Wooo hooo! For the time being I did the JMatt, sooper secret, overhead console mount. So I fooled around trying to reduce my knock retard before the gauge and was running +6,+14, +14. Turns out that was giving me 12.2, 11.3, 11.3... oops. Probably took a year off my cats. doh. My understanding is that we want to be somewhere between 12.2 and 12.8 with the sweet spot between 12.5 and 12.8? Stock,CAI, cat back. I tweaked it to +3, +4.5, +4.5 and now I'm getting 12.4/12.5 (maybe an occassional blip to 12.3 or even 12.2) below 4K and 12.7/12.8 above (maybe an occassional blip to 12.9). I would like to be conservatively optimal. I'm thinking I should shoot for 12.5 above 4K? I'm going to try +3, +5, +5 tomorrow and if that does what I think then maybe try +2.5, +5, +5. 12.5 straight across should be perfect right? and the load should be a bit less below 4K since that's all launch? I'm getting up to 5 knock retard and probably averaging 3. first 2 trys I just spun them so this one was with ESP on, automatic, and easing off the shoulder. Launching off the berm is tough. (I'm suspecting my "track" might be a bit downhill. Going to try to figure that out with google earth...)
Very nice Dave. I ended up adding 8, 5 and 5 in the end. I am running a bit leaner probably with the HF Cats. On the dyno with the wideband hooked up to the o2 bung, I was right around 12.5:1. and made more power, saw less KR. I don't know where you installed the wideband but it would read a bit lower before the cats. I never see more than 2-3* KTR and some before shifts. I'm curious to see how it'll improve my track times if any at all....it does feel stronger when compared to the 93CAI canned tune I was running. This was one of my last runs before I garaged the car for the winter and after we messed with adding some fuel to the canned 93 cai tune: It was pretty chilly out that day, so I spun pretty good out of the hole lol.
Hahaha. I WANTED your opinions!! Did you give me yours??? Not that I wouldn't have just skipped through it anyways lol...j/k j/k
Hey Quick, Have you data logged with the Predator at all while fine tuning? I'm curious to see what you're getting at the pre-cat O2 sensor and Predator log vs your wideband and Dashhawk log.
I haven't even looked at the Predator logging. Are you asking to compare the Predator narrowband reading with the DashHawk narrowband reading? That would be O2 Bank 1 Sensor 1 and O2 Bank 2 Sensor 1? The narrowband O2 sensor on each side before the cats? I could try that. It wouldn't be at the same time since you can't plug them in at the same time. And I would expect them to be exactly the same. Those are standard OBDII PIDs so there isn't any leeway on interpretation. Both the Predator and DashHawk would be polling the PCM for the value and logging what it returns. Did I misunderstand? I do remember that early on the Predator would log "AFR" using data from the narrowband. Not sure how they were interpolating that but I don't think it could have been accurate. I brought that up in the Diablo thread on LXforums way back then and there was no response. Hopefully they removed that. Then again maybe it was there for cars that come with a wideband.
I thought you had a wideband hooked up to your dash hawk. If not, never mind. I thought the 12.5AFR target was at the tailpipe, after the cats. I believe that should be about 11.5 -11.6 pre-cat.
I went to great pains (you would have shared that pain if you'd followed my wideband install thread...:cry to install a bung in front of the left cat. Should be a "true" reading there. By the way, I polled a few people as to the effect of going further downstream. General consensus (few samples) was that it shouldn't make more than .2 AFR difference. One guy said another effect is that changes would be seen a little later since the cats "dampen" changes to AFR. So if you had a change in AFR you'd see it in front of the cat and then a little while later after the cat. We might be talking milliseconds here? Don't know. I mentioned that I had just assumed that they made an adjustment when reading from the tail pipe on dynos and the guy just sort of laughed. Yea, your mods are different, you're using a different tune, different gas, and I think gravity is different up there too :harhar:. What I was asking though was (in general, like if you were on a game show and asked these questions): Is 12.2 - 12.8 the target for a stock srt8 with CAI and cat back? Within that is 12.5 - 12.8 the "sweet spot"? If you wanted to tune sort of conservatively (let's say you were going to tune Momo's car for him knowing he'll probably be driving this one until the kid gets through college) would you shoot for 12.5 or 12.8?
Well. That's SOOPER SEECRET information... haha, here's a clue. Do your windows rattle sometimes a little bit before midnight? (actually you might be able to hear it).
Well, don't take that to the bank but this was from a PLX engineer when I pressed him for an answer. "What's the AFR difference after the cats?" "Oh, not much at all but you will see changes in AFR slower since the cats have a damping effect" "Well, how much is 'not much'?" "Oh, less than .2, probably more like .1" "Really?" "Yea. You know that on dynos they take the measurement from the tail pipe right?" "Sure, but I figured those might be different sensors or they make an adjustment to the reading to account for that" "Well, maybe they should but don't count on it" We got dyno operators on here. Maybe someone could chime in here? So what were you asking for? Did you want me to try moving my wideband sensor to the rear bung and compare readings? If so, that ain't going to happen... I'm old and fat and I take blood pressure medicine and drink huge quantities of coffee and beer and wear progressive glasses. I almost threw up wedged under the car looking at stuff upside down right in front of my face installing the sensor the first time.
Better not be on WESTMONT you bad boy you, lol! Acutally with the Mopar/Corsa exhaust at WOT you can pretty much hear it from anywhere! I'd love to do more WOT runs and work on my launch technique but only places open enough close by are the X-ways, San Tomas from Bud up to Campbell Ave. or Lawerence after Prospect up to Bollinger but there's always too much traffic to have any fun. And unlike YOU apparently I have a hard time getting out of the house at midnight, lol! "Uh honey, I'm gonna go out and ..." "YOU'RE NOT GOING ANYWHERE, YOU KNOW WHAT TIME IT IS!!!" :argue:
haha, I can just imagine getting up to 120 on Westmont. I'd need a Back To The Future flux capacitor so I didn't punch a hole at the other end. Think 85. go east and check for cops on the way to the next exit. Get off, get on coming back. At the end of the retaining wall there is a small pull off spot to wait until there's no one in sight. Start there. Repeat as necessary. Data log on the way back to the start and 1/4 mile log for the run. I use the same track (budd to campbell) for the 0-60 runs. but sssshhhh don't tell anyone.
Ok, I think I got the AFR where I want it? maybe? thoughts? 1K - 3.8K = AFR 12.6/12.7 4K - 7K = AFR 12.4/12.5 Here's a shocker. The Predator lists the rpm ranges as 1K-3.8K 4K - 4.8K 5K - 7K I was thinking WTF? there's a 200 rpm gap between them... must be a typo or something like that. Well. There IS a gap! I tried this about a dozen times. lock the car in 3rd at about 3.5K and floor it. Sure enough AFR goes to ~12.5. As you get to around 4K it jumps to 12.9 ~ 13.2 (mostly around 13.0) until you get over 4K and then it goes to ~12.5 again. I'm guessing the canned CAI 91oct tune has it around 13 and the adjustments don't cover outside of the range? something like that? very odd.
Diablotoona (I think Johan) said in the early Diablo thread at LXF that our Hemi's (he was referring to the SRT8 at the time) like to run rich and loved the gas...he said he found 12.2 to be optimal. Now, my dyno guy is also an SCT tuner and hooked up his wideband to my left 02 port, he did say it was about a .1-.2 difference from before the cat and after the catalytic...but made it a point to say that this may be lower when you have a high flow cat such as I do. So, I was happy with a 12.5 and only using the handheld to make adjustments.
Huh? What do you mean the adjustments don't cover outside the range?? Which version are you running? How much fuel (in percentage points can you add in each range) with the version you're using? I'm still on 16a? or was it b? I forget now lol. It's been a lonnnngggg winter. Finally back. :towel: Oh and sorry about not reading through your wideband thread...I guess I should but I need a discrete place to put on too! I kind of like JMatt's setup even though I put my shades there too. Could always velcro them to my forehead.
