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V8 Dakotas
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KahunaGrande
Dodge Dakota
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6/14/2005
10:57:28
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 Subject: Spark Knock after Plenum Gasket?!?!?!?!
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Message:
'99 5.2, 4x4, Auto, 110,000 miles
Replaced intake plenum gasket, intake manifold gaskets, byapass hose, upper hose, 16# pressure relief cap, cap, rotor, plug wires, PCV valve. Currently running with no t-stat but seeing normal operating temps.
Even after wasting a weekend on the plenum gasket and carefully assembling and torquing everything I am still getting the spark knock ~1800-2500RPM. Only happens when warm (~200 degrees), only when under significant load (accelerating uphill, etc.). Seems slightly less intense than before and only happens when the engine is pretty warm.
No MIL, no error codes on odometer with trip reset igntion on method. I will run by AutoZone for an OBD code download today but have had the battery disconnected recently for the plenum gasket repair. Do not appear to be consuming oil or coolant (but probably filled too recently to tell).
What else can cause the knock?
Battery is less than 18 mo's old (although the negative connection is not as tight as I would like), plugs are in good shape, new plug wires, cap and rotor. Ambient temps yesterday were high 80's low 90's, and I am at 5200 feet in Albuquerque.
Is there another possible vaccuum leak that could do this (booster, PCV, EVAP)?
Sounds to me like a timing issue (from experience with previous vehicles) but it appears I can't check\set the timing myself due to the fuel synch and other BS in the electronic distributor. Any idea what that little gem of a repair might cost?
I am at my wits end. I followed the destructions on the disassembly and reassembly, followed the torque patterns and stepping, am wondering if it is not the plenum gasket but something else.
Any help is appreciated.
John
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KahunaGrande
Dodge Dakota
JOIN HERE
6/14/2005
12:50:13
|  RE: Spark Knock after Plenum Gasket?!?!?!?!
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UPDATE:
Forgot to mention in previous posts that the only modification to the truck from stock is a K&N drop-in filter and I'm running 32x10.50x15's on stock wheels and 3.73 gears. Running 7.5mm Bosch plug wires.
Checked the OBDII at AutoZone, pulling no codes, zip, zero, nada.
Tech at AutoZone suggested it could be fuel, specifically octane, so I put in a bottle of Prestone Octane Boost with Synthetic Fuel Injector Cleaner. I shook the truck up, and drove it around for about 40 minutes.
With A\C on and at about 160 degrees temp (70's outside) I only got a little knock at WOT in 3rd\4th when really pulling going uphill, it seems to be getting better. Hate to think it is as simple as a clogged injector or too low octane but we'll see how it goes over the next day or so.
I rented a Grand Cherokee for my trip, just don't want to deal with potential failures on the road (vacation should be relaxing).
John
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daddio
Dodge Dakota
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6/14/2005
15:57:25
| RE: Spark Knock after Plenum Gasket?!?!?!?!
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Message:
have you tried a colder range spark plug?
you could also try cleaning the combustion chambers using seafoam or water. carbon buildup in the combustion chamber will add to the cause for pinging.
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