Stutter or stumble under slow acceleration?
11-10-2010, 07:13 AM
#1
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Stutter or stumble under slow acceleration? I am not sure if this is a part issue or tuning issue, so I figured I would post it here. Under light acceleration (like one would accelerate if leaving a stop light with a cop behind you) my car gets a nasty stumble and feels like it loses a little power. At WOT it is an animal and will break the tires free no problem. Also I scanned the computer there are no codes. Any input? Is this a tuning issue? TPS? The only mods are Lid, Headers, Exhaust, ORY, and Motor Mounts. The car is still on a stock tune and runs super pig rich.....Could it be loading up with fuel? I hope its a tuning issue. Any input would be appreciated.
11-11-2010, 05:21 PM
#3
does it happen every time? id start with fuel pressure first. my car did that when it had a bad fuel pump. if its fine then go to spark plugs and see what happens from there.. good luck
EDIT: you might wanna check your fuel filter too!
11-11-2010, 05:46 PM
#4
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I'd like to hear any advice on this too, I was going to post this but never got to it. I have the same problem. For me, though, I don't have to be that light on the throttle. Even if I give it a little kick, it does it to me. However, just like you, OP, on WOT, I don't have this problem.
11-11-2010, 06:42 PM
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I'd like to hear any advice on this too, I was going to post this but never got to it. I have the same problem. For me, though, I don't have to be that light on the throttle. Even if I give it a little kick, it does it to me. However, just like you, OP, on WOT, I don't have this problem.
11-11-2010, 07:00 PM
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also interested,
My girlfriends new (to her) '99 has a similar problem, just seafoamed it and it seams better, still feels a bit wierd on part throttle tho.
Mine doesnt do it at all
My girlfriends new (to her) '99 has a similar problem, just seafoamed it and it seams better, still feels a bit wierd on part throttle tho.
Mine doesnt do it at all
11-12-2010, 10:46 AM
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I had a vacuum leak that caused problems at light throttle. Check all your PCV/vacuum hoses for that.
I also had a problem that was open/closed loop related. At full throttle the fueling is taken from a table, so it ran OK. In my case I think 7 out of 8 cylinders were running OK.
At part-throttle/cruise (closed loop) it ran badly. Long story short, for me it was a bad injector. I think what happened was the bad injector made 1 bank of the engine look like it's running lean. To compensate the computer richens the mix on the entire bank, and then you have 4 cylinders with a bad mixture.
I think an exhaust manifold/header leak can give a similar case. I replaced the gaskets there before the injectors but it was OK.
If you have access to a logging tool like efilive you can see this case. For me in cruise mode 1 bank had 2x as much injector duty cycle as the other bank when it ran like crap.
I also had a problem that was open/closed loop related. At full throttle the fueling is taken from a table, so it ran OK. In my case I think 7 out of 8 cylinders were running OK.
At part-throttle/cruise (closed loop) it ran badly. Long story short, for me it was a bad injector. I think what happened was the bad injector made 1 bank of the engine look like it's running lean. To compensate the computer richens the mix on the entire bank, and then you have 4 cylinders with a bad mixture.
I think an exhaust manifold/header leak can give a similar case. I replaced the gaskets there before the injectors but it was OK.
If you have access to a logging tool like efilive you can see this case. For me in cruise mode 1 bank had 2x as much injector duty cycle as the other bank when it ran like crap.
