Dyno sheet question...

[Wildpony_2]

Hey guys, I know most of you on here are wizzies at this stuff, hence why I am on here askin'. Ok this is my first time on a Dyno so be patient please.

Ok for mods below in my signature, she put out 272 rwhp/329 rwt.(Keep in mind this is a GT, NOT a Cobra, no flames please.) That was after first run. Then he shut her down during 2nd run because she seemed to be "sputtering" after 4K to reach the 5K mark.

HP is in Red
Torque is in Blue
Air/Fuel is the Light Blue

** All was done in 4th gear**

Picture is crappy quality cuz I don't own a $300-$600+ digi cam, just a 2.0mp. So it's just a $100 cam that takes decent pics.

My question is this. What is the little splutter at the end on all 3 lines? The guy working on it said it might be an Air/Fuel issue. If this is the case, any insights as to what I might be able to do to correct/fix it?

Thanks in advance,
Mike

 

[Bullitt995]

Lets put it this way. A/F line is supposed to be flat. Your a/f is really ****ed up considering you're N/A. I can't read the picture but what's the a/f at most of the time?

 

[Wildpony_2]

I'd say the average is about 50.

 

[cobraboy169]

those are sum good numbers for your vehicle. No one should be flaming you for that. Didn't those things come with 260/270 from the factory or something close. That is good. As for the sputter you could be maxing out your MAF sensor. I don't think that is very likely but it could happen. Where was the A/F ration at that point? If it is some crazy # off of 12.0-12.5 then that could be the problem.

 

[Wildpony_2]

those are sum good numbers for your vehicle. No one should be flaming you for that. Didn't those things come with 260/270 from the factory or something close. That is good. As for the sputter you could be maxing out your MAF sensor. I don't think that is very likely but it could happen. Where was the A/F ration at that point? If it is some crazy # off of 12.0-12.5 then that could be the problem.

Yeah 260 at the flywheel. About 73 on A/F when it started to "sputter". Yeah the average is between 35-70, sorry crappie pic.

How can I correct the MAF if it is maxed?

 

[hmmmidunno]

damn either its smoothing or uve got some bad O2 sensors that arent adjusting fast enough

 

[Wildpony_2]

Ok so things to look at, Bad 02's or MAF diagnostic.

What about plugs? These things come stock with platinums good for 100K miles, could it really be the plugs?

I purchased a new fuel filter yesterday, just trying to start with some ez stuff.

Thanks again guys, keep the suggestions comin'.

 

[jugsreturn]

You might have better luck with responses if you post this in the mustangs section a little ways down.

Good Luck with the problem.

 

[hmmmidunno]

if your on stock injectors than that is ur problem they are only good for 300 crank HP and ur making way more than that.. so while it hit optimal for a second as the RPM increased it just got leaner and leaner

 

[GTO30272]

Yeah 260 at the flywheel. About 73 on A/F when it started to "sputter". Yeah the average is between 35-70, sorry crappie pic.

How can I correct the MAF if it is maxed?

Am I missing something here? What the hell does 73 on A/F or avg 35-70 mean? Do you understand what A/F means? If not, I am not trying to flame you, but your response doesn't make sense and I just want to educate you a little. An Air Fuel ratio is a calculation of how many particles of each, represented in a ratio. Typically in an Naturally Aspirated motor you want 12.8:1 to 13.0:1 as a ratio to stay fairly safe. Of course this does depend on the motor and power. On boosted motors, you want to be more rich, which would be indicated by a lower numerical air fuel ratio. "73 and avg 35-70" means you are reading the graph wrong. However, even without the numbers, based on your graph, you have a problem. An NA AF ratio should pretty much be flat. Rarely do you ever want the ratio to change, unless you are talking about a boosted motor or an N2O motor when you want to richen it up for the trq spikes and then can let it lean out a little on the top end. Hope this helps, as I would be guessing to say you do not have a big enough fuel supply and when you fix that, you will need to tune for it. Best of luck :beer: