1965GP

So I put a new(er) harness and computer in my 25th anniv and it will now run.... sorta. The car will start and run but will shut off after about 5 minutes and not re-start. sometimes if you disconnect the battery it will re-start. I actually drove it around the block - it drove and shifted good... then wouldn't start when I got it home.

I took the car to Pep Boys on hwy 6 out of desperation and they said they could not figure it out. My next step is to take it to the dealer for a diagnostic.

The car drove too good under load for it to be the opti and is not throwing any codes..

Any ideas? I have all the body parts and a shop ready to paint it so i really want to get it going but can't afford to spend thousands on it.

1965GP

The car's original harness was hacked in several spots and the car would intermittently get spark with a new coil and module.

I took the car to pep boys for them to track down the bad connections and they said the harness was too far gone and that the computer had been spiked (received direct current) and needed to be replaced.

I bought a harness and computer from a 94 A4 Z28 on this site that spun a bearing so it was getting parted out. Owner said the car ran fine before the motor started knocking.

Harness has all good connections except 1 butt connector on the coil.

Car fired right up and ran for a while then shut off.

I was able to drive the car around the block and it drove fine under load so I do not think it is the opti (and last owner replaced opti before I bought it).

We put it on a scanner that my buddy had and everything was showing normal.

The cut out is random and I am losing patience. I have all the body parts and a body shop waiting on the car but I want to get in in decent mech condition before spending $$ on the paint.

car is getting towed to Beck and Masten Buick GMC (sounds weird with no Pontiac) now. They said diagnostic is $105.00 which willbe well worth it to me if they can figure it out.

1965GP

Should have thought about this one....

Dealer is saying that the waterpump is spraying on the opti and shorting it out.

Makes sense since the car would start and run fine when it was cold (or dry) and after it ran for a while it would cut out and not start....cause it was soaked.

Now- guess how much the dealer wants to replace the opti and water pump?

1965GP

Dealer wants $2500!

I did one on my firehawk and it isn't that bad.

I'm researching which one to buy now- I had a few people say the new MSD was the way to go but from the LT1 tech page it doesn't get good reviews.

I'm thinking Autozone lifetime warranty.... they all go out eventually.

Looks like I'll be buying some beer and having an install party.

At least they figured it out- I hope.

neil350

I haven't spoke to you in a while (5+ years), but let me know if you need help/advice. Stick with a GM Opti, search partsldi on e-bay, they sell OEM Optis. The MSDs seem to have a good bit of issues, I have seen shops install them and have cars come right back. I have also had good luck with ac delco pumps, parts store ones cary life time warranties. But be warned we have had a couple cars go through one or two before we get a good one. Also while changing the opti you should change the opti harness, EFI connection sells them. I wouldn't pay 2500 for a pump and opti swap.

texas94z

I bought a opti from thepartsladi and i could be happier with it.

So it cranks over when you try to start it, but doesn't start?

Are you getting power to the coil and opti? It sounds like you have a bad connection somewhere.

mitchntx

It starts and runs fine and then shuts down? The reason it shuts down is because the WP is spraying water on the Opti?

Why replace the Opti? Sounds like its working just fine.

Replace the water pump and go from there.


I too have a partsladi Opti and have had no issues. I bought an MSD cap and rotor for it. I completely disassembled the Opti and silicone sealed all the housing components. I also used thread locker on all the parts. The rotor has its conductor screwed to the rotating arm instead of held in place by melted bosses like the stocker. Finally, I used more silicone seal on the cap.

mitchntx

Weird things happen ...

I had a customer's car that would run great and then it would just die and not crank. A real head scratcher.

Some one had taken the braided ground strap at the coil and laced it through the coil's wiring harness. Over time, the braid had chaffed the insulation off of a wire and due to motor torque, would shift the braided cable around just a smidge.

When it got just right ... zap! A direct short.

Weird stuff.

AdioSS

People are always quick to blame the Opti getting soaked by the Waterpump. My Opti was fine when I took it off after 166k miles. A few years before, I had a leaking waterpump, but I changed it and there were no issues with the Opti. I am sure that it wasn't putting out as much spark and there were a few misfires going on, but I blame the stock plug wires for most of that.

1965GP

Thanks for all of the advice on this- sorry I haven't posted but I have been traveling.

I am surprised the dealer is asking that much- its about 1000 more than I expected... but they did offer a 10% discount!

The car will start selecively- sometimes it will sometimes it won't. Usually it will run fine for a few minutes and then cut off and not restart. May restart the next day which is why I thought the opti getting wet made sense.

I have had the car at Pep Boys twice and to the dealer and no one has been able to figure it out 100%.

A friend of mine that works at G Force came over and went through all of the grounds and connections. His suggestion was to put the original computer back in.

Being that the opti's are so tempermental I think I am going to replace it to eliminate it as a variable.

I was trying to decide what to buy and it sounds like the the OEM at the partsldi is the way to go.

I noticed Jegs sells a GMPP opti for less than $400- assuming this is just a stock replacement?

I have a lifetime warranty one in the Firehawk from Autozone and go figure the car isn't running right.

Any reason not to buy the waterpump from a local supplier?

I don't think I will be able to get to it until the weekend after Christmas but anyone that wants to drink a beer is welcome.

Neil- did you move to Barker Cypress area? I though I saw your T/A in my old hood.

1965GP

leaning toward buying the MSD billet opti- any reason not to or anything I need to do to it prior to installation?

SS RRR

Just because the opti was exposed to coolant doesn't mean it's bad. I had one spray the opti as well. I couldn't figure it out after a weeks worth of it sputtering. I dried it out and it worked fine (actually still works and have it as a spare). I'd make sure it's bad before replacing.

1965GP

Well I just ordered a MSD opti for the 94. I was going to go OEM but figured the advantage of being able to vent the MSD would be worth it in the long run.

I also ordered a set of Taylor spiro pro's- in blue to match the stripe of course.

We'll see what happens after this goes on...I am so ready to get this thing painted and start enjoying it.

Sparkz28ss

I had an issue with my LT1 running for about 2 or 3 min .. and then shutting off and not restarting for a short time..

I had a spade connector on the factory wire harness that I had run to my MSD box.... after looking for the issue for a few days I found that this connector would get really damn hot .. hot enough to burn me ..I cut it out an soldered the wires and didnt have that issue again

1965GP

I am going to solder the wire on the coil- I was concerned about it getting hot.

I'll take care of this when I put the opti on- it's on it's way now so it's going on the car.