Seriously bucking under full throttle
Seriously bucking under full throttle
I don't know when this started, but my engine bucks and jerks really badly under full throttle, especially at low RPM's. I've read that a bad TPS could cause bucking under deceleration, which it does too to a lesser extent. What I don't understand is that I pulled this TPS off a 626 that ran really well and smoothly. I adjusted the idle switch with a ohm-meter and feeler gauges, but that didn't help much. Did I screw up adjusting it?
Also, I'm getting codes for my O2 sensors (unplugged because they're so fouled up it actually runs better without them), and the VRIS#1 solenoid. Could that have anything to do with my problem? And which VRIS is #1? The one with the white or blue sticker?
Also, I'm getting codes for my O2 sensors (unplugged because they're so fouled up it actually runs better without them), and the VRIS#1 solenoid. Could that have anything to do with my problem? And which VRIS is #1? The one with the white or blue sticker?
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Re: Seriously bucking under full throttle
You could be running uber rich/lean b/c of no O2's. Thats the only thing on the ehaust side that tells your ECM how it's doing with the fuel ammount. VRIS shouldn't change much except powerband ![Smile :)](./images/smilies/icon_smile.gif)
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Re: Seriously bucking under full throttle
I guess it could be that, but I always though they were for pretty much just fine-tuning the mixture.
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Re: Seriously bucking under full throttle
I'm trying to think if the ECU doesn't care about the o2's @ WOT
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Re: Seriously bucking under full throttle
yea doesn't it go open loop? Apart from the likes of the knock sensor, clt, iat, I think it just goes open loop - no feedback from o2s.
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Re: Seriously bucking under full throttle
Still...if you know you have bad O2 sensors wouldn't you just replace them?
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Re: Seriously bucking under full throttle
maybe a fuel issue? bad FPR or clogged fuel filter or injectors?
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Re: Seriously bucking under full throttle
I'm gonna replace them soon anyway, I was just asking if maybe it was something else. I got a set of injectors and and FPR mounted to rails from solo-ryder a while back, so I assume they're good. Maybe the fuel filter, but it only started doing that suddenly after changing the timing belt, I tried re-timing it again after and it made no difference, so it's not that. Could it be a clogged cat?
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Re: Seriously bucking under full throttle
So it started doing it after you did your timing belt and you're wandering if it could be a clogged cat? Unless your old timing belt somehow got sucked into the cat, I doubt it.
Re: Seriously bucking under full throttle
I know it sounds stupid, but that thing is, it ran stupidly rich for a while after that a flooded more than a few times because I damaged a coolant temp sensor while unplugging to to get the wire out of the way, and I heard that can seriously screw up a cat, that's probably also what ruined my O2 sensors. I replaced that sensor and it's pretty much fine now.
I'm just throwing ideas out there because I honestly don't know what could be wrong.
I'm just throwing ideas out there because I honestly don't know what could be wrong.
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Re: Seriously bucking under full throttle
what about your timing belt tensioner - did you replace it or are you sure it's working?
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Re: Seriously bucking under full throttle
I replaced it, it was knocking a bit before.
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Re: Seriously bucking under full throttle
my friends klde pgt has bad o2 sensors and it bucks hard under accell sometimes. you are probably right about the oxygen sensors being the problem.
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Re: Seriously bucking under full throttle
I guess I'll try that, also, I just realized it can't really be a fuel or air problem because it gets better at higher RPM's, it's worst around 3-4k.
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Re: Seriously bucking under full throttle
I just had this issue where I was driving and I had major hesitation, etc ONLY between 3-4k and my tach needle was going crazy... it turned out that something was wrong with my distributor - I haven't tested it yet but I believe its something to do with the pickups inside.
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