Ok, so I am having this issue where at a certain throttle percent and rpm my fuel cuts out, like trying to pull out from a stop or something. Matt H and I figured it was a tps senor issue for a while, but it has gotten gradually worse and worse. It spits and sputters, and the second it gets 50% or more throttle it works fine, the other day it got gradually worse and worse to the point where I had to like launch the car to pull out. After it sat 1 day it was fine. Also that day it was idling and misfiring like crazy and going to - - - on my WB when it misfired as if there was zero fuel. My buddy says it sounds like the factory pump is dying and can't keep up the volume. I ordered a racetronix pump and I hope this fixes my issue.
The factory pump has 106k on it. Never been touched, however rare, sometimes if the car has less then 1/2 tank and sits on a weird hill it wont start, so I have to shake the car or add 2 gallons and it fires right up..
Fuel filter has 20k on it, I will replace it when the racetronix goes in...
Any thoughts...
LE61T PTE6262 Powered 
Hmm maybe a pinched line back there all of a sudden? You know, the gay plastic fuel line hoses we have. That was my problem for the longest.
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The gauge will go to ---- because all it is, is a Oxygen sensor, when you misfire oxygen is going out the tail pipe not C02, H20, N, ect.
I know I explained it bad, but when you misfire the gauge will show lean. The pump may very well be dead. Or vacuum leak, is the 2.4l manifold installed correctly.
13.3 @ 106 mph Cammed
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8 psi with m62 and IAT under 100
huh? I have the hahn port fueler, and turbo kit...
and yes I know why the gage does that, that was just info I posted, and reinforcing the fact that I think it's a fueling issue
Edited 1 time(s). Last edited Tuesday, June 29, 2010 8:59 PM
LE61T PTE6262 Powered
I have went thru alot of tps sensors..
97cavalier
Sounds like what happends after a Racetronix install when the little line on top of the pump isn't secured like an Army fort.
IAC valve?
Mine went bad about 2 years ago, and I experienced some of the same issues as you, as well as my rpms dropping tp almost 100 when hitting the clutch at highway speeds...I first went after the TPS and fueling issues, then it turned out to be the IAC sensor.
so I need to find a new tps sensor iac sensore replace fuel filter fuel pump and fpr, if that dont work im donating my car to charity
LE61T PTE6262 Powered
My car does the same @!#$ from time to time. Found out that my fuel pressure had dropped to 30 PSI, so I bumped it back up to 40. Seems to have fixed my issue for now. my pump is on its way out and I will have to replace it soon. I need to hook the fuel pressure gauge back up as the intermittent lean and tip in stutter is comminng back.
Qwibby {T3H Old QBE} wrote:so I need to find a new tps sensor iac sensore replace fuel filter fuel pump and fpr, if that dont work im donating my car to charity
Phil, I would try just the IAC before spending the money on the tps as well...when mine went bad, obviously the first thing I thought of was the tps, so needless to say, I was kind of pissed when I bought that and it didn't remedy the problem...
The thing in my case that seemed to be the biggest red flag pointing to the IAC is that the symptoms gradually got worse, and in my case, didn't always exist...a lot of times, the car would act fine when the motor was cold, and quickly surfaced as it heated up. I ran that past a few of the service techs that I used to work with, and everyone of them said the IAC...low and behold, after replacing my tps, fuel filter, map sensor, and IAT sensor, spark plugs, and testing the coil pack and ignition module with no results...I replaced the IAC and problem solved.
Make sure you get an IAC that comes with a new O ring, it is suggested not to reuse to old one.
Gimme a call if that doesnt fix it for you
alrighty...
So I need to find a yard that has an eco. I am laid off so pretty much free time is plentifukl
LE61T PTE6262 Powered
Check Harry's in Pennsburg....there were two Eco Sunfires..one was completely untouched when I pulled a valve cover about 2 weeks ago, the other one I think the TB and sensor was long gone.
Though you might have better luck finding some Eco J's at Allentown Harry's
IAC causes part throttle issues?
can anyone explain this to me, because I'm confused.
phil, I'm calling around 7 if thats ok.
DaFlyinSkwirl (Pj) v2.0 wrote:IAC causes part throttle issues?
can anyone explain this to me, because I'm confused.
Doesn't make sense to me either, lol...I always thought the IAC could only have effects at idle...but when I had stalling problems + some of the problems Phil is having, several techs told me to check the IAC and that's what it turned out to be...to this day I'm still not sure how it was causing the part throttle issues (or honestly if it really was), I just know that replacing it fixed my problems immediately.
Have Rodimus log your data in HPT while driving, and install a fuel pressure gauge, we do have a tap on the fuel rail for that, and monitor TPS, IAC, MAP, and WB02, and keep an eye on the fuel pressure gauge as well. It should never go below 45 PSI. On another note, pull and visually check your coil pack for carbon tracking/arcing through the boots, and have the ignition module tested if everything else checks out ok.
Currently #4 in Ecotec Forced Induction horsepower ratings. 505.8 WHP 414WTQ!!!
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Ok I see you're turbocharged. Now I've had the same issues for years. It took me a while to connect the dots and I did not want to believe this explanation, but I was experiencing vapor lock due to excessive underhood temps. I repalced both fuel pumps (Hahn kit) more than once. Checked all relay wiring, connections, etc. The only thing that I knew was that when sitting on hot concrete/asphalt after long periods of hot running, the heat soak would vaporize the fuel in the underhood lines. It's very difficult to get it to idle smoothly again and yes you have to use almost all of the throttle to get it running. Sounds crazy I know, but do you think that this issue is heat related for you? Look at the proximity of your fuel lines to your turbo and how close the heat is trapped around the firewall and fuel lines. A ton of heat just sits there cooking that fuel. After all this time, that is the only thing I could come up with.
"If you aren't shifting, then you certainly aren't driving!"
roofy I have a gauge its 50 psi
silvercav - you make way to good apoint, the day it was happening bad it was 99 degrees out and the fuel lines were hot to the touch, right over the dp... hmmm, I'll heat wrap those too... but thats makes great sense because the next day after it cooled down it was fine
LE61T PTE6262 Powered
That sounds exactly what is happening with me at the moment, and I have the racetronix pump. Driving in 110+ heat, park the car for an hour or two, come back out and it barely runs for a few minutes. The AFR gauge leans out completely and it's sputtering like crazy.
What would you guys suggest to fix this? Heat wrap like he said above?
"You can only feed them semen for so long before their legs fall off."
Yes it's in the summer when you have it happen - not sure on your hood, but I'm going with a hood design to get heat OUT!! Don't need scoops, you need to get the heat outta there. I'm thinking like the Evo hood or the Invader. Or just cut some massive holes on top of your stocker.
There are much more elaborate ways to cure this problem using afterrun pumps or fuel pump timers, but I haven't been able to evaluate my new heat wraps and hood ideas yet. Let me know if you find any success.
"If you aren't shifting, then you certainly aren't driving!"
Would a turbo timer help out in this situation? (yeah, im turbo'd)
"You can only feed them semen for so long before their legs fall off."
Sorry to Seniorguitar - missed your post while typing. I haven't cured mine yet due to the car still being rebuilt...almost there! The ideas I mentioned above can help and certainly won't hurt to try.
To truly kill this issue, simply put, you must prevent the heat from vaporizing the fuel in the lines when stagnant. If the fuel is moving, it is very difficult to boil it. That is why you have the issue after starting up - you just heat soaked the stagnant fuel after putting it away with a hot turbo. So the way to kill it is either, remove all heat (impossible), remove enough heat, or to keep fuel circulating until you reach a more desireable underhood temperature.
Maybe if we all work together on this we can solve this problem!!
This issues has literally killed my car at serveral racing events after travelling long distances to get there. I know how frustrating this can be.
"If you aren't shifting, then you certainly aren't driving!"
