SRT4 93tune Improvment request U7134

Krazyrdr83 · Post by **Krazyrdr83** » Thu Sep 10, 2009 8:59 pm

sounds good...wondering if i should update to the new crom? yes...no? also, I went to upload a tune into the DSP, and it said that my PCM may require a TCM file. What's that about?

duster360 · Post by **duster360** » Thu Sep 10, 2009 9:12 pm

See, I told you that commanded 11.9 can produce a final A/F anywhere from 12.5 to 11.5. Thats why I suggested leaving them alone because its not very precise.

With rescaled 2004/2005 S1 injectors and my 2003 PCM + 93 tune got me a vicious A/F curve.[Black=rpm; Green=TPS; Pink = A/F]

Here it is just the 93 tune when the PCM thinks the Injectors are smaller than they are, not so bad except for the Lean spike.

Letxen3 · Post by **Letxen3** » Thu Sep 10, 2009 11:03 pm

don sorry i have been able to test the crom. problem is i can not use the 93 tune ever since i removed the cat it wil spike 25+ psi of boost.

SCGt94 · Post by **SCGt94** » Fri Sep 11, 2009 9:28 am

spikes 25 lbs after a cat removal huh? That's strange. Letxen send me a copy of your ori to my email please.

Letxen3 · Post by **Letxen3** » Fri Sep 11, 2009 1:14 pm

25psi or more i just like to let off the gas once i hit 25psi ish will email the tunes now.

sfla_srt4 · Post by **sfla_srt4** » Fri Sep 11, 2009 5:09 pm

Hey Don, I did a 3rd gear roll today about 60mph and it initially hit 12.5ish on the hit and them immediately leaned out to the high 11's during the pull. No knock, but the hit was lean. I will do some more pulls but this was only a quick one getting on the highway this morning. I ll let you know any updates.

Thanks a lot for the all of the work!!!! I appreciate it!!

Matt

Krazyrdr83 · Post by **Krazyrdr83** » Mon Sep 14, 2009 11:41 pm

updates?

SCGt94 · Post by **SCGt94** » Tue Sep 15, 2009 8:33 am

I was out sick yesterday, i have the gentlemans stage 1 cal added to the tool, still waiting on the boss for the ability to make cat over temp an adjustable parameter

Quick · Post by **Quick** » Tue Sep 15, 2009 9:30 am

I understand that there could be many other factors involved like overlap, etc., but are cat over temps likely to be loosely correlated to chamber temps?
Wouldn't a higher (modeled or not) cat temp generally indicate a higher chamber temp?

SCGt94 · Post by **SCGt94** » Tue Sep 15, 2009 10:47 am

yes i am sure they are are loosely associated. Like we all know, dodge runs the cars extremely fat in the wot a/f department. By leaning these cars out to 11.9 egts are significantly raised. However duster has mentioned on another forum about cat over temp and its function. It uses a pre set exhaust temperature table in the pcm...map v.s. rpm = a specific exhaust and/or catalyst temp. By running the car much leaner then the factory calibration is set up for, this table is now pretty much useless as the temps are significantly different v.s. what they were with an a/f of w/e the factory was calling for.

KBzPTGT · Post by **KBzPTGT** » Tue Sep 15, 2009 11:11 am

SCGt94 wrote:I was out sick yesterday, i have the gentlemans stage 1 cal added to the tool, still waiting on the boss for the ability to make cat over temp an adjustable parameter

Can you please tell your boss to get a move on it

j/k

Quick · Post by **Quick** » Tue Sep 15, 2009 12:24 pm

SCGt94 wrote:yes i am sure they are are loosely associated. Like we all know, dodge runs the cars extremely fat in the wot a/f department. By leaning these cars out to 11.9 egts are significantly raised. However duster has mentioned on another forum about cat over temp and its function. It uses a pre set exhaust temperature table in the pcm...map v.s. rpm = a specific exhaust and/or catalyst temp. By running the car much leaner then the factory calibration is set up for, this table is now pretty much useless as the temps are significantly different v.s. what they were with an a/f of w/e the factory was calling for.

Yes. I was just thinking that the cot might be working as a sort of fail safe for excessive chamber temps as a side effect of protecting the cats. If you guys modified that I wouldn't worry about it being within the reasonable range. On the other hand, without an EGT wideband, and the ability in the handheld to turn it all the way down or off I can imagine a whole lot of people blowing themselves up. Of course they can do that now with afr, timing, and boost but this would be a bit more removed/subtle.

By the way, I'm all for it. I'd rather you didn't gear these things towards selling in Kmart

duster360 · Post by **duster360** » Tue Sep 15, 2009 1:52 pm

Quick wrote:
SCGt94 wrote:yes i am sure they are are loosely associated. Like we all know, dodge runs the cars extremely fat in the wot a/f department. By leaning these cars out to 11.9 egts are significantly raised. However duster has mentioned on another forum about cat over temp and its function. It uses a pre set exhaust temperature table in the pcm...map v.s. rpm = a specific exhaust and/or catalyst temp. By running the car much leaner then the factory calibration is set up for, this table is now pretty much useless as the temps are significantly different v.s. what they were with an a/f of w/e the factory was calling for.
Yes. I was just thinking that the cot might be working as a sort of fail safe for excessive chamber temps as a side effect of protecting the cats. If you guys modified that I wouldn't worry about it being within the reasonable range. On the other hand, without an EGT wideband, and the ability in the handheld to turn it all the way down or off I can imagine a whole lot of people blowing themselves up. Of course they can do that now with afr, timing, and boost but this would be a bit more removed/subtle.

By the way, I'm all for it. I'd rather you didn't gear these things towards selling in Kmart

Unlike most Hemi guys, nearly all SRT-4s users have a widebands installed. Its purchase usually precedes the Predator.

The true the EGT might be higher or it very possible that it might be lower. The bottom line is that the table the PCM bases its EGT guestimate is invalid.

Either way, it is common practice for SRT-4 CMR dealers and SCT tuners to disable COT with little if any negative effects reported. I believe this successful track record substanciates how little COT benefits the engine/owner and imo it was always just a cya.

SCGt94 · Post by **SCGt94** » Tue Sep 15, 2009 2:32 pm

if worse comes to worse and i get a red light. I will just offer anyone who wants it shut off to just email me and i will turn it off for you.

Post by **mikel** » Tue Sep 15, 2009 2:41 pm

SCGt94 wrote:if worse comes to worse and i get a red light. I will just offer anyone who wants it shut off to just email me and i will turn it off for you.

No can do as an adjustable param??