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Discussion Starter #1
Hey guys, not new to the tuning world but new to the challenger in particular. My 2010 SRT8 is bone stock aside from corsa exhaust and I've noticed that even with me adding fuel and retarding timing there's always some timing being pulled by the ecu here and there throughout a pull. It seems to me that the stock knock sensor is hyper sensitive or perhaps the ecu is adding timing back in when it doesn't see knock for a moment and thus causing it's own problem. This is a problem with subarus but can be disabled as needed. The lancer evolution doesn't have that feature and knock sensor sensitivity tweaks are essential especially with upgraded valvetrain/turbos etc...

I have the diablo trinity and of course it doesn't have any knock sensor control to experiment with. Is there a guru here that's more familiar with how the stock ecu works. I'm considering going with the CRM software but don't know if it has any control either.
 

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I don't have a 6.1, but generally a lot "problems" with excessive ST and LT KR can be traced back to using poor quality gas and/or no catch can which can mean you have carbon hot-spots that are contributing to preignition. You could also have problems with oil in the intake and the oil vapor dropping the fuel's AKI which will cause pinging and KR. Do you have a catch can? How many miles on your engine?

Where are you getting your fuel? Have you tried Shell or Chevron 91 or 93?

I'd also suggest running a bottle of Chevron Techron concentrate through your engine. It works best if put through drive then sit cycles instead of burning through the entire tank at once, IMO. This is the stuff...

Amazon.com: Chevron 65740 Techron Concentrate Plus Fuel System Cleaner - 20 oz.: Automotive

Point is, you need to make sure your engine is in top shape before chasing problems with a tuner and if you say it's stock except for the exhaust then I'd be inclined to believe you have a nice pool of oil inside your intake and that your valves are all gummed up with carbon as well.

Check out this thread, it's with a 6.1L as well.

http://www.challengertalk.com/forums/f5/catch-cans-im-believer-71764/
 

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Discussion Starter #3
68k miles, no catch can unless the previous owner had one. I've tried two different 93 octane stations here, about to try a 3rd to see if it makes any real difference. I pulled up to 4* of timing across the whole rpm range, power went down and ST knock looked about the same. also richened it up to 12.0 afr across the board, same thing.
 

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Be sure you don't have any exhaust rattles, body parts rattling or drivetrain vibrations as they can cause KNKs. I have a ST KNK when shifting into 3rd that the only way I can suppress it is with water/meth but then I’m running 23 degrees of timing.
A VVT 392 can get 22 degrees of timing max on good 93 octane with .5 ST KNKs. 20 Degrees on winter blend. I’m an auto and I pull 5 degrees at shift to prevent KNKs.
Not sure about the 6.1s. Custom tunes can turn down the sensitivity of the sensors but not sure if it can be done with CMR tuning. I use a B&G ECU which is not done with CMR.
So you have a wideband? A trinity won't tell you your A/F ratios, only the trim adaptives. Your ECU will adjust the fuel trims based on the narrow bands (front 02s).
Four degrees is a bunch so sounds like you have false KNKs which could be a bad sensor or issues mentioned above. You can use a voltmeter to see which sensor is reregistering the KNK.
 

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Tuners can turn the sensors completely off but thats a dangerous move. I had that issue this weekend while dynoing. My engine had settled in on its mounts and the passenger side header was rubbing against the front sway bar. We used a welding glove to cushion it so that the tuner could tune as he did not want to turn them off.

Sent from AutoGuide.com Free App
 

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Discussion Starter #6
I'm logging both knock sensors and they pretty much agree, big volt spike and right after, knock retard kicks in. adding more timing makes it worse so I do believe it's a real issue, not phantom knock. I've had good success with seafoam on my 700awhp stealth tt and 450awhp vr4 and 790awhp evo 8 so I'll give that a try and also get a catch can on the way. I'm also almost out of shell vpower 93 which is the worst of the bunch I've tested here so far. I'm going to try another station next and see how it behaves. Most of the guys around here prefer the next station I'm talking about but I don't know if they have data to back it up or just a butt dyno reading. I prefer to rely on real data for tuning.
 

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Since you have a 2010 I would double check and make sure you have the short/stubby IAT sensor that comes with the car. Lots of people try to "upgrade" to the longer 2011+ IAT sensors which are a different voltage than the original ones for the '09s and '10s. I know this because I had the long sensor, and when getting a custom tune Johan said I was getting excessive knock. Once I swapped out the long IAT sensor back to the stock one, the knock went away.

just a thought
 

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Discussion Starter #9
odd that an intake air temp sensor would set off knock,maybe he means the incorrect sensor was showing the ecu too much heat and thus pulled timing for safety.
 

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Discussion Starter #10
tried my 3rd and final gas station, no difference, cleaned the intake system with an entire bottle of seafoam, no difference, new airfilter (needed to be done anyway) no difference.

next up:
compression test to look for a weak cylinder
adding a gallon of race gas to see if it's the fuel around here
removing a few resonators to see if it's causing to much back pressure/heat
 

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I have been chaseing timing for four years. FOUR LONG YEARS !!! lol the Hemi sucks when it comes to the knk sensors. They get alot of false knk, but the Hemi has its own issues as it is.
Without a catch can or even with a CC you will get some oil in the intake and in the fuel. Save a headache now and get TWO catch cans and run them in and out with each other. Add stainless steel pads to each catch can, will grab more oil.
Now, since its not had a CC, i will bet my paycheck you have carbon on top of the pistons. Use water / meth to remove carbon or what method you want.
Next, open your throttle body and look into the intake, you will see oil in the intake floor. Yep, bet my paycheck lol lol
Remove intake and strip down and take it to a shop that has a parts cleaner. We have a hot water degreaser in our that circulates and sprays and spins the parst being cleaned. You will need to do this. Or a car wash works too..
Then Change your plugs right away after doing all the above.
Course make sure no exhaust leaks, front end parts poping, headers hitting or even an axle being bad can resinate through the car, depending on other mods.
Then get some 93 and try it after your done and check for knk. If so still go 100 or 104 octane fuel without any octane boosters. Just race fuel, and check it from here.
I had a bend push rod that casused knk. Motor ran fine, 1150s then idle fine ect. never rattled. Once wot it heard them and set off the knk. there 98 cent pushrods stock and bend easy.
BTW CMR program runs a nice cool 5000.00 bucks lol lol SCT has tuneing software on its way, in Beta testing now
Good Luck
FlatTop
 

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Discussion Starter #12
I appreciate the advice guys. I remember having some blowby get into my FMIC on the evo which then became a massive catch can essentially. I took it off, put some gasoline inside and shook it. Rinse and repeated until she was clean. The IAT post FMIC was down considerably after a hard pull. I think the next mod for the challenger will be a catch can or three and some cleaning as advised.
 

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Discussion Starter #13
yeah that CMR software is expensive as hell but the handheld tuning rpm break points blow even worse. I'm planning a built motor/TT setup so it might be worth the investment since I prefer to do my own tuning on my cars.
 

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tried my 3rd and final gas station, no difference, cleaned the intake system with an entire bottle of seafoam, no difference, new airfilter (needed to be done anyway) no difference.

next up:
compression test to look for a weak cylinder
adding a gallon of race gas to see if it's the fuel around here
removing a few resonators to see if it's causing to much back pressure/heat
There are two tanks so I never had much luck with just adding a gallon or two of race fuel. Never seemed to get mixed up well enough to raise the octane at the track but then I only have a 1/8th of a tank of gas. Add it to 1/4 tank of gas and drive around to mix it up.
 

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Since you have a 2010 I would double check and make sure you have the short/stubby IAT sensor that comes with the car. Lots of people try to "upgrade" to the longer 2011+ IAT sensors which are a different voltage than the original ones for the '09s and '10s. I know this because I had the long sensor, and when getting a custom tune Johan said I was getting excessive knock. Once I swapped out the long IAT sensor back to the stock one, the knock went away.

just a thought
thats strange...i actually put the long sensor in my 09 and i got LESS ST knock after back to back data logs between it and the stock stubby short sensor. it was reading closer to the actual air temps is my guess. when i showed both data logs to my tuner, he said the longer sensor actually allowed for more timing during most of the WOT pulls because it wasnt heat soaked as quick.
 
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