2001 impala 3.8 no power at WOTk

Ok so our car drives pretty normal for low and mid range throttle... it does has a noticeable low idle misfire thst csn be felt but nothing that shakes the car it can just be hear thru the exhaust... not throwing any trouble codes or anything unless you floor it to pass someone then the car goes into like a burned out transmission mode and redlines at 3000 rpm with no power.. if u do it from a stop car wont reach 2nd gear on flat ground.... o2 sensor reads 0.000 volts the whole time fuel pressure is is above 50 while running and doesnt appear yo have any mad drops when snapping the throttle... clean the maf and the max reading is 80 grams per sec... unplugged it with no improvment... hooked up my scope and the back three cylinders had some shitty secondary waveforms at idle but the injector waveforms showed good pintle movement even tho i didnt photo those... so idk what to do

can you get under load data? fuel trims o2 sensors? in the picture you have the bank 1 sensor 1 reads rich at 770 mv. what about an injector balance test?

I'm with Cheryl, data when it won't get to second gear would be ideal. Be sure to get the Calculated Load in there. Those secondary patterns definitely suggest a lean issue, and the trims at idle agree.

I will def try to get those screenshotted today... the 770 millivolts was at idle... underload it reads a flatline 0.000 and stays there until u let off the gas pedal... ud swear the cars converter is blocked but ive done cut it down n had it welded back up its completely fine and see through

Put a fuel pressure gauge on, tape it to the windshield or put the hose under a wiper blade and drive it. See what the fuel pressure drops to

16 long term at idle but it jumps to 0 under heavy acceleration and o2 voltage drops out completely the whole time... car literally has no power to even upshift until u pull back off the throttle... itll wind out 2nd gear at 35 with ur foot on the floor barely even reaching 3500 rpm

Ninjaxchicken wrote: 16 long term at idle but it jumps to 0 under heavy acceleration and o2 voltage drops out completely the whole time... car literally has no power to even upshift until u pull back off the throttle... itll wind out 2nd gear at 35 with ur foot on the floor barely even reaching 3500 rpm

Thanks for the capture. The Load at 51% is horrible. It's low for a reason, and from what you stated earlier, it isn't the exhaust.

Will your BlueDriver allow you to watch the MAP? Try another WOT run with the engine speed, Load, upstream O2, TPS, MAF and MAP. If the MAP is low, we're looking for an intake restriction.

Bruce's idea of watching the fuel pressure while driving is still a good idea, if possible.

Yeah i can do map readings... as soon as i can get those readings for you and the fuel pressure test i will... i appretiate all the help with this

I should mention on april 30 i put a brand new carter fuel pump in bc the old went to crap on us.... idk if this unit the cause or what

Ninjaxchicken wrote: I should mention on april 30 i put a brand new carter fuel pump in bc the old went to crap on us.... idk if this unit the cause or what

Eh, maybe? :huh: In my experience, vehicles with low fuel pressure still generate good Load readings at WOT, so I still think we're looking at a VE issue.

But, stuff surprises me all the time! :silly: Had a Nissan last week with a bug in the MAF that made the fuel trims super high at idle, but decent under load - the exact opposite of what it should be. :blink:

These fuel trims are abt 16long and 3 to 0short at idle but if i hold it steady abt 2000 all that high fuel trim goes away so i thought vacuum leak... i cant find a leak anywhere and when i put a vacuum gauge on the intake it holds at 20inhg steady so idk... got 180psi compression thru all cylinders, ive swapped coils and when i test the car i get p0300 and p0301 no matter how i arrange them... ive unplugged each injector one by one and theyre all contributing bc the engine starts missing and shaking on each unplug... unplugging each plug wire at the coil i get good spark... this car gives me a headache

I had to remove the trim data so everything wld fit but they flatlined at 0 anyways during the test i was doing

Ok i think i have good direction here... i hooked up a fuel pump gauge to my windshield tonight like yall suggested and when i started to drive and gave it a cpl revs it blipped a little bit but as soon as i floored it it dropped to 20 psi

Voltage drop tested the fuel pump with the car running straight at the fuel pump connector from the battery directly.... 475 millivolts on the ground and 850 millivolts on the power side... pumps running at abt 7.5 amps

Ninjaxchicken wrote: Voltage drop tested the fuel pump with the car running straight at the fuel pump connector from the battery directly.... 475 millivolts on the ground and 850 millivolts on the power side... pumps running at abt 7.5 amps

Oooooh I like the current reading. Electrical side is good.

The only concern I have left is the pressure regulator. It's possible it could be stuck open, never closing off the return side and causing low pressure under load. It's unlikely, but possible. From Engine Performance Diagnostics:



Pinching off the return side is a good idea, as it'll force the pump to dead head and show how much pressure it can generate by itself. I'd expect at least 75 PSI, closer to 100.

The pump i ordered a month and half ago was a cheap 50 dollar pump off ebay(i know right) and the intake screen was completely filthy so my feeling is the intake screen is getting stopped up again... if thats the case ima have to clean the tank out before changing out the pump again except this time ima buy an acdelco pump instead... the regulator is faily new bc the system kept draining pressure real fast when i turned the key off so idk if its an issue again or not

Ninjaxchicken wrote: The pump i ordered a month and half ago was a cheap 50 dollar pump off ebay(i know right) and the intake screen was completely filthy so my feeling is the intake screen is getting stopped up again... if thats the case ima have to clean the tank out before changing out the pump again except this time ima buy an acdelco pump instead... the regulator is faily new bc the system kept draining pressure real fast when i turned the key off so idk if its an issue again or not

Let us know what you find! Delphi would be a good alternative if ACDelco is not available.

Will do buddy thanks for all the help and replys