Roe Running Rich at crusing speed

[uvbnbit]

Can't remember if you said you replaced the O2's??
That's what solved my problem. I still get black/stain on rear bumper, but that's because I don't have cats.

http://forums.viperclub.org/gen-ii/624358-running-rich-hwy-speeds.html

http://forums.viperclub.org/rt-10-gts-discussions/624956-rich-f-cruise-issue-resolved-thanks.html

 

[EllowViper]

Yes it was a brand spanking new bosch OEM 4-wire replacement sensor I installed. $63.00 at Autozone...LOL. Back to the single tube for me.

 

[KNG SNKE]

I don't have the black soot issue. Only reason I thought it started running really rich was because the popping on decel increased a lot! I took a trip to Maryland this weekend and hit the average gas mileage that I hit when I drove my car home from Jersey, 17mpg. My old one hit 23mpg so I am wondering why this one consistently gets 17. I was not in boost all the way home and only twice for a 2 second spurt on the way up.

 

[99 R/T 10]

Black soot on the bumper takes time to accumulate................

If I am trying to get mileage out of mine, I am right at 16-17 MPG too.

 

[Red Snake]

Black soot on the bumper takes time to accumulate................

If I am trying to get mileage out of mine, I am right at 16-17 MPG too.

I can hit 10 mpg if I really lay off the throttle.

 

[KNG SNKE]

Doesn't make sense though. My old Viper, mostly stock with smooth tubes, K&N filters was able to hit 23mpg highway coming back from Northern Virginia. This one can't get past 17.6. Couldn't when it was mostly stock and is running about the same now. I don't have cats either, thinking about adding some though.

 

[BOTTLEFED]

when I added the Roe on my car, my off-boost hwy mileage went from 21 to 18mpg
not sure why, but the Roe just seems to **** gas even when not in use

 

[KNG SNKE]

Bigger injectors. They would have to be dialed in as precise as the factory ones, that would be why I believe. Thing is my normal driving before the car was supercharged yielded 17mpg and now after supercharger 17mpg. Doesn't seem right.

 

[plumcrazy]

no cats here and getting like 22+mpg at 80-85mph with A/C on the highway, but i dont have a roe.

coming back from DLM last year i got 20+mpg and that was averaging over 100mph between 2 drivers.

 

[Steve 00RT/10]

Bigger injectors. They would have to be dialed in as precise as the factory ones, that would be why I believe. Thing is my normal driving before the car was supercharged yielded 17mpg and now after supercharger 17mpg. Doesn't seem right.

I believe the injector base set is what fools the pcm. That shouldn't cause a big decrease in MPG if set right.

With 3.45 gears, I have gotten as high as 22.5 with the 5 pounder and other bolt on mods we have. Typical highway MPG on a trip is 20 at 75-80 MPH in 6th gear and getting into it a time or two. I think 1600 RPM is the sweet spot for Vipers and MPG

When the car was bone stock, we would get a little over 24 sometimes....with 22-23 being the norm. Adding the gears took about 1.5 MPG away. The blower took 1-1.5 or so.

Steve

 

[EllowViper]

John, During my 1600 mile trip to visit you I averaged 17 MPG on the highway. I thought it would be higher given my 22-23 MPG without the blower. I still get a solid 11 around town. My AFR at around 1600 RPM on the highway is 13.8-14.2. The ROEs are notorious for poor cylinder loading under 2000 RPM. Thus it gets hard to precisely dial in the LTFT across the entire closed-loop RPM band. Tuning at WOT is very easy. Optimizing the injectors for closed-loop operations is the big compromize we face. What is optimized at idle does not mean it is optimum at cruise due to load and RPM dynamics. I had a BIG issue with off-idle idle hang with the engine leaning way out (18-19 AFR) leaving a stop sign and then catching back up once the RPMs and load adjustments in the VEC caught up. This was really an issue when I had the 02 sensors in the collector. Simply undriveable. I don't have this condition running the 02 sensors in the single tube on each side however. AFR stays right at 14-15 off idle and tips in slightly lower during light acceleration. I guess tuning with a SCT can eliminate this condition totally since you can change the tip-in fuel offsets and related factors right at the PCM. You don't have to trick the PCM through the VEC. Running colder plugs aggravates the situation too. Sean Roe is currently working an SCT tune for the ROE that eliminates the need for a VEC. That should be a killer solution.

 

[KNG SNKE]

I asked Sean a long time ago about using the SCT for the Roe and he said because there was not enough interest in doing it he was not going to dial it in.

 

[Steve 00RT/10]

I asked Sean a long time ago about using the SCT for the Roe and he said because there was not enough interest in doing it he was not going to dial it in.

Stay 'tuned'

Steve

 

[EllowViper]

02 sensor back into the single tube and all is well. I'm getting pretty good at swapping those things around. I think if I ever totally remove the headers, I'm going to weld bunds in each tube so I can put my Wide Band sensor in each one one at a time and log/tune the AFR on each cylinder. I bet that would be interesting....time consuming, but interesting.