96 sunfire, hesitates around 2500 rpm

Asked by Apr 20, 2010 at 09:50 AM about the 1996 Pontiac Sunfire

Question type: Maintenance & Repair

my 96 pontiac money pit/sunfire with 2.4 has a weird hesitation. Its like its running out of gas. It seems like if u accelarate lightly it does it and if u accelarate hard its fine. well kinda. sometimes u can drive it with no problems, other times it acts up. I just bought the car it has 220 000 km. I just replaced the head gasket and the valves as when i got it it had a burnt vavle because it had a bad plug the previous owner could not get out. no check engine light, plugs r new, found a couple of bad orings on fuel rail have been replaced. think i need to replace the coolant temp sensor as the fan doesnt come on, but the fuse, relay and motor r all good.

yes i replaced the fuel filter...lol

o aswell when it warms up to temp, and u hold it at 1500 rpm its hesiates aswell, kinda seems like it is goen to died but it has never stalled out on me yet....knock on wood....all vacum lines r good.

o and one more thing to my novel, i checked the fuel pressure and it reads 44psi with key on
40psi after sitting for ten mins
40psi idling
in the haye manual it sayes to pinch the return line if u have low pressure and if the pressure goes up its the regulator.
but mine dosent have low pressure so i would assume i can rule that one out.




HHHHHEEELLLLPPPP!!!!!!!!!!

13 Answers

another thing, the fuel pressure dosent change when it hesitates at 1500rpm,

helppppp......any body out there.....

8,580

Possibly a dirty or bad maf or throttle position sensor.

ha larry, no maf on this one, not sure if it rules it out or not but if i unplug the tps it runs the same

2,935

You could have a plugged exhaust. Pull the B1S1 HO2 and then go drive it and see if your hesitation goes away. Your cat or muffler could be plugged or have loose internals causing limited flow and your hesitation.

1 out of 1 people think this is helpful.

worth a try, had to replace the cat with a used one because the flex pipe broke. it looked good when i put it on like two weeks ago

8,580

It shouldn't run the same with the throttle position sensor unplugged. Use a multimeter and check your voltage. Measure the voltage across it with the key on as you move it. Chances are you will see a sudden drop while opening it indicating that it needs replaced.

35

hey check your block.

(I am just learning car terminology and how to work on cars; so bear with me) I have the same problem. My 99 sunfire 2.4 GT hesitates exactly like yours. All the typical things, that are often responsible for the hesitation, as you have already listed, have been checked on my car. The only thing I can say is that the air filter was dirty one time so I removed the hose all together (that the MAF meter is connected to) so that unfiltered air went directly into the resonator. My HESITATION ACTUALLY WENT AWAY for about 5 hours. Then came back!!! PLEASE PLEASE PLEASE let me know if you fixed your problem and how you did it! I am so pissed about this (aside from this minor problem the car is great). Cheers man, Shawn.

Was anything brought o light on this subject? I have a 2000 sunfire with he same deal- plugs and wires are new"er" havent checked fuel pressure yet but will tomorrow- car has 141,xxx on it @ this time Help?

5

These cars do have a maf sensor it is actually right at the top of the throttle body that hole on the left side is it

I had similar problem and while i was looking for the TPS I noticed the tube(hose) from the intake manifold to the intake pressure sensor was slightly cracked. I replaced it and my sunfire has been purring like a kitten since. Hope this helps. I suffered with this hesitation for more than 3 years.

10

I had the same problem in my 02 GT 2.4. I changed EVERYTHING. coils, ICM, MAP sensor, TPS, plugs, plug boots, fuel filter, ALL with OEM parts, AC DELCO, Delphi, auto lite boots. Nothing helped. The Coil housing looked brand new. No burns no carbon buildup. Nothing. So I didn't replace it until today, and that is what finally fixed it. The COIL HOUSING which has no electronic parts nor moving parts fixed the problem.

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