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I have a 2002 Corvette Conv.. I just finished a cam, heads, FAST 92mm Intake & 92mm throttle body install.
I started it up tonight & it was at full throttle. I immediately shut it down & tried again. It was still @ full
throttle. Does anyone have an idea what is wrong?
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
if I had to guess I'd say there's an issue in the throttle body wiring... did you use a conversion harness or hardwire it?... I would double check all of that wiring... also what tb did you use?
I used the conversion harness by Casper... LS2 to LS1. I know an LS2 is 90mm. This is an LS2 92mm by Speedster.
When I first turn the key to accessary (just before ignition), the throttle body partially opens and closes twice in a second. I watched the throttle body blade, had my wife start the car, and the blade remains closed.
On the conversion harness... the Casper harness has (4) pins and my original harness has (6) pins. Just something I noticed. I was sure all of the pins were not needed in the conversion.
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
check for a big vacuum leak as stated above... did you replace the valley cover bolts with button head bolts?... the harness should use all the wires, both throttle bodies utilize the same functions but the plugs are different so that's why you need a harness or hardwire it which I personally prefer... post pics if you can
Last edited by StingrayRebel; Feb 15, 2020 at 10:45 PM.
Yes, I did replace the bolts on the valley cover. The new conversion harness should have all (6) pins? I'll get pictures and look this intake over with a "fine toothed comb" for air leaks, tomorrow.
I really appreciate your help. I was lost and did not know where to start looking. Thank you.
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
whew I'm glad you replaced the bolts, if you don't then the intake usually gets busted when bolted down and that would explain a big air leak... just spray starter fluid around the vacuum connections, gaskets, etc, and you will find the leak if you have one... here is the wiring for an ls1/6 throttle body and then the ls2, so according to that it drops one 5v reference wire and one low reference wire so that would explain only having 4 wires being used on one connector... so that may be ok but check just to make sure
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
it should bog down when it sucks the fluid in but if it's revving that high maybe that isn't a good idea, do you have an air compressor and pressure regulator?... you could rig one up to pressurize the manifold with the engine off and use a squirt bottle with water and dish soap to spray around all those areas and you will see bubbles where the leak is... if it's big enough you may hear it without having to spray the water
That's a good idea. I don't have a compressor but always needed one. This is the perfect justification to buy one. I can easily seal the TB and use the PCV system port in the intake. Trying that beats removing the intake, which I may have to do anyway.
I'll post how that experiment goes.
Thank you.
I got the compressor, hoses and fittings. I blocked off the passage so air couldn't escape by putting heavy plastic around the end of the Vararam and inserted it into the red rubber tube going to the TB and clamped it down. I worked!
And, I found the leak. It's coming from 3/4" hose that hooks up to the back of the intake. I found it by using soapy water. It looks like I put the hose in place but failed to put the hose clamp in place. I see the clamp on the hose but it's too far back.
The leak is substantial. Plus, it's impossible to get to.
A leak like that will make it run at full throttle?
2020 Corvette of the Year Finalist (performance mods)
C5 of Year Winner (performance mods) 2019
if it's a big enough leak yes, well it's not really running wot as you already stated your throttle blade is closed but it can certainly cause this condition... sounds like the brake booster hose?... you might be able to get it with some cable hose clamp pliers if you happen to have some of those... if not you may need to remove the manifold bolts and slide the manifold forward enough to get access to that hose... get that buttoned up and try again
I'll try anything. What's hose clamp pliers?
I don't want to loosen up the intake, but of course I will if I have too.
You have been a lot of help. I sure appreciate it.
I had an intake leak on a swap. As soon as I bumped the key, the dash lit up like it was Christmas time and the the engine went straight to about 3000+ rpm. Those connections on the back of the intake will get you. My issue was the intake gaskets were not nearly thick enough to seal the aluminum intake to the heads. An old school mechanic knew right away before I finished explaining....
Figure on another two hours and just pull the intake. You are now proficient and will not have to worry about trying to maneuver the clamp and "hope" you have it on sufficiently.
I had an intake leak on a swap. As soon as I bumped the key, the dash lit up like it was Christmas time and the the engine went straight to about 3000+ rpm. Those connections on the back of the intake will get you. My issue was the intake gaskets were not nearly thick enough to seal the aluminum intake to the heads. An old school mechanic knew right away before I finished explaining....
Figure on another two hours and just pull the intake. You are now proficient and will not have to worry about trying to maneuver the clamp and "hope" you have it on sufficiently.
Glad you found it.
Same happen to me when I had a leak. What's weird is his is going full throttle past 3k rpm with that leak so I'm thinking something else is going. Hope not because that would be a nice easy fix.
Starts @ WOT
