LT Knock and ST Knock Issues at Cruising Speeds

[sharkcohen]

Thanks Mike, I'll try it out.

[txsport]

Not sure if y'all intended to fix the LT and ST knock but it is still there. I turned a corner doing about 5 to 10 mph and when i straightened out and gave it a little gas i got knock like crazy. I got 6.5 on ST and 3.5 on LT I let off gas as soon as I could.
I went back to stock tune and I can not replicate it.

ANY IDEAS?????

[RT23]

Learning more about knocks, pre ignition and detonation..... I know what a knock sounds like, and different things cause them, but seeing it on a screen is alot different. I have a 2012 Challenger RT, (345 ci) and am seeing alot of the same symptoms as some of you. Yesterday I recorded a log, some at WOT and some at highway cruising (75-85mph). I had kock fuel retard 2 deg @ 4537 RPM, same knk 4.5 deg @ 3614 RPM at 77mph. The knock fuel retard was at WOT. I had knock short term 2 deg @ 4537 RPM and at 2.5 @ 5408 RPM 72mph same knock 4.5 deg at 3684 RPM at 78 mph. I can cause the knk ST just by driving at moderate RPMs (under 1900) and applying light throttle. I drove normally this evening on the way home, no WOT and at under 1900 RPMs at about 75-80 mph and, again, applying light throttle, have ST at between .5 and 1.5 deg. I also had three misfires from the time I started my car, until I pulled in the driveway! WTH! I am using 93 oct fule (Exxon and added an octane booster) and 93 tune with throttle boost at 10. I have considered going to the lower tune and modifying, but I'm a little stubborn. I am up to + 7, 6.5 and 6 percent fuel added WOT across the board, the 7 being low end RPM and 6 high. I have an Airraid "CAI", 180 deg stat, no factory mufflers, cat only with flowmasters. I thought about adding more fuel but don't want to foul plugs. I have not adjusted the spark timing. I don't know if this helps any but here it is.

[eric.hauptman]

91 is the highest they offer in az and i won't use anything less and i won't use bad gas, haven't tried this new tune yet but I can't wait to see what results it will yield

[txsport]

My next deal is to log actual advance and see what the difference is between stock and DS tunes. Looks to me like actual timing is different between stock and DS.

[RT23]

From what I understand, the spark timing is advanced for for the tunes. Some for the 91 and more for the 93. But I don't know enough to begin to touch spark timing, I'll stay away from that for now. What I am curious about though, is I have an 85mm TB that should be here tomorrow. That, along with the change in air filter, will lean out the air fuel mixture. If I/we are seeing these knocks as is, what will it be like when I change that. As the original poster stated, his is all stock and he is seeing it.

[txsport]

Leaning it out will make it worse. It would be the same as taking fuel away in the trinity.

[RT23]

Leaning it out will make it worse. It would be the same as taking fuel away in the trinity.

Right, thats what I mean the addition of the 85mm TB along with the increased air filter will lean the fuel air mixture out more than it is now, without the TB. I just don't know how much. I'm tempted to go install the new updated tune now, test drive and see how it does.

[beachking2000]

Just curious, did any of you notice if the MDS was engaged or not??

I checked to see if the actual MDS turning on and off was causing the LT and ST knock but I didn't see/hear any correlation. I put the truck in tow/haul and still saw the LT and ST knock so its not the MDS by itself.

Hopefully some clarification will come our way soon!

Don't want no

No mine isn't from the mds.

[beachking2000]

Here is a log pre 1t09ea I will post results of the new crom sometime next week.

CW.LOG

log file

(730.69 KiB) Downloaded 234 times

[RT23]

Installed the new update and noticed that it has the feature added to disable MDS. This brings up another topic about the timing chains breaking on the 5.7 with auto trans at just before, around or after 50k miles. I have read discussion that MDS may be one of, if not the, main contributing factors. And the reasoning behind it, along with the circumstances that the posters, who say that the chains on their cars broke, do make sense. I don't belive everything I read, and take it all with a grain of salt, but if these are true, then this may help some. Most of the breaks seem to happen at highway cruising speed, when MDS is most likely active, the vehicle reaches a point, a hill or driver applies throttle, and the MDS turns off. I'm just glad I have the six speed standard.....

[mopar-srt8]

I installed the new update and it kicks ass. We have 92 octane here in WA and I used the 91 tune in My 2011 challenger srt8. I get a little st/kr .5 to 1 at part throttle at low rpm. It will roast My nitto 555 drag radials with roll on in first gear and it gets alot of rubber when I shift to second [six speed] it was 36 deg. I did some data logging on a couple of sprints but have not looked at them yet. Did 0 to 60 4.25 1/8 mile 8.17@90 evic with 1/4 tank gas.

[Peter_beresky]

I tried this update tonight and I'm pretty pleased with the results. I have a 2012 challenger rt 6 speed. My mods on the car is as follows: k&n cai, Arrington 85mm throttle body, 180 thermostat, flowmaster cat back and added a catch can last week. I still got some light knock with the 93 tune under normal driving conditions. However with the 91 tune I had 0 consistently across the board. I only use Exxon 93 octane fuel with 10 ethanol. You guys may want to try the 91 tune instead of the 93 tune. Oh and I also had the throttle boost set at 10, I've tried them all and this one seems to be the smoothest for normal driving conditions. I'm curious to see if the rest of you will see the same results after switching to the 91 tune.

[RT23]

That is very encouraging to hear Peter. Our cars are very similar, although my 85mm Tb won't be here until tomorrow. I have had some concern with installing it. I've read of some installing them and having a code. I wasn't sure if tuning would cure that problem or not. If you don't mind, could you give me your impressions/experience of the 85mm? I'd appriciate it. On the knk, on the 93 tune, have you tried adding any fuel to the tune at the three given RPM ranges? I did notice some improvement, but not enough. I started with 5% across the board as suggested by some, went up but like I said in a previous post, don't want to go too high and foul the plugs. I'm not sure how much is too much.

Just reread your post Peter and noticed that you said you had slight knock at normal driving condition. Did you have this before? I did not experience knock under normal condition, unless under 1900 RPM and throttle (not WOT) was applied.

[Peter_beresky]

I am a fan of the 85mm throttle body for our cars. I've had it on the car for about 12000 miles never have thrown a code. I gained roughly 2/10 on the 1/8 mile. My best time before the tune with my mods was 9.18 with .246 sec. reaction time (Before 85mm throttle body 9.36, .253 reaction time) in Panama City beach. My 0-60 time was 5.32. Ok now on to the fuel with 93 tune. I have tried every possible combination with up to 15%. Nothing cured it. Lowest I could get it was about .5 in first and second. 3rd and 4th is a whole other story, your looking anywhere from 2.5 to 6 knk short term. I am using the 91 with wot at 3, 3.5, 3. 0 knk in 1st and 2nd, 3 and 4 I'm seeing 1 to 1.5 in knk short term. Oh and I forgot to mention before I lowered my car 2" and I also swapped my hood to the t/a hood with mopar vent system so it does function.