Whelp, im at my wits end figuring things out with my camaro, so i figured its time to lay out my issues here and see if any of the 4th gen experts can help me out.



Last October, i bought a 1996 Z28SS with 198k on it. It had a few codes for its emissions and p0336 for the crank sensor, but other than that it ran fine and would crank almost immediately, cold or hot. A couple days later, im taking my girlfriend to work and the low coolant sensor shoots out and douses my engine bay in coolant.



I call a wrecker to get the car back home. When i go to crank the car to pull it up on to the wrecker bed, it takes it 10 or so seconds and pumping the gas for it to start, and it felt like it was misfiring quite a bit. So i go to clean out and rebuild the opti with a new MSD cap and rotor. Put some RTV around the outside of it to seal it up better. I put the opti back in the car, and it cranks much quicker, almost as quick as when i first got it, and it felt like it was running better. Unfortunately, the guy i was working with had a blonde moment and pulled one of the coolant hoses while the car was running because he thought it wasnt on right, and the engine bay got doused with antifreeze again, and was pretty much right back to running bad.



Even though the engine bay got soaked again, i believed now it couldve been the injectors causing the misfire, as now it was backfiring out the intake, and a few days later, after the car would immediately die after being cranked unless you pumped the gas, i checked the brand new spark plugs they looked to be covered in soot and carbon, as well as the oil pressure was 10 psi lower and looked to have carbon in it(it was rather dark and was maybe only 200 miles old). So i figured the injectors were leaking, and sent them to be cleaned and flow tested back to stock specs. I got them back and stuck them in the car, and it still took a bit to crank but it would stay running, though at a rather high idle of about 1000-1500. Next day, it was right back to dying immediately after cranking.



I figured it was time to actually do a bit of testing, so i followed the stickied procedures for diagnosing a bad opti. A and D on the ICM harness tested fine, at 10 volts at key on. I tested the C(the black ground, i believe)for its ohms at key off and the meter was reading 5. I move on to B(the white wire on the harness)to check for 1-4 AC volts. I have someone turn the key, and bam. Nothing. The meter reads 0, and the engine just clicked like the battery was out of juice. The battery has 11 volts, which should be enough to crank the car. I plug the harness back into the ICM, nothing but clicking.



I hate posting such a lengthy and potentially hard to follow post, but i really am at my wits end here. I still only have the codes for the emissions and crank sensor. I unfortunately dont have the software to datalog, and at this point i doubt the car would stay running long enough to get good data. The little bit of spirited driving i did get to do with this car made me love the thing, so i refuse to give up on it. Any advice or explanations would be greatly appreciated.

 

Pin “C” (black wire) is grounded at the stud on the head that the ICM/coil bracket bolts to. That ground also is one of the PCM grounds. The stud should also have a ground strap from the chassis. Should read 0 ohms. What ohms scale was the meter on, or was it auto-ranging? Sort that out.

When the ignition wiring gets wet, good chance your going to have croo-firing/misfiring until it gets dried out.

Shoebox's test procedure is better and has been around for a long time:

4th Gen LT1 F-body Tech Articles

The crankshaft sensor doesn’t affect how the engine starts or runs. The crank sensor was only added in 1996/97 models to meet the OBD-2 requirements for misfire detection. But the code can be the result on an Opti drive pin that is not indexed correctly to the hole for it in the back of the Opti. The PCM uses the high and low resolution pulse signals from the Opti to time the ignition and the sequential fuel injection.

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

What are the “emissions codes”?

As far as the battery having. 11 volts but the engine doesn’t crank - starter solenoid just click, did you check both ends of the wire from the battery to the starter, and the ground to the block? Corrosion can prevent a fully charged battery from turning the starter.

 

Injuneer, the emissions codes thrown were P0403 and P0443. I cant remember for certain if it was throwing a code for EGR as well, but i know for certain its EVAP, EGR, and AIR pump systems were deleted by previous owner, yet their function wasnt disabled in the pcm. No codes for O2 sensors, so i think its good in that regard, and not whats causing its poor running conditions.

As for wiring, i used some electrical connector cleaner to clean up all the connections, even the ends of the plug wires, so im certain they’re dry. The ground and power wires for the battery are brand new, so more than likely somethings loose on that end. Ill have to check. As for the multimeter, im not sure what setting it was on when i checked the ohms, im not too familiar with them as ive only used one maybe a couple of times to simply check voltage. Ill post what I find later on this evening when i can check starter connections and that ground wire in the icm harness.

 

So i got up under the car and checked, the connections look good. I had some one get in and try to crank the car while i was up under it and the flexplate didnt budge when the key was turned, and the starter just clicked rapidly. Could it be starter failure? I didnt see the terminals arc any, and it would make sense given how long the car takes to crank, so the starter would have more wear on it from that. However, i did go back and test the ohms on wire C for the ICM harness again and came back with 0 ohms. Is there anyway i couldve fried the computer by incorrectly testing the ground for the ICM, and that could be causing it to not turnover? The dash does still light up and throw codes.

 

You didn’t harm the PCM. Starter could be bad. Slow cranking could be the result of the starter dying, not the other way around.

Stock starter on my 94 died under warranty at 30,000 miles. Dealer replaced it. After the stroker build it was struggling and cranking time to start was extended. I asked the guys that built the engine if it was the beefy rebuild, slightly higher compression slowing down the starter. They showed me the results of measuring the torque required to turn the new engine, and it was less than the stock engine. I figured the stock starter was fried from the header heat. Replaced it with a CVR Pro-Torque starter that could be rotated away from the headers. 100% improvement, engine cranked faster, started at the first turn of the key. The starter’s excessive current draw was pulling down the system voltage and affecting the injectors.

Doesn’t explain the non-starting or stalling. Check the fuel pressure. Have you physically checked for spark at several of the plugs? When the starter is cranking the engine, does the tach needle move up about 200 RPM? That would confirm the PCM is receiving the low resolution pulse from the Opti that it needs to time the spark and injectors.

 

So a bit of an update. Last night one of my buddies stopped by and heard the starter clicking. I told him what the issue was, but he was insistent on trying to jump the car off rather than outright saying the starter was bad. Hooked up the jumps, and what would you know it actually started turning over and started. Of course, it pretty much immediately died after starting but i guess i need to inspect my connections a little closer, cause my buddy also said he heard arcing somewhere when the key was turned over. We unhooked the jumps and walked away for about half an hour and it was right back to just clicking. Can a bad connection cause drain on the battery? Sound system and lighting is all stock, and i made sure everything in the car was off before walking away, and i make sure to disconnect the negative on the battery when im not trying to crank the car or test the wires with a meter.

As for checking spark, it hadnt crossed my mind to do so. The plugs and plug wires are brand new with less than 100 miles on them, and the wires are 8.3mm Taylor Thundervolts. The RPMs did jump when cranking. I wasnt looking too closely at the tach, but i did notice when the engine was getting close to starting, the RPM would spike to about 500 and then drop back down a couple times. When the engine did start, i gave it some gas and it went up to about 2000 before it started dying out, even with me holding steady on the throttle. When i let off, it dropped down to 500 RPM, shutters, and then goes up to 1000-1500 RPM before just giving up and stalling out. Havent checked the fuel pressure yet, ill head to a local parts store and see if theyve got a gauge to rent out. Only thing wrong with the fuel system that i could think of would be the pressure regulator, as i can hear the fuel pump prime, the injectors are freshly cleaned, and it has a brand new K&N fuel filter. No fuel leaks anywhere either.

 

Have your battery tested and/or charged. 11v is not enough.

 

I think ive found whats causing the starter to just click. I went back and double checked the connections and tested them too. On the junction block on the passenger side, when i tested its power wire to the ground wires its connected to, it wouldnt make a complete circuit and i got a reading of 0 volts. So, i took the nut off and tested each of those ring terminals individually. In total, there were four. 3 of the four read 11.98, 11.88, and 11.78, but one of them only read at .05 volts. Is that normal? If im remembering correctly from a few of the diagrams i looked at, those wires lead to the ignition switch. As for the battery, ill get it charged back up all the way and see if that helps any. Battery should be good, as i had it tested a couple months ago and as i mentioned previously, I disconnect the negative side of the battery due to the car not getting driven.

 

Are you indicating the red plastic positive distribution block?

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

Your test procedure is unclear. You took the nut off, removed all eyelets from the stud, then you measured the voltage between the end of eyelet (no eyelets attached to the stud) and a ground? Once you take the wires off the distribution block, there shouldn't be any voltage on them if that's how you tested them.

http://shbox.com/1/starter_charging_96.jpg

 

Yes, that little red plastic box is what i was referring to. As for the test procedure i used, i held the positive lead on the multimeter to the power wire that goes into that box, and then touched the ground test lead to each of the individual eyelets. Would that be an incorrect or useless measurement? Again, i am fairly novice when it comes to using a multimeter and testing electrical connections, so i apologize if im going about testing the connections in the wrong way. What lead me to try the method i used is when i held the positive test lead to the power cable in the junction box, and then touched the ground lead to the stud the eyelets go on i got a reading of 0 volts.

 

The “power” wire runs from the battery to distribution box and should have the same voltage as the battery. You test that by putting the red (+) lead to the stud the power wire attaches to. Then you touch the black (-) ground lead to a GROUND. The stud on the fender liner (not in the box), an inch from the distribution box, is the ground stud. You can only measure DC voltage if you are measuring between something connected to the battery (either stud in the box) and a ground - virtually any unpainted metal surface on the engine or the chassis.

The other stud in the box is connected to the stud the power wire connects to. Both studs are embedded in the metal block in the base of the box. BOTH studs are therefore at +12 volt potential (or whatever the battery voltage measures. Since bothstuds are at +12 volts, putting the positive lead on one stud and the ground lead on the other stud, the voltage meter will read 0 volts. That only proves the two studs are connected to each other.

 

If you can get a hold of an analog meter (one with needle, not digital numbers) connect the black lead to the starter casing and the red lead to the starter (+) bolt, and put it on the end of the bolt threads. then have someone crank the starter, watch the needle movement and see how it responds and note upper and lower voltages. then repeat the same procedure to the battery terminals only connecting meter to the screw heads on the side terminals of the battery. then crank the starter and watch the response you get. if the 2 test act the same, then your wires are good to the starter. if the wires are good to the starter, that only leaves the "Battery" "Starter Solenoid" OR "Starter" as being bad.

If you use a Digital Meter on this test, you won't get the right response!

 

Well, thanks for the advice on testing the connections. Also, i shouldve figured thats how the junction box worked, but hindsight is always 2020, especially when youve been given an explanation by someone who has more experience. Anyway, go figure, it was the battery. Charged it up to 12 volts and immediately the starter went to town spinning the flexplate, so i apologize for wrongly assuming even high 11s of voltage could start the car. As for diagnosing whats causing it to stall out after cranking, i finally got around to testing wire B on the ICM harness, and it tested between 1-2 AC volts, and if im remembering correctly, that wire should read between 1-4 ac volts, so it should be good. I still need to get around to testing for spark at the plugs and the fuel pressure, so ill be sure to update further once ive gotten that handled.

 

Well, no wonder the engine is running poorly. I was getting ready to run a compression test to cover all possibilities when i found the number 4 plug had oil coated in oil, and oil had even seeped down the threads a ways. What would that be an indication of? Bad piston rings? My buddy who i mentioned earlier(the guy who suggested jumping off the car)mentioned awhile back he thought it sounded like a valve could be going bad(bad seal, is what i think he said)If theres oil on the plugs, would that indicate a need to rebuild the engine?

 

Depends how many plugs have oil on them.