Dodge Challenger Forum banner

1 - 20 of 40 Posts

·
Registered
Joined
·
207 Posts
Discussion Starter #1
I'm hoping some folks here can chime in and give me some input.

Car: 2008 SRT8

Long story short: I have been monitoring my engine with a trinity tuner for a few days now and I'm seeing a lot of knock at the same range / throttle position. I started by monitoring the stock tune.

Essentially I'm seeing between .5-4.00 ST knock at around 40-60% throttle in the 1500-2500 RPM range. This eventually leads to LT knock of about 2.00

I then switch to the 93 CAI tune and see pretty much the same thing.

From what I understand, this isn't tune related as the trinity tunes only affect WOT fuel delivery. (Am I wrong?)

Does anyone else see this knock in this range?

Thanks


Sent from AutoGuide.com App
 

·
Registered
Joined
·
1,398 Posts
The Trinity also adjusts part throttle, you just dont have access to change it.

What octane/brand are you using? Here in Dallas Shell gas gave me a lot of knock even running the 93, I found that Chevron gives me significantly less knock. You should try out the different stations around you, run it almost empty then put in $20 worth and keep an eye on it. Find which station has the best gas around you.

Fill up a tank with 93 and buy NOS octane booster (the one that says 70 full points). This is a good way to test for false knock. If the knock is reduced/eliminated then you know its caused by the gas and not false.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #3
Thanks for the suggestion.

I currently use 93 from a station chain that carries ammoco fuel.

I adjusted the throttle booster, and adjusted some WOT fuel stages. At WOT I'm only seeing spikes of ST and not LT knock. I think I'm getting that dialed in.

As for the part throttle, I will try various gas brands as suggested.

Thanks.


Sent from AutoGuide.com App
 

·
Registered
http://www.dragtimes
Joined
·
1,899 Posts
I'm hoping some folks here can chime in and give me some input.

Car: 2008 SRT8

Long story short: I have been monitoring my engine with a trinity tuner for a few days now and I'm seeing a lot of knock at the same range / throttle position. I started by monitoring the stock tune.

Essentially I'm seeing between .5-4.00 ST knock at around 40-60% throttle in the 1500-2500 RPM range. This eventually leads to LT knock of about 2.00

I then switch to the 93 CAI tune and see pretty much the same thing.

From what I understand, this isn't tune related as the trinity tunes only affect WOT fuel delivery. (Am I wrong?)

Does anyone else see this knock in this range?

Thanks


Sent from AutoGuide.com App
Your getting ST KNKs on the stock tune under partial throttle with 93 octane fuel? Then you loaded the 93 tune and it does the same thing?

If this is the case, maybe your getting false KNKs.
Do you have headers or loud exhaust? Any parts of the exhaust rattling or hitting the chassis?
Do you have a long or short IAT sensor? I have read that some of the 5.7s 6.1s get KNKs with the long sensor.
Do you have a catch can? Oil vapors can lead to detonation.
Those are the normal culprits for partial throttle KNKs.

Are you a manual or auto? Sometimes KNKs will appear if you are in too high of a gear and load the engine excessively.
Do you have a 91 canned tune that you could load? I have seen some 392s have ST KNKs with the 93 tune but not on the 91 tune (makes sense) but I wouldn’t think you should ever get a ST KNK with the stock tune under normal engine load in any engine.
Could be a bad KNK sensor, bent pushrod, noisey lifter too.
 

·
Registered
Joined
·
1,398 Posts
Your getting ST KNKs on the stock tune under partial throttle with 93 octane fuel? Then you loaded the 93 tune and it does the same thing?

If this is the case, maybe your getting false KNKs.
Do you have headers or loud exhaust? Any parts of the exhaust rattling or hitting the chassis?
Do you have a long or short IAT sensor? I have read that some of the 5.7s 6.1s get KNKs with the long sensor.
Do you have a catch can? Oil vapors can lead to detonation.
Those are the normal culprits for partial throttle KNKs.

Are you a manual or auto? Sometimes KNKs will appear if you are in too high of a gear and load the engine excessively.
Do you have a 91 canned tune that you could load? I have seen some 392s have ST KNKs with the 93 tune but not on the 91 tune (makes sense) but I wouldn’t think you should ever get a ST KNK with the stock tune under normal engine load in any engine.
Could be a bad KNK sensor, bent pushrod, noisey lifter too.
In all of the last 4 dodge vehicles I have owned, I see St and even LT knock on stock tune running 93 octane. Im not saying its only dodge thats just the last 4 vehicles I have owned. thre are a few things I did to help but the only way I have ever totally eliminated knock was using the nos octane booster that tells me that its not false
 

·
Registered
http://www.dragtimes
Joined
·
1,899 Posts
In all of the last 4 dodge vehicles I have owned, I see St and even LT knock on stock tune running 93 octane. Im not saying its only dodge thats just the last 4 vehicles I have owned. thre are a few things I did to help but the only way I have ever totally eliminated knock was using the nos octane booster that tells me that its not false
Wow I can load my stock tune and never see a ST KNK with decent gas in the 392. Even if I load the crap out of it in 3rd at 30. (bog it)
Haven't check my 5.7s in the Jeeps to see if they do it.
I never had much luck with NOS or race gas.
Are you getting ST Fuel Retard too? I notice that the fuel retard follows the ST KNKs very closely. Still trying to learn about the ST Fuel Retard. It doesn't appear to pull fuel as my A/Fs don't change but whenever I do have a ST KNK, there is always ST Fuel Retard too. My Adapts are close meaning less than 10% so I don't have a clue what ST Fuel is.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #7
I loaded up the 91 tune and it seems to get worse but I haven't logged it for a long time yet.

I am going to restore back to stock just for comparisons, plus I have a dealer visit tomorrow. That should also out my at a 1/4 tank at which point I will try different gas.

With a modified 93 tune I got it pretty well under control. Only spiked above 2.0 every so often and hardly any LT.

I've also monitored my spark advance. Every time it picks up knock it pulls spark obviously.

At any rate I am going to keep tinkering around.


Sent from AutoGuide.com App
 

·
Registered
http://www.dragtimes
Joined
·
1,899 Posts
I loaded up the 91 tune and it seems to get worse but I haven't logged it for a long time yet.

I am going to restore back to stock just for comparisons, plus I have a dealer visit tomorrow. That should also out my at a 1/4 tank at which point I will try different gas.

With a modified 93 tune I got it pretty well under control. Only spiked above 2.0 every so often and hardly any LT.

I've also monitored my spark advance. Every time it picks up knock it pulls spark obviously.

At any rate I am going to keep tinkering around.


Sent from AutoGuide.com App
Just curious how much timing did you have to pull low, mid and high to rid the KNKs in the 93 tune at WOT?
Did you try adding any fuel?
I can run more timing with my A/F at 12:1 than I can at 12.5:1 WOT.
 

·
Registered
Joined
·
1,398 Posts
Wow I can load my stock tune and never see a ST KNK with decent gas in the 392. Even if I load the crap out of it in 3rd at 30. (bog it)
Haven't check my 5.7s in the Jeeps to see if they do it.
I never had much luck with NOS or race gas.
Are you getting ST Fuel Retard too? I notice that the fuel retard follows the ST KNKs very closely. Still trying to learn about the ST Fuel Retard. It doesn't appear to pull fuel as my A/Fs don't change but whenever I do have a ST KNK, there is always ST Fuel Retard too. My Adapts are close meaning less than 10% so I don't have a clue what ST Fuel is.
That was both the 5.7 and 3.6, with the 3.6 seeing the most KR.

If the NOS didnt at least reduce some of your knock then that would start to point towards false knock. If it at least reduced it then you can pin it down to the quality of the gas.

I did log fuel retard but came to the same conclusion you did.

Diablo says its best to add fuel before reducing timing. Also, the add fuel screen is counter intuitive. You have to dial it counter clockwise to add fuel.
 

·
Premium Member
Joined
·
6,492 Posts
The only time I saw such things with mine were when running cheap gas, I would get ST/LT KR when accelerating and while under load (hills) at cruising speed on the freeway.

When I started using better gas (I use Shell mostly, which seems to be different here in CA than in Texas) I no longer saw any LT KR and I only see slight, short bursts of ST KR when basically lugging the engine in a higher gear.

All 91/92/93 octane is not equal. Cheap fuel is cheap for a reason.

Also, if you don't have a catch can and you're getting a fair amount of oil pulled in via the PCV then this will also reduce the octane/AKI of your air/fuel mixture and will result in pulled timing if it's bad enough.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #11
I don't have an AF gauge ... Yet. I also don't have a catch can ... Yet. I will be ordering a catch can very soon (probably tomorrow from Speedlogix)

I haven't pulled timing yet. I've only added fuel. I had to go 7-8% across all ranges but still am getting knock. I am going to try adding up to 10% then start pulling timing.

I have to restore back to original for the night as I have to get an alignment at the dealer tomorrow.

The good news is, I have no KNK what so ever at cruising and light acceleration. It's really more 1/2 throttle - 3/4 throttle.

WOT seems to be easier to address than this part throttle knock.

I am down past a 1/4 tank and will try other fuels as well as octane booster.

I'll post more of my research tomorrow!


Sent from AutoGuide.com App
 

·
Registered
Joined
·
1,398 Posts
The catch can will help. If you have a few miles on it already you could remove your throttle body and check out how caked up the back of it is and see how much oil is sitting in your intake manifold. I had to clean the back of my 3.6 TB after 16k miles and it was pretty dirty already.

After you install the CC and figure out which stations around you have the better quality gas I think you will be good to go. If you want to go even further you could install a 180 thermostat to see if the lower engine temps help out.

If none of these things completely rid you of the LT then you could get a custom tune and they can eliminate it.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #13
The catch can will help. If you have a few miles on it already you could remove your throttle body and check out how caked up the back of it is and see how much oil is sitting in your intake manifold. I had to clean the back of my 3.6 TB after 16k miles and it was pretty dirty already.

After you install the CC and figure out which stations around you have the better quality gas I think you will be good to go. If you want to go even further you could install a 180 thermostat to see if the lower engine temps help out.

If none of these things completely rid you of the LT then you could get a custom tune and they can eliminate it.
I bought the car used and it has 40k on the clock. I'm sure there is oil in the intake, and I'm sure the TB could use a cleaning.

I won't go as far as to clean the intake as I really don't want to remove it, but I may take the time to take the TB off and clean it real good.

Of course, I have been thinking of doing a oversized TB .... Maybe I'll just replace it all together :)


Sent from AutoGuide.com App
 

·
Registered
Joined
·
207 Posts
Discussion Starter #14
The catch can is on it's way. Should be here Monday.

After my alignment and getting it back from the dealer, I put some different fuel in the tank and monitored against the stock tune.

On the stock tune I got hardly any knock. Nothing more than 2.0 and usually 0.

Switch to 93 tune and I get knock at all various ranges. However, I have the WOT fuel dialed in pretty well. Not a lot of knock at WOT. To clear that up I basically has to add fuel at all ranges (between 6-8.5%)

So, I am going to buy some decent octane booster and see of the knock lessens. If it does, that tells me I need to source better gas. Or, perhaps go with a step colder plugs (I'm wonder if perhaps my plugs are causing detonation)

My next step is to load up the 91 and monitor it for an extended period. It's my understanding the 91 and 93 tunes are identical aside from a couple degrees less timing with the 91.

I wish we could adjust fuel and spark across the entire range and not just wot.

I'll post results soon.


Sent from AutoGuide.com App
 

·
Registered
http://www.dragtimes
Joined
·
1,899 Posts
The catch can is on it's way. Should be here Monday.

After my alignment and getting it back from the dealer, I put some different fuel in the tank and monitored against the stock tune.

On the stock tune I got hardly any knock. Nothing more than 2.0 and usually 0.

Switch to 93 tune and I get knock at all various ranges. However, I have the WOT fuel dialed in pretty well. Not a lot of knock at WOT. To clear that up I basically has to add fuel at all ranges (between 6-8.5%)

So, I am going to buy some decent octane booster and see of the knock lessens. If it does, that tells me I need to source better gas. Or, perhaps go with a step colder plugs (I'm wonder if perhaps my plugs are causing detonation)

My next step is to load up the 91 and monitor it for an extended period. It's my understanding the 91 and 93 tunes are identical aside from a couple degrees less timing with the 91.

I wish we could adjust fuel and spark across the entire range and not just wot.

I'll post results soon.


Sent from AutoGuide.com App
On the 392s, the 91 tune has more tq mgmnt than the 93 tune. Best ET gain in a 2013 392 A5 was to load the 93 tune and remove a degree mid and high as it had 3 ST KNKs. It was actually quicker and had a higher MPH than the 91 tune with no timing pulled. Less tq mgmnt will yeild better ETs than adding/subtracting a degree of timing. Each degree is ~ 4HP so in the cases I saw ( a A5 and a M6), it was better to pull a degree on the 93 tune than to have the throttle blip at shift. Log the throttle pos. sensor and see if the 5.7s dip at shift under WOT with the 91 tune. If they don't, then your probably better off with the 91 tune. If they do, I would pull timing out of the 93 tune. If you have a CAI and catback your probably OK with adding a little fuel but don't add too much to a bone stock engine as you can get too rich real quick which will hurt your MPH as well. I never had any luck with the various octane boosters and minimal improvement with race fuel.
If your ST KNK is quick meaning it doesn't last long, it will pull less timing. When you have a ST KNK that starts at .5, then goes to 1 then back to .5, it does and will pull a degree of timing and it takes quite a bit of time to recover from the pulled timing.
Just curious, you stated that you had the WOT dialed in pretty good. Is that based on minimal ST KNKs or are you monitoring your A/Fs? Pig rich will hurt your MPH just as bad as timing being pulled.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #16
I see what you're saying. The problem isn't WOT knock. I'm not getting a lot of WOT knock. I was able to tune that in.

The problem is I'm getting knock at half throttle which isn't something I can tune out. The reason I was thinking about experimenting with the 91 is that I THOUGHT it had a slightly lower timing degree at partial throttle built into the tune. We just can't modify those ranges.




Sent from AutoGuide.com App
 

·
Registered
http://www.dragtimes
Joined
·
1,899 Posts
Timing, Throttle, Fuel pulled at shift

Here is what Tq mgmnt looks like in an A5.
 

Attachments

·
Registered
Joined
·
207 Posts
Discussion Starter #19
On the 392s, the 91 tune has more tq mgmnt than the 93 tune. Best ET gain in a 2013 392 A5 was to load the 93 tune and remove a degree mid and high as it had 3 ST KNKs. It was actually quicker and had a higher MPH than the 91 tune with no timing pulled. Less tq mgmnt will yeild better ETs than adding/subtracting a degree of timing. Each degree is ~ 4HP so in the cases I saw ( a A5 and a M6), it was better to pull a degree on the 93 tune than to have the throttle blip at shift. Log the throttle pos. sensor and see if the 5.7s dip at shift under WOT with the 91 tune. If they don't, then your probably better off with the 91 tune. If they do, I would pull timing out of the 93 tune. If you have a CAI and catback your probably OK with adding a little fuel but don't add too much to a bone stock engine as you can get too rich real quick which will hurt your MPH as well. I never had any luck with the various octane boosters and minimal improvement with race fuel.
If your ST KNK is quick meaning it doesn't last long, it will pull less timing. When you have a ST KNK that starts at .5, then goes to 1 then back to .5, it does and will pull a degree of timing and it takes quite a bit of time to recover from the pulled timing.
Just curious, you stated that you had the WOT dialed in pretty good. Is that based on minimal ST KNKs or are you monitoring your A/Fs? Pig rich will hurt your MPH just as bad as timing being pulled.
Now that I'm thinking about, you bring up an interesting point.

I may retard the timing by 1 degree and see if I can totally eliminate WOT KNK.

And to answer you're question: no I don't have an AF gauge yet. I'm strictly addressing KNKs and using that as a base. I've been told to add fuel before pulling timing, but to you're point, I'm going to try a little of both.




Sent from AutoGuide.com App
 

·
Registered
http://www.dragtimes
Joined
·
1,899 Posts
Now that I'm thinking about, you bring up an interesting point.

I may retard the timing by 1 degree and see if I can totally eliminate WOT KNK.

And to answer you're question: no I don't have an AF gauge yet. I'm strictly addressing KNKs and using that as a base. I've been told to add fuel before pulling timing, but to you're point, I'm going to try a little of both.




Sent from AutoGuide.com App
That was a less than desirable custom tune that I posted.
5% to 10% fuel thrown at it should be step one. Ideally if you could do it at a test and tune at a local track that would help as you can see what your MPH is doing.
I haven't done much logging at partial throttle so maybe what you’re seeing is the norm. I'll have to play with it sometime and see if mine has it on the stock ECU with the diablo tunes. I do a lot of trial and error tweaks on various cars at the track as they don't have a WB. I generally add fuel to quench the KNKs up to the point where we see the MPH drop off. After that, we pull a degree and lean it back out some. Lean runs mean but it also comes with a KNK penalty.
I'm trying to see if I can't keep my car in the high 11s in bad DA N/A'd. I'm running a custom tune on another ECU and fogging water/meth (mainly meth) and running a degree or two more timing to compensate for the hellish temps we get in Texas.
I usually keep the timing in the low end and keep it rich. An A5 is only in the low end coming out of the hole and most times you’re in 2nd before a ST KNK can register. If you pull any, just try the mid and high.
I'm battling a small ST KNK at 5K RPM in 3rd only. Doesn't happen in 1st or 2nd and being that it is in the low part of the high range (5K - 7K) it gripes me as it is such a quick spike of ST KNK yet I have to penalize the whole high range. More meth and a bigger nozzle may be the ticket. We'll know tonight... The higher % meth and nozzle means more wok pulling fuel to keep the A/Fs in the low 12s:1 range so we’ll see.
 
1 - 20 of 40 Posts
Top