having major troubles with 350z help please
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I have had my 350z since April of 2010. shortly after I bought it i had to replace the clutch. After replacing clutch everything worked well for about 3 months. For the past couple of months I have been having some issues.
1) if the car is really cold (either a cold morning or not ran for a day or two) when i crank it up until it gets warm i get a code for a multi-cylinder misfire.
2) My car doesn't not at any point actually activate the vvt.
I was wondering if anyone has had any similar problems and what you all think i need to look into the fix it.
thank you
1) if the car is really cold (either a cold morning or not ran for a day or two) when i crank it up until it gets warm i get a code for a multi-cylinder misfire.
2) My car doesn't not at any point actually activate the vvt.
I was wondering if anyone has had any similar problems and what you all think i need to look into the fix it.
thank you
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when you get up in the rpm's it never engages it just straight falls on its face no power at all.
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Hmmm... That might be the VVT not functioning, but it really sounds like it could be a lot of other things, too. Doesn't it? Maybe if you don't restrict your search to just VVT, you might find another problem that is causing this. Is the Check Engine Light on? Is it throwing a code?
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Your car could be in Limp Mode. When you rev in Neutral, can you hit the Redline? Does the CEL Flash while you're driving? So when you're driving and you floor it, it falls on it's face?
I've had similar problems before, and it turned out to be a failed cat... the driver's side cat had actually plugged up, and it made the car throw the multiple cylinder misfire code. It also stumbled really bad under load.
Last edited by dmroberson; 04-16-2011 at 01:15 PM.
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Hmmm... That might be the VVT not functioning, but it really sounds like it could be a lot of other things, too. Doesn't it? Maybe if you don't restrict your search to just VVT, you might find another problem that is causing this. Is the Check Engine Light on? Is it throwing a code?
no codes whatsoever that is what is puzzling me...
I have no idea what it could be
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Kinda sounds like you're describing VTEC. VVT doesn't "kick in". It is continuous.
Your car could be in Limp Mode. When you rev in Neutral, can you hit the Redline? Does the CEL Flash while you're driving? So when you're driving and you floor it, it falls on it's face?
I've had similar problems before, and it turned out to be a failed cat... the driver's side cat had actually plugged up, and it made the car throw the multiple cylinder misfire code. It also stumbled really bad under load.
Your car could be in Limp Mode. When you rev in Neutral, can you hit the Redline? Does the CEL Flash while you're driving? So when you're driving and you floor it, it falls on it's face?
I've had similar problems before, and it turned out to be a failed cat... the driver's side cat had actually plugged up, and it made the car throw the multiple cylinder misfire code. It also stumbled really bad under load.
it only falls on its face over 4500 rpm where the vvt should be kicking in the hardest. you can tell while driving it that the vvt never starts kicking in that is why i was wondering what could be happening to cause the vvt not to work.
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Do you have aftermarket taillights? Could be a number of things you said he clutch never engages? What clutch did you replace it with? If it's misfiring its a good time to make sure everything is plugged in and you have the correct plugs plugged into the correct coil pack, while you do this pull your spark plugs and see if they can give you a sign of whats happening....
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I have done tons of digging that is why i am on here. there are no codes currently the only code ever there is IF the car misfires(it only misfires if it is cold outside, since it has warmed up it has pretty much stopped), then the random multiple misfire code is there.
have gone though the whole engine all plugs are in proper places and all spark plugs have been changed and coil packs are hooked to proper plugs.
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Do you have aftermarket taillights? Could be a number of things you said he clutch never engages? What clutch did you replace it with? If it's misfiring its a good time to make sure everything is plugged in and you have the correct plugs plugged into the correct coil pack, while you do this pull your spark plugs and see if they can give you a sign of whats happening....
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Couple other ideas, you could check air filter, clean your MAF, get your injectors / fuel system checked out, check plenum for excessive oil, check engine for sludge... if you still can't find anything wrong, throw the car up on a dyno or hook up a Cipher and get a good sense of AFR, you could be running super rich for example.
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It sounds like the car is going into limp mode, to keep you from destroying the motor. pull your cats off and take a look at them. That'll keep your RPM's low, and make the car "stumble and fall on it's face".
I had a similar problem with getting the multiple cylinder misfire CEL, til the car warmed up... Found that the driver's side cat failed. Did you look at your cats yet? A plugged cat will cause enough back-pressure to make the engine think it's misfiring, throwing the CEL.
Last edited by dmroberson; 04-20-2011 at 05:37 PM.
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Couple other ideas, you could check air filter, clean your MAF, get your injectors / fuel system checked out, check plenum for excessive oil, check engine for sludge... if you still can't find anything wrong, throw the car up on a dyno or hook up a Cipher and get a good sense of AFR, you could be running super rich for example.
OP, it's probably not the VVT.
Here is what the variable valve timing does:
Piston engines normally use poppet valves for intake and exhaust. These are driven (directly or indirectly) by cams on a camshaft. The cams open the valves (lift) for a certain amount of time (duration) during each intake and exhaust cycle. The timing of the valve opening and closing is also important. The camshaft is driven by the crankshaft through timing belts, gears or chains.
The profile, or position and shape of the cam lobes on the shaft, is optimized for a certain engine revolutions per minute (RPM), and this trade off normally limits low-end torque, or high-end power. VVT allows the cam timing to change, which results in greater efficiency and power, over a wider range of engine RPMs.
An engine requires large amounts of air when operating at high speeds. However, the intake valves may close before enough air has entered each combustion chamber, reducing performance. On the other hand, if the camshaft keeps the valves open for longer periods of time, as with a racing cam, problems start to occur at the lower engine speeds. This will cause unburnt fuel to exit the engine since the valves are still open. This leads to lower engine performance and increased emissions. For this reason, pure racing engines which are designed to idle at speeds close to 2,000 rpm, cannot idle well at the lower speeds (around 800 rpm) expected of a road car.
Pressure to meet environmental goals and fuel efficiency standards is forcing car manufacturers to use VVT as a solution. Most simple VVT systems advance or retard the timing of the intake or exhaust valves. Others (like Honda's VTEC) switch between two sets of cam lobes at a certain engine RPM. Furthermore Honda's i-VTEC can alter intake valve timing continuously.
The profile, or position and shape of the cam lobes on the shaft, is optimized for a certain engine revolutions per minute (RPM), and this trade off normally limits low-end torque, or high-end power. VVT allows the cam timing to change, which results in greater efficiency and power, over a wider range of engine RPMs.
An engine requires large amounts of air when operating at high speeds. However, the intake valves may close before enough air has entered each combustion chamber, reducing performance. On the other hand, if the camshaft keeps the valves open for longer periods of time, as with a racing cam, problems start to occur at the lower engine speeds. This will cause unburnt fuel to exit the engine since the valves are still open. This leads to lower engine performance and increased emissions. For this reason, pure racing engines which are designed to idle at speeds close to 2,000 rpm, cannot idle well at the lower speeds (around 800 rpm) expected of a road car.
Pressure to meet environmental goals and fuel efficiency standards is forcing car manufacturers to use VVT as a solution. Most simple VVT systems advance or retard the timing of the intake or exhaust valves. Others (like Honda's VTEC) switch between two sets of cam lobes at a certain engine RPM. Furthermore Honda's i-VTEC can alter intake valve timing continuously.
If it an 07 (VQ37VHR) it has the new VVE (variable valve event) where the movement of the output cam is varied by rotating the control shaft with a DC stepper motor and changing the fulcrums of the links.
03 to 06 uses an electric solenoid that manages the VVT, but I doubt it's gone out. If it isn't a bad cat like dm said, I'm guessing it's an air issue, or your plugs are bad or you are using bad gas. Check the cats, change the filter and check the plugs.
Last edited by surfcity40; 04-20-2011 at 06:39 PM.
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