Help! Unable to rev past 5000

[chriskinzel]

I have a problem that has me stumped (not hard to do). I am unable to get the car above 5k. When it get close to that rpm it starts missing really badly. If I try to push past it I will get the camshaft sensor error, and the tach bounces from 4500 down to around 2000. This winter I removed the secondaries and installed Marc's chip. It runs great up to about 5000. I installed new fuel injectors last summer and it ran fine with those. I have installed a fuel preassure gauge. I have 42 psi on startup, and 50-51 psi at 5000 rpm. I have put on new Accel coils, new Delco spark plug wires, new spark plugs. Marc send me a spark controller and the problem is still there. I also have installed a new cam shaft sensor, but I only get the code when I don't let off when it starts missing. I have no codes being set.

I need more help from you smart people.

Thanks in advance
Chris

[tf95ZR1]

Removed.
Head up my ....

[KILLSHOTS]

You removed your secondaries and now you can't pass 5K? Hmmmm, I'm trying to get feedback on removing secondaries in another thread right now. Maybe this is something to consider. My car runs great right now; I'll be pizzed if I do the old remove-the-secondaries "upgrade" and it messes everything up! Best of luck finding the issue, hopefully something simple.

[Paul Workman]

Originally Posted by KILLSHOTS

You removed your secondaries and now you can't pass 5K? Hmmmm, I'm trying to get feedback on removing secondaries in another thread right now. Maybe this is something to consider. My car runs great right now; I'll be pizzed if I do the old remove-the-secondaries "upgrade" and it messes everything up! Best of luck finding the issue, hopefully something simple.

No, I think this is an isolated case, and I've not seen any evidence (yet) that would lead to a conclusion. (Mine and dozens and dozens of others run fine w/o SPTs from the first moment. (I'm using Marc's calibration as well.))

[chriskinzel]

I don't think that removing the secondaries has caused this problem. I just mentioned it because it eliminated a lot of extra stuff that could cause problems.

Still searching.
Chris

[Paul Workman]

Originally Posted by chriskinzel

I don't think that removing the secondaries has caused this problem. I just mentioned it because it eliminated a lot of extra stuff that could cause problems.

Still searching.
Chris

Ah! Excellent point. Removing the SPTs does eliminate an entire "sub-routine" of related troubleshooting banter!

Long story short, one of the best single investments after buying a Field Service Manual (FSM) I ever made was my scanner. That thing has put a finger right on sooo many issues on several (not all of 'em being Corvettes) cars. Having access to a scanner - especially if you can record real time windows - is a fantastic tool.

You might see if an auto parts store will scan it, and maybe do a ride-along to further diagnose the problem.

When I first got my 90, as the temperatures warmed up from early spring to summer, I discovered the plastic accordion snorkel tube between the filter housing and the throttle body horn was collapsing at WOT, causing it to nose dive and sputter at about 5000 rpm. I fixed it by making an aluminum sheet metal insert that supports the hose. No more problems.

Marc Haibeck can provide some little metal hoops that fit inside the folds of the snorkel. These, I suppose, you might be able to make yourself, if you find the right kind of wire.

P.

P.

[Tony Davila]

Last time that same situation happened to me I found out I had a weak primary fuel pump. Fuel Pressure looked good static but could not keep up with requirement. Replaced pump and it would now rev passed 7K.

[PhillipsLT5]

Originally Posted by KILLSHOTS

You removed your secondaries and now you can't pass 5K? Hmmmm, I'm trying to get feedback on removing secondaries in another thread right now. Maybe this is something to consider. My car runs great right now; I'll be pizzed if I do the old remove-the-secondaries "upgrade" and it messes everything up! Best of luck finding the issue, hopefully something simple.

my secondaries are removed & pulls to 7200, his problem is elsewhere

[GOLDCYLON]

Originally Posted by PhillipsLT5

my secondaries are removed & pulls to 7200, his problem is elsewhere

Concur.. Mine pulls like a freight train.

[GOLDCYLON]

Originally Posted by chriskinzel

I have a problem that has me stumped (not hard to do). I am unable to get the car above 5k. When it get close to that rpm it starts missing really badly. If I try to push past it I will get the camshaft sensor error, and the tach bounces from 4500 down to around 2000. This winter I removed the secondaries and installed Marc's chip. It runs great up to about 5000. I installed new fuel injectors last summer and it ran fine with those. I have installed a fuel preassure gauge. I have 42 psi on startup, and 50-51 psi at 5000 rpm. I have put on new Accel coils, new Delco spark plug wires, new spark plugs. Marc send me a spark controller and the problem is still there. I also have installed a new cam shaft sensor, but I only get the code when I don't let off when it starts missing. I have no codes being set.

I need more help from you smart people.

Thanks in advance
Chris

Spark controller? Are you stating a DIS or a Quad Driver?