Hesitating and sputtering lower RPM (datalog)
02-12-2019, 12:15 PM
#17
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Re: Hesitating and sputtering lower RPM (datalog)
No. Standard plugs - NGK 4177 was recommended by my original tuner. I would like a longer life alternative to reduce the frequency of the hassle of changing them.
I never have replaced my knock sensor. Based on the knock issues noted above, should I replace it?
I never have replaced my knock sensor. Based on the knock issues noted above, should I replace it?
Last edited by BMX Dad; 02-12-2019 at 12:20 PM.
02-12-2019, 03:42 PM
#18
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Re: Hesitating and sputtering lower RPM (datalog)
Not sure why he would recommend a conventional plug for a normally aspirated application. I would try a set of NGK TR6ix iridium plugs. Not cheap, but they should last 5X as long as the ones you're using now. And those shouldn’t be worn out in 1,000 miles. We’re they fouled, or had the gap opened up? 15,000 - 20,000 miles before the correct heat range conventional plug has issues with electrode erosion.
02-12-2019, 04:36 PM
#19
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Re: Hesitating and sputtering lower RPM (datalog)
Again, I am not sure if it was the plugs or issues with the plug wires. The plug in Cylinder 1 was dirtier than the others - I would not call it fouled. I will use the iridium next time.
What about the knock sensor?
What about the knock sensor?
02-12-2019, 06:18 PM
#20
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Re: Hesitating and sputtering lower RPM (datalog)
Did you every find an LT4 knock module?
If the knock sensor had an electrical issue, it would have a code. I recall one case years ago where someone pulled the knock sensor and found a chunk of something semi-Solid in the little hole that was open to the “microphone” and caused excessive knock retard. I mentioned in the earlier thread the possibility of something rattling, but I think that was because you even had knock retard on decel. And, with the sensor located right next to the passenger side motor mount, a loose mount could cause a problem.
If the knock sensor had an electrical issue, it would have a code. I recall one case years ago where someone pulled the knock sensor and found a chunk of something semi-Solid in the little hole that was open to the “microphone” and caused excessive knock retard. I mentioned in the earlier thread the possibility of something rattling, but I think that was because you even had knock retard on decel. And, with the sensor located right next to the passenger side motor mount, a loose mount could cause a problem.
02-12-2019, 11:17 PM
#22
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Re: Hesitating and sputtering lower RPM (datalog)
Ran an EEHack data log and sent to my tuner tonight - could not attach the file to this site. Ran well but still was missing at times. See what my tuner says.
06-17-2019, 11:58 AM
#23
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Hesitating and sputtering lower RPM - Solved
Long painful process. You can see I first posted back in Feb 2019. When I was trying to troubleshoot the car, I made the wrong assumption that mechanically the top end of the build was good. As it turns out, the machine shop that told me valves were good and that they passed both a pressure test and vacuum leak test, either lied to me and did not do the tests, or I screwed up something in the build. Turns out that cylinder 8 was only at 30 lbs. compression. Shooting oil in the cylinder did not change the compression reading.
Pulled the heads off again and found a highly (Yelp) rated machine shop. They replaced all of the intake valves, repressed some loose guides and did a full valve job. Car runs great now. I mechanically passed a CA smog check this weekend, but failed due to a technicality (had the wrong sticker for my headers). Stupid state rules require me to get the correct sticker and rerun the test.
Moral of the story – Compression check, although a pain in the ***, are a necessary evil to eliminate obvious issues.
Pulled the heads off again and found a highly (Yelp) rated machine shop. They replaced all of the intake valves, repressed some loose guides and did a full valve job. Car runs great now. I mechanically passed a CA smog check this weekend, but failed due to a technicality (had the wrong sticker for my headers). Stupid state rules require me to get the correct sticker and rerun the test.
Moral of the story – Compression check, although a pain in the ***, are a necessary evil to eliminate obvious issues.
06-17-2019, 03:37 PM
#24
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Re: Hesitating and sputtering lower RPM (datalog)
Glad you got it worked out. Not sure if that problem would have shown up in the data log. Were the intake valve burned/leaking? If it was just one cylinder, could have caused MAP to read a bit higher than normal, but that may have been masked by the cam (as mentioned in post #11), or I just missed it.
06-18-2019, 09:26 AM
#25
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Re: Hesitating and sputtering lower RPM (datalog)
Glad you got it worked out. Not sure if that problem would have shown up in the data log. Were the intake valve burned/leaking? If it was just one cylinder, could have caused MAP to read a bit higher than normal, but that may have been masked by the cam (as mentioned in post #11), or I just missed it.
Thanks again for your help and advice.
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