I know i don't have that many mods, and i have never heard of any N/A guys having to move up an injector size, but my ipws are about 20 at WOT. My fuel trims are in check, the number seems like it should be accurate, but i thought 21 or so was maxed out?

if your injectors are at 20ms, then you have a supply/pressure problem with your "mods"

Two possibilities come to mind:

1) Fuel pump is weakening; and/or,
2) Your WOT AFR is way rich.

Do you have a means of logging fuel pressure while underway? At minimum, have you gauged fuel pressure at idle?

Do you have a wideband O2? At minimum, do you have some WOT narrowband O2 values?

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2004 Buick Lesabre Limited, Gran Touring
Bone Stock

1998 Buick Lesabre Limited, Gran Touring
Retired

1.fuel pump is original, so that's possible. but i cant quite work out why that would cause the injectors to fire more?
2. possible, the ltft is good, but no wideband. the narrowband 02s are usually around 900, though i didn't check today.. i'll get the numbers on that tomorrow.

If fuel pressure/volume is dying out, especially at high revs, the injectors must fire longer to get the commanded AFR. I was having that very issue before replacing my old worn out stock pump. On L36 injectors, that fix alone dropped my WOT IPW's from 18-20ish ms to 14-15ish ms.
(After hooking up a FP sensor, I found my fuel pressure was gradually dropping into the low 40's psi at WOT )
Another potential symptom of dying pressure is if your WOT O2's tend to not hold steady and lean out throughout a WOT run (although an untuned high-end of the MAF table can do the same).

Narrowband O2's are notoriously unreliable and not necessarily comparable between cars, but my current n/a wideband set up scans say:
730-740's NB WOT O2's equal 13.4 to 13.5 WOT AFR (via WB)
770-780's equal 13.8 to 13.9
840-850's equal 12.6 to 12.7 (This is my n/a target)
900-910's equal 11.7 to 11.8 (This will be my s/c target)

I suspect you are running quite rich WOT for n/a. While I am tuning L67 injectors right now in prep for slapping on an M90 soon, I found my IPW's at 11.7/11.8 were some 10% higher than at 12.6/12.7 (i.e., 10.9ish ms vs 9.7ish ms). If you are as rich as I suspect, there's alot of injector headroom right there.

Another possibility is that one (or more) injectors is out of balance and not delivering enough fuel, whether because it's dirty/clogged, worn out, etc. Trims will effectively "learn" to that "weak" injector, bringing IPW's up, and making the other cylinders run comparatively rich. Check your plugs to see if one (or more) show signs of leanness compared to the others. Another possible sign of this is sporadic misfires on a single cylinder that aren't due to coolant ingestion and can't be solved by swapping around spark components (plug, wire).

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2004 Buick Lesabre Limited, Gran Touring
Bone Stock

1998 Buick Lesabre Limited, Gran Touring
Retired

If you have never replaced your fuel filter you might want to do that as well. It's cheap and easy to replace and I'd imagine a clogged fuel filter would rob you of some fuel pressure.

^^^ Yeah, that, too

(Good call!)

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2004 Buick Lesabre Limited, Gran Touring
Bone Stock

1998 Buick Lesabre Limited, Gran Touring
Retired

Injectors aren't a performance mod, and they add nothing unless you modded something else and outflow them. With your current mods, you're not outflowing them.

If you have lean AFR or power issues, you've got to look in other places. The injectors could be an issue if they're not delivering well, and it could be mechanical or electrical. All other issues that I can think of offhand for AFR issues:

O2
MAP
MAF
Vac Leak
EGR leak
TPS

Things that you can rule out easily are the fuel filter and fuel pump. If you have low-mid idle/run AFR issues, but are good at WOT, rule those out. If your issues seem to be more WOT related and good in other RPM ranges, you might look into those. Change the filter. The pump can provide good pressure with low fuel demand through a dirty filter, as it's bypassing most of what it delivers to the rail anyway, and it goes right back to the tank.

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93 SSEi, 95 SLE (supercharged) 97 Buick LeSabre Limited
PontiacDad at WCBF '04: Cruise control? That's like surrendering!
Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

I'm aware of that, that was the whole point of the post.

well i only know that my WOT ipws are off.. i have no wideband, so how am i supposed to know of me low-mid idle/run AFR is good? WOT isnt having issues i can feel, in fact, if it weren't for the aeroforce, i never would have known anything was wrong.

I'm going to try a fuel filter first

I was just clarifying your point for any new members that may stumble across this in future searches.

_________________

Click here for mod list for both cars
93 SSEi, 95 SLE (supercharged) 97 Buick LeSabre Limited
PontiacDad at WCBF '04: Cruise control? That's like surrendering!
Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

alright, so would the suggestions be replacing the fuel filter, and possibly the fuel pump first?

Yes, I would suggest you first replace fuel filter in any case. See if that has a significant impact on fuel trims and/or WOT O2's.

Second, find a way to test fuel pressure at the Schrader valve in the fuel rail. At the least, in the driveway with a mechanical gauge, at idle and revving by hand; ideally, with an electronic sensor hooked into a scanner/logger so you can see fuel pressure all the way out to WOT.

(While you're at it, sniff the inside of the vacuum line/fitting at the fuel pressure regulator; if you smell gas, the FPR vacuum diaphragm may be leaky or busted...this would cause low fuel pressure, especially at higher load)

_________________
2004 Buick Lesabre Limited, Gran Touring
Bone Stock

1998 Buick Lesabre Limited, Gran Touring
Retired

according to the service records, the FPR was replaced at 77k, and a fuel pressure test was performed. I pulled the vac line off before and it was clean, i suppose it wouldn't hurt to try again. I don't see the fuel filter on the list anywhere, i will start there.

OK, i know this is an old thread, but here's the deal - I replaced the fuel filter, my IPWs are still about 19, give or take at WOT. I don't go WOT often since my trans doesn't like it.. My fuel trims are great. Is this something I need to worry about if I'm not pushing them to their limits often?

As long as you're not hitting 21, you're fine, IMO.

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RIP sandrock

Your not even pushing them to their limit, so no worries.

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