Help.... 94 dies
Thread Starter
8th Gear
Joined: Dec 2012
Posts: 8
Likes: 0
Help.... 94 dies
I have a 94 automatic with105k that just started dying occasionally. I have owned it for a year and never had an issue until a week ago driving home it died after letting of the accelerator. Would not restart just run for a second and die. Finally started after an hour and made the thirty mile trip home with out a problem. Following day died suddenly while idling and immediately restarted. On way home hit the gas hard from 20-70mph and car died again when letting off gas but immediately restarted. Today I hooked a fuel pressure gauge to it and have 39psi at idle when on the road pressure ranges from 36 to 41psi and at 2800 rpm over a half mile it stayed at 36psi. Managed to get it to die once after another 20-75mph hard acceleration it died when letting off gas and would not restart even though gauge showed 42psi. Two minutes later tried again and it started and read 39psi on the short drive home.
Last edited by Zipcity; Dec 18, 2012 at 11:41 AM.
Drifting
Joined: May 2005
Posts: 1,336
Likes: 12
From: Chicago Executive Airport, formerly known as Palwaukee
No-IL Events Coordinator
St. Jude Donor '12-'13-'14-'15-'16-'17
Is your MIL (Malfunction Indicator Lamp) illuminating? This is also called a Service Engine Soon light.
If so, you will need to pull the trouble codes. If not, there are other things which can be causing your issue.
If so, you will need to pull the trouble codes. If not, there are other things which can be causing your issue.
Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Get a spark tester. Carry it with you. When the car dies but will not refire. Pull a plug wire or coil wire and see if you have spark or not.
I think we can rule out fuel, air, and compression at this point.
Timing and ignition are next. Considering its a LT1 that is where I would focus.
I think we can rule out fuel, air, and compression at this point.
Timing and ignition are next. Considering its a LT1 that is where I would focus.
Thread Starter
8th Gear
Joined: Dec 2012
Posts: 8
Likes: 0
Ok finally had a chance to test for spark. Took car out for quick drive and it died about a mile into it coming to a stop. Immediately restarted went 300ft died again and tested for spark. No spark present and let car sit for 10 minutes and then it fired right up and died again under load at 2700rpm a mile down the road and no spark again when turning motor over. Waited a good 10 minutes and started up immediately. I'm using an inline tester that hooks between the plug and wire. What is the next step in hunting this problem down?
Drifting
Joined: Oct 2004
Posts: 1,477
Likes: 80
From: Hawaii
Follow the ignition system check on the autozone site.
http://www.autozone.com/autozone/rep...00c1528008fa13
Other helpfull infos.
http://tech.corvettecentral.com/2011...trouble-codes/
http://shbox.com/1/4th_gen_tech2.html#opti_test
http://www.autozone.com/autozone/rep...00c1528008fa13
Other helpfull infos.
http://tech.corvettecentral.com/2011...trouble-codes/
http://shbox.com/1/4th_gen_tech2.html#opti_test
Last edited by James93LT1; Dec 27, 2012 at 04:32 PM.
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Safety Car
Joined: Sep 2010
Posts: 3,752
Likes: 190
From: Indiana PA
Ok finally had a chance to test for spark. Took car out for quick drive and it died about a mile into it coming to a stop. Immediately restarted went 300ft died again and tested for spark. No spark present and let car sit for 10 minutes and then it fired right up and died again under load at 2700rpm a mile down the road and no spark again when turning motor over. Waited a good 10 minutes and started up immediately. I'm using an inline tester that hooks between the plug and wire. What is the next step in hunting this problem down?
Burning Brakes
Joined: Mar 2004
Posts: 1,108
Likes: 4
From: Plano Texas
Zipcity, I'm going to throw in my $0.02 worth and venture an educated guess that the problem is with the throttle body or TPI sensor. The original throttle bodies have a reputation for wear on the throttle shafts that allow air to bypass the MAF causing a lean condition. This additional wear will not let the throttle seat properly possibly shutting off the intake air enough to shut down the engine. A defective Throttle Position Sensor may give the same problems if it isn't set correctly. 94 Corvette TPI's were self setting, however, if the throttle shafts are worn or there is excessive build up of dirt or gunk on the throttle blade it won't set correctly. The throttle body has a tube on it that pulls internal gases from the engine and recycles them into the engine. The plastic tube is on the passenger side just above the valve cover. A lot of oil residue and crap comes thru that tube and can screw up a throttle body pretty quick if not cleaned. I doubt it is ignition if you drove it 30 miles OK. Usually ignitions just quit.
Good luck.
Mark
Good luck.
Mark
Thread Starter
8th Gear
Joined: Dec 2012
Posts: 8
Likes: 0
Had a little while to test a few things this evening. Checked for codes and C12 is the only code that comes up. Car is now dying instantly within a minute of firing up. There is also no spark from coil until car finally fires up after 5-20 minutes of waiting. Forgot to mention that the opti was replaced with a delphi and waterpump was also changed at the same time right before I purchased car. Noticed that coil and ICM are covered in 100k of grunge not sure if that could of cooked the ICM.
Drifting
Joined: May 2005
Posts: 1,336
Likes: 12
From: Chicago Executive Airport, formerly known as Palwaukee
No-IL Events Coordinator
St. Jude Donor '12-'13-'14-'15-'16-'17
ICM is very much affected by heat. Being covered in grease/dirt probably does not help.
There are many things which will cause problems and not throw a code.
Any type of wiring or connection issue will make the most seasoned technician pull his hair out.
There are many things which will cause problems and not throw a code.
Any type of wiring or connection issue will make the most seasoned technician pull his hair out.
Thread Starter
8th Gear
Joined: Dec 2012
Posts: 8
Likes: 0
Update... Decided to have the ignition control module tested at Advance Auto Parts. Failed on 1st test at two stores. Purchased a Borg Warner ICM from another store and applied the thermal compound etc. Fired up and then died instantly again after idling for a few minutes. Car restarted again after 10 mins and then died again. Planning to take this new ICM to be tested tomorrow. Can something be burning them out that I can look for if this one tests bad also.
Safety Car
Joined: Oct 2000
Posts: 4,236
Likes: 355
From: Albuquerque, NM
These problems can be aggravating. One key question is does it do it when it's hot and cold or just when hot? Things like the coil, ICM, and ECM are affected by heat. Sounds like you replaced the ICM and that's not the problem. If it's not setting codes it can be pretty hard to figure out.
I'd start by checking all the wiring and connections in the ignition system, especially the optispark harness. Make sure ignition wires are in good condition and seated properly. You may be able to have the coil tested at the parts stores. I have an Auto-X-Ray scan tool that will show values for all the sensors as the car is running. Something like that may be helpful to rule out the coolant temperature sensor, MAF sensor, TPS, etc. Other than those sensors, the problem could be a bad coil, bad ECM, or even a bad optispark although if it's not setting codes it's probably not the optispark. Good luck!
I'd start by checking all the wiring and connections in the ignition system, especially the optispark harness. Make sure ignition wires are in good condition and seated properly. You may be able to have the coil tested at the parts stores. I have an Auto-X-Ray scan tool that will show values for all the sensors as the car is running. Something like that may be helpful to rule out the coolant temperature sensor, MAF sensor, TPS, etc. Other than those sensors, the problem could be a bad coil, bad ECM, or even a bad optispark although if it's not setting codes it's probably not the optispark. Good luck!
