Back from the dyno.............AIR/FUEL ratio NFG.
- Thread starter CSXT802
- Start date
speedracervr4
Enthusiast
When was the last time you changed your o2 sensors? Older sensors with carbon build up will cause rich conditions. Easy/cheap things to change that might help the A/F.
OP
OP
CSXT802
Enthusiast
I don't think the o2's play a big role at wide open throttle. I could be wrong. Car has 9000 miles on it. don't think the o2 would be shot.
Bexar80
Viper Owner
Per the FSM, the ecm does not look at the O2 sensors during wot.
speedracervr4
Enthusiast
Yea your right, forgot they effect closed loop
OP
OP
CSXT802
Enthusiast
Well the first mod will be an sct tune to clean up the fueling. low 11's air/fuel is good for boost not an NA motor. The shop owner where i dynoed the car tunes for 13:1 on an NA motor. Right now it"s so rich it could take a 50-75 hp dry shot of NOS and still be safe.
BTW, not meaning to dis your cam, its actually not bad, just weird that it seems to take a gulp of air or something at 4000 rpm.
OP
OP
CSXT802
Enthusiast
Stock cream puff cam. Looks more like a big gulp of fuel. That's right when the A/F goes into the low 11's
OP
OP
CSXT802
Enthusiast
That seems wrong for a stock cam. Maybe you have some tired valvesprings or something preventing it from grabbing air at that frequency. I had a similar pattern on a motor before I had it redone...... but it was a strange cam and I attributed the flat mid-curve to the weird cam. That ain't your problem, so if it isn't springs, I'm out of ideas.
OP
OP
CSXT802
Enthusiast
I see what you are saying. I'm thinking it"s timing being pulled that's causing the dip in the torque curve.
IEATVETS
Enthusiast
Once you get the AF taken care of that car should make some good power! As far as I know Darren, nothing was done to the motor so everything should be stock. Wish I had some answers for you as to why it is running fat but I understand motors and electronics about as much as I can read Chinese brail.
99 R/T 10
Enthusiast
When was the last time you changed the plugs/wires?
OP
OP
CSXT802
Enthusiast
never. Picked up the car in April with 7,500 miles on it. Has 9k on it now.
OP
OP
CSXT802
Enthusiast
I have a new set of plugs sitting in a box. Who has the best wires? MSD?
OP
OP
CSXT802
Enthusiast
no worries Duane. I'll get it figured out. Car runs good as is. There is just a little left with the current set up to be had.
the besr wires are AB's. www.qualitywires.com
EllowViper
Enthusiast
Absolutely correct. Stock timing takes a dump from 4-5K and then picks back up above 5K. SCT will do wonders on this specific car.
Bexar80
Viper Owner
Your torque curve appears abnormal because of the scale that was selected. If the right side torque of the chart was scaled to the same intervals as the left side hp the curve would not look so wonky. Compared to my dyno chart your torque curve follows very close but I think you may still have more dip from 4 to 4.5k than mine. Start with the plugs and wires. It may also help to have a BG intake/injector service done. It made my car idle much better so I assume it probably helped in the higher range also.
OP
OP
CSXT802
Enthusiast
Thank you. I was looking for someone to confirm what i was thinking. So you would you leave the fueling as is and just add timing where needed to clean it up?
EllowViper
Enthusiast
As a starting point Yes. But only if you are running 93 vs. 91 octane there in PA. Basically, stock the engine starts out leans and ends up rich with timing taking some big swings along the way. You can view all these parameters in the SCT software. The stock tune is a very conservative tune for obvious reasons. You need to determine how changing the stock tune is going to be reflected in how you plan on driving the car. High load, high RPM you'd probably stay a bit on the rich side vs. quick bursts on the street for showmanship. Think about the orignal purpose of the car design and you can appreciate how it was tuned from the factory. Your tuner can work with you on how best to set the car up for how ypou plan on driving it. Have fun with it. Its a fun and relatively easy process.
OP
OP
CSXT802
Enthusiast
Thank you for the input. You have cleared the waters for me. In my case would you do a mail order tune from a vendor. Or go all in on pro software for the sct ? I have no other mods planed in the near future. I know the car is being held back. I can feel it in that rpm range. I have 93 octane here in PA. After doing the dyno pulls we had to step out side as our eyes were burning from how rich the car is.
99 R/T 10
Enthusiast
Mopar Performance wires in the classifieds:
http://classifieds.viperclub.org/sh...w-mopar-performance-gts-r-wires-8-5-mm&cat=47
http://classifieds.viperclub.org/sh...w-mopar-performance-gts-r-wires-8-5-mm&cat=47
EllowViper
Enthusiast
Personally, if your tuner is worth anything at all, I'd get the Pro Racer software and spend an hour or so with your tuner dialing in the car...both on the dyno and on the road. Ultimately, you will only end up changing a few tuning parameters to get the car where you want it...thus you can see why there is a mail order market for these sorts of things. If it were very complicated, there would be no way to do mail order tunes (generally speaking). I purchased all my stuff from Sean Roe without any drama. It is very easy software to use for just tinkering with a N/A tune and you can easily reset everything back to stock if you head down the wrong path. Plus once you get into the software, its interesting to see all the other engine parameters and how the engine is sort of tied together through the PCM. Someone once posted "I don't care to know how it works, just that it works." Well, I'm at the other end of the spectrum. I want to know how it works so I understand why it works.
