musclehead

iTrader: (2)

I am having problems with my 95 LT1 bird. The problem started off with the car not starting immediately, it needed extended cranking to start. Now it has progressed to where the car does not start at all. I am wondering wether it is the Optispark or the ICM? Any help is appreciated.

ss.slp.ls1

iTrader: (36)

Could be ignition or fuel. I would check your fuel pressure first. Then go onto diagnosing the ignition.

MrElectric03

iTrader: (71)

SRJ is on the money, sounds more like a fuel problem to me. Hook a gauge up to the rail and have someone crank it over, not too sure what the LT1 pressure is though.

An easy way to trouble shoot ignition is to hook a timing light up to one of the wires, if it doesnt flash then its not getting signal, meaning it is not sparking.

blkm6formula

iTrader: (2)

I would check fuel pressure by hooking a gauge up to the rail and just keying it ON, DO NOT crank it over! if it is good then move on to ignition, now while a timing light is not hard, it is not the easiest way, easiest way to see if you do have spark is to unhook a spark plug wire, have someone crank it over, and see if it sparks! if it does, you will want to get into stress testing a coil, and move on from there!

97lt1camaro

iTrader: (3)

+1 on fuel.

My camaro did this. Would start taking longer and longer to start. Towards the end before i replaced the fuel pump, some times it would take near 5-10minutes before the car would prime properly and fire. It was a hassle.

ss.slp.ls1

iTrader: (36)

Spec on LT1's is 41-47 psi with the vacuum line disconnected from the fuel pressure regulator. Hook up a guage and prime the pump and see if it has pressure and check to see that it doesn't immediately bleed away to zero after you prime it.

Formula350

iTrader: (3)

You sure? I thought it was 40-41 and then 43.5 with the vacuum line disconnected.

Low N Slow

iTrader: (4)

+1 on checking fuel pressure

koolaid_kid

iTrader: (21)

Those are the specs while running. Either way, fuel pressure should show with just a key on, engine off.

Formula350

iTrader: (3)

It should still be ~40psi w/ KOEO. Anything lower than 35psi and I'd start wondering if it's the pump. Also, if it doesn't hold that pressure after it primes up then it's a good chance you have a leaky injectors or a sticking check ball in the pump. All depends on how fast it drops though. If it's really slow, then it's most likely an injectors (can easily be multiple), but if it's fast then it's a good bet it's the check ball letting fuel return back into the tank through the feed line.

musclehead

iTrader: (2)

Alright guys thx for the input I will have to check on the fuel.

ss.slp.ls1

iTrader: (36)

My bad. I said that incorrectly. You are right, spec is 43.5 psi with the vacuum line to the fuel pressure regulator disconnected. But anywhere from 41-47 psi is normal.

musclehead

iTrader: (2)

just checked the fuel pressure and it was at a steady 41 psi, so good there. I checked the coil and that too was good. I want to check the ICM and the opti...does anyone have a write up on these? thx.

Formula350

iTrader: (3)

Can't exactly check the ICM by conventional means. Not sure if AutoZone can test those or not, but I think so. And the Opti, which part? The optical sensor or the cap and rotor to make sure it's sparking? If the latter, then the same way you checked the coil. If the former, well then you're on your own :\ I don't know how the make sure the optical sensor is working right, sorry.

ss.slp.ls1

iTrader: (36)

This is the way to test that the optical sensor is sending the low res signals:

http://shbox.com/1/4th_gen_tech2.html#opti_test

Test coil:

http://shbox.com/1/coil_testing.jpg

Autozone can test the ICM, but many of the stores don't have the right connection, but hit up a few stores.

musclehead

iTrader: (2)

I checked the coil per the directions of the diagram you provided (which checks the coil secondary resistance) and my msd coil read at 5.2 in all 4 terminals. This is about right being that i have an aftermarket coil which will be lower.

I may be doing something wrong when testing the ICM because I am getting a reading of 0. I used this guide http://shbox.com/1/95_ign_system_schematic.jpg. I am supposed to be testing terminals A and D on the ICM connector. Maybe someone can shed some light on what I may be doing wrong.

musclehead

iTrader: (2)

Ok I finally figured out how to test everything and it all came out good... the opti harness, icm harness, coil and fuel pressure. So I am left to believe that the cap and rotor are responsible for the no spark. Anyone have any thoughts on this?

ss.slp.ls1

iTrader: (36)

Doing the spark test at the ICM connection will test power to the coil and the hi/lo res signals of the opti. It won't tell you if the ICM is good or not. I would get the ICM tested, if that checks out as well, I would suspect that your coil wire is bad or your rotor has detached.

musclehead

iTrader: (2)

Ok. If I understand things correctly the PCM sends a signal to the ICM which in turn causes the coil to fire. So in theory if I tested the coil and it's hot/getting power, then the ICM must be hot too...right? Another question, can the ICM be hot but still bad? And in reference to the coil wire I pulled it off the coil and opti, I checked it out along with both terminals and all looked good. So maybe I have a rotor issue like you suggested. I did call around to all the local auto parts stores and none carry a ICM tester.

LT1FirebirdSLP

iTrader: (2)

If it is just a hard start I wouldn't agree on the possibility of the opti. Now if its hard start + running poor (missing) then I would scream OPTI