Leaning out in 2nd after launch

[96dreamer]

Took the car to the track for the first time last night and am having issues with it running leaner in lower gears off the launch. It leaned out so much in 2nd it tripped the AFR safety and shut the car down. After it hit the reset parameters I continued the pass in 2nd -5th with AFR's holding pretty close to the target getting slightly richer with each shift. Not sure what I should be looking for that would cause this. Tank was around 1/2 for all passes so I don't think fuel slosh was an issue. Screenshot of the data log below. AFR safety tripped where the tracer line is.

Log from just after afr safety rest finishing the pull and having great afrs.

Car is running a ms3pro ultimate, novi 2000, wastegate for boost control and fuel on these passes was around e60. I cut down e85 with 93 to try and get a bit more volume out of the pump since I was running out of full on straight e85.

 

[01yellercobra]

You don't happen to know what the fuel pressure was doing do you? How dialed in is the VE table?

If I'm reading that right it happened shortly after you shifted into 2nd?

How do you like the AFR safety set up?

 

[96dreamer]

Fuel pressure is actually on the log, it's sensor 02. I had to data log through my phone because I left my laptop at home so some of the sensors have goofy names. Pressure is dropping off around 4k rpms but afrs stay in check the rest of the gears. Duty cycle is up pretty high but much lower than when it was running true e85. I mixed it down to e60 ish to get some more volume but still have some detonation resistance. The car is getting the rest of the fuel system this winter.

This is the first time I've really used the afr safety system at the track. I guess I have to say it works pretty good since nothing melted down lol

Correct right after launch afrs were higher than I was commanding then started creeping up before it shut down. After it met the reset parameters I kept going, still in second, and everything looked fine

Sent from my SM-G950U using the svtperformance.com mobile app

 

[GNBRETT]

How many fuel pumps do u run? Seems like Ur second fuel pump might be failing when activated. I had the same issue recently at the dyno.

 

[96dreamer]

How many fuel pumps do u run? Seems like Ur second fuel pump might be failing when activated. I had the same issue recently at the dyno.

Single in tank walboro 450lph.it was the biggest in tank option at the time i could fit in the factory tank. It should be getting a big single external pump and sleeper sumped tank this winter hopefully. I knew the pump wasn't going to be adequate on e85 when I started the build so I'm not suprised it's dropping pressure

Sent from my SM-G950U using the svtperformance.com mobile app

 

[01yellercobra]

I was thinking it might be a g-force thing. Depending how hard you're launching and having a pump that can't keep up. Probably reaching, but you never know.

I was going to say you might need to bump your AE up a little to make up for the fuel when shifting.

The ECU will keep the injectors open longer at the lower fuel pressure to maintain the A/F. But I'm thinking your current fuel system just can't keep up and you should probably wait until you get the new set up installed before hitting the track again.

 

[96dreamer]

The ve table is pretty well dialed in. It's got a bunch of street miles using the ve analyze feature over a bunch of different driving situations. I've known the fuel system wasn't up to the task for a while. I've had the limiter set at 5300 on e85 for a while and dropped the ethanol content down to about e60 right before leaving for the track in order to try and get a few more rpms out of it to make it actually driveable. shifting at 5200 with 4.10s and a t56 while a riot isn't very reliable or indicative to the track. I was shifting into 5th even with having it shut down for the afr safety cut. The thing that was confusing me was why it would lean out off the launch but after the afr safety cut had reset it pulled through second fine.

 

[01yellercobra]

Have you messed with the air density table at all?

 

[96dreamer]

Have you messed with the air density table at all?

Didn't know it existed until you mentioned it.

 

[01yellercobra]

I zeroed mine out recently. I was getting weird A/F readings at odd times. Although in my case it was going really rich under boost. Figured out it was the density table adjusting the A/F. I zeroed it and ran VE analyzer a couple times. Because of the weather I needed to tweak the 140-150° range. But I want to rebin the temps as this car will never see -40 and if my inlet temps are 248 I have bigger problems.

 

[96dreamer]

Fixed a belt issue and got some more datalogs out of the car. Attached is the MSL file from one of the logs edited down to just the pull for anyone that has megalog viewer. The two screenshots below are showing the same rpm at two different times and the drasically different afrs between the two. Still having the afr issue in lower gears at the beginning of the pull, this time 3rd. AFR only saftied once during this run around 365.3 seconds with fuel pressure at ~58psi, duty cycle@ ~29%, ~3750rpm and 5.7 psi of boost but the lambda super lean and erratic right after the shift.

After the rpms came back down I continued in the same gear. At 360.1 seconds the rpms are at ~3750, 5.87psi map, 58psi fuel, ~30%duty, same as when it tripped earlier but lambdas are almost exactly where they should be.

Its not having issues with the AFR tripping later in the pull when duty cycle is through the roof and fuel pressure drops. Port eh Is my clutch switch so at 363.1 and 366.3 i'm no lift shifting and you can see the clutch switch activates. I don't understand why the afrs are so different between the two spots when loads are the same. I know the fuel pump is to small and it is causing crazy high duty cycles later in the pull but even with 130% duty cycle the AFRs are where they should be.

 

[decipha]

clearly not a tune issue its purely mechanical

looks like your fuel pulse damper has gone bad

 

[96dreamer]

clearly not a tune issue its purely mechanical

looks like your fuel pulse damper has gone bad

Thanks, I'm glad someone said something other "than your fuel pump is to small, fix it".

The fuel setup currently is a walbro 450lph in tank pump, factory line to the passenger fender well feeding a Fuelab 51505 regulator. From the regulator is a -10 line split to 2 -8 lines going to the rear of the rails and the rails are connected with a -6 crossover at the front. Return from the regulator is a -8 going to the flex fuel sensor which goes to the factory return line. I know the fuel system is not ideal, its essentially half done. I did the pump a few years ago and the regulator/fuel rails this summer. It will be getting a big single external pump this winter.

 

[01yellercobra]

Are you running a pulse damper though?

You keep saying yourself the fuel system isn't ideal, then get irked when it's pointed out as a possible problem.

If it were me I would take a couple logs then run them through the VE Analyzer. Compare the numbers VEA gives you to what you have on your table. It sounds like you have a hole in your VE table to me. You need to look in the area that is used for that gear change.

You might be able to get some help by richening the AE as well. That's why I asked how soon after the shift it happened. Depending on which version you're using at least.

 

[96dreamer]

Are you running a pulse damper though?

You keep saying yourself the fuel system isn't ideal, then get irked when it's pointed out as a possible problem.

If it were me I would take a couple logs then run them through the VE Analyzer. Compare the numbers VEA gives you to what you have on your table. It sounds like you have a hole in your VE table to me. You need to look in the area that is used for that gear change.

You might be able to get some help by richening the AE as well. That's why I asked how soon after the shift it happened. Depending on which version you're using at least.

No there is no damper, just what is listed. The FPR should be serving the same purpose as a damper.

I'm not so much irked that people are suggesting fixing the fuel system more so that the data does not support that being the issue. It just seems like throwing parts at it while crossing your fingers.

AE is what I'm suspecting at this point. I drove the car around for about an hour Sunday and VEAL didn't change anything more than .05 around where the issue is occurring. I worked with AE already but it was to try and eliminate the bog when punching it from a roll, not after a shift. The afrs are rock solid in the area its having the issue if I'm not shifting into that area which is why I don't think its a VE table issue.

 

[decipha]

lmao a fpr has absolutely nothing to do with a damper lol. Thats like saying the fuel pump should be serving the same purpose as a fuel rail lol.

I assure you a fuel pump cannot be used as a fuel rail anymore than a fpr can be used as a damper lol.

 

[96dreamer]

Ok maybe serve the same purpose as was a bit of an over statement. They serve separate purposes but a larger aftermarket fpr does have some ability to dampen resonant frequencies. My intent was to say that the fpr is suppling all of the dampening duties in my system, sufficient or not. Comparing a fpr and fuel damper to a pump and rail is a bit ridiculous.

 

[decipha]

You lost me.

A fuel damper is entirely different from a fpr. They serve two completely different purposes. A fpr cant dampen fuel pulses anymore than a fuel pump can house the fuel injectors. Its a directly comparative analogy. Thats like saying your rims dampen curbs and bumps. No, your tires and suspension do that. No matter what you might think your rims arent going to dampen any bumps anymore than your fuel pump is going to house the injectors or the fpr dampens the fuel pulses.

Entirely different components that do completely different tasks.

 

[96dreamer]

I had always been under the impression that after market fpr with their larger than oem diaphragms provided a small amount of dampening to the fuel system. Nothing compared to a dedicated damper but with the fpr having a diaphragm that extends past the spring cup there would have to be some level of dampening happening there. Either way if the problem persists after the full fuel system is done I will look into a dedicated damper.

I messed with the AE a little on the way to dinner with my wife yesterday and it seemed to help out a bunch. It did also appear then when leaving on the two step it was hitting an area of the ve table that I hadn't tuned yet so I fattened that up as well.