Picking up knock

[Riptide]

Its usually bad fuel but false knock does happen. If it is false knock it sucks. Can be a pita to figure that one out.

If you really want to completely eliminate fuel once and for all then put 5g of race gasoline in there and log it. Check the stoich before you do it though and adjust the tune if necessary.

 

[wbt]

This has been going on for almost a year. Tried multiple gas stations, even added a can of Torco to the tank and waited until it got to half tank before another log. Same knock. I really don't think gas is the problem, if it was the Torco should have at least shown some improvement. However, I will return to stock and try that. At least that will rule out the tune.

OK. Did you buy this car new? If not maybe the previous owner had work done....specifically the trans out of the car and then back in. Make sure the harness that connects to the knock sensors has not been pinched between the bellhousing and engine.

I fixed a car having strange issues that came down to that after he had a converter installed.

 

[Rypper1]

The car was purchased new. But that isn't to say that there isn't a wire pinched from the factory. Today I plan to put the stock tune back in it and datalog. If that shows good, I will get some race fuel in it and try again. Can't put race fuel today, just filled up last night.

 

[weather man]

The car was purchased new. But that isn't to say that there isn't a wire pinched from the factory. Today I plan to put the stock tune back in it and datalog. If that shows good, I will get some race fuel in it and try again. Can't put race fuel today, just filled up last night.

Run it down as close to empty as you can and add 5 gallons 110 unleaded race gas for the test.

 

[Rypper1]

Here is a Stock tune datalog. As you can see the knock indication is still there. But it comes in later in the pull and doesn't go as high.
https://www.dropbox.com/s/s25kmqy0hy1ludt/StockDatalog.csv?dl=0

 

[Marble]

How about replacing the knock sensors?

And does the OP actually hear it or is it just on the scans? I thought I read he couldn't hear anything.

 

[Rypper1]

How about replacing the knock sensors?

And does the OP actually hear it or is it just on the scans? I thought I read he couldn't hear anything.

Actually I have been thinking about replacing the sensors. But I hate to just start blindly replacing parts.
And to answer your question, no I cant hear any knock but my hearing isn't the best. Been working in Chemical plants for over 30 years. Still, with as much as is being indicated I would think even I should be able to hear it.

 

[wbt]

Actually I have been thinking about replacing the sensors. But I hate to just start blindly replacing parts.
And to answer your question, no I cant hear any knock but my hearing isn't the best. Been working in Chemical plants for over 30 years. Still, with as much as is being indicated I would think even I should be able to hear it.

Knock is far less and correlates to less timing being commanded. Nothing in the log indicates why there is knock.
Fuel trims are good.
Knock sensors working properly.

The only thing that comes to mind is fuel. If you still have knock after draining the tank and running some good unleaded race fuel, I would need to look the car over in person for hardware issues.

How do the plugs look?

 

[Rypper1]

Knock is far less and correlates to less timing being commanded. Nothing in the log indicates why there is knock.
Fuel trims are good.
Knock sensors working properly.

The only thing that comes to mind is fuel. If you still have knock after draining the tank and running some good unleaded race fuel, I would need to look the car over in person for hardware issues.

How do the plugs look?

Not sure how the plugs look. Never pulled them. I'll have to pull and check them. The car only has 21k miles and had a lot of sitting in the garage during it's life. In the last year and a half I started using it as my daily and have put 16k on it.
One thing I noticed when I put the tune back in, when it completed installing the tune it (the sct4) restarted installation of the tune. Is that normal for the x4? Also, this morning when I was driving I heard a buzzing like something metal was rubbing. I'm gonna look underneath and see if I can locate where the sound is coming from. It only did it after the car was a full temperature so it may be exhaust rubbing somewhere. Maybe I had exhaust rub before and after the header install. Probably be Monday before I can do further testing/checking, I am working nights all weekend. Thanks for all your help wbt

 

[wbt]

Not sure how the plugs look. Never pulled them. I'll have to pull and check them. The car only has 21k miles and had a lot of sitting in the garage during it's life. In the last year and a half I started using it as my daily and have put 16k on it.
One thing I noticed when I put the tune back in, when it completed installing the tune it (the sct4) restarted installation of the tune. Is that normal for the x4? Also, this morning when I was driving I heard a buzzing like something metal was rubbing. I'm gonna look underneath and see if I can locate where the sound is coming from. It only did it after the car was a full temperature so it may be exhaust rubbing somewhere. Maybe I had exhaust rub before and after the header install. Probably be Monday before I can do further testing/checking, I am working nights all weekend. Thanks for all your help wbt

Anytime!

Exhaust rattle is the #1 cause for false knock on these cars. Keep us up2date on your findings.

 

[Riptide]

Good luck OP. I've had small degrees of positive knock show up in my data logs at the race track. Both less than a degree one was during the burnout and the other one was at the end of a pull in 3rd.

I was on race fuel at the time. My tuner, VMP, didn't seem concerned with it. Since I was on MS109 I wasn't real worried either. Whatever knock I was getting there had to be false.

 

[Rypper1]

Hopefully I can get.it figured out. It Pisses me off that the car can't perform to its potential because it is pulling timing. I was about to order a stall converter but I'm gonna wait until I get this shit figured out. Been checking the local performance shops and so far all I've found is sunoco 104.

 

[Riptide]

Sunoco 104 should do the trick. Fill up!


Sent from my iPhone using Tapatwat

 

[Rypper1]

I did get a tune update from Lund. They added 4% fuel above 3500 rpm. Haven't had a chance to try it yet due to a death in the family, actually haven't gotten a chance to burn the fuel out to add any sunoco 104.

Anyway, gonna run it tomorrow and see if the datalog looks any better with more fuel.

 

[Rypper1]

Finally got to do a little datalogging. Looks like the extra fuel above 3500 rpm helped some but I haven't found the source of the knock yet. Here are the datalogs I made today.

https://www.dropbox.com/s/lyzshakr5khedwm/datalog15.csv?dl=0

https://www.dropbox.com/s/38a24txbgd0aov9/datalog16.csv?dl=0

 

[weather man]

You have been dealing with knock for quite some time, if not false knock. If there was pitting on the pistons and/or combustion chamber, that would make knock harder to control. If you know someone with an engine scope, wouldn't be a bad idea to pop the plugs and inspect.

 

[Rypper1]

You have been dealing with knock for quite some time, if not false knock. If there was pitting on the pistons and/or combustion chamber, that would make knock harder to control. If you know someone with an engine scope, wouldn't be a bad idea to pop the plugs and inspect.

Yes, I have. But I really believe it is false knock. I haven't been able to hear it nor has anyone that has ridden with me. One of the reasons I think it is false knock is that it has been showing this since I first checked. Even with the stock tune in it and running 93 octane, it still shows. I did hear what sounded like exhaust rubbing on one of the heat shields but haven't had a chance to get it up on a rack to check. And from what I read and heard, exhaust rub is the leading cause of false knock.

Also, one thing I find curious is the pattern of the knock. It shows it picks it up and pulls timing then shows a corresponding drop in knock. So it adds timing back in but doesn't show the knock jumping right back up. Is this the normal pattern of true knock?

 

[wbt]

Knock is still out of whack and significant. Load also seems abnormally high for a N/A car. Typically this is caused by a bad MAF transfer but I am not seeing that to be the case here.

I have to fall back to my previous post:
http://www.s197forum.com/forum/showpost.php?p=2312914&postcount=28

 

[Rypper1]

Knock is still out of whack and significant. Load also seems abnormally high for a N/A car. Typically this is caused by a bad MAF transfer but I am not seeing that to be the case here.

I have to fall back to my previous post:
http://www.s197forum.com/forum/showpost.php?p=2312914&postcount=28

Yes, I agree, knock is still showing significantly high. I'm guessing the extra fuel added above 3500 rpm has a dampening affect since it isn't as high.

Those are the next two things that I plan. Might get a chance to pull plugs tomorrow but being easter I probably won't. And as soon as I get this tank burned down I plan on running some 104 in it.

Does load mean that the engine is working harder than it should to get the car moving? Sorry for the dumb questions but I know nothing on what most of these readings mean.