2002 Pontiac Sunfire lack of engine power.

Scotty

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#1
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MAKE: Pontiac
MODEL: Sunfire SE
YEAR: 2002
MILES: 135,081
ENGINE: 2.2L OHV Vin 4
DESCRIBE ISSUE.... Engine is lacking power while accelaration. I just had fuel pump replaced less than 2 weeks ago due to DTC P0171 code. After pump was changed, car ran great until Sunday afternoon ( 3/12/17) . Car has no new dtcs, no power accelrating hard, but baby it, it will go. Abs light is on since i got the car on Feb 23rd. Now trac off light comes on while driving as well.when it happened i had the ac, radio, lights, and wipers on. I checked the alternator at battery. Everything off, its at 14.3 volts. All the above, 12.6v at idle, 2k rpm, down between 9 to 10 volts. Engine is shaking badly as well. So any ideas? Me and my buddy are completely stumped and i got no car now to get to work. Thanks in advance.
 

billr

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#2
Low on power and shaking badly? Take compression readings.
 

Scotty

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#3
Low on power and shaking badly? Take compression readings.
Its acting like its missfiring. I got one of the plugs out cylinder 4 and they look good but alil worn down to 0.045 in gap. I couldnt get my big hands to the others to get the plug wires off.
 
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#4
What codes are showing? You say no new DTC's.
The ABS light is on and the TC (trac control) is on - SO we know there are codes.

thoughts-
Did you change fuel filter - fuel pressure ck - new ≠ good.
Will your scanner show live data- FT's, ECT, o2 voltages, MAF, etc?
 

Scotty

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#5
What codes are showing? You say no new DTC's.
The ABS light is on and the TC (trac control) is on - SO we know there are codes.

thoughts-
Did you change fuel filter - fuel pressure ck - new ≠ good.
Will your scanner show live data- FT's, ECT, o2 voltages, MAF, etc?
We changed fuel pump and filter last friday. Weird part is that this car has no valve to check fuel pressure. Before pump was replaced, it was staving for fuel and only run for 10 to 15 mins of driving before dying on side of road. But it would idle all day long without a problem. My scan tool does do live feed. This is what i got off of it:
STFT : when cold, starts at 0.0 and go to 3.8 as engine warms up, it goes up to 10.8 sometimes upto 15.6.
LTFT: hangs between 3.8 to 4.6
MAF: this car dont have one. Looked high n low
ECT: reads fine. Goes from 100 upto 195 degress. Sensor was replaced around when fuel pump was done.
O2s: upstream s1, starts at 0.450 it will hang out between .600 and go has high as 0.890v but tries to go down as low as 0.080v
Downstream o2: reads between 0.080 to 0.350v when cold and hot.
MAP: its between 9 to 13 Hg
Fuel sys 1: its always in closed loop with HO2S. It does start off in open loop but not for long. Hope this is enough info.
 
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#6
I had to look that up - no MAF on this Vin 4 eng, my bad - sorry.
Running fine and going to crap suggests to me - fuel system not venting, or exhaust back pressure.
Try operating and as it goes to shit open gas cap CAREFULLY.
With a vacuum gauge - hold RPM @1500 - observe if vacuum drops or remains the same... You could monitor scanner for this.
 

Scotty

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#7
I dont have access to a vacuum gauge. I did try changing the ect sensor. I took the new one out and put the old one back in, now fuel trim for short term are near 0.0 also radiator fan isnt coming on nor trac off light. ABS light still on with no engine light. My scan tool only does engine computer only. Cant get any other systems.
 
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#8
Is it still stalling dying on side of road after @15 min?
There are NO current codes?
 
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#9
Scotty said "Everything off, its at 14.3 volts. All the above, 12.6v at idle, 2k rpm, down between 9 to 10 volts."

Perhaps alternator stops working at some rpm above idle rpm. Like, 2000 rpm. Gonna run like crap at 9 or 10 volts.
 

billr

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#10
Scotty also said only the plug(s???) on one cylinder was checked, because even the wires were too hard to get to on the other cylinders. What's the chance the plugs/wires have simply been ignored too long?
 

Scotty

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#11
Whoever owned this car before me changed the plug wires but not the plugs. When the ran, it was jumpy like its missfiring alil. I got cyl 4 spark plug wire off and got the plug out. It looked normal but it was worn down from 0.040 to 0.045 i have plans to change the plugs once i get money to do so. I can drive it if i baby the pedal. U try to floor it or open it up, forget it! Its gonna chug, buck, and pop until i back off. Then it will go but takes long time to get upto speed of traffic. I ended up taking to a shop. I cant be without a car any longer.
 

Scotty

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#13
Well, it turns out to be the fuel pump as the cause of the power loss. It was making enough pressure to just idle the car. Ill be having a new pump in it this afternoon.
 
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#14
OK - fuel pump - we all fall for the new has to be good. new ≠ good.
did you use a OEM pump, or an aftermarket?
 

nickb2

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#15
Fu$k, what an old debate. How many times do we tell clients to not cheap out on Gm fuel pumps.

As it is today, can't even tell anymore what is a premium FP anymore. Too many competitors announcing on e-bay or amazone. Long gone the days of good old carter pumps readily available, everybody trying to sell knock offs.

http://www.fme-cat.com/docs/1609.pdf