How do I know if Im having VALVE FLOAT
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From: Houston (The Champions)
VALVE FLOAT or Tranny issue ??????? Working on a 2002 Turbo WS6, not sure about what valve springs I have. But just started having this issue a couple of months ago. I drive the car and everything seems normal, I start to accelerate and on the top of third fourth fifth and sixth I get this weird vibration feel and sound. Almost like Im looking traction, it vibrates the rear of the car, I was thinking it was an exhaust vibration, or valve float. I dont wanna start chasing parts, that gets expensive, and I live 400 miles from the nearest performance shop. Any suggestions guys. Please.
Charlie
Charlie
Last edited by charlie c5; May 7, 2009 at 12:21 PM.
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From: Denver International Airport, Colorado USA
Charlie, if you have a good ear and quick vision you might be able to figure out if it is valve float.
Your rpm's usually 'stick' or dip momentarily. You will hear a slight pause in engine speed or slight surge.
On a dyno it is pretty obvious. A skilled mechanic might be able to detect it in the manner I described, but I would just start with the basic diagnostics to eliminate something less ominous.
Had it once myself (different setup). You do not want it.
Best of luck..
..WeathermanShawn..
Your rpm's usually 'stick' or dip momentarily. You will hear a slight pause in engine speed or slight surge.
On a dyno it is pretty obvious. A skilled mechanic might be able to detect it in the manner I described, but I would just start with the basic diagnostics to eliminate something less ominous.
Had it once myself (different setup). You do not want it.
Best of luck..
..WeathermanShawn..
If its valve float, yes new springs will fix the problem as long as they're for your application.
Since you said it only does it 4th,5th,and 6th which is hauling ***, you sure its not a wheel thats not balanced good enough?
Since you said it only does it 4th,5th,and 6th which is hauling ***, you sure its not a wheel thats not balanced good enough?
You may not be feeling it in the lower gears. With the boost, there is more stress put on the valve train to control it and if you are running stock springs they are suspect. Since a dyno run would tell you right away, but you have to travel so far to run it, wondering if its a better trade-off to just replace the springs with better ones that will last longer for your application. PAC 1518's, while a bit more money, will provide better seat/over the nose values, use your existing parts and will last a very long time due to the extra surface treatments that are used on the springs.
With a turbo car you will know for sure if it is valve float. I had a Buick GN with weak springs and at the top of first and second gear it sounded like a gun went off. It will backfire big time.
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As you are increasing RPMs you should be able to tell that the power is dropping off. Instead of having a some what linear increase in power it will feel like it is not accelerating as quickly or dying off.
That would be an extreme example with the exhaust valve spring not being able to control the valve. This causes over scavenging of the air / fuel charge from the cylinder and igniting it in the exhaust. I had it happen in my old 95 eclipse GST and it would sound exactly like what you are explaining.
That would be an extreme example with the exhaust valve spring not being able to control the valve. This causes over scavenging of the air / fuel charge from the cylinder and igniting it in the exhaust. I had it happen in my old 95 eclipse GST and it would sound exactly like what you are explaining.
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Verdad Gallardo Thread Starter
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From: Houston (The Champions)
Alright, I took the car out last night and REALLY watched everything. The MPH, the RPMs and the boost while I was getting into it. And man now Im starting to get worried. Now it feels like the tranny is going, and its only a year old T56. Im at about 40 MPH and slowly roll into it and I cant really explain the sound, but the RPMs just sky rocket and it seems like Im free reving, the car dosnt build anymore speed when this is happing, its just crazy. Im gonna make a video and try to post it up today. This is starting to sound expensive........... But Im sure its not valve float anymore. No mis or back firing. And the power isnt falling off, the RPMs tump almost 2000 from wherever I am.
Teching In
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From: Salt Lake City, Utah
When a clutch wears out, it will start slipping while it's in gear. If you want to test for this, most clutches have some weights that help it hold harder at higher revs. If you try a pull around 2k or so RPM's and another at higher revs, it will slip more at the lower revs and should hold better at high revs. Your problem does sound very much like a slipping clutch to me. If I'm wrong, about 10 guys will call bs in the next hour or two.
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From: Houston (The Champions)
Yeah, thats exactly what its doing. But this is a super nice expensive clutch. I NEVER get a clutch smell, and people will tell ya, Im a champ driving manuals. I wonder if a little oil didnt leak out the rear main and get on the clutch, but I guess it would do this all of the time then....????
Charlie we have the new EHT PRC spring kit that has a good bit more pressure than the previous LS stock spring pocket valve springs. We can set you up with a set & extra shims if you want to put more pressure on the car to see what results you get. I had the standard Platinum spring start floating on me past 15psi, but it depends a lot on the combo as well as the boost.
__________________
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Jason
Co-Owner, Texas Speed & Performance, Ltd.
2005 Twin Turbo C6
404cid Stroker, 67mm Twins
994rwhp/902lb ft @ 22 psi (mustang dyno) www.Texas-Speed.com
Yeah, thats exactly what its doing. But this is a super nice expensive clutch. I NEVER get a clutch smell, and people will tell ya, Im a champ driving manuals. I wonder if a little oil didnt leak out the rear main and get on the clutch, but I guess it would do this all of the time then....????
Thread Starter
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From: Houston (The Champions)
Well I just took the car out. And it seems to only be doing this in 4th 5th and 6th gear. I roll into in and the rpms revs up but the car doesnt speed up, and thre is some kind of vibration when all of this is happening. And when I let off the throttle, the vibration goes away and the car acts normal again.....
Yeah new springs would be nice, but I dont like chasing parts. I need to address and fix the current issue.
Yeah new springs would be nice, but I dont like chasing parts. I need to address and fix the current issue.