93 LT1 ignition test
Thread Starter
Heel & Toe
Joined: Jul 2005
Posts: 23
Likes: 0
From: Troy Alabama
93 LT1 ignition test
I think I may have a bum opti out of the box. The original sysmtoms were a code 36. But it ran fine. After letting it set up for some time, I started getting SES light. Since I just turned over 100K, and because I read so much here about it, I was convinced it was the opti. Getting the old one off was a chore. The 1st thing I noticed about the replacement unit was the 4 pin plug. The old one had a shroud around the plug,and a key so it could only go on one way. The new one has no shroud, only the 4-pin plug.
Here's my question. Is there any reason I can not get the engine to fire long enough to see if it will run with no water pump, and no air going thru the air intake (it's removed) in short, is there anything that would cause the ignition not to make a spark, that I may have overlooked. I plan to only run it for 5 or 10 seconds. Just long enough to see if it will. After this, I guess my next test is to put the old opti back in. But that's a lot of work. If I can test it before I put everything back together, that will help. If the old one works I have gotten a bad one out of the box. My fear is that it will not be replaced. Any thoughts suggestions or ideas are greatly appreciated.
Here's my question. Is there any reason I can not get the engine to fire long enough to see if it will run with no water pump, and no air going thru the air intake (it's removed) in short, is there anything that would cause the ignition not to make a spark, that I may have overlooked. I plan to only run it for 5 or 10 seconds. Just long enough to see if it will. After this, I guess my next test is to put the old opti back in. But that's a lot of work. If I can test it before I put everything back together, that will help. If the old one works I have gotten a bad one out of the box. My fear is that it will not be replaced. Any thoughts suggestions or ideas are greatly appreciated.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
1) are you certain that you mounted the new Opti correctly to the driveshaft, as it will only go on 1 way? It should mount firmly when done correctly.
2) running the engine for a minute or so without your WP won't hurt anything. Just keep an eye on your temp gauge, as it will heat up pretty fast. I tested out my new Opti before I put on my WP on my '95 just to make sure I buttoned up all the wires correctly and seated the Opti correctly. I ran it for less than 15 seconds or so.....
3) be sure your coil wire is firmly in place on both the coil and Opti.
2) running the engine for a minute or so without your WP won't hurt anything. Just keep an eye on your temp gauge, as it will heat up pretty fast. I tested out my new Opti before I put on my WP on my '95 just to make sure I buttoned up all the wires correctly and seated the Opti correctly. I ran it for less than 15 seconds or so.....
3) be sure your coil wire is firmly in place on both the coil and Opti.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
1) are you certain that you mounted the new Opti correctly to the driveshaft, as it will only go on 1 way? It should mount firmly when done correctly.
2) running the engine for a minute or so without your WP won't hurt anything. Just keep an eye on your temp gauge, as it will heat up pretty fast. I tested out my new Opti before I put on my WP on my '95 just to make sure I buttoned up all the wires correctly and seated the Opti correctly. I ran it for less than 15 seconds or so.....
3) be sure your coil wire is firmly in place on both the coil and Opti.
(sorry for the stuttering)
2) running the engine for a minute or so without your WP won't hurt anything. Just keep an eye on your temp gauge, as it will heat up pretty fast. I tested out my new Opti before I put on my WP on my '95 just to make sure I buttoned up all the wires correctly and seated the Opti correctly. I ran it for less than 15 seconds or so.....
3) be sure your coil wire is firmly in place on both the coil and Opti.
(sorry for the stuttering)
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
The new Opti should slide in and out easily.It is possible to install it a couple of teeth off.Try pulling it and re-installing it it should slide in easily and pop against the timing cover.
Thread Starter
Heel & Toe
Joined: Jul 2005
Posts: 23
Likes: 0
From: Troy Alabama
ignition failure
Because I had read in here about correct alignment, I was careful.Testing with the old distributor. Mine had a white mark on the gear. It went in at the 11-oclock position. When it was lined up right it went right in. I didn't have to force it, it just slipped in. I checked for fire at the plug wire, inserting a screwdriver in the plug wire, holding it a 1/16th" away from the block, and had the wife spin it over. No fire. I think any past experience with a old fashion distributor works against me with the opti. My greatest fear is that I have bought a bad opti, and will not be able to exchange it. It is, after all, an electrical part. Due to the short days, and my work, I can only get my hands into it on the weekend. I guess I could try the old opti. It was running when I took it off. If it fires off with the old opti I deffinatly have a bad opti as it came, new in the box. Is there another way to test an opti, off of the car?
Thank you for your help!
Thank you for your help!
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
OK so your sure the opti is in right.You are not getting any spark to the plugs.Next step is the coil.The Opti is just like any other distubutor except more accurate,same principals.There is no test off the car other than taking it apart.Since you have it torn down trying the old opti might be a good thing to do.Are you sure the plug is correct?Coil wire OK? You can use a timing light on the wires to see if any of them fire.Good Luck
Last edited by Redeasysport; Nov 15, 2005 at 11:34 AM.
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by chrishoopes
IThe 1st thing I noticed about the replacement unit was the 4 pin plug. The old one had a shroud around the plug,and a key so it could only go on one way. The new one has no shroud, only the 4-pin plug.
Don't fret too much about this type of distributor. The main difference is the optical sensor inside which tells the ECM the cam position. The frontal position of the Opti allows for direct connection to cam, without the 90 degree rotational dispalcement associated with top mount distributors. Quite a novel idea, however, placing the Opti below the WP and closer to the road surface(rain splash) made for a short lived approack.....They ditched the Opti after the '96 and now employ a crank and cam sensor on C5 and C6 models...
Thread Starter
Heel & Toe
Joined: Jul 2005
Posts: 23
Likes: 0
From: Troy Alabama
Yes. This is a new A/C delco distributor. The vender has promised me a replacement. You bring up some valid points. I didn't know it was changed after '96. Didn't GM put this engine in other cars? Or was that a different distibutor. Like the Z1 pic ups, camaros, firebirds, etc. What a pisspoor design!
I'm going to try the old opti this weekend. Can I crank it up without the harmonic balance? Or is this a bad idea?
I'm going to try the old opti this weekend. Can I crank it up without the harmonic balance? Or is this a bad idea?
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Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
Don't shoot the messenger, but I was told by my very reputable mechanic that the reason a lot of optis fail prematurly is due to improper installation. I'm sure that is not the case with a lot of you, but others? You should have a 12 month guarantee on the opti if that's really the problem.
