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Knock Sensor Code always mean a bad Knock Sensor??

8484 Views 8 Replies 7 Participants Last post by  Califrontya

I just had my supercharger rebuilt so I thought all of my problems would go away........ no such luck. :(

I am occasionally throwing a P0505 (Idle acuator valve) and Knock Sensor code but not all of the time.

My truck starts fine but once it is warmed up and then I try to start it I must tap the gas to get it to idle or else it dies. I have read that cleaning the IACV may help that so I will try that first. Could the rough idle be causing my Knock Sensor code???

I really don't feel like tearing the S/C off again and pulling the intake for this stupid Knock Sensor but it is looking like I might not have a choice. :(

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dunno about the idle actuator valve, but some people on tunfs have had good results cleaning the plug on top of their valve cover with contact cleaner and putting some electrical grease in the plug before reassembly.
hmm are all your vacuum lines hooked up properly? how many miles are on your truck?
Hi and thanks for the replies!!

128K miles on the truck...

Funny thing is that the codes just randomly show up - not all the time... Also, I don't get the KS code when cold only after it warms up and then mostly when I am stopped - code doesn't seem to show up when moving.

Truck idles fine cold and sometime fine when warm but I shut off and restart when warm it wan't to die right away and then I get the IACV code.

I get the same codes

My 99 Frontier has been getting the same codes and I can't for the life of me figure it out.
You might want to check out the coolant temperature sensor since it seems to be engine temperature related.
During cold start, the air is bypassed around the throttle via the iacv and the engine uses a slightly different fuel if you are idling okay at startup then i think the iacv might be okay. However, you will want to check that the iacv closes after warmup. When you first start the truck, the air going into the engine will sound like a hissss.....but when the operating temp gets into range, the iacv should close and the hiss should go away.

I would also check for air leaks past the MAF sensor (which usually causes poor idling). If you have an aftermarket air filter, check the intake tube to make sure all hoses (including the small one on the bottom of the FIPK for example) are connected.

As for the Knock sensor, if it is intermittent, sounds like you make have a loose connection on the connector pins for the knock sensor (connector plug on the valve cover). The KS will not set a code unless the voltage is out of range. The voltage will not be "out of range" with a good knock sensor, even when it is sensing knock. If you get code p0328, it means the knock sensor voltage is reading high....which may indicate a loose connection on the connector pin. If you get a code p0327, that indicate a low voltage reading....which means the knock sensor is either bad or shorted to the block.
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