2019 Mustang GT Spark Knock Data Log Help

[epicmilky]

I have a 2019 Mustang GT and I've been experiencing spark knock. It started back in 2021 and the dealership/engineer settled on the solution being for me to use 91 octane or better even though the engine is supposed to be designed to use 87 octane. I accepted that I wasn't going to get them to look further into the issue. However, around late last year I started to hear the knock again while using 93 octane. I waited for about 4-5 months until I was sure it was happening consistently and getting worse over time like it did while I was using 87 octane. I'm getting what I feel like is the run around at the dealership and even by the service director for the Southern Maryland Auto group. I've been looking into the issue the best I can and even have run two tanks of fuel system cleaner to see if that would help, but no joy. I have been doing some data logging with Forscan but I have no clue what I'm looking at.

I'm hoping someone here can help me understand what the log is saying. I downloaded the log from Forscan into Excel and did a little formatting for aid readability. I also added a column for minutes/seconds. In addition to this, I did audio recording from the engine compartment to go along with the data log. I tried my best to hit record on both at the same exact time, but I think they may be off by up to a second.

If anyone can help me understand if the log is telling me anything about the spark knock that I'm hearing, I would appreciate it. I hope that this log proves what I'm hearing, so I can give it to Ford and may get some help from them.

Sponsored

 

[ice445]

I looked through your log and while the knock isn't terrible or anything, it's definitely there. Seems to be pulling a degree or two of timing when you get into it. That's about what you'd expect to see on 87 octane on a hot day, definitely not what you should see with 93 octane. It should be giving you some timing. I can hear it in your video, so you aren't losing your mind. Some of that noise is just the cam phasing, but the little rattle is spark knock. I've dealt with similar issues on my car, although it's not nearly as bad as yours on the stock tune. I typically get 1-2 degrees added on 91 octane in hot weather.

Some things you can try include:
1: Replacing the spark plugs with a ruthenium/iridium heat range 7 plug that's gapped a bit tighter, like .40 or something.
While you're replacing the spark plugs, check how much carbon is covering the pistons. If your car is an oil burner this may be the crux of the problem.
2: Cleaning MAF sensor with the appropriate cleaner. Especially relevant if you have an aftermarket oiled air filter.
3: Check your long term fuel trims for any oddities. The car runs a tight electronic control and will correct for air leaks, but it seems like the smallest ones can still cause knock at part throttle before the car brings the AFR to where it needs to be. I figured this out when I had a small air leak around the throttle body when I was testing. There were no codes, but the fuel trims ended up being about 2% positive on both banks. Normally that would be fine, but at almost 5000 feet the car should be pulling fuel, not adding it. In addition I got way more knock than I normally would despite there being no evidence of anything wrong. I think because the car uses a mapped point system, it takes a long time for it to properly correct AFR in every possible instance.

That's really about all you can do. I don't know why some cars have lower tolerance for fuel than others, but I've seen a few cases on here, so you aren't the only one. The fact it's gotten worse over time is interesting though. It's worth me pointing out that this type of knock won't hurt the engine at all since it occurs at part throttle. You can probably run forever like this if you can stand the noise. Probably part of why Ford/the dealer doesn't want to do anything about it.

 

[Weyland-Yutani]

I dunno. Mine "pings" when the cylinder heads get hot, but it's faint and more like rattling BBs in a can. I get no codes. I've done stuff that ice445 mentioned and get less pinging, but the ping is always there.

This is purely anecdotal, but for what it's worth, yours does sound pretty bad. I've kind of settled into mine, but your knock would make me crazy. Have you logged cam(s) actual position vs. commanded? I want to try this on mine.

 

[epicmilky]

I dunno. Mine "pings" when the cylinder heads get hot, but it's faint and more like rattling BBs in a can. I get no codes. I've done stuff that ice445 mentioned and get less pinging, but the ping is always there.

This is purely anecdotal, but for what it's worth, yours does sound pretty bad. I've kind of settled into mine, but your knock would make me crazy. Have you logged cam(s) actual position vs. commanded? I want to try this on mine.

I took a look at what PIDs related to the CAMs I could find in FORSCAN and I added:

VTC_INTK_DSD = Variable camshaft timing intake desired angle
VCT_INT_ACT1 = Actual intake A camshaft position bank 1
VCT_INT_ACT2 = Actual intake A camshaft position bank 2

VCT_EXH_DSD = Variable camshaft timing exhaust angle desired
VCT_EXH_ACT1 = Actual Exhaust B camshaft position bank 1
VCT_EXH_ACT2 Actual Exhaust B camshaft position bank 2


Not sure what any of it means, but I drove around a bit to get some datalogs.

 

[epicmilky]

I looked through your log and while the knock isn't terrible or anything, it's definitely there. Seems to be pulling a degree or two of timing when you get into it. That's about what you'd expect to see on 87 octane on a hot day, definitely not what you should see with 93 octane. It should be giving you some timing. I can hear it in your video, so you aren't losing your mind. Some of that noise is just the cam phasing, but the little rattle is spark knock. I've dealt with similar issues on my car, although it's not nearly as bad as yours on the stock tune. I typically get 1-2 degrees added on 91 octane in hot weather.

Some things you can try include:
1: Replacing the spark plugs with a ruthenium/iridium heat range 7 plug that's gapped a bit tighter, like .40 or something.
While you're replacing the spark plugs, check how much carbon is covering the pistons. If your car is an oil burner this may be the crux of the problem.
2: Cleaning MAF sensor with the appropriate cleaner. Especially relevant if you have an aftermarket oiled air filter.
3: Check your long term fuel trims for any oddities. The car runs a tight electronic control and will correct for air leaks, but it seems like the smallest ones can still cause knock at part throttle before the car brings the AFR to where it needs to be. I figured this out when I had a small air leak around the throttle body when I was testing. There were no codes, but the fuel trims ended up being about 2% positive on both banks. Normally that would be fine, but at almost 5000 feet the car should be pulling fuel, not adding it. In addition I got way more knock than I normally would despite there being no evidence of anything wrong. I think because the car uses a mapped point system, it takes a long time for it to properly correct AFR in every possible instance.

That's really about all you can do. I don't know why some cars have lower tolerance for fuel than others, but I've seen a few cases on here, so you aren't the only one. The fact it's gotten worse over time is interesting though. It's worth me pointing out that this type of knock won't hurt the engine at all since it occurs at part throttle. You can probably run forever like this if you can stand the noise. Probably part of why Ford/the dealer doesn't want to do anything about it.

Thanks for the info. I'm still working with my local Ford dealership and Ford Customer Care. This has been a huge fight and a lot of Ford ignoring me. The local Ford service department told me they did hear back from their regional engineer. While he couldn't come out to look at the car, he directed them to do some additional testing and compare the data to another car (I think that's what they had told me). I supposedly have an appointment on September 2nd, but the service manager hasn't replied to my emails asking what specific time I should bring my car in. Hopefully, they find something or perhaps their testing will lead them to some of the things you mentioned. If this all goes bust, I'll be taking a look at the things you mentioned.

I did some more data logging to record CAM information that Weyland-Yutani mentioned in his reply, and I did observe some very audible knocking happening at much higher RPMs than I've ever noticed before. I was hearing knocking in the 3000 and 4000 RPM range and the data logs confirmed this. I filled up the tank this morning with 91 and it had just under a tank left of 93 in it when I filled up.

 

[RiotfunK]

Try some octane booster and see if it goes away.

 

[mejohn50]

Try some octane booster and see if it goes away.

Priority #1. Do this and see what happens.

I don't think it's been asked here, and I am certain I know the answer, is the car modified at all in any way? I am going to assume it's not since you are logging with Forscan and not HP Tuners or something else.

For a little context and background, the Ford OEM logic (along with many of the big name tuners) runs the car into knock using the knock sensor logic in the PCM. Ford sets the borderline ignition timing tables up for 87 octane then let the knock sensor logic add timing until it knocks, hits one of many limiters, or hits the MBT timing table values.

Ford has obviously determined that the engine can tolerate some amount of knock, to include at wide open throttle on 87 octane. Nearly all stock Mustang GTs, even on 93 ocatne, will exhibit knock at various points throughout the RPM and load range, to include part throttle and WOT. This is also even true on boosted calibrations by the big name tuners and even on near OEM-level integrated kits from Roush and Whipple.

The bottom line is these cars are frequently knocking, to include basically every single WOT pull, when stock and modified. I easily have dozens, if not hundreds, of logs both NA and boosted showing knock at all manner of RPM and load ranges.

Without more information, like logs that can be easily reviewed in HP Tuners, SCT, or PCMTEC software, I think you are chasing normal operating characteristics of the engine and engine control system.

 

[epicmilky]

Try some octane booster and see if it goes away.

It may go away with an octane booster since the initial occurrence of the spark knock happened with 87 and went away with 91/93, but I don't see that as the solution to the issue. This has been a degenerative issue where it came on very slightly with 87 and got progressively worse and then went away with higher octane fuel. Then it started very slightly with 91/93 octane and it's been getting progressively worse over the last eight months.

 

[epicmilky]

Priority #1. Do this and see what happens.

I don't think it's been asked here, and I am certain I know the answer, is the car modified at all in any way? I am going to assume it's not since you are logging with Forscan and not HP Tuners or something else.

For a little context and background, the Ford OEM logic (along with many of the big name tuners) runs the car into knock using the knock sensor logic in the PCM. Ford sets the borderline ignition timing tables up for 87 octane then let the knock sensor logic add timing until it knocks, hits one of many limiters, or hits the MBT timing table values.

Ford has obviously determined that the engine can tolerate some amount of knock, to include at wide open throttle on 87 octane. Nearly all stock Mustang GTs, even on 93 ocatne, will exhibit knock at various points throughout the RPM and load range, to include part throttle and WOT. This is also even true on boosted calibrations by the big name tuners and even on near OEM-level integrated kits from Roush and Whipple.

The bottom line is these cars are frequently knocking, to include basically every single WOT pull, when stock and modified. I easily have dozens, if not hundreds, of logs both NA and boosted showing knock at all manner of RPM and load ranges.

Without more information, like logs that can be easily reviewed in HP Tuners, SCT, or PCMTEC software, I think you are chasing normal operating characteristics of the engine and engine control system.

You are correct, I have not modified the car. What you're stating does make a little sense and since these engines will knock a little bit at least, that is probably why Ford put the statement that it is normal if the engine knocks lightly.

However, the problem is that this is an issue that gets worse over time. It didn't start happening until around 20k miles and went from very slight and barely noticeable to aggressively loud. When I switched to higher octane fuels, it completely went away (I tried my damndest to induce the knock upon switching to the higher octane fuels) and I was good for around another 20-25k miles and it started knocking again. Again, it started knocking occasionally and very lightly, but I immediately knew what the sound was. Over the last 8 months, it has been getting much worse. It knocks nearly every time I am on the throttle to some extent. Sometimes it is a slight knock and other (and more often) times it's far more aggressive.

If this were just an occasional light knock I would just live with it, but it is becoming obnoxiously loud and I'm confident that in about 6 months the knock will be as aggressively loud as if I were using 87 octane. I'm hoping the local service department in consultation with their regional Ford engineer can figure something out, but I've also been down this road before, so I'm not so confident. I may quickly be left with doing the things ice445 suggested, or just trade the car in for something new if it gets too bad.

 

[K4fxd]

Are you still in warranty? If so and if they say it's normal do some up the mountain runs......

 

[mejohn50]

You are correct, I have not modified the car. What you're stating does make a little sense and since these engines will knock a little bit at least, that is probably why Ford put the statement that it is normal if the engine knocks lightly.

However, the problem is that this is an issue that gets worse over time. It didn't start happening until around 20k miles and went from very slight and barely noticeable to aggressively loud. When I switched to higher octane fuels, it completely went away (I tried my damndest to induce the knock upon switching to the higher octane fuels) and I was good for around another 20-25k miles and it started knocking again. Again, it started knocking occasionally and very lightly, but I immediately knew what the sound was. Over the last 8 months, it has been getting much worse. It knocks nearly every time I am on the throttle to some extent. Sometimes it is a slight knock and other (and more often) times it's far more aggressive.

If this were just an occasional light knock I would just live with it, but it is becoming obnoxiously loud and I'm confident that in about 6 months the knock will be as aggressively loud as if I were using 87 octane. I'm hoping the local service department in consultation with their regional Ford engineer can figure something out, but I've also been down this road before, so I'm not so confident. I may quickly be left with doing the things ice445 suggested, or just trade the car in for something new if it gets too bad.

My personal opinion, for what it's worth, is you need more tanigble data. If it's under warranty, I would be treating the car like it's worse than a rental car until something happens.

If I were experiencing this problem, and I wanted to "solve" it, I would do the following:

- Buy something like an HP Tuners MPVI or an OBDX Pro and PCMTEC so I could data log better
- Reset keep alive memory
- Data log every single drive, with the least amount of data channels, so you can track what it's doing over time

If you can see in the logs that the knock is indeed getting worse, then maybe you're on to something. I am still leaning towards it being a normal operating characteristic of the car and you might just be getting sensitive to it.

 

[epicmilky]

Are you still in warranty? If so and if they say it's normal do some up the mountain runs......

It was under warranty when I brought it back in for this issue in May, but the service department drug this whole process out and it just dropped out of warranty earlier this month. They claim they are confident that they can get Ford to cover this issue under the warranty since there is some history of it while under warranty, but I don't trust this service manager or the service director for the auto group that I dealt with.

 

[RiotfunK]

You're getting a good amount of knock. You could buy a datalogger/tuner and log some runs and then submit them to a tuner to see what they think would be causing it and then get a tune.
Most dealers wont go that deep unless theres a CEL. And even with warranty youre lucky to get anything done, and or done correctly.

 

[K4fxd]

I'd get an extended warranty wait a month and 1000 miles then try to blow it up.

I see some tip in knock in my logs but never hear it.

 

[ice445]

I'd get an extended warranty wait a month and 1000 miles then try to blow it up.

I see some tip in knock in my logs but never hear it.

If he's getting high knock retard on wot it will blow itself up eventually for him, lol.

Personally I think there's a mechanical issue going on here. I'm curious what all the cylinders look like on a scope and what the compression numbers are

Sponsored