I have a 97 Sunfire with a 2.4 engine. I don't know what year the motor is for sure (it was replaced).
There is a REALLY bad hesitation (almost a sputter) below 2 grand and the car cuts out to a much lesser degree about 2 to 3 times between 2 grand and redline at WOT. The more gas I give the car, the worse it is. I replaced the plugs with stock autolites (the denso Iridiums where burnt pretty bad), and the problem went away for about an hour then came back.
If I just give it enough gas to barely accelerate the car is fine. It seems like the plugs are foweling. The car just started doing it on its own (not after a modification). I don't know for sure whats causing it, but it's driving me crazy.
Anyone have this problem before, I'm not sure what to do, thanx I could really use some help.
This sounds like it could be a bad TPS sensor. Still pull your plugs again and see how they look. If you can find a local J with the same motor to loan you there TPS sensor see if it fixes the issue, or go to the junkyard and get one off a wrecked J.
FU Tuning
Pour some TB cleaner on the throtle body with the engine on and reving it up so it won´t come off.
It does sound like a TPS problem, but I'm also wondering if the FPR is going out too. I don't have a doner car so I'll have to buy the parts wich means I wan't to be pretty sure before I replace anything. Last time I checked TPS's arn't very cheap. I don't have an ohm meter to check the TPS but I should be able to just pull the vaccum line off the FPR and see if the idle changes. Just in case, the FPR just unthreads out of the fuel rail right?
It's dark out but I'll check some stuff out closer and see what I can find. I just hope it's not a coil problem again.
Well I pulled the vaccum line off of the fuel pressure regulator (wich should make the car run at max fuel pressure), and it didn't make any difference in how the car ran. I even drove around with it like that and I couldnt tell a difference. Normally when you pull the vacuum line off of a FPR the idle gets really eradic for a couple of seconds before it adjusts itself and the car runs like crap after that. When I did it to my car, the idle didn't change at all and it runs like crap all the time either way (as if the FPR isn't working).
I can get a new FPR for $56 from NAPA, I'm just wondering what you guys think before I do it. Next stop is the TPS if this doesn't fix the problem. Thanx
Well I replaced the FPR and the fuel filter, and there's no change. It turns out the FPR was bad, but replacing it didn't help any. A TPS cost just under $40 so if it comes down to replacing it, I can afford it. I'm going to run a crap load of injector cleaner through it, and replace the plugs with AC Delco's gapped the way they are out of the box and see what happens once I wash all the asphalt out of my hair.
If anyone knows of a common cause for this problem let me know, Id'e rather not blow a bunch of cash trying to fiqure it out.
Well the car is "better" now. I poured some cleaner in the tank, found a plug setup that works 'OK', and put the stock gas cap back on. It's not perfect yet. (still a little pissy below 2 grand). but it's getting better. Hopfully I can find an ignition setup that works well. Either way the car just ran a 15.8 so it's OK for now. Thanx to the people that tried helping, although I'm really the only one posting on this thread.
Weebel wrote: and replace the plugs with AC Delco's gapped the way they are out of the box and see what happens once I wash all the asphalt out of my hair.
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did you check that gap with a gauge before you installed them, the gap isn't always right out of the box.
Edited 1 time(s). Last edited Saturday, July 14, 2007 1:56 AM
What plugs were you running?? I run NGK's. Love them runs great. I did not think it was the FPR, I can take the vaccum off ine and it does not change either.
FU Tuning
my 2.4 does the same thing but just when i first take off after the car has been sitting for like 10 minutes or longer, its like i'm trying to take of fin 5th gear and the car just bogs down and i have to keep hitting the gas and finally it will start to rev up. I posted a topic about this but never found a solution to the problem. the girl i got the car form said it has done it since she bought the car with 22k on it and her dad has had dam near everything replaced at a shop that could cause something like this.
The coil hausing is a suspect.... always!
98CavalierZ24...That might be an O2 sensor or an IAC problem, at least that would be my first 2 quesses without actually seeing your car, but it could be a lot of things. It's hard to tell without actually checking it out myself. It definatly sounds like a fuel or air problem to me though.
Well I had the car running perfect. the only plugs I could find a 2am where Bosch Platinum's at Wal-Mart, and the car seems to like them. I had to old plugs gapped at .050. I also ran some cleaner through the tank, and put the stock gas cap back on. The FPR was bad, but didn't fix the problem. I'm not sure yet wich of the 3 fixed the problem though.
After the car was running really well for a few day, my #2 injector started leaking really bad at the fuel rail, and the hesitation came back. I got it to stop leaking, and the car is getting better again, I just hope it goes away all together like it did before the leak. Sometimes I hate EFI cars and miss good old carburated engines.
Is there a way to test the IAC? I did notice that the car is making a sound like its sucking air when it idles at first start up and when its doing its not wanting to run thing, kinda like its getting ready to die but then revs back up a little(I call it surging). And wouldn't the 02 sensor cause the ses light to be on if it were bad? Or at least show up when i scan the car?
a bad 02 wont always throw a code..it could be bad..or you could have the wrong brand in..if its a bosh take it back immediatly...also kinda sounds like maybe the MAP? have you checked the vaccum lines to it?
Ha ha ha dam... Hey scott I love your sig man..funny stuff.
The rubber elbow for the brake boost that goes to the throttlebody cracked on my car once and caused a lot of the same problems, I would check all your vaccum lines before replacing anything first just in case.
Btw, my cars doing better now, I'll just have to wait a couple of days and see if it comes out of it all the way.
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