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Old 05-27-2012, 08:46 PM   #1
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Default any techs? 1999 silverado help

I got a 1999 chevy silverado extended cab 4x4, has the small v-8, 4.8 liter. It wants to ping (detonate) when going wide open throttle. I have installed a new fuel pump, fuel filter, plugs and wires. We hooked up a tech2 at work and looked at the fuel trim with it running and the tech said they looked good. Then we drove it with tech2 hooked up, i nailed the throttle and he watched the tech2 and it did indeed retard the timing, so apparently the knock sensors are working.I did a carbon cleaning on it yesterday but it still pings at wide open throttle. It does a little better with premium gas but still get some pinging.
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Old 05-27-2012, 08:48 PM   #2
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forgot to mention. there are no codes being thrown.
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Old 05-29-2012, 08:50 AM   #3
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you look at the fuel pressures and or sniff the line for gas, to see if the fpr is bad?
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Old 05-30-2012, 05:58 AM   #4
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That would be the vacuum line on the FPR that Justin is talking about.
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Old 05-30-2012, 09:09 AM   #5
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Are you actually hearing the pre-detonations (pinging, sounds like popcorn popping) or is this because you know the knock sensors are pulling timing? In other words, is it possible you are getting false knock from somewhere in the drive train? If you actually hear the pinging, it is obviously not false knock.

Check the FPR like Justin suggested. There is a small diaphram inside the FPR that can rupture and reduce fuel pressure. If it ruptures, fuel will be sucked in to the vacuum line that feeds the FPR. If you pull the vacuum line off you will smell gas in it if the FPR diaphram has failed.
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Old 05-30-2012, 08:53 PM   #6
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yes, i can hear the pinging. I will check the regulator, is the regulator a common fail item on these trucks by chance?
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Old 05-31-2012, 08:37 AM   #7
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Quote:
Originally Posted by mopower440 View Post
yes, i can hear the pinging. I will check the regulator, is the regulator a common fail item on these trucks by chance?
No more a common fail on your vehicle than any other that I know of. We are only pointing to it as a possibility based on all the other things you have already addressed. Plus, its a no-cost, two minute check to see if there is a problem. Always check the easy stuff first.
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Old 06-30-2012, 05:01 PM   #8
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I had the same problem with my 1995 Blazer and it was the fuel pressure regulator and it would leak gas in the intake and detonate when I really pushed it. The regulator on the Blazer is located under the intake header which was wierd,
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