Dyno flatlines after 5500RPM

[JimMueller]

I'm kinda pulling my hair out on this. I'm under the impression that there's something wrong with the tune, and/or parts selection which is causing the HP to flatline after 5500RPM. I'd like to collect whatever data logs you deem necessary to help isolate if a problem exists. Voltage remains around 13V at WOT through fuel cutoff, fuel pressure is about 60psi until the upper RPM's where it drops to low 50's. New plugs and wires a few months ago. Compression test in September gave results of 200-205psi on all cylinders. Could it be a valvetrain or lifter issue?

Prior tuning was first done by Frost mail order, then touched up on the street using NGK AFX & AFR, then touched up on a Mustang dyno, then touched up again using lambda because the AFR tuning was wrong according to feedback here. Most recently I made a group of 10 calibrations, the only difference being a PE EQ Ratio mimicking 12.0 to 13.0 in .1 steps. I used that to determine which EQRatio gave the lowest elapsed time between RPM ranges and between speeds on a long level road. Only tried up to 12.6 though as I ran out of time and read that LS3's like it a little richer anyway. Intended to do the same thing with advance but never got around to it.



Thank you for any help you can offer.

[mcfarlnd]

I'm kinda pulling my hair out on this. I'm under the impression that there's something wrong with the tune, and/or parts selection which is causing the HP to flatline after 5500RPM. I'd like to collect whatever data logs you deem necessary to help isolate if a problem exists. Voltage remains around 13V at WOT through fuel cutoff, fuel pressure is about 60psi until the upper RPM's where it drops to low 50's. New plugs and wires a few months ago. Compression test in September gave results of 200-205psi on all cylinders. Could it be a valvetrain or lifter issue?

Prior tuning was first done by Frost mail order, then touched up on the street using NGK AFX & AFR, then touched up on a Mustang dyno, then touched up again using lambda because the AFR tuning was wrong according to feedback here. Most recently I made a group of 10 calibrations, the only difference being a PE EQ Ratio mimicking 12.0 to 13.0 in .1 steps. I used that to determine which EQRatio gave the lowest elapsed time between RPM ranges and between speeds on a long level road. Only tried up to 12.6 though as I ran out of time and read that LS3's like it a little richer anyway. Intended to do the same thing with advance but never got around to it.

Thank you for any help you can offer.

FYI, you will not get much help without a log or knowing what you have done to the vehicle.

[JimMueller]

I'd like to collect whatever data logs you deem necessary to help isolate if a problem exists.

FYI, you will not get much help without a log or knowing what you have done to the vehicle.

That's why I asked for suggestions on what to log, to avoid time wasted because I was monitoring the wrong PIDs.

[mowton]

RPM, Speed, ECT, IAT, MAF AF, MAF Hz, Dynamic Air, MAP, Knock Retard, Advance, TPS% AFR Commanded, WB AFR, AFR Err, injector PW Banks 1 and 2 and cylinder airmass

Ed M

[JimMueller]

Thanks, Ed. I haven't done any lambda logging since I installed 3.0, so I need to research how to create and log the lambda error. My sensor is connected to EIO#1, I added MPVI.1 and I used the NGK-AFX lambda transform.

[mowton]

Jim,

schpenxel, put together a great how to. try this http://www.hptuners.com/forum/showth...PRO-Interface). There are other How to's as well in the Scanner stickies. If you are still having issues let me know and I can make a quick video.

Ed M

[mcfarlnd]

That's why I asked for suggestions on what to log, to avoid time wasted because I was monitoring the wrong PIDs.

My bad. We still don't know what is done to the motor? Heads/ cam/ intake???

[JimMueller]

Ed: Thanks for the list. I found his link earlier and will try to collect the log this weekend. Normally I do my street WOT tuning in 3rd gear as 4th gear requires more real estate. Are you looking for just one good WOT pull to fuel cutoff, and does it matter which gear?

Mcfarlnd: LS3 longblock, LS7 clutch with 13lb flywheel, stock crank, K1 rods, SRP flat top 4.07" pistons with 5cc reliefs, 222/230 112+2 .596"/.600" cam, LS7 lifters, OEM 7.400" pushrods, PAC 1518 springs, OEM rocker arms, milled but unported LS3 heads with OEM valves, ARH 1.75" primaries, ARH cat'ed y-pipe, 3" intermediate pipe, SLP 1in/2out muffler, modified LS3 intake manifold, 92mm throttle body, 100mm MAF. Compression is around 10.8:1.

The only thing that has changed since it was built in June 2010 is the modified intake manifold. Although I was regularly street tuning it, I didn't get around to dyno'ing it for the first time until February 2014.

[mowton]

Can go with what ever gear gets you to the issue the fastest and safest. Look at the log when complete and we are looking for signs of issue like MAF Hz maxed, IPW >19ms at or over 6000 rpm, maybe even Torque management (spark, Fuel or TPS%) in play etc. Maybe ad a pedal parameter so we can see where it is during the pull.

Ed M

[JimMueller]

A pedal parameter, is that different than TPS? Not sure us old fogies with VPW have such a thing, unless it's new in 3.0?

[mcfarlnd]

Were you getting the same flat spot prior to the intake? Or are you saying it was never dynoed prior?

A pedal parameter, is that different than TPS? Not sure us old fogies with VPW have such a thing, unless it's new in 3.0?

I assume he is speaking of the pedal position, yes they are different and it has been a feature in the scanner since DBW throttle bodies have been installed.

[JimMueller]

Don't know about before the intake, the intake went on November 2013 which was a couple of months before I first dyno'ed. I had to send back the original one as a core, but I do have data at home on how the new intake affected the fueling. I do see a 'Accelerator Pedal Position' PID which I've never used, I'll see if that works.

[GHuggins]

Really too early to be saying this since there is no log or tune, but the ls3's in general are real sensitive to knock settings and will flat line at 5500 rpms like this because of timing pull or timing being too low... Especially after a head swap... Like I said too early, but something for people to think about when looking at things when they're posted... Really needs to be on a dyno for dialing in correctly.

[mcfarlnd]

Don't know about before the intake, the intake went on November 2013 which was a couple of months before I first dyno'ed. I had to send back the original one as a core, but I do have data at home on how the new intake affected the fueling. I do see a 'Accelerator Pedal Position' PID which I've never used, I'll see if that works.

That's the one and should work

[JimMueller]

The accelerator pedal position PID always reports 0. Technically the heads are completely stock except for some minor milling and the valvesprings. The Mustang dyno tune done in February 2014 the operator tried adding more timing and it didn't gain anything so he left it as-is.

I've overlooked how I add the lambda error parameter so that it plots in the charts, though. I have a custom math parameter imported from 2.24 but it looks like it's broken. What's the correct way to get the lambda error to populate in the charts?

By the way, the tune is in the first post.

[mcfarlnd]

Is that the only pedal PID showing for you?

There is a good write up for the lambda here:
http://www.hptuners.com/forum/showth...l-VE-Vehicles)

[JimMueller]

I have 'Accelerator Pedal Position' and 'Accelerator Pedal Average' when I search for 'pedal'.

That was the thread I followed. Do these snapshots happen to show what I'm doing wrong? It would seem as if I need to also log both EQ Ratio and Commanded EQ Ratio, but only one of those PIDs show up my parameter list.

It'll be just my luck that I'll get the charts populating and then I'll fall into the "V3 Scanner External MPVI channels freezing" crowd.

[mowton]

Jim,

You don't have to generate a Math Parameter for Lambda Error in the Maths -User area. Simply go to Maths - Predefined>Lambda & AFR> and select the EQ Ratio Error. This is the parameter you will use in the Charts and Graphs. If you have used all sensor based parameters, you will be good to Go.

Ed M

Update -- see if this helps....EQ commanded_EQ Err_NG lambda WB.Chart.xml

[JimMueller]

But the predefined math EQ Ratio function is dependent upon both ID 50118 (EQ Ratio Commanded) & ID 50119 (EQ Ratio), and only 50118 shows up in my parameter list. If I am not logging both 50118 and 50119 in my channel list, then the function won't work, correct?

Edit: Ahh, I think I see what's going on... when we transform the MPVI port, it's reporting the WB sensor as EQRatio, which in turn places it on PID(?) 50119. I was getting confused because the math function reported it as EQRatio instead of the wideband. So It probably wasn't working before because I was logging AFR Commanded instead of EQR Commanded. I'll run out and test that.

[mowton]

EQ commanded (50119) has to be in your channel table, not AFR commanded ---WRONG disregard

I'm sorry got that backwards, you do need 50118 which is the EQ Commanded. When you transform the MPVI AD-1 into the NGK-AFX Lambda sensor it creates the 50119 parameter. Math parameters don't get inerted into the Channel.

Ed M