FI troubles
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TECH Apprentice
Joined: Feb 2005
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From: Glen Allen, VA
FI troubles Something strange has been happening lately to the Z06. Under hard acceleration in 3rd gear, the acceleration tapers off. It does not pull all the way to redline like it used to. At first, I thought it was the clutch slipping. However, it does not do it in 1st or 2nd (m6). I have tried watching the boost gauge, but it's kinda tough when going that fast. I'm going to make more runs with someone watching it.
Any ideas? How can I narrow it down? What does it feel like when the belt slips? Could the clutch only slip in 3rd? Springs? I have babied this things since I have had it; I cannot imagine this clutch slipping. See mods in sig below.
Any ideas? How can I narrow it down? What does it feel like when the belt slips? Could the clutch only slip in 3rd? Springs? I have babied this things since I have had it; I cannot imagine this clutch slipping. See mods in sig below.
Thread Starter
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Joined: Feb 2005
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From: Glen Allen, VA
I took a quick glance at it yesterday and the belt looks ok and I did not see any belt dust. However, it was a very quick look; plus this has only been happening the last two times out. I will check this afternoon. Steve, when I took you for a ride, it was pulling all the way through. Now it falls off in 3rd. I want to get this fixed before going to the track with ya'll.
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From: Glen Allen, VA
Originally Posted by Frost
I don't remember seeing it/them, but do you have a fuel pressure guage and/or wideband?
If it was running out of fuel, wouldn't it have happened from the start? I have been trying to figure out why it only happens in 3rd. I have not pushed it to 4th (dont need to spend time in jail).
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Originally Posted by CHRISPY
Clutch slip will be worse in 3rd and 4th versus 1st and 2nd.
On a side note...You should at least get a fuel pressure guage...I started running out of fuel at 550rwhp in my 2004 Vette with a boost a pump and 42lb injectors. Also if you fuel pump ever starts to weaken and fail at least you will see it with a guage...
If you engine if pulling to red line in 3rd and 4th but the car doesn't seem to be accelerating at an equal rate then its probably the clutch slipping...
If you engine if pulling to red line in 3rd and 4th but the car doesn't seem to be accelerating at an equal rate then its probably the clutch slipping...
Thread Starter
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Joined: Feb 2005
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From: Glen Allen, VA
thanks for all the help guys!
It pulls HARD in 1st and 2nd. Then around 3500 RPM in 3rd, the acceleration goes away. The RPMs do not rev up fast (like I would think they would if it was the clutch).
Is there anyway to test for valve float?
It pulls HARD in 1st and 2nd. Then around 3500 RPM in 3rd, the acceleration goes away. The RPMs do not rev up fast (like I would think they would if it was the clutch).
Is there anyway to test for valve float?
No way to test except to pull a valve spring and see if its still at spec with a valve spring pressure tester. It could be fuel pressure problems with the higher load in those gears or it could be the computer pulling timing because of engine knock, it could be blet slip but it doesnt sound like it, could be a boost leak some where ..All just ideas of what it could be...
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Joined: Feb 2005
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From: Newark,DE
My car does the same thing on occasion. Stock clutch here. I have noticed the car does not make as much boost in 1st or 2nd (about 5 psi in 2nd) as it does in 3rd or 4th (8psi). I think boost is kind of referenced to load on the vehicle. So technically your are making more power in 3rd than 2nd causing the clutch to slip there only.
Thats my theory anyway.
Thats my theory anyway.
TECH Resident
Joined: Jan 2004
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From: Castro Valley, CA
See if the same thing happens in a lower gear when you're going up a fairly steep hill. If it does, your loss of power is load related and most probably the clutch slipping, IMO.
You'll also see the obvious blip to redline mentioned above.
You'll also see the obvious blip to redline mentioned above.
Thread Starter
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From: Glen Allen, VA
RW, no loss of power going up hill in 1st and 2nd.
Graham, I have not tried it in 4th. Not ready for a ticket going 100+.
I guess no one thinks much of the Ethanol theory?
Graham, I have not tried it in 4th. Not ready for a ticket going 100+.
I guess no one thinks much of the Ethanol theory?