Mystery rev limiter
Thread Starter
Teching In
Joined: Dec 2003
Posts: 32
Likes: 0
From: Pleasanton, CA
Mystery rev limiter I'm still chasing the Mystery Rev Limiter. This morning's data says that the engine will rev beyond 6800 with the blower belt removed:
http://para.noid.org/~lj/NA-NoRevLimiter.gif
My first test run this morning, which resulted in the engine refusing to rev beyond 6800, was with the blower hooked up. I thought I heard a noise like a pop-off valve when the engine stopped gaining revs. This makes me wonder if the Vortech Mondo bypass is misbehaving.
But I cannot understand how that would create a rev limiter!
Can anyone think of a way that the intake tract from K&N, through the blower, bypass, intercooler, and elbow, could fail in a way that prevents the engine from gaining revs?
I guess it could still be ignition, but this seems like a solid system:
MSD Digital 7
MSD 8251 coil
MSD Opti cap and rotor (less than 100 miles)
MSD 8.5mm Super Conductor wires, inspected and heat shielded
NGK iridium plugs, BKR9EIX gapped at .030
http://para.noid.org/~lj/NA-NoRevLimiter.gif
My first test run this morning, which resulted in the engine refusing to rev beyond 6800, was with the blower hooked up. I thought I heard a noise like a pop-off valve when the engine stopped gaining revs. This makes me wonder if the Vortech Mondo bypass is misbehaving.
But I cannot understand how that would create a rev limiter!
Can anyone think of a way that the intake tract from K&N, through the blower, bypass, intercooler, and elbow, could fail in a way that prevents the engine from gaining revs?
I guess it could still be ignition, but this seems like a solid system:
MSD Digital 7
MSD 8251 coil
MSD Opti cap and rotor (less than 100 miles)
MSD 8.5mm Super Conductor wires, inspected and heat shielded
NGK iridium plugs, BKR9EIX gapped at .030
Thread Starter
Teching In
Joined: Dec 2003
Posts: 32
Likes: 0
From: Pleasanton, CA
I'm trying to rev beyond 6800. I'll set the shift light at the point where the power starts to fall off, probably ~7200 or so. This graph is from the track:
http://www.acceleronics.com/images/AFR-RPMgraph.gif
and you can see that the rev limiter steps in before I reach the traps. I'd like to see what the car can do on a full pass.
To rule out valve float I just finished swapping in these springs about 3 weeks ago:
Manley p/n 22440 H11 tool steel
seat: 250lb @ 1.850"
nose: 680lb @ 1.150"
I think they are huge overkill, and they didn't make the limiter go away.
Neither did exchanging the stock Opti cap and rotor for MSD parts.
I rigged up a test set yesterday to blow shop air into the Mondo air path and manifold reference port with the Mondo sitting on the work bench. At 20 psi it does leak out of the air path, but not very much. The diaphragm holds vacuum, so I don't think it's ripped.
I still haven't found the smoking gun
http://www.acceleronics.com/images/AFR-RPMgraph.gif
and you can see that the rev limiter steps in before I reach the traps. I'd like to see what the car can do on a full pass.
To rule out valve float I just finished swapping in these springs about 3 weeks ago:
Manley p/n 22440 H11 tool steel
seat: 250lb @ 1.850"
nose: 680lb @ 1.150"
I think they are huge overkill, and they didn't make the limiter go away.
Neither did exchanging the stock Opti cap and rotor for MSD parts.
I rigged up a test set yesterday to blow shop air into the Mondo air path and manifold reference port with the Mondo sitting on the work bench. At 20 psi it does leak out of the air path, but not very much. The diaphragm holds vacuum, so I don't think it's ripped.
I still haven't found the smoking gun
Thread Starter
Teching In
Joined: Dec 2003
Posts: 32
Likes: 0
From: Pleasanton, CA
Originally Posted by 9secz
http://para.noid.org/~lj/2006-03-19-R1.gif
http://para.noid.org/~lj/2006-03-19-R2.gif
It pulled through the limiter, but not happily. The only thing I changed is this $2.50 engine restraint
http://para.noid.org/~lj/NewChain.jpg
I added that because I noticed the blower intake pipe moving around after a test drive. The intake pipe attaches to the lower radiator support via a rubber isolator.
I guess the next step is to drop the plug gap to .025 and try again.
Even with the misfires, it sure 'nuff sounds good at 7000+
