1993C4LT1

Car is a 93 LT1. When I've gotten the car up to temp, and let it sit for 15 minutes or more, it cranks for a while. Once it fires up, the idle is rough and the engine sounds like it's not running on all 8 cylinders. So is there a way to test a coil? If so, do I test the coil when it's hot or cold? No service engine light, then again, OBD1 hardly throws it. Runs good until I restart it after sitting for 15 minutes or more.

Car has new:
Opti
Plugs
Wires, just installed Taylor wires yesterday
O2 sensors
CTS
Injectors
Fuel filter
Fuel pressure regulator

antfarmer2

Half way down page
http://www.mainstreamtopics.com/foru...rt-diagnostic/


Or just change it for $20

Did all the plug wires click twice and did you use dielectric grease

1993C4LT1

Yes and yes My dad and I were replacing the wires one at a time. If the coil is that cheap, I may as well replace it.

antfarmer2

Might want to take the icm in and get it tested and put new thermal grease under it. make sure the wires and ground are tight and clean.

1993C4LT1

Will do

TorchTarga94

Take a look at your fuel pressure when it is acting up. Sounds like a fuel pump and/or fuel pump pulsator (remove and replace with submersible fuel hose).

1993C4LT1

Will test fuel pressure when the car starts acting up. Thanks, that's actually a good idea. In fact, I don't hear the pump prime.

antfarmer2

When you turn the key on without starting it should run for two seconds.

higgyburners

Just buy mine brother...problem solved

1993C4LT1

I'm getting tired of this car honestly, but I've done so much to it. Not sure if it would make sense of me to sell it.
Well, finally got the problem to come back. Hooked the fuel pressure gauge, and gas kept coming out of the schrader valve. That was dumb of me

antfarmer2

After the gauge was off? Stuck or bad valve try flicking it.

1993C4LT1

When I connected it, with the engine warm.

pcolt94

You can actually install the coil without formally mounting it. If you just want a test, you can just hang it in there where all the wires and connectors will reach for a test.

Installation is quite a job with cutting rivets and new screws for installation.

The ICM is easy to swap out.


But here is my suggestion, first check the temperature sensor in the water pump to make sure the connector is connected. If not , engine goes real rich. Also check the digital temp (coolant) display on dash to make sure it is indicating correctly.

1993C4LT1

I will double check the connector. Just replaced the CTS last week. But the digital coolant readout seems to be fine.

GS977

I have a good coil I took off mine when I went to the delteq ign. your welcome to try it and see if it fixes your prob.

1993C4LT1

Yes, CTS is fully connected. My car went from 41 psi to just about 0 in 2.5 hours. Runing, psi was at 38. When the car was running like crap, fuel seemed to be unaffected. Thanks for y'alls help

pcolt94

This is all good.

What brand of O2 sensors did you use. Some aftermarket sensors don’t work well. I have not dug out the data yet, but if I remember correctly I think GM and Delphi are the ones to use.

If you had a Tech1, I would want to know the fuel trim numbers in closed loop.

Did you use the same pound injectors?

Afterthought - make sure the vacuum line for the FPR is dry and has no fuel in it.

antfarmer2

I used bosch on mine

1993C4LT1

I put Bosch in there. One was a direct fit, other was a universal. I do have the aldl droid app, but everytime I connect it, it tells me "checksum mismatch". So I'm not sure if it's giving me accurate data. Yes, Jon(from FIC) told me to buy the specific ones for a 93 LT1. Vacuum to FPR is dry. Even primed the pump a few times, and checked after I drove the car.

1993C4LT1

Got back to town. Datalogged my vette. O2 sensors are good. Numbers bounce back and forth rapidly on datalog. What I do see is that my left bank is lean, 144. Right bank slightly rich at 124. What should I look fot that is making the left bank go lean?