Dyno is that rich?

[sirhc76]

Finally found a local place that has a new dyno. Took it over to them today after work and got some numbers. Can or should I have the PCM adjusted to gain anything. On a good note I had never heard my exhuast from outside the truck. I thought it had a horrible sound inside the cab while driving. I liked what I heard today. Its good when one of the gear head mechanics walk by during the run and say wow that gave me goosebumps. They actually did 4 runs, the second was better than the first and the third didnt read. I didnt stop to think that I havent cleaned my KN and it has 7k miles on it.

 

[Dave T(BADVENM)]

You've got room for improvement with your a/f ratios around 10-10.5. Ideal a/f is closer to 12. From what I understand the trucks run rich from the factory. You might be able to forward your graph to Boomer so he can see where to tweak/adjust your pcm to improve your a/f numbers and in turn your hp/torque numbers.

Did you have the overdrive turned off and stuff like that for the quad cabs?

 

[Annu Kumar]

I got realtively the same numbers with just a stage 2 and K and N. I hope you had a super cold engine that way you get good numbers. I think I was running rich with my Stage 2.:dontknow:

 

[FlyingLow]

I think you are too rich. Send the PCM back with a copy of the dyno run.

 

[Annu Kumar]

Hey dave My ratios were at 10.5 also does that mean I can get more power also. But dude didn't have any tuning software for Our trucks:dontknow:

 

[Dave T(BADVENM)]

Hey dave My ratios were at 10.5 also does that mean I can get more power also. But dude didn't have any tuning software for Our trucks:dontknow:

You could send your pcm back to DC Performance along with the dyno graph. They can then adjust your pcm based on the dyno...optimizing your a/f and in return better hp/torque. When you re-dyno (if you do) try to go back to the same place so you'll get a true reading of any differences between pcm adjustments. I think they'll error on the side of caution (not blowing up the motor) and keep the a/f a bit on the rich side...you'll have to discuss that with Dan at DC.

 

[sirhc76]

I have no cats either so that should have an impact on the air/fuel as well correct? I have a B&G flash, I may try sending it to DC with my numbers to get their flash and maybe a little more of a custom tune. I guess it wouldnt matter who does the adjustments? The overdrive was turned off during the runs. It was hot a humid today, had just rained so Im not sure how much of an impact that had on the numbers.

Thanks everyone,

Chris

 

[FSTJACK]

I have no cats either so that should have an impact on the air/fuel as well correct? I have a B&G flash, I may try sending it to DC with my numbers to get their flash and maybe a little more of a custom tune. I guess it wouldnt matter who does the adjustments? The overdrive was turned off during the runs. It was hot a humid today, had just rained so Im not sure how much of an impact that had on the numbers.
Thanks everyone, Chris

The atmospheric conditions that you dynoed at would cause the motor to run very rich.

 

[mmmmtorque]

Already running B& flash :dontknow:

That looks like a stock PCM dyno run......pig rich.

I have at least 50-60 tuning dyno runs under my belt, 12.5-13 is the sweet spot.

 

[sirhc76]

I will get another one when the weather is a little more dry to compare. Then I can see what needs to be done at that point. I would hate to send it back for a re tune and then have detonation issues. I guess this would be a complete charge for a flash? I may throw the stock PCM and get a few runs on it as well for comparisons. The shop charged $50 for two pulls.

Chris

 

[mmmmtorque]

I will get another one when the weather is a little more dry to compare. Then I can see what needs to be done at that point. I would hate to send it back for a re tune and then have detonation issues. I guess this would be a complete charge for a flash? I may throw the stock PCM and get a few runs on it as well for comparisons. The shop charged $50 for two pulls.

Chris

Thats why I have a VEC3


If its a good shop, work out a tune package deal. You can save alot of $ if you are planning alot of dyno time.

I probably average around $5 a run.

 

[sirhc76]

What is the average cleaning interval on the KN filter. Would it have that much of an impact on the air/fuel if the filter was dirty. Just thinking that not getting as much air naturally would cause it to run rich? In looking through the dyno numbers it really seems like I should have better numbers than what I have. Mods in Sig

Thanks

Chris

 

[wyoramsrt-10]

What is the average cleaning interval on the KN filter. Would it have that much of an impact on the air/fuel if the filter was dirty. Just thinking that not getting as much air naturally would cause it to run rich? In looking through the dyno numbers it really seems like I should have better numbers than what I have. Mods in Sig

Thanks

Chris

You said you had about 7k miles on the filter right? I hear the K&N will perform a little better with some dirt on it than it would if you just cleaned it.

 

[FSTJACK]

You said you had about 7k miles on the filter right? I hear the K&N will perform a little better with some dirt on it than it would if you just cleaned it.

Thats what I have seen also, from a filtering point of view.
I don't know if that is the best for air flow.
I have never done a clean vs dirty test on a flow bench, or seen the results of such a test, and don't know of anyone that has.

The Viper car & trucks use a speed density system to control timing and fuel flow.
This system does not measure air flow like the systems that use a MAF Mass Air Flow sensor. GM and Ford as well as many others use a MAF so the computer knows how much air is going in the motor. And adjusts fuel flow based on air flow, along with temperature (intake and coolant), rpm and vacuum.
The speed densiy systems use, temperature (intake and coolant) rpm and vacuum.
This is at wide open throttle, in open loop.

In closed loop (cruising at part throttle or normal driving) the O2 sensors are also used to keep the mixture close to " stoiciometric" which is 14.7 to 1 air to fuel ratio. That is the ideal air fuel ratio for complete combustion. This is an over simplified explination, but is basicly how it works.

Anybody know if this might be an issue ? How dirty can an oiled gauze filter (K&N type) be before it starts to affect performance by becoming restrictive.

 

[wyoramsrt-10]

Yeah that's what I was thinking too Jack. It will filter better but I was not thinking about the airflow. Much better explanation than mine.

 

[BOOMER]

did you record the IAT temps when it was dynoed. a higher temp (thermal expansion of the air) causes it richen up from less density. and the factory pcm pulls timing as the IAT temps climb, when the timng is pulled, it also runs even more rich.
the trucks have a VERY hard time of disapating the heat from the engine compartment. when you dyno the truck have a blower pushing under the trucks engine to help pull heat away from it.
use a scan tool, if the dyno doesnt have OBDII interface, so you can record the Air Intake Tempatures, and make sure you havent heat soaked it.