93 LT1 only fires when throttle is pushed

[Gene D]

Exhaust on, New O2's. Cats gutted. Still timing off

It will still idle good, will not rev up.
I got tunerpro to work. Tunerpro says timing is at 34 at 650 RPM.
I think I got the correct info files for a 93 corvette for tunerpro. That was an interesting adventure.
If I have the correct info files. No way should it be at 34 deg. at 650RPM.
Could this be the ECM trying to adjust properly to something being wrong?
Or, no way, I got a bad info file for tunerpro?

 

[Gene D]

Started the job of new opti, new oil pump.

I got a new opti, a new oil pump ,a new oil pump drive, front gasket kit and a oil pan kit. I got a timing chain and gears also.
I got water pump off.
I decided to lift engine. That would help with crank pulley removal and would need done to do timing cover.
I removed lower motor mount nuts.
The engine will not lift high enough to get crank pulley above steering rack.
I gave up on the whole job(for now). The timing and opti was 1st goal.
I put the new opti on. I bolted the pulley back on.
The engine started without touching throttle. It revved right up. I smacked 4000rpm a few times, and shut her down.
There was something wrong with opti, or I got something wrong.
Can the engine be lifted to remove pulley and hub from crank? Or does the steering rack need dropped?

 

[DonB]

Congrats!!!! I would guess there was a problem with the old opti. Glad she runs now.
Make sure nothing is keeping you from jacking the engine up far enough. Take the through-bolts out of the motor mounts. The trans bell housing should(has to) be up against the "tunnel." Make sure the wire harness to the trans., the trans dip stick, or maybe the oil pressure switches or something else aren't restricting your movement. I can't see having to remove the rack for this operation. Although I don't have a '93 FSM. Maybe another member will chime in. Or just Google "timing chain replacement for 1993 corvette."

If you decide to proceed with the oil pump and timing chain......
Old mechanic Trick......
To gain a couple extra inches of lift on the front of the engine; First drop the starter and the lower cover. Unbolt the torque converter from the flex plate. Remove the bottom bell housing bolts(2 each side) and loosen the top bell housing bolts about 1/2 inch. DO NOT stress the remaining bolts and pull the threads out. Jack the trans up against the tunnel while raising the engine off the mounts. You will gain some front lift.

I'm assuming the exhaust and frame gussets are still off too.

PM me if I can help. I'll send you my phone #.

 

[Gene D]

Exhaust is on. Frame gussets on

I got that all back together. I wanted to make sure running without O2 sensors were not my issue.
I left the nuts under the cross sections that goes to mount off. Those studs for mount did lift.
Motor stopped lifting... and whole car started to move. I stopped there.
I will lift gently again and look what is hitting... Thanks. I see what you mean by letting the motor gap a little from trans.
Also. If anyone can help me make sure I have the proper .ads/ .xdf files for tunerpro...

 

[Gene D]

Uggghhh.

Water pump/hoses back on, coolant in.
Engine fires right up. Sounds great. Idles very high. Responsive throttle.
Dash tach says 3000rpm. TunerPro says 1825. My inductive pickup tach says 1750.
I put a new TDC mark on crank pulley. Timing looks about 18 to 20 BTC at that RPM.
I looked for vac leaks. I guess I'll look at IAC tomorrow.

 

[Gene D]

Correction -Timing is at 30 -32

Timing is at 30- 32 degrees BTC at 1800rpm.
I am starting to think the cam socket is messed up and will let the opti in at spots that are not right.
I would think timing should be around 15 at 1800rpm.
If I squeeze the throttle a little, the timing jumps to around 45.
I looked at the old opti. The tab for #1 cylinder is just on the passenger side of being straight down.
I am thinking if I put the #1 cylinder on the compression TDC the opti rotor should be straight to #1 tab or a little to the passenger side of tab.
That would hit the #1 a little before TDC. And have room to advance to 40 for high RPM.
What I mean by to the pass side is , still within the rotors tab, just moved to the pass side of center.
Or should I put the engine at #1 20 degrees btc and center the rotor there.
That would give it the ability to move to 0 for starting and 40 for high rpm.
Any thoughts for a guy who can mess things up that can't get messed up?

 

[DonB]

Gene this opti is beyond my expertise. But I would imagine it is like a normal distributor, only it is driven off the front of the camshaft instead of the rear. But.....Having #1 cylinder at TDC on the crank pulley should relate to the rotor pointing to #1 wire terminal on the opti. Then you set base timing from there. As far as the opti retarding timing to start, I have NO idea why it would need to. It shouldn't be necessary, BUT I am NOT very experienced with the opti.

May I suggest you get a FSM. Corvette Central has them for about $30. They come on a CD and include electrical supplement. It is a great tool and a MUST HAVE for working on these Vettes.

I'm surprised some of the EXPERTS on this blog haven't offered any advice.

 

[Gene D]

Two Opti- two different engines

I have water pump off. I have good access to opti.
The new cardone opti fires right up. Idles at 1800. Engine sounds good.
The timing is running 38 BTC at 1800rpm. I don't touch throttle because of timing.

I don't touch anything else.(except pulley)
I put original opti on. Engine fires up. Idles rough at 600rpm.. Wont come above idle.
Timing is 12 degrees AFTER top center.

I have tried to install both opti's in the wrong place...can't be done without a big hammer.

I was wondering if an ignition control mod could be my problem?

I do have the FSM's the red cover books. For my "P" engine it says "timing is not adjustable"
All the checking things for timing and ignition is for the ZR engines.

 

[dougelam]

Is the Cardone part an OEM rebox or an aftermarket part?


Sent from my SM-T530NU using Tapatalk