1996 muiliple distributor falures

[eddie 96]

I have a 1996 Corvette, with opti-spark. It has 7100 miles on it, and I have replaced the opti-spark 7 times in the last 8 months, or so. I always replace the oil seal, and the water pump does not leak. I have changed the ingnition module 3 times, and I had the car in an electrical shop to check for: tray AC voltage from the distributor, possible bad grounds, PCM, and they said that the car checked out fine, and to try a MSD distributor instead of an OEM Distributor. I installed the MSD, and it worked as a little solver for about one month. Now I am back to where I start, when a snap on scanner is hooked up to the car, it points to distributor failure. I have looked at the wire harness, and the car has never been butchered up. I got it with 42,000 miles on it, from the original owner.
If anyone can help, it would be greatly appreiciated, and I mean some one who really knows. I have been changing parts from the fuel pump to the ingnition switch, I have gotten suggestions from folks who were trying to help but really didn't know. I of course do apprieciate suggestions but if some knows anyone who has had this particular problem please help!
Thank You,
Eddie O

 

[TWISTERUP]

If i don't ask someone else will--what codes are you getting? The opti harness itself may have a intermitent problem at either end making it appear that the opti is bad. Does it develop a no start problem and that's when you get the codes?

 

[eddie 96]

If i don't ask someone else will--what codes are you getting? The opti harness itself may have a intermitent problem at either end making it appear that the opti is bad. Does it develop a no start problem and that's when you get the codes?

i hope i am doing this reply correct im new to the site ,any way the code i get at first is a po372,then as is gets worse i will get a i think po134 a manufactuer controled ingnition device ,also if the car stalls out while running it will set a map code.now after i take out either 1 through 7 distributors and replace them all of the codes clear the car runs perfect ,i had at one point changed the harness from the oem opti spark to the plug at the intake under the plastic cover no difference the msd comes with a new harness that does away with the oem harness all together ,i had one wrok for two weeks ,one ran for a month, one ran for almost 3 months then it seemed like between two weeks and a month for the rest when the car runs it runs perfect no stumbling no hesitation and all codes will clear if i change this new msd but for how long i have no clue i have had the car at two different auto electric speacialist who say its the distributor ,it did run for two years with no problem i am at a completet loss i changed the module 3 times ,changed the ingnition switch triple checked battery terminals ,put in a new fuel pump , right now the car will start if i put my foot on the gass slightly and it sets the po372 code.

 

[eddie 96]

i hope i am doing this reply correct im new to the site ,any way the code i get at first is a po372,then as is gets worse i will get a i think po134 a manufactuer controled ingnition device ,also if the car stalls out while running it will set a map code.now after i take out either 1 through 7 distributors and replace them all of the codes clear the car runs perfect ,i had at one point changed the harness from the oem opti spark to the plug at the intake under the plastic cover no difference the msd comes with a new harness that does away with the oem harness all together ,i had one wrok for two weeks ,one ran for a month, one ran for almost 3 months then it seemed like between two weeks and a month for the rest when the car runs it runs perfect no stumbling no hesitation and all codes will clear if i change this new msd but for how long i have no clue i have had the car at two different auto electric speacialist who say its the distributor ,it did run for two years with no problem i am at a completet loss i changed the module 3 times ,changed the ingnition switch triple checked battery terminals ,put in a new fuel pump , right now the car will start if i put my foot on the gass slightly and it sets the po372 code.

oh one thing i have noticed the car does kind of miss at idle right before it sets the first po372 code in other words if i am at a light i feel a slight miss i know that soon it will code and need to be replaced agin there is a positive i can remove an opti spark from a 96 corvette in 15 mins ...........

 

[gmjunkie]

First thing I'd do is clean and inspect All the grounds and replace the Bank 1 upstream O2 Sensor!

 

[eddie 96]

First thing I'd do is clean and inspect All the grounds and replace the Bank 1 upstream O2 Sensor!

i change the 02 sensor a week before the car died again for the 7th time it set a the code bad o2 sensor on bank one its changed and all the grounds have been checked .

 

[eddie 96]

i change the 02 sensor a week before the car died again for the 7th time it set a the code bad o2 sensor on bank one its changed and all the grounds have been checked .

this is what has been checked
1 all plugs to every sensor to insure they are clean and have resitance pulling them off a test probe.
2 new ignition switch in case there was an intermitten loose connection in the switch
.3 battery terminals and a new battery.
4.alteranator for stry ac voltage .
5.pcm ws checked at an automotive elctrical shop.
6.harness to distributor has been chaged 2 times a new one installed when still trying to get the oem to work and the msd has a new harness with it.
7 new o2 sensor bank one up stream of cat after it poped its code it reset and the car ran great after it was changed.
8ingnition module changed 3 times .
9 new crank sensor
10 new fuel pump
11 7 distributors ,one was after market then i went to oem ac delco then i went to an msd,in almost a year they all seem to have a problem with optical sensor it gets 5 volts going in but not out .oil seals for distributors changed every time .new gaskets for water pump and checked for leaks every time.
has anyone even heard of anyone having this exact problem?

 

[TWISTERUP]

I've been looking at the wiring diagrams--both high and low resolution opti signals go from opti to connector at right valve cover--then directly to the PCM w/no connectors/splices etc. As "Junk" said-- check the grounds--one ground point which the ICM and PCM have in common is at one of the left side lower bell housing bolts. Even if the bolt is tight and appears ok, I'd take the bolt loose-clean all the contact areas and retighten. If I have doubts I have used star washers on bolts/screws which are ground points before because they dig in and contact some "fresh meat"--so to speak. I think that's where I'd start at this point anyway.

 

[gmjunkie]

I've been through this crap seems like just in the last 3 weeks!!!
Fact the car is still here,But it runs great now!!

This one had been checked out by not 1,but 2 Chevrolet dealers!!

How many grounds was checked under Hood,Engine and Chassis?
I'd bet it was only the 3 easy ones if at All!!
Bad grounds make electronically controlled engines "Do Weird SH*T"!!!
But I still think the Oxy sensor is faulty too!

 

[gmjunkie]

As "Junk" said-- check the grounds--one ground point which the ICM and PCM have in common is at one of the left side lower bell housing bolts. Even if the bolt is tight and appears ok, I'd take the bolt loose-clean all the contact areas and retighten.

Oh hell yes,That is the suckyest on the whole car!!:L I take the stud out and clean it good too!! It's nothing that a 3 ft extension,wobble socket and a piece of coat hanger can't fix!!This last one I had the exhaust off of it so it wasn't too terrible!!Theres a grounding point above the cat on the side of the block right above the oil filter and 2 behind the battery,Kinda sucks to clean too!

 

[eddie 96]

how many grounds do you know of besides the one you mentioned the auto electric shop said they checked all of the grounds he had showed me the drawings but i dont remeber the locations of all of them the 02 sensor throws the o2 sensor code when it goes out i just changed it a week or so ago it poped an 02 sensor bank one sensor 1 and a couple of other codes they all cleared when i changed the sensor this code is a distruibutor code .

 

[eddie 96]

how many grounds do you know of besides the one you mentioned the auto electric shop said they checked all of the grounds he had showed me the drawings but i dont remeber the locations of all of them the 02 sensor throws the o2 sensor code when it goes out i just changed it a week or so ago it poped an 02 sensor bank one sensor 1 and a couple of other codes they all cleared when i changed the sensor this code is a distruibutor code .

ill take a look at them what just kina has me wondering is every time i change the distributor the car will clear all of the codes and run why does it run if the grounds were bad? it ran once for almost three months then it craped out again ? i mean if it is a bad ground why would changing the distributor get it running again?i like the pics of the grounds i will check them all agian

 

[eddie 96]

I've been looking at the wiring diagrams--both high and low resolution opti signals go from opti to connector at right valve cover--then directly to the PCM w/no connectors/splices etc. As "Junk" said-- check the grounds--one ground point which the ICM and PCM have in common is at one of the left side lower bell housing bolts. Even if the bolt is tight and appears ok, I'd take the bolt loose-clean all the contact areas and retighten. If I have doubts I have used star washers on bolts/screws which are ground points before because they dig in and contact some "fresh meat"--so to speak. I think that's where I'd start at this point anyway.

i will check theses grounds again my self although they have been checked i was told what gets me is why would every time the distributor go out and the car not run why will it run agin perfect if it had a bad ground and wouldnt it be more of a consistant problem? i truly dont know thats why im asking i am ready to have this one crushed.i may just trade it for an old sting ray never had any of this grief with my 71 or my 75

 

[TWISTERUP]

i will check theses grounds again my self although they have been checked i was told what gets me is why would every time the distributor go out and the car not run why will it run agin perfect if it had a bad ground and wouldnt it be more of a consistant problem? i truly dont know thats why im asking i am ready to have this one crushed.i may just trade it for an old sting ray never had any of this grief with my 71 or my 75

IMO a dirty/slighty corroded ground MAY be damaging the opti decoder over time. The sensors which the PCM looks at use a 5 volt reference signal(from reading your posts you already know this) so it is critical that any sensor or PCM grounds be perfect. A completely open ground in the right system on the car could/would cause a consistent problem such as no start. Since your optis are failing over time-- I'm guessing you have some sort of a ground but not a good one.

The later C4s are rolling computers w/many ground points (having your own FSM is very important)and the wiring diagrams and diagnostics can be "priceless". Couple of side note statements/questions---the crank sensor on your car has nothing to do w/ignition-- it is there solely for OBD2 missfire detection. Has anyone disasembled any of the failed optis to check internal damage? My most recent opti on my '96 failed because the rotor screws worked loose and the trigger wheel chewed up the optical decoder (the rotor screws need loctite)--- I'm getting way off track here--once again your repeated opti failures sound like a poor ground problem and that's where I'd start.

 

[gmjunkie]

how many grounds do you know of besides the one you mentioned the auto electric shop said they checked all of the grounds he had showed me the drawings but i dont remeber the locations of all of them the 02 sensor throws the o2 sensor code when it goes out i just changed it a week or so ago it poped an 02 sensor bank one sensor 1 and a couple of other codes they all cleared when i changed the sensor this code is a distruibutor code .

There are 9 grounding points from the cowl forward with with about 17 (Depending) wire ends on a 94 LT1 6 sp and 96 LT4 6 sp,automatic cars may have a couple more! 2 on frame rails at very front(1 wire each),1 on rail at front cross-member left side top(2-3 wires),1 on front of engine block around Coil and Ignition Module(1 wire),On top of right rail just behind the cowl brace below AC Unit(1 wire),2 behind the battery on rail under the power Brake Booster(1 wire each) 1 on Engine Block just above Oil Filter(3-5),and 1,2 nd bolt up on left side of bell housing!!(3-5) Some older L98 cars have them on both sides of bell housing!!

ill take a look at them what just kina has me wondering is every time i change the distributor the car will clear all of the codes and run why does it run if the grounds were bad? it ran once for almost three months then it craped out again ? i mean if it is a bad ground why would changing the distributor get it running again?i like the pics of the grounds i will check them all agian

There are 3 kinds of grounds Intermittent,High Resistance, and Good!!Each will make things act differently!! As I said,Bad Grounds make Electronics do weird SH*T!!:L:L:L

i will check theses grounds again my self although they have been checked i was told what gets me is why would every time the distributor go out and the car not run why will it run agin perfect if it had a bad ground and wouldnt it be more of a consistant problem? i truly dont know thats why im asking i am ready to have this one crushed.i may just trade it for an old sting ray never had any of this grief with my 71 or my 75

Oops,Now you've ticked me Off!!:eyerole:eyerole:eyerole
Life's too short for Negative BS,Your on your own now!!
Anybody that has put on 7 new Opti-Sparks in 8 months and hasn't figured out that something else has to be the problem, Must be a Rocket Scientist and don't need my help!!
Thats 3 more than I've replaced since they came out in 92,with 100,000's miles and 100's of customers cars!!

Perhaps a Mustang is more your speed,But they have Grounding Issues too, Good Luck and Good Day!

 

[eddie 96]

There are 9 grounding points from the cowl forward with with about 17 (Depending) wire ends on a 94 LT1 6 sp and 96 LT4 6 sp,automatic cars may have a couple more! 2 on frame rails at very front(1 wire each),1 on rail at front cross-member left side top(2-3 wires),1 on front of engine block around Coil and Ignition Module(1 wire),On top of right rail just behind the cowl brace below AC Unit(1 wire),2 behind the battery on rail under the power Brake Booster(1 wire each) 1 on Engine Block just above Oil Filter(3-5),and 1,2 nd bolt up on left side of bell housing!!(3-5) Some older L98 cars have them on both sides of bell housing!!
There are 3 kinds of grounds Intermittent,High Resistance, and Good!!Each will make things act differently!! As I said,Bad Grounds make Electronics do weird SH*T!!:L:L:L





Oops,Now you've ticked me Off!!:eyerole:eyerole:eyerole
Life's too short for Negative BS,Your on your own now!!
Anybody that has put on 7 new Opti-Sparks in 8 months and hasn't figured out that something else has to be the problem, Must be a Rocket Scientist and don't need my help!!
Thats 3 more than I've replaced since they came out in 92,with 100,000's miles and 100's of customers cars!!

Perhaps a Mustang is more your speed,But they have Grounding Issues too, Good Luck and Good Day!

thanks for your help i did RECHECK THE GROUNDS AND THEY ARE ALL GOOD!!!!!I RECHECKED THE O2 SENSOR ITS GOOD!!! I DIDNT JUST CHANGE DISTRIBUTORS 7 TIMES WITH OUT CHECKING INTO OTHER POSSABLE PROBLEMS ! in fact as i told you i had many suggestions of things to check and change all have lead me to a dead end including the rechecking the grounds and rechecking the os sensor i replaced recently .thanks for the location of the grounds but this hasnt fixed the problem ill wait maybe grumpy has something to say .my wife has had a couple of mustangs there no better with all of this jap obd II crap detroit instisted on putting on our american cars .