I was curious as to what might cause a knock reading and how to narrow it down to a possible false reading. I've been running a 91 octane tune and got the datalog files which allowed me to view the knock sensors. Knock was really high, ranging from -4 to +7. I inspected the harness and the wires didn't seem to be worn through, but I fixed them up anyway. I went through the bay and zip tied whatever may have the potential to tap on the engine while running, then added royal purple octane booster to a fresh tank of 91, but I'm still having the high knock readings. The knock seems to occur at low rpm and slight acceleration but are not present at WOT. I'm trying every option before I take it in. Know anything else I could try or something that might be giving a false reading? Thank you.
Engine Knock
- Thread starter Cacuate
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krewat
SHO Member
It's interesting to note that this light-load/low-RPM is normally when an EGR equipped car would knock when the EGR wasn't working. Now, of course, this car doesn't even HAVE an EGR, but is it possible the cam phasing is slightly off without throwing a code?
What oil are you running?
(yes, this post is "out there" in terms of "normal" diagnosis, but this has tickled my curiosity)
What oil are you running?
(yes, this post is "out there" in terms of "normal" diagnosis, but this has tickled my curiosity)
EcoBoostSHO
SHO Member
Cars can definitely knock under light load conditions (Google LSPI Low Speed Pre Ignition) which can be an issue in Direct Injection. Do you have any E85 available ? If so add a gallon to about 13 gallons of 91 and see if your knock goes down. If it does it's most likely real. That said it may not be a huge deal as the knock sensors in the SHO are pretty quick to react although if it is drastically lowering your OAR it will eventually impact your WOT timing I believe which will hurt the power you are making. Who is it tuned by if I may ask?
Who are you currently tuned with? Maybe we can help you out with this issue!
Johnbigdog
SHO Member
Maybe he openwd the door becase he got sick of it knocking all the time.
Whose tune are you running? I assume 93 is not available to you? Is this right after fuelup, what does the OAR look like? How many miles on your SHO (model year?), when were the plugs last changed?[/QUOTE
91 unleashed. 93 is not available in my area2 weeks on 2 stage colder ngk plugs mobile 1 full synthetic, 69.8k miles on the 2011 sho
Choppa
SHO Member
Stands for Octane Adjust Ratio. It was an issue in my Focus ST. This is one of the parameters I always have reading on my Aeroforce gauges.
Here is a really good article explaining it: (Keep in mind the mentioned Cobb Accesport is not usable on our vehicles)
http://stratifiedauto.com/blog/unde...ons-in-your-high-performance-ecoboost-engine/
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Low speed pre ignition is not happening at light load. If you read any of the articles that come up when you google low speed pre ignition, you find that it happens at low engine speeds with high load, as a consequence of trying to get high torque out of a slowly turning little engine with lots of boost. The OP said "slight acceleration", which is not high load. Under light load, engines to not really knock, so it must be false positives.
They were temperature NGK-LTR7IX-11. I ordered the plugs when I ordered the tuner, just didn't install them until I got the datalog files and was told my knock was heavy. I read that with a tune and colder plugs spaced at .030, I would benefit. So I got colder plugs and it didn't change anything as far as knock. Definitely needed new plugs though. Also, I don't have a PID to read the OAR.
In your case, with the mods given, you don't need a colder plug at all. Stock Motorcraft SP534s will serve quite well. People are using those at 0.030 even AFTER meth injection kits are added on, and that is 400 awhp (500 crank hp) easy. The problem is not the plug, I feel, but somewhere else: fuel, pcv valve, inappropriate wastegate behavior, tuning etc. No codes 4 sure tho? Any fuel smell, either in oil or out the exhaust? Puffs of smoke (idle, WOT, etc)?
There is a custom formula for Torque Pro to calculate OAR. I see the X4 has a PID for Octane Adjust Ratio as well.
In the meantime, if you could post the datalog files prior to plug change and after plug change, we can look through them to see what might stand out. Maybe add some PIDs to monitor.
Using top tier gas (is chevron available 2 u) is highly recommended, as is full synthetic engine oil of the correct viscosity for your 2011.
Typical PIDs to monitor during a datalog
Time (sec)
accel pedal position relative|1|224|6|0
ambient air temp F|1|224|10|0
Boost in PSI|1|224|12|0
frp mpa dsd|1|224|59|0
fuel rear pressure|1|224|59|0
gear commanded|1|224|71|0
intake air temp2 F|1|224|10|0
knock Sensor|1|224|79|0
lambse bank 1|1|224|97|0
lambse bank 2|1|224|97|0
line pressure kPa|1|224|73|0
load|1|224|98|0
load absolute|1|224|98|0
long term fuel trim bank 1|1|224|86|0
long term fuel trim bank 2|1|224|86|0
measured afr bank 1|1|224|97|0
measured afr bank 2|1|224|97|0
Octane Adjust Ratio|1|224|2|0
rpm|1|224|29|0
short term fuel trim bank 1|1|224|6|0
short term fuel trim bank 2|1|224|6|0
spark advance v2|1|224|79|0
throttle angle Actual|1|224|79|0
throttle angle desired|1|224|79|0
throttle position absolute|1|224|6|0
tip prs boost kpa|1|224|73|0
tip prs boost kpa dsd|1|224|73|0
torque source|1|224|71|0
total misfires|1|224|2|0
trans fluid temp f|1|224|10|0
turbo wastegate percentage|1|224|2|0
vehicle speed mph|1|224|74|0
There is a custom formula for Torque Pro to calculate OAR. I see the X4 has a PID for Octane Adjust Ratio as well.
In the meantime, if you could post the datalog files prior to plug change and after plug change, we can look through them to see what might stand out. Maybe add some PIDs to monitor.
Using top tier gas (is chevron available 2 u) is highly recommended, as is full synthetic engine oil of the correct viscosity for your 2011.
Typical PIDs to monitor during a datalog
Time (sec)
accel pedal position relative|1|224|6|0
ambient air temp F|1|224|10|0
Boost in PSI|1|224|12|0
frp mpa dsd|1|224|59|0
fuel rear pressure|1|224|59|0
gear commanded|1|224|71|0
intake air temp2 F|1|224|10|0
knock Sensor|1|224|79|0
lambse bank 1|1|224|97|0
lambse bank 2|1|224|97|0
line pressure kPa|1|224|73|0
load|1|224|98|0
load absolute|1|224|98|0
long term fuel trim bank 1|1|224|86|0
long term fuel trim bank 2|1|224|86|0
measured afr bank 1|1|224|97|0
measured afr bank 2|1|224|97|0
Octane Adjust Ratio|1|224|2|0
rpm|1|224|29|0
short term fuel trim bank 1|1|224|6|0
short term fuel trim bank 2|1|224|6|0
spark advance v2|1|224|79|0
throttle angle Actual|1|224|79|0
throttle angle desired|1|224|79|0
throttle position absolute|1|224|6|0
tip prs boost kpa|1|224|73|0
tip prs boost kpa dsd|1|224|73|0
torque source|1|224|71|0
total misfires|1|224|2|0
trans fluid temp f|1|224|10|0
turbo wastegate percentage|1|224|2|0
vehicle speed mph|1|224|74|0
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I religiously used chevron up until i knew it was sensing knock, now I'm experimenting with Shell and sinclair. I'll upload data logs that I have when I get to my pc. And No codes have come up and I check frequently for something that might show. No smoke or oil burning that I've noticed, but it's always cold enough outside that I always see the exhaust. Any ways to check the wastegates or pcv valve?
Most of use the CSV files to share data. Unfortunately, snapshots may or may not be helpful as you do not have access to view the "running" behavior of the vehicle. You can export the logfile to CSV, then upload here, or save it to dropbox & share a public access link, for example. There is a CSV sharing site also, but I have found it a hinderance in analysis compared to having the file available to me locally.
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