Roe Running Rich at crusing speed

[KNG SNKE]

Went out for a drive today and I noticed the car was running really rich. Idle was between 13 and 14, crusing in 3rd at 25 and 35mph was reading between high 12 and low 13's. Seems way too rich. Today was a slightly cooler day, mid 50's, but not that cool. Wondering if I have a sensor going bad or if my VEC is adjusting for the cool air by adding too much fuel. Running a vec 3 with a 5lb pulley. WOT was fine though.

 

[Red Snake]

FYI, 10 is rich. 13-14 is lean. The guage is measuring Air to Fuel ratio, ie..10:1 means 10 units of air to 1 unit of fuel. 14:1 means 14 units of air to 1 unit of fuel.

12:1 at WOT is where you want to be. 14:1 at idle is considered stoich (where you want it to be).

Sounds to me like your tune is very good.

 

[mbccenter]

I would say that is normal. What is it at 55-70mph? That is were you do most of your driving.

 

[KNG SNKE]

I am aware of how to read the AFR meter . At idle, should be between high 14 and low 16. At WOT should be at 12 or slightly below. At normal cruising (maintaining speed) I don't think I should read 12 afr at all on the car. At 55-75mph is was reading in the 13's. Normally it is in the 14's.

 

[Steve 00RT/10]

Went out for a drive today and I noticed the car was running really rich. Idle was between 13 and 14, crusing in 3rd at 25 and 35mph was reading between high 12 and low 13's. Seems way too rich. Today was a slightly cooler day, mid 50's, but not that cool. Wondering if I have a sensor going bad or if my VEC is adjusting for the cool air by adding too much fuel. Running a vec 3 with a 5lb pulley. WOT was fine though.

I wouldn't worry about those readings. I have found that running at low rpm in a higher gear (3rd in your case)...the afr runs richer than say the same speed in 2nd. Unless using the IAT feature, the VEC is not capable of doing any adjusting..... and even then only in open loop. If you think you're running too rich, pull the plugs after a while and have a look. LTFT would be another test to do to see if the pcm is trying to remove a lot of fuel in closed loop

14.7 is what the pcm looks to do in closed loop if conditions are right...not 14.1

Steve

 

[KNG SNKE]

I'll check LTFT tomorrow. I am using the IAT feature of the Vec as well. I have not tuned anything besides the upper rpms to account for the headers.

 

[Red Snake]

14:1 at idle is considered stoich (where you want it to be).

............
14.7 is what the pcm looks to do in closed loop if conditions are right...not 14.1

Better put your reading glasses on

That's a colon, not a period. It says 14:1 NOT 14.1

I think if it's reading 14 point anything at idle its going to be fine.

 

[Steve 00RT/10]

I'll check LTFT tomorrow. I am using the IAT feature of the Vec as well. I have not tuned anything besides the upper rpms to account for the headers.

I should have added, or included, that the VEC is not capable of adjusting for cold air temps in open loop conditions without the IAT feature being used. I think I sent you a screen shot of where my parameters are for the IAT variables. Remember - the steeper the line, the more you will see an impact on WOT tuning.

Also, I should have added that if the LTFT is running way negative (or positive), you can use the VEC (regardless of IAT function) to modify closed loop operation by adding or subtracting from the injector base set and / or cylinder trim. IMO, the base set is the better way to go.

If you redo your base set, you will need to pay particular attention to your tune, especially if going leaner...as the pcm is feeding less gas in closed loop than it was when the tune you have was made...thus under WOT....there is less fuel going in than before. This is why I think one should set LTFT first before doing any tuning with the Roe. Of course, I learned that after the fact. I had to add 5% to my base set after setting a lean light. I had to re log to get my tune back in place.

Better put your reading glasses on

That's a colon, not a period. It says 14:1 NOT 14.1

I think if it's reading 14 point anything at idle its going to be fine.

Yup, I need to up the prescription I guess. 14 point anything is good at idle. Mine bounces from 13.7 or so up to low 15s as the STFT continually tries to find the magic nunmber

If conditions merit, 14.7 : 1 is the stoichiometric number the pcm strives for though

Steve

 

[EllowViper]

John, Did you get the headers on? If so, where do you have the 02 sensor? Your tune from running the stock manifolds to headers will change your base tune settings...sometimes significantly.

 

[KNG SNKE]

Headers are on , the o2 is in the 3rd cylinder tube, just like the belangers. I expected it to change the tune but not run richer, expected leaner. I have driven the car at least 5 times prior with the headers on and didn't have the same issue.

 

[Steve 00RT/10]

Headers are on , the o2 is in the 3rd cylinder tube, just like the belangers. I expected it to change the tune but not run richer, expected leaner. I have driven the car at least 5 times prior with the headers on and didn't have the same issue.

I know every car is different, and that Ellow Viper's experience with the 3rd tube set up is what works best for him, but it is not possible to properly adjust LTFT reading only one cylinder. Yes, you can keep an eye on the plugs and trim accordingly, but LTFT is meant to collectively read all 5 cylinders.

I have the opposite story of Ellow Vipers regarding this exact situation on our yellow car. It is written about somewhere in here. Bottom line for me was that the 3rd tube sensing thing actually caused black soot to come out on every start up and a big cloud on transition to WOT (or less throttle). LTFT was right on. 3rd tube was nice and tan....the rest were not really that dirty. QFs in the collector a year ago and LTFT showed awful close to setting a rich light. ..... Removed LOTS of fuel, re-logged, and completely got rid of all soot on start up. No more big smoke on throttle tip in either. Picked up 39HP/50TQ from redoing tune it came with.....O2 in 3rd tubes. I may be the exception to the rule. It's likely less an issue with a NA car, but with the Roe, you definitely need to stay on top of the AFR for all 10 cylinders.

The 3rd tube solution from Belanger was a band aid fix back in 2002? (and not a proper one) for the 00-02 Belanger cars to stop the O2 heater code lights from continually coming up.....which of course puts the car in safe mode until reset.

Steve

 

[KNG SNKE]

I am not sure about this since this was how the headers were designed and are said to be the best headers for the car. I have the M&M headers which are belanger replicas minus the pickle so I am unsure what to do then. There is not another spot to put the stock 02 sensor into the headers.

 

[BOTTLEFED]

Listen to Steve, he knows of what he speaks

Good info.
As stated, there is no way for the VEC to change closed-loop driving except for the fuel injector trims. If you haven't messed with that, then there should be no reason it would be driving any different when the weather changes.

If you are still worried about it, check your AIT sensor and coolant temp sensor. They are the sensors that deal with the fuel and timing concerning outside temp.

 

[Steve 00RT/10]

I am not sure about this since this was how the headers were designed and are said to be the best headers for the car. I have the M&M headers which are belanger replicas minus the pickle so I am unsure what to do then. There is not another spot to put the stock 02 sensor into the headers.

If you decide to move them, you will need to burn a **** into the collector area...approximately where the OEM sensor was on the stock set up. Any muffler shop worth their salt can do it. The rub is you will have to buy quick fires or a 96 PCM to get rid of the heater code light. You can try your stock O2 sensors in there, but like the rest of us, you will likely set a light. Roes on 00-02 cars also have a tendency to set a misfire code due to instant revs (even more so with a lightweight flywheel which we have on both cars). The misfire code is pesky, but will not put the car into safe mode. We have one car with a 96 pcm, one without. The yellow car sets an occasional misfire light, but as we only run it a little over 1000 miles a year, it's not worth the expense of the older pcm. It ususally sets during parades when we rev the engine for the kids.


I pretty certain there was no such thing as the 3rd tube deal before the 2000 cars started setting lights. No multiple cylinder production car anywhere would have the computer sense only one cylinder per bank to set fuel trim.

Steve

....Thanks BOTTLEFED

 

[mbccenter]

Watch out for locating the sensor down in the collector. Some cars like to start a bucking issue with them down there. I would not do that. It is still just an average of the 5. You would need one per hole to make it perfect.

 

[1TONY1]

I am not sure about this since this was how the headers were designed and are said to be the best headers for the car.

Who said that and where is the info to back it up ?

 

[1TONY1]

FYI, 13-14 is lean.

That should be clarified to say at wide open throttle, WOT. Normal cruise there really isn't a "too" lean.

 

[KenH]

I absolutely agree with Steve about the way most cars behave and the 'right' way to do it and not arguing that point. But as with everything else with Vipers, one size does not always fit all. There are some like mine which do not run well in closed loop with the O2 in the collector area. In my case, my closed loop was always running too lean and I spent months on the problem. Once the sensor was moved up to the 3rd tube, it ran perfect.

Since you are running a bit rich, perhaps moving it down to the collector will help in your case and that is what I would try. Only other option would be an SCT tune.

Did you get a new air intake? I know you were thinking about the JMB. That puts the AIT into the incoming airstream and can have an effect on the tune as well, but usually affects WOT rather than closed loop.

As far as setting the injector offsets using the collector vs. the tube, I don't think it makes that much difference. In the collector, you could also have some cylinders pig rich and some detonation lean and have the average mix look good down in the collector. Same basic situation you have with reading one tube. No matter where the O2 is positioned, you really need to do a couple of plug readings and adjust the individual cylinder trims if needed to help equalize the cylinders otherwise you are flying blind.

 

[Steve 00RT/10]

Watch out for locating the sensor down in the collector. Some cars like to start a bucking issue with them down there. I would not do that. It is still just an average of the 5. You would need one per hole to make it perfect.

The collector area is where my Belangers had their ****......just like from the factory. ...That was 2001 and 85,000 miles ago. I thought all aftermarket headers did before 2000....trying to replicate the factory set up and still be able to use the same O2s for cable length. I've never heard about a bucking issue due to an O2 sensor in the collector area. All Vipers...at least my vintage.... buck a little at low speed when cold whether they have headers or not.

Exactly right about the average. I guess anywhere you can grab all 5 conveniently for cutting a **** in will work just fine. You would need one per hole in a perfect world.

Steve

 

[Steve 00RT/10]

I absolutely agree with Steve about the way most cars behave and the 'right' way to do it and not arguing that point. But as with everything else with Vipers, one size does not always fit all. There are some like mine which do not run well in closed loop with the O2 in the collector area. In my case, my closed loop was always running too lean and I spent months on the problem. Once the sensor was moved up to the 3rd tube, it ran perfect.

Since you are running a bit rich, perhaps moving it down to the collector will help in your case and that is what I would try. Only other option would be an SCT tune.

Did you get a new air intake? I know you were thinking about the JMB. That puts the AIT into the incoming airstream and can have an effect on the tune as well, but usually affects WOT rather than closed loop.

As far as setting the injector offsets using the collector vs. the tube, I don't think it makes that much difference. In the collector, you could also have some cylinders pig rich and some detonation lean and have the average mix look good down in the collector. Same basic situation you have with reading one tube. No matter where the O2 is positioned, you really need to do a couple of plug readings and adjust the individual cylinder trims if needed to help equalize the cylinders otherwise you are flying blind.

Hi Ken,

Well, I guess it's not the first time we've all had this discussion Yes, one size does not fit all. Completely agree!


I could be wrong, but I slightly disagree with something above here as far as collector/single tube fuel adjustments.

The VEC is a supplement to the factory pcm. Other than fooling the pcm for injector offset in closed loop and setting LTFT if necessary, it pretty much leaves closed loop operation to the OEM tried and true set up.

Is it not true that if there are cylinders running pig rich / detonation lean when the O2 is in the collector....that would be a pcm problem and should show up as rich /lean light at about +/-28% ....when the pcm is unable to level trim out. I understand the average thing, but Dodge engineers made a program they feel works well enough to sense all 5 and correct accordingly within the set parameters and no engine damage. With a single cylinder sensing, you would never set a light whether the other 4 were dangerously lean or too rich. Therefore, plug checking becomes a necessary task. For you, and any others who are 'one with their ride' .... not such a big deal. For the majority, including me, I would rather have all 5 tubes sensed...especially with the blower.

I also agree about trimming cylinders regardless of O2 placement. I modified my cylinder trim a little after setting my base set correctly for LTFT..........based on the ol' 5 cylinder average. I pull my plugs every spring and have a look. That's typically 9-10K miles between checks. I'd be pulling them a more often if in the 3rd tube.

Steve

 

[KNG SNKE]

Keep in mind I do have an aftermarket o2 sensor downstream in the turnout to monitor this AFR. So if any of my cylinders start acting up or something bad starts happening I will be paying attention. I am always glancing at that gauge to make sure everything is smooth.

 

[EllowViper]

I found out the VEC also manages not only the individual cylinder offsets (across both closed/open loop) but the fuel enrichment percentages and fuel load in closed loop as well. The reason I know this is that I could not get my LTFT dialed in at idle utilizing just the individual cylinder trims. I started messing with the fuel load and RPM tables just to see what impact they would have at idle in regards to LTFTs. Walla. At idle (about 750 RPM), my fuel enrichment percentage had been around 80% pulling about -15 vacuum. When I lowered that percentage to around 18%, my LTFTs came rignt in with very little individual cylinder trim (actually trimming only #9 and #10 right now...all others are ZERO). My fuel load at that vacuum was only about 0.2 ms additional injector duty cycle. What I also discovered is that I can basically remove all off idle hesitation by ramping the fuel enrichment percentages back up to over 100% at 1000 RPM. I also increase the fuel load ms offsets in a corresponding manner and get great throttle response without the idle hang-lean condition during off-idle accelleration. I know its basic VEC tuning 101 but it did surprise me to see the impact the fuel load and fuel RPM settings have during closed loop operations. Its not just an open loop system but impacts closed loop parameters too. Try messing with your load and enrichment percentages at idle just to see what happens to your LTFTs. IMO, these parameters really make or break the closed loop drivability of your set-up.

 

[KNG SNKE]

So when are you going to be local again?

 

[EllowViper]

Probably in January. Going to pull my blower in the next few weeks and refinish the tubes (Yellow) with the ROE stickers. Maybe do the blower case in a black finish too. Also start my fuel system upgrade and maybe a shot of Nitrous as well. Trying to talk the Mrs into the SCT deal that Viper Specialties has going on. I am also doing the rough math regarding fitting a Whipple 3300 under the hood. I'll do a mock-up dimensionally when I have the current autorotor off. Kenne Bell has a new 2.8H blower but I can't get the dimentions for that. Still too small in my opinion regardless. Too bad the car is running so well right now. Just want to drive it and not tinker! There was a Whipple 3300 bare blower on EBAy a few weeks ago. Missed that deal. Don't really want to drop $2300 to PSE for a new Whipple just to mess around with. Oh well. Love doing this sort of thing.

 

[KNG SNKE]

Well when your local again if it is warm enough I would like you to tinker with the tune a little

 

[EllowViper]

Put that W/M kit you've got laying around on...

 

[mbccenter]

Keep in mind I do have an aftermarket o2 sensor downstream in the turnout to monitor this AFR. So if any of my cylinders start acting up or something bad starts happening I will be paying attention. I am always glancing at that gauge to make sure everything is smooth.

Is this the gauge you are looking at? I thought mine was always running to rich but then I learned that my gauge was not right. It was off almost 1 point and it would not recalibrate. I tried to talk to inovate about it but they wanted nothing to do with fixing a brand new gauge.

Get your car to a dyno and tuned.

 

[mbccenter]

Who said that and where is the info to back it up ?

I say they are the best But then again I am one of them M's

 

[KNG SNKE]

I have talked to many people about the headers and they came with a higher recommendation then any other set. I have not read 1 bad review on them as well.

As far as getting it dynoed and tuned I will, just is going to be a little bit. Still kinda shaky about letting my local tune shop do the tuning.

The readings I am providing are coming from my AEM UEGO o2 sensor. Now the location has changed with the M&M setup then where it use to be, it is further down stream.

Probably not going to use the W/M kit, I find it unnecessary for the goal that I have.

 

[EllowViper]

SO where are you with this issue? I just relocated my passenger 02 sensor back into the collector just to see how it would run and how the LTFT's would look. Well, it runs like CRAP yet again. Set a cel for bank 2 too rich even with my LTFTs at idle set +/- 3%. Driver's bank remains solid and my wide band is in the drivers side as well and all looks good. SLow speed driving is bucking and jerking. Transition accelleration is terrible....no its worse that terrible...it embarrasing. Idle *****. Not smooth and purring like a kitten as it had been. Terrible backfiring under decel too...just undrivable. So the 02 is going back into the single tube and I'm loading my original tune back in. Every now and then I just have to prove to myself that the collectors just don't work for my Viper. I do know I'm running a bit rich since I have the soot issue in the tailpipe and rear facia, but I get nothing at startup or WOT so its not that bad. Probably just that my el cheapo cats are fried and I have 02 sims in the rear anyways. I stil think tuning to one cylinder and then basically matching injector offsets simplifies the PCM from searching for a correct AFR by modulating five injectors. In my case with putting the sensor in the collector, the PCM has to try and adjust 5 injectors to reach a correct AFR and can't do it given the inherent variation in five individual cylinders and the crazy ROE manifold. For me, tuning cylinders 2,4,6 the same (based on the 02 in #4) and then simply dialing out just a bit of fuel in #8 and #10 really simplifies the PCMs math. I like to reduce the variables in the tuning equation and trying to get all five cylinders tuned the same via the collector just doesn't work since #8 and #10 tend to run so rich in closed loop under 2000 RPMs which causes the PCM to wildly trim 2,4,6,8,10 (in a firing order fashion) trying to get the collective AFR within spec. The PCM doesn't know which cylinder needs to be trimmed so it just trims each one until the AFR comes into spec. I still suspect that #10 overly influences the AFR of all five cylinders and you can trim it too much thereby creating a lean cylinder condition under boost. If the ROE equally filled each cylinder and each cylinder had a great fuel burn, then the collector would work in theory (like the stock manifold/tune does). Just fueling the debate some more since I'm pissed I put the sensor back into the collector and wasted a bunch of time again. My $.02