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I would consider this a more normal power curve and thats out of an engine 20 odd years old,
yours has problems no way the power curve should move around so much you must have some sort of ignition problem to make your graph move around so much,
i suggest you go out and buy some new leads its not expensive and the lead doesn't have to be earthing to be classed as faulty if the resistence in them is too high then that will effect engine performance as well, get new leads and try again,
and i'm sure your car has a 1:1 ratio, only reason it wouldn't is if you have changed all your gear ratio's???
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