Spark Knock... why? Predator tune?
Sep 22, 2012 | 05:37 PM
#1
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Spark Knock... why? Predator tune?
2006 GMC Sierra 1500 5.3 Flex, only mod is a Spectre intake tube
44,323 miles
1843 hours
I had a Diablo Predator 87 Octane tune in until a couple weeks ago without problems. I had previously modified the transmission settings. It had been on the truck about 8 months. I decided to go back to a more factory trans setting. Reloaded with the 87 octane tune. Since then I had had some knocking issues. Thought it was fuel. Tried a tank full at another place and still have knock. I had pulled the tune back out of it and returned it to stock. Still have knock. I logged today and the Maximum Fast Spark retard was 1-4. usually get about 3-4 on part throttle spirited acceleration. I noticed that I was getting a 2 count on total misfires. Logged some more and I had cylinder 8 have a 2 count of misfires and cyinder 1 had 1. I was planning on doing a big tune up at 50K. I clean my MAF and throttle body when I change my oil. I use Castrol 5/30 and the last time I used Castrol Synthetic. About 500 miles from needing a change. I can hear the knock and it is worst when cruising in o/d and give it part throttle. Before it kicks down it knocks to a 3-4 on the retard scale. I am pretty mechanically inclined but am stumped. TIA
Can it just be I need a tune up?
Can knock make a very intermittent misfire?
The manual states not to use fuel additives, I guess due to the flex fuel sensor, but should I seafoam it to make sure it is not a carbon issue?
44,323 miles
1843 hours
I had a Diablo Predator 87 Octane tune in until a couple weeks ago without problems. I had previously modified the transmission settings. It had been on the truck about 8 months. I decided to go back to a more factory trans setting. Reloaded with the 87 octane tune. Since then I had had some knocking issues. Thought it was fuel. Tried a tank full at another place and still have knock. I had pulled the tune back out of it and returned it to stock. Still have knock. I logged today and the Maximum Fast Spark retard was 1-4. usually get about 3-4 on part throttle spirited acceleration. I noticed that I was getting a 2 count on total misfires. Logged some more and I had cylinder 8 have a 2 count of misfires and cyinder 1 had 1. I was planning on doing a big tune up at 50K. I clean my MAF and throttle body when I change my oil. I use Castrol 5/30 and the last time I used Castrol Synthetic. About 500 miles from needing a change. I can hear the knock and it is worst when cruising in o/d and give it part throttle. Before it kicks down it knocks to a 3-4 on the retard scale. I am pretty mechanically inclined but am stumped. TIA
Can it just be I need a tune up?
Can knock make a very intermittent misfire?
The manual states not to use fuel additives, I guess due to the flex fuel sensor, but should I seafoam it to make sure it is not a carbon issue?
Sep 22, 2012 | 05:43 PM
#2
Sea Foam is a Petroleum based product so I would think it would be safe to use.
If you have an audible knock then you have an issue.
Another person on here had a similar problem and it was found to be the hand held unit's tuning software.
Can you flash it back to bone stock and see if you have the same issue???
If you have an audible knock then you have an issue.
Another person on here had a similar problem and it was found to be the hand held unit's tuning software.
Can you flash it back to bone stock and see if you have the same issue???
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Sep 23, 2012 | 11:53 AM
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