replaced intake manifold, now chk engine-knock sensor?
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
replaced intake manifold, now chk engine-knock sensor?
My buddy came over last night and we did a Z06 intake manifold swap. Everything went smoothly, we had the stock one off in short time...
we even had the small coolant lines and coolant block off fittings that go underneath the intake manifold (one of the lines runs to the TB). When we removed the existing one there was still pressure in the coolant line and we had the pleasure of spraying everything down with coolant!
We took our time to make sure everything was cleaned and continued with out swap. once everything was buttoned up, we went ahead and fired it up....
a few notes here: the vette' ALREADY had a z06 intake manifold on it... (as far as we can tell the z06 has the "flat" surface underneath the intake manifold in relation to the stock LS-1 intake manifold which bulges in the center). So the swap was basically pointless.
Regardless, we went for a spin, and my buddy got on it... shortly there after the check engine light came on. We went over to the local auto parts store, they hooked up the diagnostic port and told us the code was for BOTH the front and rear knock sensor?
(FYI: we also replaced the fuel filter)
any thoughts? We can certainly use the help.
we are thinking that we "might" be going lean up top... thus the reason for detonation?
we even had the small coolant lines and coolant block off fittings that go underneath the intake manifold (one of the lines runs to the TB). When we removed the existing one there was still pressure in the coolant line and we had the pleasure of spraying everything down with coolant!
We took our time to make sure everything was cleaned and continued with out swap. once everything was buttoned up, we went ahead and fired it up....
a few notes here: the vette' ALREADY had a z06 intake manifold on it... (as far as we can tell the z06 has the "flat" surface underneath the intake manifold in relation to the stock LS-1 intake manifold which bulges in the center). So the swap was basically pointless.
Regardless, we went for a spin, and my buddy got on it... shortly there after the check engine light came on. We went over to the local auto parts store, they hooked up the diagnostic port and told us the code was for BOTH the front and rear knock sensor?
(FYI: we also replaced the fuel filter)
any thoughts? We can certainly use the help.
we are thinking that we "might" be going lean up top... thus the reason for detonation?
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
BTW- the small vacuum line that is located on the back of the intake manifold was a pain to get on. "as far as i can tell" we got it on there.... but would a vacuum leak cause a knock sensor code?
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Look on the BOTTOM of your OLD C5 ZO6 intake manifold. Is there an area that is cut out to the bottom to allow the old cross over piping to remain in place and the KNOCK SENSOR wiring to fit into?? It normaly fits fine but some intakes have damaged the knock sensor wiring.
If there is a cutout on the old manifold,,,your NEW to you, ZO6 manifold doesnt have this (HOME MADE ) piping/ wiring channel area and when you installed the manifold, that knock sensor wiring could have gotten damaged/cut.
Thats the FIRST place that I would look. Once you remove it again, inspect the Knock Sensor wiring for being crushed/cut and remove the rubber plugs and MAKE sure that theres no water/moisture in the sensor wells. Also check the knock sensor connector at the back of the intake area.
Them use RTV and seal those rubber plugs in place to make them water proof! Its bad if the plugs leak and water gets into the wells.
BC
BC
If there is a cutout on the old manifold,,,your NEW to you, ZO6 manifold doesnt have this (HOME MADE ) piping/ wiring channel area and when you installed the manifold, that knock sensor wiring could have gotten damaged/cut.
Thats the FIRST place that I would look. Once you remove it again, inspect the Knock Sensor wiring for being crushed/cut and remove the rubber plugs and MAKE sure that theres no water/moisture in the sensor wells. Also check the knock sensor connector at the back of the intake area.
Them use RTV and seal those rubber plugs in place to make them water proof! Its bad if the plugs leak and water gets into the wells.
BC
BC
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
bill- the two intake manifolds are IDENTICAL. there was actually NO different between the two manifolds... when we took the existing one off and compared it to the "new to me z06" manifold. We came to the conclusion that the one on the car was already a z06 intake manifold. There was no clearance issues at all with the new manifold. We actually didn't even have to replace the coolant line in the front of the intake manifold, we just thought it was a "good idea" to replace it while we had it off.
It's inevitable, we're going to have to pull the manifold one way or the other. I figured that the wiring might not have been routed correctly, I'll double check that. I wasn't aware that the seals around the knock sensor are not water tight. I will go ahead and seal those with RTV.
I am curious to know if a few "heat cycles" will just evapurate any trace of moisture?
It's inevitable, we're going to have to pull the manifold one way or the other. I figured that the wiring might not have been routed correctly, I'll double check that. I wasn't aware that the seals around the knock sensor are not water tight. I will go ahead and seal those with RTV.
I am curious to know if a few "heat cycles" will just evapurate any trace of moisture?
Last edited by mnstrlt1; Jun 8, 2009 at 02:46 PM.
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
You either pinched the wires for the knock sensors on the install OR the connector on the bacl of the drivers cylinder head is not/poorly connected. That's where the knock sensor pigtail connects to the wiring harness.
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 3,022
Likes: 3
From: Chandler Arizona
thanks again for your help everyone. I will pull the intake, check the wiring and go from there. i.e. clean the connections, removed the rubber boots and clean around them etc.
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