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94 LT1 no spark

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Bradleywrench13

Guest
Hey,
I know I have a C5, my brother has a 94 LT1 that has no spark. The computer is new, the distributor has been replaced 2X, the coil has been replaced 3X, and the ignition control module has been replaced. The TPS tested bad and we replaced it today. The engine is getting fuel, but no spark. also the ALDL is not working when you try to go into Diagnostic mode. there is a whirring sound from the cowl area, but the "SERVICE ENGINE SOON" light goes out and doesn't come back on. Any help is greatly appreciated. I am only in Michigan with hm for a few more days. Thanks again Guys and God Bless
Steve
 

jmccloud

Well-known member
Joined
Feb 1, 2003
Messages
694
Location
Maryland
Corvette
1995 White Coupe LT-1 Auto
No Spark - from left field

We are related by C4's and your symptoms, so second cousins perhaps, no spark and no "Service Engine Light" when reading codes.
I had a 91 Regal with your symptoms - especially the "Service Engine Light" not being on when the ALDL was connected for reading codes (if I read your description correctly).
Chased the problem for weeks (the car would often run but was undependable). Eventually bought a service manual on ebay.
The manual for that 91 Regal said that the absence of the "SEL" light meant that the ECM ground was bad or the ECM itself was shot. It's ground was under the coil pack and the ECM was behind the left wheel well. After cleaning and confirming the ground I bought a rebuilt ECM and the problem was solved. Yes this is a very different auto but could be the same cause. Do you have a 94 Corvette service manual that you could check this out?
Before laying out the money for an ECM, confirm its ground and also check whether there's high voltage coming out of the coil and whether there's 12v going into the primary. Many would quickly condemn the Opti-spark but if there's no signals to it, look upstream.
Hope this helps.
 
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Bradleywrench13

Guest
i thought of that already but thanks, it is a new ecm and its been flashed properly, i sprayed sarter fluid into the throttle body and still nothing so its got to be a spark situation .. its driving me insane not to knowwhat is causing it.. new ecm, new distibutor (from auto zone and i have exchanged it 2 times just to be sure) new coil, new msd wires, new plugs, new ign. control module still nothing. i re-replced the coil with a known good msd coil ( came out of my buddys 94 lt1and his runs ! ! still nothing this car hasnt run in 2 years because of this.. it was running when my brother took it off the road to change the oil pan gasket and while the that was being done he decided to put a new water pump, new distributor, cap and rotor, wires and plugs in it when he got it all back together it wouldnt start.the time period it was down was 2 weeks thats when the no spark situation started now its been 2 years and still nothing again any help would be greatly apprceiated . thanks again
steven
 

jmccloud

Well-known member
Joined
Feb 1, 2003
Messages
694
Location
Maryland
Corvette
1995 White Coupe LT-1 Auto
No spark

Just to be sure of 'no spark', have you removed one plug wire and secured it to a spare plug that's laying on the plenum or other good ground, cranked the engine and observed no spark in the gap??
There's a thread on a 'competing' forum that says it's possible to get the opti connected 15 degrees out of 180 degrees error and the engine won't start. It's really far fetched but could explain why the car won't start even if you DO see spark in the above test.
Gosh, what a pain!
Good luck.
 
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Bradleywrench13

Guest
thanks again. yes it is a true no spark condition . i tried the # 1 spark plug to the manifold, then i tried the # 4 spark plug , then ,just for gigles i tried the #5 and no spark on any of them i also tried a spark tester on the #1 and #4 still no spark. im starting to lean twords the ground on the ecm . or could auto zone just have a bad run on the opti 1 . both of the opti's i got was from auto zone??? give me a non-computer controlled car any day over this madness!!! thanks for the fast reply jmccloud. im going to get a tech scan tool tomorrow to see if it will give me any codes if not ill just have to start tracing the problem but again any thoughts or ideas are always greatly appreiciated thanks again
steven
 

BLACKTALON

Well-known member
Joined
Sep 12, 2005
Messages
130
Location
N.C Greensboro
Corvette
1994 ADMARIAL BLUE Z-51 COUPE
Mabe a shot in the dark, but the opti needs to be degreed.Like mention before you can be off by a couple degrees.And just wondered why you would buy a opti fom auto zone?;shrug
 

onefast95vette

Well-known member
Joined
Oct 23, 2003
Messages
48
Location
Jacksonville, FL
Corvette
White 1995, 383, 671 RWHP, NOS, all the goodies.
jmccloud,
I have a very similar problem and I really hope you can help me. I also have a '95 LT-1 (modified) and it's been a royal pain in the last year and 1/2 since I brought it back from Hawaii. It doesn't have any emissions control, my mech pulled all that out when I started racing it in 2002. When I got it back here to Florida, it ran great, then after a few days of heavy rain it spent 4 months in the driveway, dying as soon as it got to 190 deg., then just coughed and sputtered until it cooled down. I took it to a performance shop that did some work to it and it still died on the way home (at 190 deg.). Two months later, I fired it up and it ran like a scalded dog. We just had another three day blast of rain and now it won't even start. I've been told it's the "opti-crap" that's doing it. What do you think?

Dan
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
The engine is getting fuel, but no spark. also the ALDL is not working when you try to go into Diagnostic mode. there is a whirring sound from the cowl area, but the "SERVICE ENGINE SOON" light goes out and doesn't come back on.

Can you pull codes by using the CCM?
The diag. connector looks like this.

[01|02|03|04|05|06|07|08]
[09|10|11|12|13|14|15|16]

Connect a jump wire from pin 12 to either pin 4 or 5 which are both ground.
Turn the ignition key to run (don't start the car).
Look at the dash speedometer display.

It will display the different modules and any codes.

Module 1 is CCM
Module 4 is PCM
Module 9 is ABS/TCS
Module A is Air bag
 

BLACKTALON

Well-known member
Joined
Sep 12, 2005
Messages
130
Location
N.C Greensboro
Corvette
1994 ADMARIAL BLUE Z-51 COUPE
jmccloud,
I have a very similar problem and I really hope you can help me. I also have a '95 LT-1 (modified) and it's been a royal pain in the last year and 1/2 since I brought it back from Hawaii. It doesn't have any emissions control, my mech pulled all that out when I started racing it in 2002. When I got it back here to Florida, it ran great, then after a few days of heavy rain it spent 4 months in the driveway, dying as soon as it got to 190 deg., then just coughed and sputtered until it cooled down. I took it to a performance shop that did some work to it and it still died on the way home (at 190 deg.). Two months later, I fired it up and it ran like a scalded dog. We just had another three day blast of rain and now it won't even start. I've been told it's the "opti-crap" that's doing it. What do you think?

Dan

Yours sounds like the opti. what are your mods.I see a 383, but what else?To get 671 at the wheels.
 
B

Bradleywrench13

Guest
same question i asked... anyways hes not rich and at auto zone he paid 120 for a reman opti with a life time warranty.. we are going to get a real opti but i want to help him get the car running first.. even if the opti was out a few degrees it would still get spark... THERE IS NO SPARK . not saying car would start but at some point there would still be spark, just not at the right time.. am i correct in thinking this? ? all help and suggestions are welcome thanks again guys
 
B

Bradleywrench13

Guest
we tried its an obd 1 and only has 12 pins but when you try to jump it thyere is a whirring noise at the front cowl area and the ses light goes out and does nothing. thanks again
Can you pull codes by using the CCM?
The diag. connector looks like this.

[01|02|03|04|05|06|07|08]
[09|10|11|12|13|14|15|16]

Connect a jump wire from pin 12 to either pin 4 or 5 which are both ground.
Turn the ignition key to run (don't start the car).
Look at the dash speedometer display.

It will display the different modules and any codes.

Module 1 is CCM
Module 4 is PCM
Module 9 is ABS/TCS
Module A is Air bag
 

BLACKTALON

Well-known member
Joined
Sep 12, 2005
Messages
130
Location
N.C Greensboro
Corvette
1994 ADMARIAL BLUE Z-51 COUPE
Gonna sound dumb, but after replacing all that stuff did ya put new plugs in?;shrug and are they gaped to the recamended spec.I think .050
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
we tried its an obd 1 and only has 12 pins but when you try to jump it thyere is a whirring noise at the front cowl area and the ses light goes out and does nothing. thanks again
You sure it's a 94? 94 and 95 had 16 pin diag. connectors but were not fully OBDII compliant. 93 still used the 12 pin connector.

If you can't pull codes from the CCM you need to check all of the fuses.
 

ecss

Well-known member
Joined
Nov 27, 2004
Messages
649
Location
Windsor Mill, MD
Corvette
89 Brilliant Red Metallic
On a 12 pin connector

[F|E|D|C|B|A]
[G|H|J|K|L|M]

Short A to B to flash PCM DTC's on Service Engine Soon light.
Short A to G to see DTC's displayed on the Speedometer display.
 

jmccloud

Well-known member
Joined
Feb 1, 2003
Messages
694
Location
Maryland
Corvette
1995 White Coupe LT-1 Auto
94 lt1 no spark

Bradleywrench,
I dug around in the service manual for my '95 (there are differences from your '94 and I don't know what they are) and found that there are 3 or 4 ccm fuses. Some are in the dash fuse panel (on the passenger side facing the door) and another one is in the 'under hood fuse panel'. I'm not sure where this under hood fuse panel is. Somewhere in the book it says but I couldn't locate it. Some of the fuses inhibit the ability to read codes (if blown) and some inhibit the 'mil' or malfuncion indicator lamp (this sounds like the service engine soon light but I couldn't find that in the manual either). Some of the fuses also feed the PCM (power control module) and will kill spark when blown.
Anyway, find those CCM fuses and make sure they're good.
After that, the manual says to trouble shoot the connections between the coil, ground and 5volt supply leading to the ICM=ignition control module (located just to the rear of the coil). The fourth of four leads (D) to the ICM is really suspicious as it leads to the PCM and it's break will kill spark. You really do need some schematics and the trouble shooting tree for a '94. Since you've already replaced many of the components, look carefully at the connectors and the continuity of their attached leads.
'Onefast95vette' may have heat related breakdown of these same ICM connections, the ICM itself or the coil. ICMs and Coils are perhaps more likely to heat destruct than the opti and a lot cheaper and easier to fix. You might want to start another thread while monitoring this one.
Please post the solutions when you find them.
Good luck.
 
B

Bradleywrench13

Guest
jmccloud! you r a life saver.. ok played around with this p.o.s all day yester day and this is what i found.1st .DONT EVER (and i mean ever) buy electrical things such as an opti from auto zone !!!!!!!!!! 2nd. i put everything back together and still no spark(at this point i was about to pull my hair out and throw myself on the ground and start pounding my fists into it!!) so i started tracing the wires on the ign. cont. mod and at port a and d i had 12.27 volts so i knew i was getting power into the module, then i probed port b and found that there was a complete ground from the ecm then i took the c port and probed it while i had my brother turn the engine over and the manual says i should of had between 1 and 4 volts ( it is the pulse that ecm sends to the igntion control mod to fire the coil ).. at this point i was getting very confused because sure enough it had the pulse at the first crank it went to 4.0 then went to a 2.7 and stayed there as he cranked it over. then the manual says to pull the coil wire and ground it to the block then take an led type test light and while cranking the engine over probe the white with black stripe and you should see the pulse from the distributor..NOTHING!!!!!! imagine that!!!! so at this point distributor is not sending the pulse to the coil to fire it... Damned ole auto zone.. going to go tuesday to try to get his money back and go get a (now dont be suprised) GENUINE GM OPTI-SPARK and an IGNITION CONTROL MODULE from the dealership .. you guys have been great and i gave my brother this website to help him out in the future .. i pray that this is the only problem with it but if its not youll be seein me or him again.. thanks again for all your suggestions and helpful insight..
thanks for everything and godbless
steve
 

MIKEM3401

Member
Joined
Dec 28, 2006
Messages
13
Location
Simi Valley
Corvette
1995 white coupe
jmccloud,
I have a very similar problem and I really hope you can help me. I also have a '95 LT-1 (modified) and it's been a royal pain in the last year and 1/2 since I brought it back from Hawaii. It doesn't have any emissions control, my mech pulled all that out when I started racing it in 2002. When I got it back here to Florida, it ran great, then after a few days of heavy rain it spent 4 months in the driveway, dying as soon as it got to 190 deg., then just coughed and sputtered until it cooled down. I took it to a performance shop that did some work to it and it still died on the way home (at 190 deg.). Two months later, I fired it up and it ran like a scalded dog. We just had another three day blast of rain and now it won't even start. I've been told it's the "opti-crap" that's doing it. What do you think?

Dan
Onefast95vette; I too have similiar problem, however my sputtering does not always begin when temp hits 190, it appears more random. but does start clean and goes downhill from there.
Wierd, but when the check engine light comes on it appears to clear up, until it subsequently goes off again.
dealer ran diagnostics and stated error code P0016 comes up, and that it represented the opti spark distributer.
i suspect I'll replace the distributer and waterpump and go from there.
I will keep posting on my efforts.

Regards,

Mikem3401
 

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