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2002 Pontiac Sunfire lack of engine power.

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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.
  2. Low on power and shaking badly? Take compression readings.
  3. 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.
  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.

    Did you change fuel filter - fuel pressure ck - new ≠ good.
    Will your scanner show live data- FT's, ECT, o2 voltages, MAF, etc?
  5. 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.
  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.
  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.
  8. Is it still stalling dying on side of road after @15 min?
    There are NO current codes?
  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.
  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?
  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.
  12. You might want to suggest an exhaust system backpressure test, as Kev mentioned.
  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.
  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?
  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.

  16. Had to buy a fuel pressure in 85, little 15 psi gauge didn't work any more, fuel pump pressure had to be greater than the regulator setpoint or would not get recirculation, and the pump would burn out. Besides the pump, its voltage has to be the same as the battery, typical current draw is 4 amperes, if the voltage is less than this, motor cannot get up to speed to develop BEMF and the input current will skyrocket and burn it out in a hurry.

    Long path from the positive side of the battery, firewall connector, fuses, ignition switch, fuel pump relay and clear back, dirty contacts cause voltage drops or a very poor ground someplace.

    Regardless of what you have to pay for these POS for lack of a better word, long brushes, cheap armature and plastic check valves and not quite the easiest things to replace. When does it go out? After you top off the tank with gas, with no easy way to drain it. Very few vehicles have an access plate and if the exhaust runs under it has to be dropped first. Dey all do dis.

    85 Honda SEI was one few vehicles I had that used an external fuel pump, and since it was so easy to replace, never had problems with it, story ends here. On this newer stuff, everything has to be tight or will get fuel evaporative codes. Another PITA. Then E10 comes along, more problems, 2002 is marginal, some say you can use E10, but not E15, E10 just takes longer.

    Sure have to load those spark plug boots with silicone or will never get them off, they bake on hard. The they are like a Chinese finger puzzle, harder you pull, the tighter they get. Made my own tool with a piece of 3/4" strap steel, put a notch in it at a right angle that goes under the boot so it compresses rather than stretch it out.

    45 mils is way too much gap on spark plugs, ignition systems are so weak, get a blow out, misfire that toasts your cat. 26 mils works fine, but to do this, ground electrode has to be bent out so the electrodes are in line.
  17. Early or repeat fuel pump failure is sometimes caused by high resistance in circuit connectors. Specifically, the wires inside the tank. Jostling the wires during pump replacement can get them to work briefly. Hanging a replacement pump on it's mount without addressing possible harness issues is a fools game.
  18. this comment is freakish, ground on rear bumper.
  19. I'm not sure what you are saying, nickb2. I thought Dan's post was reasonably valid.

    Maybe we should take this to the Lounge for debate?
  20. Hmm, ok, maybe my last post was confusing, but the ground choke point is G304. I have seen numerous bad FP diagnosis due to not checking this ground out. It is close to rear bumper under license plate light.

    Also, I posted while buzzed on zambooca flambé. Last night was fun night out with the boy's, but most of us have a head ache now. Anyway, back to the problem. see snapshots

    Proof of what I am saying, this ground can throw a fp diagnostic way out of whack. See snap shots below. If that ground isn't clean and tight, find another location and use 12gua wire.

    Screenshot (61).png Screenshot (60).png
  21. Often the splice for the pump is grungy too. I always redo wiring to new, so I don't have to see that particular car for that particular problem again.
  22. Splice S330 that is.
  23. Update: its been 12 days since fuel pump was changed and its still running great again without it dying. I dont know what the guy at the shop put in for a fuel pump assembly but it was $265 for it. I had a spectra premium put in on my old car (2005 Chevy Cavalier ) and never had pump issues even the the day i traded it in it was running great.