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LT1 Corvette - no spark FML!


zeitgeist57

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Just finished buttoning up my '95 LT1 Corvette after replacing the Optispark distributor. My Delteq (aftermarket coil-pack distributor) has an LED that indicates when it has a good Opti signal. It looks dead.

 

There is no spark. I pulled two plug wires and laid them on top of the intake manifold so I could see them spark from inside as I started the car. Cranked and cranked. Nothing. Strong smell of unburnt fuel.

 

I know "no spark" issues are as old as cars, but I really need a second set of eyes since my brain is fried.

 

Oh...pulled codes and nothing major...just a couple of codes associated with disconnected sensors (I reconnected and cleared the codes)...

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I grabbed my wife to turn on the ignition, then crank the car for a few seconds while I look at the DelTeq ignition control module. It flashes once when the key is turned, but then dead...looks like the DelTeq is good, but not getting a signal at all. Not good.

 

Shouldn't have bought the $110 Opti. :) (When a ACDelco Opti costs nearly $400)

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Damn, that sucks. I was crossing my fingers for you that it would work out since all you needed was the optical sensor. Hopefully you haven't buttoned everything up completely. School is getting started so I don't have as much time, but get ahold of me if you want a hand working on it.
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Thanks, Rick. The biggest pain over the last couple of weeks was the headers. If I need to yank the Opti, it shouldn't be so tough now.

 

Delteq manual says that the Opti-Box is not getting an Opti signal at all. I may put the old Opti in to see if it fires...

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  • 2 weeks later...

I swapped Opti's...returned the shit Cardone reman unit to Advance Auto and put my old one back on. Now it's getting a spark, but misfiring badly and won't run. THe old gas has been siphoned and fresh super unleaded put in. I thought I had it on the proper cam keyway, but I'll pull the dizzy tomorrow to check that it's mounted properly on the front of the engine.

 

I contacted Dal Slabaugh on a new ACDelco Opti, but does anyone else have a good Opti they would loan me to see if it fixes the issue for a couple of days?

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FUCKING FIXED!!!

 

I'm an Opti-idiot and clocked it incorrectly on the cam. Repositioned it and it fired up on the first revolution. I won't lie...I shed a tear I was so happy/relieved.

 

Waterpump gasket is leaking. No surprise, as I had the WP off/on fucking 3 times as I fucked around with the Opti. Exhaust header needs tightening at the collectors.

 

I'm happy as can be right now. Going to have one of the most satisfying night's sleep I will have in months. :)

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I've been enjoying the Vette after getting her cleaned up this weekend. Unfortunately, while the car runs well otherwise, the ignition/timing/electrical problem that it had for the last couple of years remains. I did a few tests and feel 99.9% sure it has something to do with the computer and electric radiator fan.

 

Essentially, when the fans kick on (due to climate control or A/C compressor turning on, or coming on at 205*F to help cool the engine) the engine momentarily lopes at idle like an electrical load comes through the charging system, a CEL comes on, and the engine sounds like timing is pulled way back. It still runs and drives, but the exhaust note is considerably noisier and the CEL stays on. Also, acceleration is sluggish.

 

So, could this be a fried PCM? Bad electric fan? Bad fan relays...or bad wiring? Again, any help would be appreciated.

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Guest 614Streets

Don't you just <3 working on cars?

 

 

 

FUCKING FIXED!!!

 

I'm an Opti-idiot and clocked it incorrectly on the cam. Repositioned it and it fired up on the first revolution. I won't lie...I shed a tear I was so happy/relieved.

 

Waterpump gasket is leaking. No surprise, as I had the WP off/on fucking 3 times as I fucked around with the Opti. Exhaust header needs tightening at the collectors.

 

I'm happy as can be right now. Going to have one of the most satisfying night's sleep I will have in months. :)

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Howard.....Code H41, H42...open loop and closed loop. Electric cooling fans are now on all of the time.

 

Also, the A/C compressor doesn't engage when climate is on "auto"...nice hot air all the time, compressor pulley not spinning. I am starting to think the ECM is fucked.

 

Is a GM dealer the only local spot to reflash a new/reman ECM? For $150 I'm inclined to just get a new compy...

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Howard.....Code H41, H42...open loop and closed loop. Electric cooling fans are now on all of the time.

 

Also, the A/C compressor doesn't engage when climate is on "auto"...nice hot air all the time, compressor pulley not spinning. I am starting to think the ECM is fucked.

 

Is a GM dealer the only local spot to reflash a new/reman ECM? For $150 I'm inclined to just get a new compy...

is your car OBDI or OBDII? if it's OBDI and you have a copy of the PCM file, I can flash it for you. if it's OBDII sorry, can't help ya :) (If it's OBDI with an OBDII connector, even better because then I won't have to charge my car's battery to help you flash your PCM)

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It is OBDI with OBDII ALDL.

 

I heard on CorvetteForum that some auto parts stores "test" your ECM, but my call to Advance Auto let me know their only capability is in operating an OBDII code reader...talk about going to the free clinic for neurosurgery! :lol:

 

I did notice one of the O2 sensor 4-pin harnesses was a little melty from being too close to the pass-side header, but the wires were not brittle and the connection still disconnected and connected fine. This clip was fine over the weekend when I was under the car last, and the ECM problems were still present then as well so I don't think the heat affected anything there...other than that I cannot find any wiring issues.

 

If I have to f**king OHM-test every wire under the engine bay, I'd rather waste money on the ECM and get that fix wrong before resorting to a wiring problem. :)

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It is OBDI with OBDII ALDL.

 

I heard on CorvetteForum that some auto parts stores "test" your ECM, but my call to Advance Auto let me know their only capability is in operating an OBDII code reader...talk about going to the free clinic for neurosurgery! :lol:

 

I did notice one of the O2 sensor 4-pin harnesses was a little melty from being too close to the pass-side header, but the wires were not brittle and the connection still disconnected and connected fine. This clip was fine over the weekend when I was under the car last, and the ECM problems were still present then as well so I don't think the heat affected anything there...other than that I cannot find any wiring issues.

 

If I have to f**king OHM-test every wire under the engine bay, I'd rather waste money on the ECM and get that fix wrong before resorting to a wiring problem. :)

 

Take the ECM to one of the orielly stores they can test em

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If Oriellys can test it, that sounds like a decent idea. If you want we can plug in my laptop and look at the data while it's running. We can even download the stock ROM in case you want to get another PCM we can re-flash it to factory.

 

Where did you get the codes from? All the research I've done indicates the 41 and 42 codes are for the Ignition Control Module and ICM circuit (which would make sense because you replaced them with the Delteq). The A/C may not be charged and the PCM is detecting low pressure which would keep the compressor from coming on. Some codes trigger the cooling fans to come on immediately.

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put a coolant temp sensor in it should be a multipin that does the fan and tells the pcm what temp it is probably wasted inside and shorts to voltage when it reaches temp and turns on the fan the pcm uses the coolant temp sensor on older cars to control the fuel trim
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Your car is just pissed that it still needs a bath......with soap :bangbang:

 

No shit. It looks like a dust storm driving down the freeway! J/K Clay

 

I looked in the book, and found some dead ends. So I searched online and actually found some post of your on DC.com I see you've been fighting this for quite some time now. I read quite a bit of that thread to find that you and Spark or whoever didnt get too far.

 

Like Dave said, one recommedation would be to put a temp sensor on it. Then I would go from there.

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