Whats up guys. Im on several other SRT forums and was reminded of this one today. heres my question. Ok, what is the most % of fuel you guys have had to add to get the knock retard to zero in the 91cai or 93cai tunes?? I just had to add 13% in all ranges in the 91cai to get the KNK to zero with an intake air temp at 75*. Also this was with a 93 octane 10% ethanol based fuel. I had to add 10% in all ranges with a 100% no ethanol fuel. Just wondering because this seems like alot but it damn sure runs better. I was seeing a max timing of 21* in the mid and high ranges. This is a 2007 CSRT8 with Mopar CAI and 180t-stat and B/T catch can.
What was your AFR with that extra 10% fuel? My buddy runs at 11.3 (according to his Predator logging, not wideband) with 0 knock and loves it.
No wideband yet. Im just going by what the KNK is telling me. I havent looked into what the Predator is telling me with the AFR but I think thats just commanded AFR and not really what you AFR is. Ill see what its telling me though.
I wouldn't lean anything out, but fattening up should be safe without a wide-band. You'll just be burning more gas.
I'd have to guess there is oil contamination if you need to add that much fuel, unless it really needs that much fuel to correct a lean condition. Thanks Mike
Agreed! Wasn't there individuals awhile back who hurt their motors adjusting the fuel tables???? Definitely need a A/F meter
I believe they were heads and cam cars and possibly more. Also heard they turned the knk sensors OFF. Mines stock with just a CAI. Im only adding fuel. Cant hurt by doing that. I know its better if I had a wideband but for now im just adjusting by what the KNK sensors are telling me. My stock tune was seeing 22* of timing with spikes of 2* KNK. The 91cai tune is seeing 20-21* with zero knk with +13% across the board fuel. I can go down to +8% fuel but I get several spikes of 2.5knk and only see 18* of timing. I believe that the 10% ethanol has a BIG part of this. Its hard to find 100% fuel where I live so im just tuning for the 10% ethanol. Maybe my car likes a ton of fuel. LOL. Like I said, it definately runs better. I have noticed when it was cooler out it didnt have anywhere near as much KNK. Since its been getting into the 90's here its just gotten worse. Hell, maybe I should make 3 different tunes. Cold weather, warm and hot. Yeah, thats real technical.:bigwink:
Your correct, I was not sure exactly what it was, but yes i remember now they turned the knock sensor off and then had the problem.
I'm running version 17, 91 CAI tune. I have catbacks, cai, and high flow cats. I added 4% fuel across the board with and AFR of 12.12 and zero knock retard and about 20-22 spark advance.
The E10 blend has some to do with it...but Mike is also correct in that the oil in your intake manifold may be causing some of it as well. I added 8 5 and 5 to the 93 cai tune and get very little KTR....as little as -1.5. My car made more power on the dyno and I ran a comfortable 12.2-12.4 A/F ratio. Here, we get Sunoco 94 octane but it has upto 10% ethanol blend in it.
Milan, what made you go with those numbers specifically? I just went with the arbitrary 4% across. In other words...what am I looking for in the graph in order to add a little here, and more there, etc!!!
Rick, I had 9 pulls on the dyno with a wideband hooked up after my cats (so the reading is a little off...probably by .2). I logged with the DiabloSport DL for KTR and some of the other parameters like Spark, RPM etc. Every time we tried adding timing, I'd see some KR....when we added fuel in increments, it kept getting better and making more power. Using SAE smoothing 5, I ended up with 401 rwhp and 419rwt. The car pulled harder and I saw a WOT A/F ratio of 12.4 after the cats. This was all done by my local dyno guy on the handheld...he's an authorized SCT tuner but was familiar with Diablo Predators. What I should have probably done was put some miles on it and returned later...I could see it needing some more fine tuning. So really, adding that much fuel just resulted in less KR and more power.
We should have a How To for "Tuning in the dark". My "Help me tune my engine" thread was supposed to be something like that but interest died pretty quickly. Some have said they see good power around 11.8:1 - 12.2:1. Others say that with the new engines you should be shooting for 12.8:1. I've sort of decided that a good method to tune without a dyno (and without CMR) is to pick an a/f and then adjust timing to get the knock where you want it. I was going for 12.2:1. Added fuel to the CAI 91 Oct tune until I got it as close to 12.2:1 through the entire rpm range (through a 1/4 mile run). I was seeing pretty consistent knock retard on the order of 3 to 5 degrees pretty much thoughout. Then I started pulling timing until the knock went to zero all the way though and then added 1* back. This left me with a couple of knock retard bumps at a couple of rpm spots in 2nd and 3rd gear so I added one step more fuel in the mid and upper rpm ranges. Now we're running 12.2 to 12.4 in the low rpm range, 11.8 to 12.0 in the mid rpm range and 12.2 in the upper range. Who knows if I'm getting the best power? Probably not but it is faster and I feel real good about it and I think I'm on the conservative side and I'm having priceless amounts of fun tinkering with it myself. Maybe I could get more power with a different a/f and the appropriate timing. The Predator doesn't give you access to everything and you don't get a lot of granularity. You don't have a wideband... so I think what you should do is add fuel until you get the knock retard where you want it. In general it's ok to see some bumps around shifts, when you first put your foot down and when you take your foot out of it. If you think you've added a shitload of fuel then start pulling timing a degree at a time. End result is that I've decided "if it isn't knocking you aren't doing any damage". I think you need a dyno with a/f to tune for optimum power. Since a lot of people ended up around the low 12's, if you tune the best you can for that then you're probably doing "ok". You already got a tune right? and then you added cats? So you might need a bit more fuel assuming the cats are working. The tune was good before so I think you should look for knock and add some fuel to eliminate it or get it back where it was with your original tune. You did pay attention when you got the tune and have some logs of the pertinent information?
I asked a question on that thread and you told me this thread was specifically for you....so I STF'dU!!! lol As for the tune. I have 0 knock retard up until 5k rpms where it goes to -2 until it shifts at 6600rpms. Thanks for the explanation as always buddy!!
Rick I have the same KR on my Jeep with an A/F from 12.2-12.8 with my B&G nitrous tune...Should I worry about .5 - 2.0 of KR ???
I did not. I just said I'd be a good example of the majority. hmmm, wasn't your 1 liner something like "what predator does logging? and how do I do it?".... I didn't answer it at all. So there. Now you managed to weasel an entire How To on it out of me :dumb: That's cool. Smooth all the way across is easier to deal with than bumps at particular rpms. Add an increment of fuel in the high rpm range and see what that does. If it drops it then add another. Until it's just gone.
Alright, alright....I mispoke! I went back and read the thread and misinterpreted what you were saying! I was wrong. :hug: I had to figure out the data viewing on my own...and a little help from John, lol. I'll add a little fuel at the higher end and see what happens....thanks buddy!
After talking with John (SDCarguy) tonight and a few of Dave's comments, I wouldn't worry about that KR...but you could do what Dave (Quick) mentioned and add a little fuel and go log it and see if the KR drops...and repeat as long as the KR is reducing.
SRT8Tech, did you start with a B&G tuned PCM? If so, your rich % numbers are on par with what I'm using, and I'm tuning with a wideband. My B&G ran at like 13.8 AFR out of the box. I never measured my stock PCM, but I'd have to assume that it's richer than that since most people aren't adding nearly as much fuel to their stock PCM tunes. I had to add about 13% (+/- a couple at different ranges) to get it to 12.1-12.2 across the board with my B&G PCM. Dave
