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Opti-Spark, OBDII, Fuel and you

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Mciamp99

Guest
I had posted a while back regarding a 1996 LT-4 plaaced in a 1975 Vette. My porblem is the Fuel Injectors wont fire. Plenty of spark and Fuel Pressure. No codes on the scanner. Low Res signal was 60.21 on the scanner. It has been suggested that the Opti Spark is bad. I have heard of the Opti Spark stopping Spark, but not fuel. Is it possible that the Opti Spark is not sending some signal to the Computer that controls fuel injector flow? I have had the Computer out twice and it is believed that the computer is not the problem. Any feedback would be greatly appreciated as this does not seem like any other Opti Spark problem I have read about.
 
M

Mciamp99

Guest
Am I doing something wrong? seems there are lots of posts to other Opti Spark Problems, but very few to mine. Does the envelope with the little circle prohibit people from responding or is this just a problem noone has ever heard of. Please respond with either help or just to tell me I have posted correctly
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
You have posted correctly

But this a dangerous post.
(To give you accurate info)

It's a cross platform problem........

So I need to know how you did the wiring....

Was it a painless..or other aftermarket setup?

Is the fuel pump running.. and how is it being driven?

The PCM/CCM combo has to be talking in order to allow the fuel injection to light up
(In a factory setup)

So more detail is needed.....

So you have spark....

Does she light when you squirt gas down the intake?

How did you deal with the pass key ( if you used the stock harness).

Do you have a CCM hooked up or just the PCM?

Vig!
 
M

Mciamp99

Guest
thanks for replying

Thanks for replying, I thought I was doing something wrong. To answer some of your questions. The 1996 Engine/PCm harness was adapted to interface with the 1975 A/C, Forward Lamp and main Harness. It was done by Chris Petris in Florida. I believe it is in order.

The Fuel pump is internal to the tank and runs for 2-4 seconds when the key is turned on. It runs again after the motor starts to turn. There is a relay and I believe it is controled by the PCM.

I am just running the stock PCM which has ben reprogrammed with a Camaro VIN. The VATS is out of the programming(i have had it out twice and believe at this point it is working properly.

If I shoot fuel into the Throttle Body, The motor will fire and run until it is empty(Runs good also).

So I am only running the PCM with No VATS. Hope this information helps you when thinking about my problem. It is believed the Low Reselotion signal is not going to the Computer. The scanner had it at 60.21 with no fluctuation when engine is trying to start. Any help would be appreciated.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
So my next thoughts

1) Whats the monitored pressure @ the fuel rail.

2) Do the injectors have POWER ( check with a test light)

3) Are the injectors PULSING get on the LOW side of the injector with the test light and see if the light strobes......

I assume all your connectors are in and tight.

and NO ERRORS/ DCM's right?


Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
And if you have SPARK

The engine knows it's rotating.. So I'm thinging the Opti & the PCM are talking!


Vig!
 

vigman

Motor head!!!!
Joined
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Messages
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Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Is the CHECK engine light hooked up?

Still thinking....

Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Opti spark connections

on the side of the opti.. there is a 4 pin connector

A) BLACK /RED Low rez signal/ ECM pin 5

B) Purple/White Hi rez signal/ ECM pin C-14

C) Yellow Ignition feed ECM pin C-18


D) Black PINK System ground ECM pin C-9



This is the feed to the ECM to let it know whats happening...If this connector is missing


The fuel Injection will not know what's going on~

What do youi have in regards to a fuse panel??????


Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Ok yes Opti feed data

These two pins ( Hi & LOW rez will have a 5 volt square wave on them)

So the HIGH REZ & the LOW rez signals are what drive the ECM... if that doesnt happen

I do not think the injectors will pulse.

The pinout/colors are for a 93 which should be what YOU have.


Now I'm really curious......

Vig!
 
M

Mciamp99

Guest
More data for you

The Fuel Pressure at the head of the rails is 49 psi. There is power to the Fuel Injectors, but no pulsating with a noid light attached. If I ground one out it will let fuel into the manifold and the motor will fire for a moment. I did this with all eight so I know the Injectors are good. There is a check engine light that comes on with the key, I do not remember if it goes out during cranking, which is 165 RPM(from Scanner).

I have a stock 75 fuse panel and an additional 4 port panel from the 96 harness. It has the O2 sensors, Fuel Pump and MAF power through it. I have relays for the Fuel pump and Fans, which(Fans) will turn on with the scanner.

Most of the 96 engine harness is tied to the 75 A/C Harness. I think the Tach Relay, Amp Meter, Ignition, Power to PCM, Power when key is truned to on position, Cranking. The Water Temp Wiring is connected to the Forward lamp harness, as is the Old Brown Field wire from the Alternator.

I will have to look tomorrow as I believe the color of the wires off the Opti Spark may be different than you suggested. I think the 96 is a one year only animal. It was suggested at one time I switch to a 95 PCM and harness. Seems to me there is a green wire in there somewhere, but can not see the car until monday.

Thank for help, It is just nice to be able to bounce stuff off someone. I would have just changed the Opti-Spark, but could not convince myself that it would stop fuel flow. Guess I am finding out it can.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Opti crap....

92 part number 611-046 $489.99
93-94 661-026 $489.99
94L-96 661-027 $149.95( No typo )


So that's the Mid America version of reality!


Vig!
 
M

Mciamp99

Guest
Thank You

Thanks for the info, I hadnt even looked at Mid America as I got a price of just over 225 from a local dealership that is nice to Our Club.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
I'll bet it's a misprint in their catalog

But nail em on it
CAT 102B
PG 4-19


Vig!
 

compyelc4

Well-known member
Joined
May 1, 2002
Messages
607
Location
Dayton, Ohio
Corvette
'95 LT1 Coupe, Comp Yell; C6 Roadster, Vel Yell
I believe that very low Mid America opti price is just for 1/2 of the Opti unit. It is the white plastic distributor cap, containing the spark plug outputs. The "beef" is in the cast aluminum half I believe. Someone correct me if I am wrong.
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
So where are we at now?

Any updates? Oh and I wouldn't change the OPTI yet..until you confirm that there are NO pulses leaving the opti crap to the ECM.


Vig!
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
I guess what I am trying to figure out is....did it ever run right since you have had it?

If so, did you wash the engine, replace the water pump, etc. before it went crazy on you?

Remember that 36 Ford I was working on with the 95/96 LT1? It was actually a 96 engine and trans down graded to a 95 puter because the 96 OBDII is too complicated in comparison. This is how 99% of them are done to reduce hassles.

The opti will cause these problems. All it takes is ONE time of spilling coolant, engine cleaner, etc. on it and pooof, it is a dead instrument.

You may find like I did your water pump is bad. The one on the 36 Ford was new when I installed the engine, but I guess it sat around so much that it developed a slow drip. Not enough to notice any big deal, but enough to keep the opti moist.

Good luck!
 
M

Mciamp99

Guest
No News yet

I did get over to the car monday and Vig was right about the wire sequence off the Opti. The green I was thinking of was from the ignition coil. A friend was going to put a Tech II Scanner on it last night and I havent heard from him yet. I do believe at this point from all I have done and researched that the Opti Spark is bad and will probably change it when I come home from Carlisle Next Week.

I have followed the trials of the 69 guy since this started in June. I did not hear the motor run, but bought it from a very close friend who did hear it run. His original intent was to put it into a 32 Plymouth. To make a long story short he ended up getting a ZZ-430 and wanted to just use the 6-speed with the 430 in the street rod. When I shoot gas into the throttle body the motor runs strong and on all eight.

The more I think of it, it is possible the motor was washed, if not by my friend by the people who removed it from the original car. either that or they did not drain the coolant enough and when the motor came out antifreeze seeped into the opti spark. Too many possibilities to think of. It was suggested that I change that while the motor was out, but I figured with 8000 miles it could not possible be bad. This is out of character for me, as I have learned the short cut usually cost more $$$$ and take twice as long.

Needless to say If and when I do change it, I will do the water pump at the same time. The worst part of the whole saga is waiting for things to be done. I did the body off on this car for my wife and got this far, but could not finish the deal alone. I finally sent the car to a friend that is a GM tech because I was not sure I was checking things the right way. I hope he has some news for me tonight when I see him. I did share with him all the research and the posts from this thread and others I have been following. He did agree that when he has had to change an Opti it was because of no spark, not no fuel, but with a unique set up we must have unique problems.

Thanks for all replys, I will keep this thread up to date as I find things out.
 

69MyWay

Well-known member
Joined
Jul 3, 2001
Messages
4,364
Location
Auburndale, Florida
Corvette
1969 Killer Shark
ah, at last, this may be a simple fix!

Okay, what you have said is great news.

It has been my experience with every port fuel motor I have brought back from a long slumber, that they don't want to run (pulse the injectors right away).

I had just put a 94 LT1 in a 90 Chevy truck and had been cranking on it until I thought the starter motor would melt. Once in a while it would bark, but never enough to run. I Could get it to run on either or gas rags.

I called Street and Performance (the harness manufacturer) and spoke with Mark.

He suggested I have somebody crank the engine over, and while they do gently tap/rap on the injector housings with like a 3/4" box end wrench.

Low and behold, after a few tries she sprang to life.

I have done the same on everyone since, since everyone since has been hard to start if the motor sat more than a year.

Give it a try. It may just work!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Opti-CRAP

So I was not suggesting that the OPTI was good.

Where I was trying to steer you was to ACTUALLY CHECK if the OPTI was OUTPUTING.

Hey the OTHER test you can do... is get an LOOSE opti hook it up to the 4 pin connection point, get your NOID light turn the key on and spin the external opti by hand.... see if the NOID NOW blinks...

THE ERROR CODES MUST BE CLEARED FIRST!

That way you have the smoking gun.. shell casing.. AND the slug.

In addition.. you can safely state that after you have all that OPTI-FUN she WILL fire...

Just another WHACKY THOUGHT!

Vig!
 
M

Mciamp99

Guest
Seems to me I tried the tapping on the fuel rail thing, but have done so many little tests I cant say I did for certain.

I do understand Vig that I can check the the Opti the way you have said, I was told that If I put a drill on a loose one and crank the motor it should start if the the fuel signal is not being sent by the Mounted Opti. The one problem I have, is actually coming up with an Opti to do this checking with. (short of buying a new one). The one person I know who changed one for spark tossed the old unit. I have a Club Cruise tonight so I will ask around.
 

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