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Offline ToniJ1960

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spark knock or predetonation?
« on: September 16, 2011, 11:18:16 PM »
 My pinto,2.3 liter 4 cyl, has started to make that rattle sound I guess its spark knock or predetonation. At night it doesnt do it,I think because the air is cooler.

 It never did it before,but I did recently redo the carb top half,so it could be running lean or leaner.Thats the only recent change I could connect it to.

 Is it likely to be that,or the cold air intake not being on it and it getting under hood air all the time?

Or would it be more likely the spark plugs are too hot? Cooling system problems?

Offline Starliner

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Re: spark knock or predetonation?
« Reply #1 on: September 17, 2011, 11:37:59 AM »
Does it run good in the evening when there is no spark knock?
If so, the fuel mixture is probably not that far off.
 
It could be the EGR valve not operating.  The EGR valve reduces spark knock under load while reducing emmissions. (The EGR introduces exhaust into the intake under load and cruise)  However, not having the EGR operating can yield more power and gas mileage. 
 
Instead of fixing the EGR I would try the following:
What fuel grade and brand are you using?
If you are running 87 I would recommend running 89. If you are using 89, use 92.  You get the idea.  Jump up one grade of fuel.
This should cure the spark knocking and give you better mileage.
That extra cost of the fuel is offset by the better mileage and power.
So it really does not cost you more in gas.
 
I bet this takes care of the problem and it will have more torque.
 
 
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Offline ToniJ1960

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Re: spark knock or predetonation?
« Reply #2 on: September 23, 2011, 10:16:33 PM »
 Richened up the mixture a little two days ago,still does it.So I bought 92 octane and theres now just a hint that it wants to do it.I really dont think I should need 92 it was always fine with 89. But I suppose for now,until I think of other things to try,ill just get the 92.