JSkeet

Gentlemen,

'94 Z28 will start when cold (once a day is all I ever tried) and idle for 3 seconds then dies. Afterwards will crank but not fire up at all, not even stumble.

Diagnosed with the sticky thread "proper way to diagnose bad opti" and found bad opti. It had every sign the diagnosis looks for. Upon removal the old opti had a rattle inside of it and the spline drive was rusted on each end of the opti so I know moisture got to it.

Swapped with Lifetime Warranty Opti and new pigtail from Chandler Motorsports Ebay Store (took the risk).

Got everything bolted back together and fired the car up, idled for 3 seconds and died. Will only crank after that.

Now I didn't do the "proper way to diagnose bad opti" yet, but I did some casual troubleshooting and found the following:

I'm getting spark from the coil into the opti.
There is no spark coming from the plug wires to the spark plugs. (from opti to plugs)
38psi fuel at rail with key on, 40 while cranking.
I tried OEM opti pigtail and new pigtail, made no difference.

Any ideas? I'm going to do the proper diagnosis this afternoon but was wondering if anyone else has had similar issues and it not been the opti? I only wonder this because it's doing the exact same thing now it did before, so I wonder if the problem is elsewhere.

Guess I'll know when I diagnose it tonight.

RamAir95TA

If you have good strong spark coming from the coil to the opti but no spark coming out of the opti then it's the opti. Like you said, you took the risk, unfortunately.

Dave89IROC

Did you remove the cap and locktite the rotors screws?

JSkeet

Nope, I didn't want to open it up because of warranty... plus I don't have that tiny little inverted torx socket needed to open them up.

JSkeet

Well, as expected... diagnosis points right to the opti again.

moparman

Go to Rock Auto and see if they have any new Delphi optis left.

JSkeet

I should've done that originally but I thought the lifetime warranty opti would be a good idea.

HOPEFULLY the next one I get on warranty works... or else this will get old real quick.

JSkeet

Since my symptons were identical with the old opti and the new (ebay) opti, I've decided tonight I'm going to get back into this thing and troubleshoot the various parts that I've found could be causing this through extensive research.

For future referrence I'm going to list them here. Through research I've read that these parts also caused the exact issue I'm having, sometimes only one of these parts, sometimes several all at once:

oxygen sensor
MAF sensor
Coolant Temp Sensor
ICM pins not making contact inside connector (slightly bend them downward to make snug connection)
VATS system (check key, clean key/ignition cylinder
clogged injectors (fuel pressure at rail isn't always what the injector is spitting)
IAC
Oil pressure sensor

JSkeet

IDK why I have faith in the ebay opti but it makes me think it's something else since it's acting identical both before with old opti and after with ebay opti.

Car will start up when cold an idle smooth for 3-4 seconds then dies.

Troubleshooting according to shbox.com all points to Opti. All the voltages and ohms check out fine.

Getting voltage from coil to opti but no voltage from opti to plugs.
40psi at back of fuel rail.

Injuneer

You indicate you have 40psi fuel pressure while the engine is cranking. What is the pressure when it starts and runs for 3 seconds?

JSkeet

I didn't check and at this point I don't think I can. I have put the ebay opti in 3 times now to troubeshoot and it only got the car started the first time. The 2 following times it won't even give me that initial 3 seconds.

SCHOOL ME ON THIS: If I remove the spline drive from the opti to find where the notch is on the cam and then reinsert the spline drive into the opti, can I screw up it's timing? If not, then I'm going to put my OE opti back in and get the fuel pressure during that initial 3 seconds. I removed the spline drive as recommended to help aid in my install of my new opti.

On a side note, the fuel pump doesn't sound very strong like it used to w/ the key in the RUN position. Initial prime was a loud whine last year, car sat since October and here we are 11 months later and it's just a low hiss noise but like I said, still getting 40psi at back of rail and I installed new fuel filter already, old one wasn't barfing rust or anything, was pretty clean actually.

But, as mentioned, there is spark going from coil to opti and no spark coming out of opti to plug wires. I checked this with an in-line bulb indicator.

JSkeet

Now that I can't get it to fire up for that 3 seconds at all I'm thinking I should stop avoiding this and go ahead and order the Delphi opti.

Also for referrence - In an attempt to clean any visible grounds I shorted the main ground for the fusible links w/ the positive battery distribution post on the passenger side of the engine bay, you know how they're only a few inches apart from one another. After that I had all kinds of goofy problems w/ the key in RUN position - erratic gauges, erratic relays clicking, starter would just click when I tried to start it, fuel pump was sounding goofy... I removed that ground and cleaned it, disconnected battery for 5 minutes and put it back on, everything acted normally afterwards. I didn't find any blown fuses. Car would then crank and not fire up, which has been the issue all along.

southpole9347

Sounds like a bad opti, I had a security problem with mine once, cranks but no start.

JSkeet

Got a Delphi Opti on the way gents. I will update once she's up and running.

If I was more inclined I'd go ahead and remove the timing cover and swap to a double roller now since the car has 140k on it and I'd like to verify the timing chain is still initact anyway, but then I'd get in that deep and want to cam swap, then I'd need to do valve springs and RR's, and before you know it, with all that extra power, I'd be breaking other parts... like that AutoZone clutch I put in the car 4 years ago that has 11 autocross events on it. lol



It's funny how priorities change. I just hope I can keep off the loud pedal once she's up again. As evident, you can break plenty of parts running minimal bolt ons as well.

JSkeet

I never thought I'd see the day... but she's running!

And now I know better than to use Ebay Opti's.

The new Delphi Opti fired right up and within 10 seconds I started getting lots of backfire and very poor running... I'm suspecting the 1-year old fuel would be the cause. I'm going to syphon the fuel and put fresh 93 octane in with some octane boost and see what happens this evening.