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mikev7

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I have a little problem with my 97 trans am. I was drag racing a guy friday. We did 4 races and i lost 3 cause he wouldnt allow nos. The engine is mildly built-much more than your average muscle car but i can still drive it on the street.

Yesterday i fueled up on 93 cause its all i can use and i noticed the power started surging and sputtering. I put octane boost in and fuel cleaner and burned the gas out to empty than refilled it and its still doing it but now its more on the weak side of the sputter meaning the car feels weaker. It starts/idles fine.

Heres what its got.
Performance:
-Custom grind Comp Cam- 224, 224 / .538, .538 on 112 LSA
-Crane 10308 Dual Valve Spring kit
-GMPP 1.6 3/8 SA Roller Rockers
-Hooker long tube headers, heat treated black
-Hooker offroad Y-pipe
-Dynomax 3" bullet muffler
-SLP Loudmouth catback system
-Taylor over the valve cover black plug wires
-Factory Ram Air
-Free mods including: TB bypass, MAF descreened
-Tune by FLP
-Nitto 555R drag radials, 315-35-17 out back
-Mohawk Predator VRS up front, 275-40-17
Nitrous:
-Nitrous Works wet LT1 plate basic kit
-NX iceman pure-flo solenoids
-Mallory 685 Ignition box for window switch and timing retard functions
-Harris Speed Works purge
-Harris Speed Works Fuel pressure safety switch
-860 quick release blowdown tube
-Dynotune Fuel pressure gauge
-Dynotune Nitrous pressure gauge
-NGK TR6 plugs
 
Optispark.

Does it start and idle alright?
Does it still pull hard but sputters?
Does it sputter and surge at part throttle when you're cruising?
Does it act like it's got bad gas in it?

If so...it's the optispark, I'd put money on it.
 
Optispark.

Does it start and idle alright?
Does it still pull hard but sputters?
Does it sputter and surge at part throttle when you're cruising?
Does it act like it's got bad gas in it?

If so...it's the optispark, I'd put money on it.
That is exactly what it does. What exactly is the optispark.
 
I did a search and found a little out. I might try to replace it myself. I see msd makes a upgraded ignition and i might get it.
 
my advice would be when you replace one component replace all components. It's not hard to replace if you have the tools and patience; it's a one-person job
 
Replace everything. Do NOT just replace the cap and rotor. It's going to be an unpleasant job. You can tackle it if you've got a garage, tools, initiative, and a lot of patience. The water pump and crankshaft pulley are going to have to come off.

Even better, get an aftermarket replacement. The aftermarket one may end up being cheaper than the OEM from GM. If you REALLY want to do the right thing, get a DIS setup like the one Delteq makes, it's about $700 and it's almost an exact copy of the distributorless system on the Northstar engines. It'll solve your Opti problems forever.

Are you running an aftermarket ignition box like an MSD? Something high voltage with a capacitive discharge?
 
ya like the guys said.... gotta pull the water pump and crank pulley. this is the part that fails almost all of the time on the LT cars. The earlier models (93-95) had the gen 1 opti. 96-97 had the gen 2 opti, had vents and improved electronics.

If you are gonna keep the opti, get an MSD billet replacement. It costs around $550 or so, but will last forever. You should also replace the coil with an aftermarket one. that should keep you going trouble free for a while.

it would be a great idea if you had the funds to totally get rid of the opti-junk and get a full digital ignition. i know there is a couple different setups out there to replace the opti with a crank trigger and reluctor wheel setup, but dont know them off the top of my head. Im an LS1 guy that has rebuilt a couple LT1/4's. good luck with the car.... they are fun to drive, but a PITA to work on
 
Alright so i had a change of plans as to my job and ended up spending the day replacing the parts. I got it finished and now it backfires. I started it up and it took a little gas to get it going. I let it run for 10-15 seconds then i heard a loud backfire. I cut it off and made sure everything was connected, started it up and the same thing happened. Could i need a timing adjustment?

When i was removing the crank shaft pulley, i turned the shaft a little. I had marked all the positions on the ignition as i striped it down and put it back exactly as it came off.

I thought it had a little more response like a stronger spark but it sounds different and like i said backfires every 15 seconds at idle. What could it be?
 
so you got fuel, started acting up and so you replaced the ignition system?

if you got some bad fuel (water perhaps) it could have caused some issues.. I would have thrown a set of plugs in it (after inspecting the ones that were already in it) and give it a tank or two of fuel to push out what you may have gotten..

if issue persists, then get more serious..
 
Check plugs and wires.

Do you have a capacitive discharge ignition?

Did you get an aftermarket Optispark or an OEM?
 
Well, i didnt think twice about it being the potispark, i mean optispark system after 2 days of reading flods of information about it being of notoriously poor performance. I put so much fuel system cleaner and octane boost in it that it burned my nose when the exhaust blew in the car on the street. After the second tank of gas i knew it was either a ignition problem or a fuel pump problem and i have a digital fuel guage right on the dash.

After i saw a ebay page 2 pages long devoted solely to the optispark i decided to change it. It was worn pretty good too. Now someone please help me so i can enjoy the car?
 
Well, i didnt think twice about it being the potispark, i mean optispark system after 2 days of reading flods of information about it being of notoriously poor performance. I put so much fuel system cleaner and octane boost in it that it burned my nose when the exhaust blew in the car on the street. After the second tank of gas i knew it was either a ignition problem or a fuel pump problem and i have a digital fuel guage right on the dash.

After i saw a ebay page 2 pages long devoted solely to the optispark i decided to change it. It was worn pretty good too. Now someone please help me so i can enjoy the car?
It was the Opti. You've done the reading, you know how many people have had the exact same issue. Don't worry about second guessing yourself at this point, you did the right thing. You just need to get everything dialed in right. We might need a little more information about the car and what you did to help you out, but there seem to be enough LT1 guys here to point you in the right direction.

Where did you get the replacement unit? Are you certain you got version two (95-97) and not version one (92-94)? The two are NOT interchangeable. High voltage ignitions cause all kinds of problems with the Optispark because of the "correct-a-cap" that GM used, that's why I asked if you're running a CD box like an MSD or something equivalent. Did you replace the water pump gaskets when you put it back on? If the pump leaks it can get the Opti wet, that can cause all kinds of issues.
 
Get out your timing light. Sounds like you're advanced a few degrees too many. I dont' know what it should be, sorry.
 
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mikev7 @ Jul. 21 2008 said:
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Well, i didnt think twice about it being the potispark, i mean optispark system after 2 days of reading flods of information about it being of notoriously poor performance. I put so much fuel system cleaner and octane boost in it that it burned my nose when the exhaust blew in the car on the street. After the second tank of gas i knew it was either a ignition problem or a fuel pump problem and i have a digital fuel guage right on the dash.

After i saw a ebay page 2 pages long devoted solely to the optispark i decided to change it. It was worn pretty good too. Now someone please help me so i can enjoy the car?
It was the Opti. You've done the reading, you know how many people have had the exact same issue. Don't worry about second guessing yourself at this point, you did the right thing. You just need to get everything dialed in right. We might need a little more information about the car and what you did to help you out, but there seem to be enough LT1 guys here to point you in the right direction.

Where did you get the replacement unit? Are you certain you got version two (95-97) and not version one (92-94)? The two are NOT interchangeable. High voltage ignitions cause all kinds of problems with the Optispark because of the "correct-a-cap" that GM used, that's why I asked if you're running a CD box like an MSD or something equivalent. Did you replace the water pump gaskets when you put it back on? If the pump leaks it can get the Opti wet, that can cause all kinds of issues.
I got the unit from autozone. It was a kit built for the pre 97 and 97 after cars. They changed to a vent tube and nothing else for the opti2. I replaced all the gaskets and was even going to get a new water pump. I am running a cd box. Its for the timing retard for the nos from what i understand. I dont know anything about the box. Im learning as i go. I build houses not cars.

Since my truck is in the shop i was going to take the car to pep buys tomorrow morning and let them worry with it. If i put it in the dealerships shop i wont see a vehicle for 3 weeks easy. My truck has been in there for 3 for something that takes 2-3 days to fix tops. 2 1/2 of the days being used waiting on parts.

Could it be the coil? One of the plugs was corroded a little.

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Coil is a possibility. Autozone will test it for you. Also check plugs and wires while you're at it. I remember one time on my old '93 T/A I was getting some missing and backfiring (I assumed it was the Opti, the car was on its second unit at the time) then I discovered I'd run a plug wire too close to a pulley and the spinning belt had sliced through the insulation on the wire.

About the ignition box...is it only a timing retard or is it also a capacitive discharge/high voltage/ignition amplifier? Is it an MSD unit?

The problem with high voltage and Optispark units lies with the "correct-a-cap" design. To make it easier to run wires to either side of the engine, GM put the terminals inside the distributor cap VERY close together, that causes premature wear and arc over when you run high voltage through it.

Not that it matters for your application (I just saw that you said it was a 97), but there were other differences between version one and version two besides the venting system. If you wanted to put a version two unit on a pre '95 car you'd have to change the timing cover, the electrical harness for the distributor, the vacuum harness, the cam gear, and the timing set. The camshaft also needs to have a longer dowel pin in it to fit the '95 and up gear and cover.
 
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