Did I ruin my injectors? AFR max lean for 15 sec after 8psi

[5.3LS10]

You have to prove to yourself that the fuel is not starving. We could be looking at a fuel pickup issue. It could be a fuel pump with not enough capability to keep up. It could even be some sort of ignition issue. The trick is to find a way to prove things one at a time.

Andy

I will install the fuel pressure sensor tomorrow evening and update with what I see.

Thank you for everyone's input!

[gjestico]

Certainly check out your fuel pressure to be sure.
The thing is with fuel pressure issues under high load, They generally recover quickly once the throttle and engine speed drops. Like right after you let off at the finish line. I am not seeing that in your logs. Its looks like it takes about 7 secs in Pull2 for the AFR reading to come back after the run.
Its possible your issue is eomthing else and the egine is dropping a cylinder or 2 causing lean spike in AFR. Have you got single wideband after the turbo ?

[whittlebeast]

This could be an overheating wideband but we still need to rule out things that can melt the motor first.

[5.3LS10]

Certainly check out your fuel pressure to be sure.
The thing is with fuel pressure issues under high load, They generally recover quickly once the throttle and engine speed drops. Like right after you let off at the finish line. I am not seeing that in your logs. Its looks like it takes about 7 secs in Pull2 for the AFR reading to come back after the run.
Its possible your issue is eomthing else and the egine is dropping a cylinder or 2 causing lean spike in AFR. Have you got single wideband after the turbo ?

Yes the wideband is on the downpipe about 18-20" downstream from the turbo. Looks like all 3 of the passes it takes about 6-7 seconds after TPS goes down for the AFR to recover.

[Blown88GT]

These are your injectors.
https://performanceparts.ford.com/part/M-9593-MU52

These is the Calibration Data for your injectors.
https://performanceparts.ford.com/parts ... 3-MU52.pdf

Input data into TS Fuel settings. Use this Dead Time calculator. Follow his instructions.
https://docs.google.com/spreadsheets/d/ ... =302838282

BTW, what kind of FPR do you have that does not have a vacuum line attachment? If it does, it will do boost compensation.

[5.3LS10]

These are your injectors.
https://performanceparts.ford.com/part/M-9593-MU52

These is the Calibration Data for your injectors.
https://performanceparts.ford.com/parts ... 3-MU52.pdf

Input data into TS Fuel settings. Use this Dead Time calculator. Follow his instructions.
https://docs.google.com/spreadsheets/d/ ... =302838282

BTW, what kind of FPR do you have that does not have a vacuum line attachment? If it does, it will do boost compensation.

Thank you for those links! that is good information to have. I will update it tonight. It is a factory replacement fuel pressure regulator and filter assembly for a 2002 corvette (WIX 33737). It is a popular regulator for LS swaps that utilize a single feed rail.

[Joe Clark]

I would certainly be concerned about engine damage if you ran lean for 15 seconds, I would be doing a leakdown test as a matter of course,

as said you need to establish what the fuel pressure is doing in relation to boost,

Also that the wideband is not lieing, what one is it? I have had big issues with an LC-2 in the past calibrating itself due to ground issues.

as said I would be suprised if any harm has come to high Imp injectors, i would be more concerned about the injector drivers, bt they should be pretty imune too.

also form experience, its often woth swapping the plugs for a new set, cooking them from being lean could have caused issues, opened the gap etc....

[racingmini_mtl]

I don't think anyone has mentioned it but if you have misfires or even a cylinder not firing at all, that will show up as lean. I don't know if it can be as extreme as what you're seeing but that's something to check. By the way, this lean reading is due to the extra oxygen that comes from the unburned mixture and that the sensors sees as a lean indication.

Jean

[whittlebeast]

Jean. I thought about bringing that up but that issue normally shows up as an AFR that is erratic, looking like noise.

[racingmini_mtl]

Jean. I thought about bringing that up but that issue normally shows up as an AFR that is erratic, looking like noise.

Agreed but if it is a cylinder dropping completely instead of random misfires, it might look more consistent and really lean. But I'm only speculating here because I don't have any actual data to back it up.

So it still might be a possibility that should either be confirmed or eliminated.

Jean

[5.3LS10]

Thanks for all of the input everyone!

I did not have time to install the fuel pressure sensor yesterday but instead went out and did some testing.

So the strangest thing about this issue is all of those times it had the issue was at the track. I do not know if it was a fuel slosh issue or something with the car actually hooking instead of spinning like it does on the street. Also we did change out the Walbro 255 for their 450 about 2 weeks ago. Not sure if that fixed the issue but it did not seem to have the issue last night.

On a side note I turned the boost solenoid duty back up to get back around to 14psi. Made about 8 pulls 1st through 4th on the higher boost level and AFR stayed solid in the low 11s although injector duty was around 115%.

I will try and get the pressure sensor wired in so that we can monitor it but I do not see the AFR cutout issue at the moment.

[Blown88GT]

It's not clear it the "problem" was before or after you changed out the Walbro 255 for their 450.

[5.3LS10]

It's not clear it the "problem" was before or after you changed out the Walbro 255 for their 450.

The problem was before. Do you think if the pump couldn't keep up that it would consistently take 15 seconds for it to catch back up?

[Blown88GT]

It's not clear it the "problem" was before or after you changed out the Walbro 255 for their 450.

The problem was before. Do you think if the pump couldn't keep up that it would consistently take 15 seconds for it to catch back up?

... It could be a fuel pump with not enough capability to keep up...

No way to know now, since the pump was changed. With FPR so far from the fuel rail & no boost compensation, you can only guess about the 15 sec "delay".

[turbo conversion]

If it is still at 115% duty cycle then you need larger injectors or a rising rate fpr.

If you go with larger injectors you will have to retune the entire VE table.

If you go with a rising rate fpr set the base pressure as before and maybe you can get by just retuning above 100kpa.

David

[5.3LS10]

If it is still at 115% duty cycle then you need larger injectors or a rising rate fpr.

If you go with larger injectors you will have to retune the entire VE table.

If you go with a rising rate fpr set the base pressure as before and maybe you can get by just retuning above 100kpa.

David

Yes over winter the plan is to run a return line and 1:1 regulator at the rail and ditch the factory dead head setup.

[5.3LS10]

So since the fuel pump was upgraded we have not been able to reproduce the issue on the street (never could before either). Took it back to the track with fuel pressure gauge and had the same issue where the wideband went max lean for 15 seconds although the car still ran fine. Fuel pressure dropped a few psi but not a lot. I am wondering if maybe the ground is getting interrupted (due to the car actually getting traction on the track vs the street where it spins a lot )which is causing the wideband to basically reboot.

Does the wideband have any sort of over temp protection that would cause it to cut out like this?

EDIT: pairs = psi autocorrect

[billr]

" Fuel pressure dropped a few pairs but not a lot."

I gotta ask... what it the conversion factor from "pair" (of pressure) to psi?

[turbo conversion]

What do the spark plugs look like after a pass, that will tell you if it is actually going lean or not they can't lie.

David

[5.3LS10]

" Fuel pressure dropped a few pairs but not a lot."

I gotta ask... what it the conversion factor from "pair" (of pressure) to psi?

That is a classic auto correct error.