Got a 94 Camaro with a 95 LT1 in it. Optispark was replaced not that long ago, however, I went ahead and replaced it again with a reman ACDELCO. Still nothing. I did shobox's tests and the ICM is getting the proper power is should, and did the tests on the optispark wiring harness, again proper power. The coil is shooting out good spark, however, I tried one of the spark plugs and the spark is very very poor. Its acting like its out of time, shooting back out the intake and not starting. I also replaced the ICM, because why not its only money. Still nothing. I attached two log files, one before I replaced the optispark/ICM and the other after I did. This is a short log file as its only during me trying to crank it. I don't really understand log files, but maybe someone else does and maybe it shows something. It almost seems like this new optispark is already bad. I also double checked the wiring diagram on the spark plugs on the optispark just in case something weird happened and they are all aligned up correctly per shoboxs diagram. I also checked fuses, doesn't seem like any issue there. Fuel pump does turn on when key is on. Scan tool did not indicate any engine codes ( but its also OBDI so I have no idea if any would come on ). Any ideas before I say screw the optispark and do the conversion?

 

Are you absolutely certain you indexed the cam dowel pin (95 LT1) to the Opti? If alignment is off, it's going to be “out of time”.

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

I can look over the data logs, but before I invest the time, we need to resolve the above question. The data log won't show whether the Opti is installed correctly.

 

I had wondered about that, it seemed to be right, it should only go in one way from the way it looks and from what I've looked in, but I have seen some forums where people took it apart and back on and it worked. it went right in and didn't have to force or manipulate anything. I've replaced one before and it went smooth so I guess before I take it all apart again I just wanted confirmation that that's all that's left to consider.

 

Based on doing this for 20+ years on this site (and other LT1 oriented sites), it is a problem of not being in the correct location for as many as 10% of the installs. Happens more with the spline drive 93/94, but sometimes with the pin drive. They can “slip” if the dowel pin is on the short side.

I'm assuming is has never started with the rebuilt AC Delco. Where did you find that brand? Seems like they have been hard to come by from AC Delco. Did you check the rotor screws before you installed it, perhaps applying some Loc-Tite? Screws backing out is another potential problem, and that’s going to cause random plugs to fire out of time. But that usually doesn’t happen until it’s been running for a while.

Before you pull the Opti let me look at the logs. Might take a couple days.

 

Thank you, I did locltite bolts, the opti went in pretty well and bolts tighten without issue. ( the three bolts behind were tight ) the acdelco I actually got from Amazon, sold by Amazon. no idea where they got it. I did read up more about that slipping and see some people talking about a similar instance. it also has never ran with ac Delco. I'm just curious since the issue before was the same, it's possible other opti was bad and this is just installed wrong, but who knows.

 

Just to be clear - it was not starting with the old Opti. You replaced it with the AC Delco, and it still will not start?

Not a lot to be seen in the brief cranking data logs. Your TPS closed throttle volts are too high, but that wouldn't be preventing it from starting. Address after you get it running. Should be in the range of 0.25-0.90 volts to avoid a code, yours is -.94-0.96 volts. Blades may be sticking slightly open. Typical factory value is 0.60-0.67 volts. Values like coolant temp, inlet air temp, injector pulse width, ignition advance (value commanded by PCM, not a feedback of actual) look rational. The IAC valve is commanded wide open. If the throttle blades are open too far, may be a bit lean on A/F ratio, making it hard to start???? Check the throttle blades to make sure they are not hanging up slightly open.

The barometer (84.15 kPa) reveals you are at about 5,500-ft above sea level. Generally it helps if you include your location in your profile.

The fuel enable (VATS) signal is present, so it's not a problem with the SECURITY system.

In the log dated 2021MAR30 the battery was struggling, with readings as low as 8.5 volts.

Have you checked the fuel pressure?

The fact you have spark and the logs show an RPM reading would indicate the Opti is working. But as noted earlier, there is no way to tell if the timing is correct.

Not sure where to go from here. You used the Shoebox diagram for the cam dowel pin?

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

 

Correct, the old opti was not working. The old opti didn't have a lot of miles on it, but has been on since probably 2018. Given their reputation I figured it was probably bad. Looked up on shobox how to reset the IAC and looks like its a process involving the engine running, but I'll check the throttle blades. Apologize about not adding profile info, updated it now. I am in Denver so ~5280ft above sea level, I'm originally from 400ft above sea level, had the camaro retuned up here, maybe my tuner made it run a little on the leaner side to account for the air density/low oxygen? I don't know exactly what he did to get it running smooth. The battery before was just low charged, it was a new battery, just had been sitting for a while, charged it up. ( Battery was bad when the camaro first wouldn't start properly, so replaced it recently ). I haven't yet checked fuel pressure, you think its possibly not getting fuel? I did use Shoeboxs diagram for the cam dowel pin, but who knows if somehow it went on wrong. I might just take everything off again and put optispark back on and try to start it ( and immediately turn off ) without putting water pump and everything back on since if there is something timing related I would need all that off anyways. I guess I should have tried that first, just was so sure it was the opti and so sure I couldn't put it on wrong.

I appreciate your quick and thorough replies.

 

I hat to point you in the direction of all that work, pulling it off the check the pin. But I'm not sure what else to say. If you had a 96/97 OBD-II setup, there is another way to compare the Opti timing position to the crankshaft position sensor reading (which was only added for misfire detection). If the Opti cam position sensor and the crankshaft position sensor do not match within a certain number of degrees, it sets a code. But you need a high end scanner with GM enhanced parameters capabilities to measure the qctual difference. I have found a "slipped" dowel pin using that data.

It's normal for the IAC valve open all the way for startup, it just that if the throttle blades are also open a bit, might just be too much air. But the MAF sensor is not active during cranking.

Wirth a MAF sensor, the PCM knows the correct air flow without regard to elevation. The MAF sensor measures the mass of the air (pounds), not the volume (cubic feet). It's possible a slight recalibration of the MAF sensor table in the PCM is helpful with such a drastic change in altitude. And for all practical purposes, without the MAF sensor the speed-density calculation uses the barometric pressure to calculate the density/mass of the air entering the engine, but may need a tweak of the volumetric efficiency (VE) tables. If your MAF sensor fails, the PCM defaults to the speed-density calculation.

 

The only insight I can offer in addition to all the excellent advice Fred has already contributed to this thread, involves this comment: "I haven't yet checked fuel pressure, you think its possibly not getting fuel?"

Before you go through all the trouble of pulling your Opti again, spray a liberal amount of starting fluid into your throttle body while someone cranks the engine .... and see if you can start, and keep, the engine running with repeated squirts of starting fluid. Maybe just maybe (?) your original "no start" condition was fuel related. And, (of course!), do test for proper fuel pressure ........ before taking off that Opti ....... again.

 

Update, but not much of one. I tested the fuel by just pressing the connection down and fuel came out, wasn't very strong, but wasn't very sure it was fuel related. Pulled everything apart, took opti off, double checked it was exactly as the picture and put it on. No success. Said screw it, bought another opti, installed it, nothing. Realized I can rent a fuel tester gauge, put it on and I'm getting no PSI. Fuel pump is for sure coming on, Don't remember last time fuel filters been changed, probably never. Pulled it off, tested fuel pump there, fuel is coming out, but very slowly, not quite like it should be. So going to replace to fuel pump anyways cause it appears it needs it, but I'm not convinced that's the problem with starting just given that spraying starting fluid directly in won't even give me a second of starting and shoots flames out, which usually indicates that its out of time.

My only other concern that I'm not sure if its correct thinking or not with these optis as I'm no expert, but in that picture it shows the cam pin next to the "1" on the opti. the cam pin is not next to the "1" in the opti, but the opti did line up that hole with the cam pin. With this being said, should I make sure Cylinder one is in the proper position before putting on the opti? I didn't think it mattered, but I'm also running out of options. Going to replace fuel pump either way, but getting frustrated. Its tough to find a reputable shop that doesn't sit on it for a year.

 

The cam dowel pin hole is only next to the “1” when cylinder #1 is at TDC on the compression stroke. The only thing important is that the dowel pin has to be in the slot labeled “cam dowel pin slot” in the photo. Read the note on the right edge of the photo.

Are you sure you didn't align it with the unlabeled hole 120° away from the correct location?

 

Okay, just to review, (primarily for my own benefit): 1) You've now installed (what?) three (3) Opti's, and .... you're SURE you're installing them correctly. 2) You're addressing the lack of fuel pressure "issue" by installing both a new fuel pump and fuel filter, right? And, 3) you are witnessing flames shooting or popping back through the throttle body/intake manifold when you attempt to start it with starting fluid, sooooooo ........ let's focus in on that ........ "it's out of time" ....... diagnosis.

First off, triple check, (not double check!), that you've got your spark plug wires on correctly, and have NOT crossed any of them. A great way to do this is to just take one (1) wire off at a time from the Opti end and the spark plug that it's supposed to be going to, and check the resistance through each wire with a ohm meter. Also, any resistance reading that you find with the ohm meter that's over or greater than 1,000 ohms per foot of ignition wire ...... means that wire needs to be replaced anyway! After ALL your ignition wires both test good for resistance, and, you're SURE they are correctly routed ... let's proceed to step two here.

Secondly, remove your water pump, etc., and get back down to your Optispark. Remove just the Opti's distributor cap, so you can watch the rotor move. Now remove your No. 1 spark plug and "feel" for the compression stroke as you rotate the engine by hand. Once you're convinced you're on the compression stroke for #1 cylinder, put a straw through the spark plug hole, watch it rise up, (pushed by the piston), until you get the engine at TDC for cylinder #1. Now look at the position of the rotor on your Opti. The rotor should now be at (i.e. within +/- 5 degrees, of course), the six (6) o'clock position, (i.e. the clock "bottom" position), where, if you have a "see through" Opti cap like I do, you will see that's where the No. 1 cylinder's "contact post" is located .... in the distributor cap!!!

If for some reason you've gotten #1 cylinder at TDC of the exhaust stroke rather than the compression stroke, (so that the No. 6 cylinder is really at TDC of it's compression stroke), then your rotor will just be pointing straight "up" at the Noon/ 12 o'clock position, (where cylinder #6's "contact post" is located, again ..... in the distributor cap!!!).

If you're engine passes this test, you will have insured that BOTH the Opti is installed correctly, and furthermore ....... that your timing chain has not slipped or "jumped a tooth".

And, again ..... Good Luck!