Hey guys I have 92' LT1 automatic with a little bit over 152k miles. I replaced the optispark/water pump and spark plugs about 7 months ago. I have fairly new plug wires. I received a H16 code, erased it, started the engine again, and got the H16 back. What is different here is that if I keep on the gas so the car is running at regular idle speed in park the car will run perfectly. Once I take my foot off the gas the car will stall. I checked the spark and it looked like I was getting good spark. It even electrocuted my dad.

Has anyone seen or heard of this and can explain why the car will run while giving it gas?

Could this be my coil?

I'm hoping it's not the opti but I'm 75% certain it is. There may or may not be an oil leak underneath the opti (it's dark out now and am not 100% certain) but I'll update this tomorrow.

Also, transmission fluid has been leaking in the VSS and is all over the harness plug. Speedometer will work if I clean off the plug but stops working properly after a couple days of driving. When the speedometer stops working, the car will have a jerking rev when going over 35 m.ph. if on the gas to maintain speed. I believe this a separate issue but was wondering if anyone could piece them together. I'm fairly sure the gasket inside the VSS is blown because it works after cleaning the plug and stops after continued use.

 

H16 is usually caused by the wiring/connectors associated with the opti-spark. You might want to look at the ignition module also. It should have thermal grease under it.

If you had an L98 I'd tell you to do a minimum idle adjustment. I assume there is something similar for LT1s, but I have never seen it spelled out anywhere. Maybe someone else can supply that info.

This problem comes up once in a while (leaking trans fluid through VSS). Something is broken inside the VSS. The only way to fix it is to replace it.

The ECM uses the vehicle speed for many things and it will have problems if it doesn't have that information.

 

You need a new opti. People will tell you it will not start with a 16 but I know it will.

 

Thanks for the replies. Now that it is daylight it looks like there is not oil underneath the opti. The car started up today and ran without dying at idle. BUT the idle was really weak as if the car was in a defense mode. The fan came on immediately without the car warming up which I thought was bizarre.

I am going to throw a new ICM and Coil at it since I have not replaced them yet. In addition, I'm buying a new VSS. I'll update once I get em' on.

 

Just a thought about the fan coming on that fast. If you don't have a good connection on the temp sensor the fans will come on also the e.c.m. reads the temp as cold all the time and will richen the fuel mxture

 

Don't waste your money on coil and ICM. It is the opti and the h16 will cause the fans to come on and throw the car into limp home mode.

I had 2 new optis give me a 16 immediately upon install. OEM unit fixed my car. Petris sent me 2 junk ones in a row.

 

The car was running rich when I got it started. I also had a coolant temp. sensor code but it erased and did not come back. I thought for $15 replacing that sensor is a good shot in the dark.

MINE IS A PETRIS! Did they refund you? Mine is still under their 1 year warranty since I bought it in late Aug.

The Coil and ICM together were about $120. I don't really mind throwing cheap parts at it. On the other hand, if I threw another opti at it and it didn't fix it. = me.

 

The 2 he sent me were junk right out of the box. I decided I would not install a 3rd and that is where the fun started. He refused to refund my money but Visa, Bank of America, Attorney General's Office, Experian and Transunion all got involved. He tried to ruin my credit as well by attempting to report me to the credit bureaus after Visa issed the chargeback. He lost that too.

I try to make this known to as many people as I can.

 

Careful when you order your vss and do it local so you can physically take it back when you get the wrong one. I eventually put my old one back on [even though it does not always work] because I could never get the correct part.

 

Sounds like a messy situation. I'm really hoping it's not the opti, partly because I don't want to run into a problem like that.


Yeah, most of the VSS sensors I saw online are for manual trans. and the auto vs. Manual VSS look exactly the same in the picture.

 

Guys, I just put the new coil and ICM in and it's fixed. Car runs and does not throw H16 anymore.

 

These parts have nothing to do with a 16.

 

Just kidding apparently the vette played a late april fools joke on me. It wasn't funny. Put the wheels back on, tried to go for a drive, and car's rough idle was back to where it was and sending the code 16 again. I don't understand how it could run last night without sending a 16 but it did.

 

May as well get ready to swap it out. Don't let the warranty expire

 

unfortunately, that is what I am about to do. (swap it)

I should hire a priest to exorcise my car too. That tease was pure evil. It was seamless I installed the coil/ICM and boom it worked, now it doesn't. Tell tale signs of that a demon has took possession of my car.

 

Got the optispark out. It looks like a screw came loose. Maybe the manufacturer forgot to use locktight...At least there's a warranty.

 

updates?

 

Hi,
New here and need help. I need some help/info on the replacement of the optispark. I have a 93 which I got new. 20 years later I have had the optispark replaced 6 times. Each time cost over a grand. I have babyed the car all that time and now I have just pass it on to my son. With only 41,000 miles on it I just could not trade it in when I got my new stringray. So with that said. has anyone out there themselves installed the optispark on a 93 40th anniversary with the lt1? I would like to replace it with my son as a father and son project. So it's something he will have to learn down the road where he has to do it himself. Pulling off the water pump and the optispark seem easy enough. But the front pulley in front of the distrubitor will be a problem. If anyone out there have done it please let me know how It can be done. With only about no more than 2 inch between the front of the pulley and the front cross bar. Any info would be appreciated. Thank you

 

Wow, you replaced your opti 6 times in 41,000 miles. I just replaced mine at 120,000 only because the water pump was bad and figured since I was already that far into it. Found the rotor and cap were pretty worn. If it's been off six times the pulley should come off pretty easily. I suggest doing what I did and do a search on this forum.. This has been addressed many times as has the brand of opti you should buy. Great to hear your keeping the C4 in the family and making it a father/son project.

 

I suggest you get a Factory Service Manual, and follow the procedure it lays out.

A few tips (I'm going from memory here, so I'll probably forget a few things):

Drain the cooling system.

Disconnect the MAF sensor and IAT sensor and remove the air intake duct with the MAF and IAT as an assembly.

Disconnect the ECT sensor and remove it from the water pump.

Remove the serpentine belt and tensioner.

You may find that you’ll need to unbolt the coil/ICM bracket from the front of the right cylinder head. I can’t recall for sure whether or not I did.

If you're planning to replace the plug wires while you're in there, (recommended unless they're fresh) unbolt, but don't remove the power steering pump. This will help you to sneak the new plug wires in/out behind the pump, but may also be somewhat helpful when working on the water pump/Opti.

If you want more room to work, you can remove the radiator, but it isn't strictly necessary, and it involves considerably more work to remove it (I left mine in place).

The FSM will tell you that you need a special Kent-Moore puller to remove the crank pulley/damper. You don't. Here's how to get it off:

1. Raise the front of the vehicle enough that you can get under the car (it's also helpful to have it at a more comfortable height while you're working from above).

2. Remove the three bolts that secure the pulley/damper to the hub.

3. Mark the damper and hub so that you can easily see how to realign them to each other later.

4. Slide under the car with a long pry bar or hardwood dowel (I use a jumbo Snap-On screwdriver that's around two feet long) and a mallet.

5. Place the tip of the pry bar against the rear face of the damper, as close to the hub as possible (Ideally rest the tip alongside of the hub).

6 Give the pry bar a few whacks with the mallet, and with any luck the damper will pop off without too much of a fight.

You may find it helpful to apply a few whacks, then rotate the crankshaft in 120* increments, whacking it a few times at each interval (I haven't needed to do this).

It's also helpful to, if possible, shoot a bit of penetrating oil where the damper meets the hub, a day or more in advance of doing the job.

After you get the damper off, clean the damper/hub mating surfaces to remove all corrosion, etc, and apply a very thin coating of anti-sieze compound to these surfaces before you reassmble the damper to the hub. This should make it a lot easier to get the damper off next time.

Once the damper is removed, rotate the crankshaft so that one wing of the damper hub is at the six-o'clock position. This will position the other two wings at around the ten- and two-o'clock positions. In this orientation, the Opti will clear the hub as it is being removed/installed.

The Opti basically unbolts and pulls off as you'd expect, once you have the water pump and damper out of the way.

Once the Opti is out of the way, inspect the shaft seals for the Opti, water pump, and crankshaft. If they show any signs of leakage, replace them now.

When you install the new Opti, be sure to align it correctly with the cam gear, and don't force it into place against the timing cover (do NOT use the bolts to draw it into place). At most, give it a gentle bump with the heel of your hand to encourage it to pop into place.

Reassemble everything else.

Follow the cooling system refill procedure in the FSM carefully, and you'll have no problems with this. In particular, be sure to bleed the air out of the system as it's being refilled.

Hope this helps a bit. Good luck with it.

Live well,

SJW