when i floor the car the tach jumps all over the place. it did not do it before the cam install.

any ideas?

 

that happened to me right before my battery died.

 

anyone else have this problem

 

that happened to me twice. both times it happened right before my opti died. hope thats not the case for you though.

 

So part throttle it runs just fine?

Maybe you have some plug wires crossed or burnt wires. Checked fuel pressure yet?

 

Optispark low-res signal is used for tach input. I'd check that first.

 

Mine would jump and then die,then you could hear the injectors pulsing like the car thought it was still running. I pulled my opti and found that the female plug had a crack in it. Changed opti=problem fixed.

 

when it does it the car runs fine. the tach just jumps all over. the more i throttle i give it the worse it gets.
also the car tries to die sometimes when it returns to idle.
idle is set at about 900 when it does this it goes down to about 400 and stumbles until it dies.
it also has a hard start issue but not every time.
do you guys think its the opti or should i send the computer back for a retune ?

now that i wrote all this down i've got more problems than i thought.

 

Actually, I think you should check your maf. Have you done anything to it recently? Are you sure it's plugged in? Any broken or burnt wires leading to it?

I've had my maf unplugged before and the car ran/drove like normal. Only problem was a jumpy tach that usually went to 7k right before I shifted. Plugged back in the maf, and problem solved.

 

is there any way to check it with a multimeter?

 

Check the opti pigtail harness which runs from the opti, up to the intake manifold. If it has corrosion and crap in it, clean it out. If not, make sure the connections are tight.

Also check the connections on the coil to make sure its all tight there.

 

Sounds opti related to me.

 

checked the maf showed 4.2v moved around as i moved the throttle.
also checked the harness showed 5v on the red/wht wire what should the other wires show while running?

 

altjar
i read i another post about a car dying you said the iac might not be keeping up with the cam could that be my problem if so how could i fix it.

 

Well the tach jumping is the foremost concern. Like everyone else is saying i think its opti wiring related, or coil wiring related.

Here is a full test, but I would still try wiggling around those wires and see what happens. Maybe do a continuity test on the opti harness.
http://shbox.com/1/4th_gen_tech2.html#opti_test

For the IAC, thats a secondary problem IMO. You need to adjust the set screw for the throttle stop so the throttle body blades are open a little more. The screw is a Torx head, and its head is facing the firewall on the top right part of the throttle body.
Its not shown here, but it is right by number 8. Its threaded end sticks out and hits the TB stop
http://shbox.com/1/throttle_body_93.jpg