SRT4 93tune Improvment request U7134

[duster360]

It seems that 90% of all "problems" SRT-4 users experience with the 93 Oct tune revolves around the perception that they have too much Knock Retard.

I think a very low risk improvement to the SRT-4 Predator 93 Octane tune would be to up the Knock sensor threshold to equal those of the Mopar stage PCMs.

Every MP stage PCM has the Knock sensor sensitivity "turned down" a little and has been proven over a few thousand vehicals and several years to be safe and reliable.

Many new SRT-4 Predator users experience up to 4-6 degrees of Knock retard with thier new "93 Octane tune" and are discouraged. Even though they are told 1.5-2 degrees of KR is acceptable, many insist the Knock must be 0 and can often wind up having a negative opinion of the DSP and its tune because they believe the must now pay for a custome tune.

I think this small change to the Knock tables would improve initial customer satisfaction with little to no risk to the customer's vehical reliability.

[duster360]

Examples of guys getting Knock and getting pissed off.

http://www.srtforums.com/forums/f384/kn ... on-507651/
http://www.srtforums.com/forums/f384/st ... ck-506399/
http://www.srtforums.com/forums/f384/93 ... on-506945/
http://www.srtforums.com/forums/f384/ds ... tf-482305/

[mikel]

I have not looked, but I have to imagine the sensitivity is reduced in the tunes, much as we do in the HEMI applications.

[duster360]

I have not looked, but I have to imagine the sensitivity is reduced in the tunes, much as we do in the HEMI applications.

Can you double check on your end?

On the few stock pcm +93 tune .drg files I can find, it looks like the Knock tables are stock BUT 2-3 degrees of timing is taken out from 4k-6k.

[theathleteih]

I have a stage two pcm and had knock in the 4-6k range. But I pulled 2 degrees of timing there. And now have basically 0 knk rt. Get like a blink your Eye fast -1 degr of knk rt. I was gettting -4 hold when i started tuning. But I was also very lean so pulling fuel and timing got 11.8 AFR's and that 1 degree knk rt. So i know you guys here at diablo have been getting ripped about the diablo predator, but I'm at least one who will say it works. I am on a Big turbo set up with all the trimings.

[duster360]

I have not looked, but I have to imagine the sensitivity is reduced in the tunes, much as we do in the HEMI applications.

I've checked a few more and the Knock threshold tables are deffinately left stock

[mikel]

I have not looked, but I have to imagine the sensitivity is reduced in the tunes, much as we do in the HEMI applications.

I've checked a few more and the Knock threshold tables are deffinately left stock

Interesting.

I will discuss with our tuners how they feel about reducing the sensitivity a bit...

[Letxen3]

i agree in reducing the sensitivity. what i normall do is not retard the timing, i just bite the bullet and buy 100, 105 octane fuel at the track.

[mikel]

I asked around, and the reason we did not mess with the knock sensors is because we do not add any timing inthese tunes, in fact some have a bit of timing pulled, thus we did not think it would be necessary, especially on a stock car.

The idea was if you really wanted the sensors desensitized, you'd likely be running a custom tune anyhow, and you could have the tuner set your knock thresholds however you'd like.

Thanks
Mike

[slyder]

Mike,

on a stock set up why am I and others seeing so much knock then?? Trying to resolve my 6* of knock myself. Since I am stock and the 93 tune if for newbies with stock (mostly) set up.



Hoping for some help
-Slyder

[SCGt94]

I have an srt4 coming in on friday...ill look into it guys. I see how the brian did the tables and really dont understand why the knock would even happen, so i will check it out and post up on friday. If something needs tweaking/fixing...i WILL get it done. Are these cars stock or mildly modified when you guys get the knock? I believe the car i have coming in is stock w/ 17lbs.

[SCGt94]

nevermind, it helps to read the above post. Alright good then this car SHOULD be a perfect test subject for this issue.

[slyder]

here is a video of my runs with knock



my runs with KNOCK



-Slyder

[Letxen3]

damn you global warming!

[solodogg]

A few months ago I had just the 93 tune on my car, and got a ton 5-6KR also with a 100% stock SRT. http://www.tristatecarz.com/solodogg/ds93tune.log

After having Rage play with the tune for a while, and me having to pull 4 degrees of timing to get the knock to disappear, I finally just sold the tuner, since it was doing me no good with all of that timing pulled.