Little to no timing at speed, knocking like crazy! Help! - Pontiac G8 Forum: G8 Forums - G8Board.com
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post #1 of 22 (permalink) Old 01-11-2017, 09:31 AM Thread Starter
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Little to no timing at speed, knocking like crazy! Help!

So we've been having an issue where the car has been knocking like crazy up top and now more recently a report that the car had 2 degrees of timing at 45 mph. We have exhausted just about all possibilities that we could think of that would cause this issue, and now have turned to you guys. So the back story.....

Changed tuners and cam's, when the last cam was pulled, we discovered the car had a bent valve and a nice little impression in the top of the piston, however, the car ran completely fine with in that condition with the last cam. After the new cam was swapped in, troubles started. Decently rough idle and of course the knock up top (3-7 degrees at 4500 rpm and up). I'm not understanding how it ran fine, bent valve and all with the last cam but with the new cam, were getting headache. Any ideas?

New Cam specs 223/231 .625/.622 111+0
About .025-0.030 clipped off of the heads, stock LS3 valves.

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post #2 of 22 (permalink) Old 01-11-2017, 09:57 AM
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after the tear down on the first time finding the bent valves ,was there a piston to valve clearance check? and I would have checked the piston to valve clearance on the new cam for sure ,,,, I wouldn't run it to long in its current condition , due to more damage

kook 1 7/8 long tubes, ls3 cam,dod delete,tuning school transmission tune,cai,corsa exhaust,lowered 1",staggered wheel set 19x8.5 19x9.5 breyton gts av
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post #3 of 22 (permalink) Old 01-11-2017, 10:11 AM Thread Starter
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We should have done so, but did not, we figured it ran fine before tearing it apart, so we put it back together as is. What baffles me is the tuners comment of him seeing only 2 degrees of timing at 45 MPH, I cant put that together of how that could happen.

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post #4 of 22 (permalink) Old 01-11-2017, 11:14 AM
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Was the cam that you swapped out also aftermarket? Or was this the first cam job you've done on the car?

If it was a previous swap, did you degree it in? Did you degree the new cam in?

Always need to be sure to replace known damage parts, and new valves generally require a valve job especially when the sucker was struck and bent.

Until you properly fix your valve problem and verify that your cam meets spec and is installed properly, you can't otherwise observe to detect additional potential problems. You may want to price a full valve job to see how much it would be per cylinder. I would rather not do a single cylinder anyways, but with a single damaged seat you can probably get away with it as long as the other valves are fine.

There is no evidence of other problematic valves?

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post #5 of 22 (permalink) Old 01-11-2017, 11:49 AM
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So many variables here.

Is there audible knock?
Can you post the tune file and or the log file?
Plugged fuel injectors?
Low fuel pressure?
Plugged cats?

Lots of variables here

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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post #6 of 22 (permalink) Old 01-11-2017, 11:57 AM Thread Starter
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Fueling is fine, though fuel pressure hasn't been logged, i think my tuner would have pointed out anything else out of the ordinary. It is not necessarily an audible knock, but you can hear the car "breaking up" through the exhaust in the higher rpm's. What specifically would you like to see in the log? I can screen shot and post it up, I appreciate the help.
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post #7 of 22 (permalink) Old 01-11-2017, 12:07 PM
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Okay, it sounds like an ignition problem, and an ignition problem WILL cause KR.

Scan for current misfires on each cylinder using the Hp Tuners scan tool. Make sure the misfire tables in the tune are set to stock before doing this or the misfires will not be detected in the log!!

Keep us posted

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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post #8 of 22 (permalink) Old 01-11-2017, 02:27 PM Thread Starter
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Quote:
Originally Posted by STAGEUP View Post
Okay, it sounds like an ignition problem, and an ignition problem WILL cause KR.

Scan for current misfires on each cylinder using the Hp Tuners scan tool. Make sure the misfire tables in the tune are set to stock before doing this or the misfires will not be detected in the log!!

Keep us posted
Stock tables on both "Cylinder mode" and "SCD mode" correct? And great idea by the way, I didnt think of this.

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post #9 of 22 (permalink) Old 01-17-2017, 10:57 AM Thread Starter
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So, I finally had a chance to pull the heads, prior to doing so, I found plenty of oil around the intake ports and a decent bit inside of the parts and on top of the intake valves. This car has a catch can, that was not full, not even a little, so I'm not understanding why so much oil build up, catch can is routed like any other basic on (valley cover and driver side valve cover). I'm thinking the unburned oil getting into the combustion chambers is what could have been causing detonation and in turn knock? Any thoughts?

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post #10 of 22 (permalink) Old 01-17-2017, 11:00 AM
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Did you already check for misfires?

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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post #11 of 22 (permalink) Old 01-17-2017, 11:34 AM Thread Starter
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I did, and majority of them came from the driver side bank.

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post #12 of 22 (permalink) Old 01-17-2017, 12:20 PM
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Did you have the injectors checked? Did you try new plug wires?

Also, how is your catch can hooked up?

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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post #13 of 22 (permalink) Old 01-18-2017, 09:45 AM Thread Starter
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Injectors are good, and installed new plug wires prior to posting this thread. The catch can is hooked up via the driver side valve cover and the valley cover.

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post #14 of 22 (permalink) Old 01-18-2017, 10:38 AM
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Sounds like your catch can is hooked up incorrectly.

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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post #15 of 22 (permalink) Old 01-18-2017, 10:55 AM Thread Starter
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How should it be hooked up on these cars? Via the valley cover and where else?

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post #16 of 22 (permalink) Old 01-18-2017, 11:28 AM
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Valley cover to the vacuum port on the intake if you have a two port can

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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post #17 of 22 (permalink) Old 01-26-2017, 11:23 AM Thread Starter
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Let me ask you guys....lets say we mucked up cam timing some how and cam and crank dots were off by just one tooth....would a correlation code necessarily be thrown or would the vehicle still operate as normal?

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post #18 of 22 (permalink) Old 01-26-2017, 12:25 PM
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yes ,the engine would idle but once you accelerate you will notice power and torque is way off ,also with the cam you have shown in your first post, I would figure you would have some piston to valve contact happening ,, there would be a code associated as long as the dtc wasn't turned off by the tuner, I don't know the code number(s) off hand but ,it will be a cam/crank sensor correlation description ,,in other words the ecm is picking up from the top gear that it is not in sink with the crankshaft

with that note to that: if the oil pump wasn't removed while doing the cam swap that might be the possible issue ,, it can be hard to see the marks on the lower gear


what was the specs on the last cam?

kook 1 7/8 long tubes, ls3 cam,dod delete,tuning school transmission tune,cai,corsa exhaust,lowered 1",staggered wheel set 19x8.5 19x9.5 breyton gts av
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post #19 of 22 (permalink) Old 01-27-2017, 10:23 AM Thread Starter
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The cam that is in now, should not have PTV clearance issues....shouldn't...but there could always be that other percentage...i have something else for anyone who wants to look at it...this is a clip of the histograms from a recent log, I am wondering why the timing is negative (-) in some spots...surely this isn't knock? But why negative?
Attached Images
File Type: jpg Timing.jpg (91.8 KB, 10 views)

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post #20 of 22 (permalink) Old 01-27-2017, 10:52 AM
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We need more info.

Can you post an actual log and the tune?

PBM G8 GXP M6-Self flex fuel tune,OBX LTs, Kooks A/B, Monster Stg 3 clutch, LSA S/C, cam, fuel system, stock block and stock heads. Best e.t 10.81/ best mph 135
2007 TBSS-Self tune, bolt ons 13.06@106.7, 2,200 D.A
1991 GMC Syclone- Self tune/catback 12.8@104, 4,200ft D.A
2002 Bonneville SSEi- Self tune, 3.4" pulley, FWI. The beater
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