Well, goes like this. Once the car is warmed up, say the fan cycles on then off, at 3700rpms, be it wot, part throttle, or no load, it pops. When driving the car and having it happen, feels like somebody just hit me... with their car. I used a scope and checked the high and low res on the opti, checked out fine, no discrepancies, no blips or faults either in the high or the low res. Pulled out the IGN scope, and checked secondary, voltages are all normal, burn times are all normal, but patterns are all normal. Checked injectors, peak times are all there, as are curves and pulsewidths. Checked the MAF, no problems there. Even pulled the maf and drove the car, still happens. Fuel pump has great pressure and flow numbers, no signs or armature wear either. Knock sensor isnt seeing any knock, its an LT4 KM. TPS is fine, IAT is fine, IAC is fine. Funny you might say... yes. Oh and one more thing, it has Delteq setup as well. Anyone have any clues as to wtf is going on? I think my last test will be to place the ign back to stock and see if the delteq is a fault.

Anyone have bright ideas on what else I may have missed? A mechanical failure somewhere? Got me man, got me.

Thanks

94Z28, 6spd, 132k on the clock.

 

Possible broken valve spring, did you do a leak down test for the mechinal condition of the motor? I noticed your sig states some high miles.

 

Is the fault something that just happened or did it start to occur after you made some change? I don't mean to insult you by stating the obvious, but the first place to look is at what the last change you made was, if anything.

Rich

 

hot Rod Hawk - Well, as far as valve springs go, I have not done a compression test on the car, perhaps it is in order just because I should check up on the condition of the rings, valves etc. But the reason I haven't tried that is the miss isnt something that would make any sense to be a valve spring. Its a miss only at 3700 above 3700 its ****, pulls like a raped ape, below that same thing no probs whatsoever. usually to somewhat 'avoid' it, i just break the tires loose in first(which is reeeeeally tough ) and just stay in the rpms above 3700.

rskrause - I hear ya, no offense taken. As far as if I changed anything, thats a negatory. I installed the Delteq system and the car ran like a champ for several months, ran better than when on stock opti arrangement. Then the car started its little hissy fit. But I am going to try and stick the old stuff back on and try to get a repeat out of it.

thanks guys

guess i should put some warm clothes on and just it over with lol

 

Is it possible you have some of the high voltage plug wires running very close to, and possibly in parallel with the signal wires from the Opti?

 

Thats a negative on the wire running. I even checked the opti signals with a scope, no traces of spark fouling the signal, high or low res.

On another note, I went ahead and set back the ign to stock with MSD 8.5 wires. Car runs rougher through the rpm range, but for the life of me I couldn't get it to repeat the problem. I'm gonna email Delteq and see whats up from there. So far they have been great as far as help goes! Unheard of with most places now... Gotta be a hickup in the module or a coil on the fritz I'll try and update this post just because, but Don't think it will help too many lol. BUT, never the less, thanks for your time and thoughts.

 

I've worked on a bunch of factory ignitions that share the same basic design as the old HEI ignition dating back to the 70s (including a few Optis, which still share a lot in common with the old HEI). If it was a stock ignition system (and I know it's not) the first thing I would replace would be the module. They sometimes pick up a bad RPM "window" where they basically lose their mind. Coils can have similar problems, but they are usually much more "organic" in their failure, not like somebody throws a switch at a certain RPM.

 

Well it seems I am not the only one who has had this problem. I just went through this and it turned out to be the Opti. First thing you need to do is give pete a call at Delteq. My car would miss at 3900 at all throttle positions and under any load conditions. It would not miss a lick at 3800 or at 4100. Try this run the car up to 4500-5000 RPM in gear then let off the gas. If the Tach acts squirly at the RPM range it missing at while the car slows then it is an ignition problem with out a doubt and more then likely the Opti. As I said give Pete at Delteq a call and mention that you think your problem is simmilar to Paul's corvette and see what he ghas to say. Took me three weeks to figure this one out BTW.

 

Yes, Pete did speak of you being the only other person to have similar symptoms. He said that your opti was the cause, which is good to finally find out no doubt. However, on the updated side of things, I received a new set of coils and ign module from Pete at Delteq, and went ahead and swapped them onto my car, just in time for my passenger side rad end tank to split and take a wizz all over the freakin place! Doh! However, I measure the resistance of the coils and 3 of the 4 were 4.6k ohms and the last coil, my 1/6 coil measured in the millions of ohms... the dead give away was the number 6 plug tower, which looked like it was growing/burning something obscenely odd. Checked my wires and plugs for that coil and they were just fine... little sooty (the plug), my guess is from the miss.
Aside from that I can't say if it fixed my problem because I don't to abuse the car with a cracked rad... But I'm looking for one right now.

-Polo-94Z28

 

What about "JC" at Delteq.... what does he say? I ran the Electromotive Opti-Eliminator/SDI setup for a couple years, and ended up with a similar problem. It would just shut down for an instant... like someone hit you. Injector pulse width would drop to "0". "JC" was the engineer at E'motive at the time, and the O-E/SDI was his baby. Although I had spent a lot of time discussing the O-E/SDI with him (I had one of the first installs), including a visit to Manassas with my car, photos, tech info, etc., when I developed the "shut off" problem, he decided to ignore me, and that was the last contact I had with E'motive. Now appears that the Delteq may have a similar problem.

 

It sounds like you definatly have a bad coil pack because a coil shoul read near short w/o power or ground applied. Sold an F-bod radiator about a month ago so I can't help you there. For your sake I hope the coil pack corrects your problem because as you probably know it is a hell of a lot simpler then an opti swap. I have to give it to Pete at delteq he realy stands behind this product, he could have just told me to pack sand but instead he took the time to walk through my problem untill I felt comfortable that it was the opti then I pulled the triger,

 

try fbodyjunk.com for a radiator. Good people

 

I don't recall ever talking to JC Hyde, I've gone through Pete, who like egfagala said, stands behind his shiz. And he does. It blew my socks off to find that out! It is interesting to notice that both of the systems have a similar problem, the result of your injectors going to 0m/s pw is odd... Thanksfully mine weren't doin that, not yet anyway lol. I'm willing to bet some moolah that the oem computer has some software leeway in it. It will let some bogus signals slide so that the car will continue to run even if it misses a little bit of a signal for a blip in time. prolly just uses past info to calculate. But the delteq, or maybe the SDI setup takes everysignal for what its worth, and if it sees something blip out it does what its sposed to , garbage in garbage out... but what do I know, im not ece major!

Anyway, looks like i found a rad here on the forum, hopefully its a solid deal so I can get some results back here and stop spammin my own post up lmao.

Laterz all

 

I'm bringing this TTT for follow-up. Hey Polo-94Z28 , have you resloved the problem? I'm considering purchasing a Delteq system.

Thanks,
Mike

 

Well, got the whole radiator thing taken care of, and took the car out for a spin. The miss is still there, even after replacing essentially every component of the Delteq system. Which leaves me to conclude that it has to be something within my cars system thats giving me this problem. Perhaps the delteq is just bringing out this problem. I am going to try routing the wires a different way (again), even though I feel it wont solve anything. If youre considering a Delteq, is a good system, I definatly notice the difference when its there vs using the opti. But in this instance it makes no sense to have more power and better idle with a nasty *** miss at 1 point in the rpm range lol. I'll prolly try something in a few weeks, its frickin cold out and my garage is occupied by another piece of work...