1994 Vette No injector pulse
07-22-2015, 12:12 AM
#21
Melting Slicks
Member Since: Aug 1999
Location: Baltimore, MD USA
Posts: 2,240
Likes: 0
Received 34 Likes
on
30 Posts
Here's one on e-bay for $150 shipped or make an offer. Says its from a 94 Vette with auto trans and no core is required. If doesn't fix your problem you can sell it.
If your current computer has a modified program yes Tuner cat LT1 Kit will allow you to save the program so you can re-program the replacement computer. You need a pc with a usb port and it appears the software comes on CD.
You could buy a used PCM and if that fixes the no injector pulse then buy the Tuner Cat program.
All of the error codes you posted are from your testing.
What would be interesting to see is when you say the injectors sometimes pulse a couple of times on cranking the engine, does any fuel come of the injectors?
http://www.ebay.com/itm/ECM-Engine-Control-Module-94-C4-Corvette-Automatic-/121705916530?hash=item1c563ce872&vxp=mtr
.
Last edited by Hooked on Vettes; 07-22-2015 at 12:14 AM.
07-22-2015, 12:47 AM
#22
I don't know how I missed that one on ebay. Unless it was just listed today. I have been looking for a used one or reman for weeks.
I didn't think twice about buying it. LOL
I have turned the engine over with the rail and injectors pulled from intake.
No spray but had like likely turned it over before I removed them from intake and before I got the noid test lights. Didn't discover the momentary flash on injector harness and that it would reset till recently.
I have been working on the no start issue almost daily for a couple of months now.
Hopefully the used computer that I just purchased thanks to you will fix my problem.
I have been thinking since I got my computer back from electronics shop that maybe the Vats module was bad or the Body Control Module. I hope not. Fingers crossed.
I think all the guy done was solder usual connection problems and visually check board for issues. No other test I am thinking.
Cost me 70.00 and 4 hours driving time for checking it out.
I didn't think twice about buying it. LOL
I have turned the engine over with the rail and injectors pulled from intake.
No spray but had like likely turned it over before I removed them from intake and before I got the noid test lights. Didn't discover the momentary flash on injector harness and that it would reset till recently.
I have been working on the no start issue almost daily for a couple of months now.
Hopefully the used computer that I just purchased thanks to you will fix my problem.
I have been thinking since I got my computer back from electronics shop that maybe the Vats module was bad or the Body Control Module. I hope not. Fingers crossed.
I think all the guy done was solder usual connection problems and visually check board for issues. No other test I am thinking.
Cost me 70.00 and 4 hours driving time for checking it out.
The companies who sell re-manufactured units will usually program the computer using the vin from your car. They also require a core.
Here's one on e-bay for $150 shipped or make an offer. Says its from a 94 Vette with auto trans and no core is required. If doesn't fix your problem you can sell it.
If your current computer has a modified program yes Tuner cat LT1 Kit will allow you to save the program so you can re-program the replacement computer. You need a pc with a usb port and it appears the software comes on CD.
You could buy a used PCM and if that fixes the no injector pulse then buy the Tuner Cat program.
All of the error codes you posted are from your testing.
What would be interesting to see is when you say the injectors sometimes pulse a couple of times on cranking the engine, does any fuel come of the injectors?
ECM Engine Control Module 94 C4 Corvette Automatic | eBay
.
Here's one on e-bay for $150 shipped or make an offer. Says its from a 94 Vette with auto trans and no core is required. If doesn't fix your problem you can sell it.
If your current computer has a modified program yes Tuner cat LT1 Kit will allow you to save the program so you can re-program the replacement computer. You need a pc with a usb port and it appears the software comes on CD.
You could buy a used PCM and if that fixes the no injector pulse then buy the Tuner Cat program.
All of the error codes you posted are from your testing.
What would be interesting to see is when you say the injectors sometimes pulse a couple of times on cranking the engine, does any fuel come of the injectors?
ECM Engine Control Module 94 C4 Corvette Automatic | eBay
.
07-25-2015, 02:03 AM
#23
More bad news.
Got the used computer today.
Changed the knock sensor module from my PCM to the used one I bought on ebay. Put used pcm on car
No change.
Same symptoms.
Engine will start and run about 3 seconds. With noid lights attached to one injector plug on each bank. I get pulse,engine starts and dies. Try to start again bright flash from noid light on both banks at same time then nothing.
Wait a couple of hours leaving battery connected and it will repeat the same process.
Injector pulse seems weak even when engine starts. Not near as bright of flash on noid light as when both flash at the same time after engine dies and I try to
restart. Get the bright flash from both banks only once then nothing till I leave it set for a while.
Where do I go from here. Vats module? BCM?
Do I have short or bad ground I haven't found yet?
Injector pulse test with all injectors unplugged same results.
So no shorted injectors I am thinking.
Could a bad ignition coil cause this problem?
How about the Tach or oil pressure sensor. Already tried unplugging the speed sensor. Had a dodge fail to start due to spensor wires being naked and touching together.
One other thing I have noticed is the heater/ac comes on by itself after I leave the ground battery cable disconnected over night. I have put the ground cable back on in the morning and turned on the ignition and tried to start engine. After a few min. with the ignition left on the heater/Ac turns on by itself.
Got the used computer today.
Changed the knock sensor module from my PCM to the used one I bought on ebay. Put used pcm on car
No change.
Same symptoms.
Engine will start and run about 3 seconds. With noid lights attached to one injector plug on each bank. I get pulse,engine starts and dies. Try to start again bright flash from noid light on both banks at same time then nothing.
Wait a couple of hours leaving battery connected and it will repeat the same process.
Injector pulse seems weak even when engine starts. Not near as bright of flash on noid light as when both flash at the same time after engine dies and I try to
restart. Get the bright flash from both banks only once then nothing till I leave it set for a while.
Where do I go from here. Vats module? BCM?
Do I have short or bad ground I haven't found yet?
Injector pulse test with all injectors unplugged same results.
So no shorted injectors I am thinking.
Could a bad ignition coil cause this problem?
How about the Tach or oil pressure sensor. Already tried unplugging the speed sensor. Had a dodge fail to start due to spensor wires being naked and touching together.
One other thing I have noticed is the heater/ac comes on by itself after I leave the ground battery cable disconnected over night. I have put the ground cable back on in the morning and turned on the ignition and tried to start engine. After a few min. with the ignition left on the heater/Ac turns on by itself.
I don't know how I missed that one on ebay. Unless it was just listed today. I have been looking for a used one or reman for weeks.
I didn't think twice about buying it. LOL
I have turned the engine over with the rail and injectors pulled from intake.
No spray but had like likely turned it over before I removed them from intake and before I got the noid test lights. Didn't discover the momentary flash on injector harness and that it would reset till recently.
I have been working on the no start issue almost daily for a couple of months now.
Hopefully the used computer that I just purchased thanks to you will fix my problem.
I have been thinking since I got my computer back from electronics shop that maybe the Vats module was bad or the Body Control Module. I hope not. Fingers crossed.
I think all the guy done was solder usual connection problems and visually check board for issues. No other test I am thinking.
Cost me 70.00 and 4 hours driving time for checking it out.
I didn't think twice about buying it. LOL
I have turned the engine over with the rail and injectors pulled from intake.
No spray but had like likely turned it over before I removed them from intake and before I got the noid test lights. Didn't discover the momentary flash on injector harness and that it would reset till recently.
I have been working on the no start issue almost daily for a couple of months now.
Hopefully the used computer that I just purchased thanks to you will fix my problem.
I have been thinking since I got my computer back from electronics shop that maybe the Vats module was bad or the Body Control Module. I hope not. Fingers crossed.
I think all the guy done was solder usual connection problems and visually check board for issues. No other test I am thinking.
Cost me 70.00 and 4 hours driving time for checking it out.
07-25-2015, 12:44 PM
#24
Melting Slicks
Member Since: Aug 1999
Location: Baltimore, MD USA
Posts: 2,240
Likes: 0
Received 34 Likes
on
30 Posts
From your symptoms and no codes for the BCM there is no reason to suspect the BCM as your problem.
A bad ignition coil would cause a spark problem.
A bad tach No.
When you crank the engine does the tach show rpm? If yes that indicates the ignition control/coil module is firing the coil.
Oil pressure sensor or vehicle speed sensor will not cause your problem.
.
That's normal. The HVAC Programmer is recalibrating the blend door position because the negative battery terminal was disconnected.
With a volt meter, back probe the Pink wire at the ignition coil. This is 12 volts for the coil, ignition coil module and fuel injectors. While cranking the engine verify the tachometer displays rpm and the 12 volts is always there.
To verify the 12 volt wires for the injectors are not shorted to another 12 volt source do the following. Remove fuse 22 and 23 which are for inj1 and inj2. (passenger side end of dash fuse panel).
Attach the noid lights. Crank the engine. No noid lights should light.
Really need a scope to look at the signals and scanning software to see what the PCM is seeing in real time.
Another method to verify you have spark at all times during cranking is to use an inline spark tester. This will give you a visual indication that you have consistent spark. The PCM depends on a reference signal from the Optispark or it doesn't know the engine is cranking and the PCM will not pulse the injectors.
A bad ignition coil would cause a spark problem.
When you crank the engine does the tach show rpm? If yes that indicates the ignition control/coil module is firing the coil.
Oil pressure sensor or vehicle speed sensor will not cause your problem.
.
One other thing I have noticed is the heater/ac comes on by itself after I leave the ground battery cable disconnected over night. I have put the ground cable back on in the morning and turned on the ignition and tried to start engine. After a few min. with the ignition left on the heater/Ac turns on by itself.
With a volt meter, back probe the Pink wire at the ignition coil. This is 12 volts for the coil, ignition coil module and fuel injectors. While cranking the engine verify the tachometer displays rpm and the 12 volts is always there.
To verify the 12 volt wires for the injectors are not shorted to another 12 volt source do the following. Remove fuse 22 and 23 which are for inj1 and inj2. (passenger side end of dash fuse panel).
Attach the noid lights. Crank the engine. No noid lights should light.
Really need a scope to look at the signals and scanning software to see what the PCM is seeing in real time.
Another method to verify you have spark at all times during cranking is to use an inline spark tester. This will give you a visual indication that you have consistent spark. The PCM depends on a reference signal from the Optispark or it doesn't know the engine is cranking and the PCM will not pulse the injectors.
Last edited by Hooked on Vettes; 07-25-2015 at 12:58 PM.
07-26-2015, 08:33 PM
#25
Checked coil voltage. It has 12 volts.
Pulled injector fuses no voltage or noid light flash with fuses pulled.
Tach moves up about the width of the hand with engine turning over.
I used ohm meter to check injector pulse wires to computer.
All of them ohm zero.
Checked injector pulse wires to engine for shorts. No shorts to engine.
Checked power circuit for injectors for short. No short to engine. Did find low ohm reading from positive pin on right bank injector harness to left bank injector harness positive pin with both injector voltage supply fuses pulled. 3 to 4 ohms. I thought that was unusual.
Would it be a good idea to attach wire from battery ground to ground pin on computer harness.
Would this eliminate any possibility of poor ground to computer?
I have been looking at scanners on ebay.
Item number 191379292204
Item number 221801902054
Item number 2306606671735
Would dealer do anything I haven't done?
Would their equipment find anything I can't if I buy one of the scan tools I listed?
Pulled injector fuses no voltage or noid light flash with fuses pulled.
Tach moves up about the width of the hand with engine turning over.
I used ohm meter to check injector pulse wires to computer.
All of them ohm zero.
Checked injector pulse wires to engine for shorts. No shorts to engine.
Checked power circuit for injectors for short. No short to engine. Did find low ohm reading from positive pin on right bank injector harness to left bank injector harness positive pin with both injector voltage supply fuses pulled. 3 to 4 ohms. I thought that was unusual.
Would it be a good idea to attach wire from battery ground to ground pin on computer harness.
Would this eliminate any possibility of poor ground to computer?
I have been looking at scanners on ebay.
Item number 191379292204
Item number 221801902054
Item number 2306606671735
Would dealer do anything I haven't done?
Would their equipment find anything I can't if I buy one of the scan tools I listed?
From your symptoms and no codes for the BCM there is no reason to suspect the BCM as your problem.
A bad ignition coil would cause a spark problem.
A bad tach No.
When you crank the engine does the tach show rpm? If yes that indicates the ignition control/coil module is firing the coil.
Oil pressure sensor or vehicle speed sensor will not cause your problem.
.
That's normal. The HVAC Programmer is recalibrating the blend door position because the negative battery terminal was disconnected.
With a volt meter, back probe the Pink wire at the ignition coil. This is 12 volts for the coil, ignition coil module and fuel injectors. While cranking the engine verify the tachometer displays rpm and the 12 volts is always there.
To verify the 12 volt wires for the injectors are not shorted to another 12 volt source do the following. Remove fuse 22 and 23 which are for inj1 and inj2. (passenger side end of dash fuse panel).
Attach the noid lights. Crank the engine. No noid lights should light.
Really need a scope to look at the signals and scanning software to see what the PCM is seeing in real time.
Another method to verify you have spark at all times during cranking is to use an inline spark tester. This will give you a visual indication that you have consistent spark. The PCM depends on a reference signal from the Optispark or it doesn't know the engine is cranking and the PCM will not pulse the injectors.
A bad ignition coil would cause a spark problem.
A bad tach No.
When you crank the engine does the tach show rpm? If yes that indicates the ignition control/coil module is firing the coil.
Oil pressure sensor or vehicle speed sensor will not cause your problem.
.
That's normal. The HVAC Programmer is recalibrating the blend door position because the negative battery terminal was disconnected.
With a volt meter, back probe the Pink wire at the ignition coil. This is 12 volts for the coil, ignition coil module and fuel injectors. While cranking the engine verify the tachometer displays rpm and the 12 volts is always there.
To verify the 12 volt wires for the injectors are not shorted to another 12 volt source do the following. Remove fuse 22 and 23 which are for inj1 and inj2. (passenger side end of dash fuse panel).
Attach the noid lights. Crank the engine. No noid lights should light.
Really need a scope to look at the signals and scanning software to see what the PCM is seeing in real time.
Another method to verify you have spark at all times during cranking is to use an inline spark tester. This will give you a visual indication that you have consistent spark. The PCM depends on a reference signal from the Optispark or it doesn't know the engine is cranking and the PCM will not pulse the injectors.
07-28-2015, 12:38 PM
#27
Yes all wires connected and back probed to PCM with ohm meter.
Your car has an OBD2 style connector, but it isn't an obd2 car. If VATS is on, you will see SECURITY light steady on, no flashes. Which won't even let the engine crank. Look at the injector wires for cuts/tears. Dumb question, but are the injector connector things connected?
07-28-2015, 12:39 PM
#28
07-29-2015, 01:58 AM
#29
Race Director
When you measure the fuel injector connectors you need to unplug ALL of them. They are all connected in parallel and even one plugged in will give strange results because you're seeing the resistance of that injector or whatever other injectors are plugged in.
02-21-2016, 07:18 PM
#30
At this point I will likely buy the used computer and the program you metioned.
Remans are unavailable. I have checked many places.
If I had a reman will the program you mentioned allow me to program a reman computer if I could find one?
I think my computer has been program modified. Car has many other performance additions.
Will I be able to save the programming from my computer to transfer to another?
After the last tests. I have history codes Mod. 4 H18 H34 H15. Mod.9 H64 H72 H73.
I pulled the speed sensor plug on transmission and tried starting with it unplugged. Speed sensor is wet with fluid and leaking.
I tested injector harness with noid lights with all injectors unplugged. I get about 3 seconds of injector pulse then it stops. Turn of ignition and try again one bright flash from both banks at same time then nothing.
It will reset about every 2 hours with battery connected and will repeat same results.
Remans are unavailable. I have checked many places.
If I had a reman will the program you mentioned allow me to program a reman computer if I could find one?
I think my computer has been program modified. Car has many other performance additions.
Will I be able to save the programming from my computer to transfer to another?
After the last tests. I have history codes Mod. 4 H18 H34 H15. Mod.9 H64 H72 H73.
I pulled the speed sensor plug on transmission and tried starting with it unplugged. Speed sensor is wet with fluid and leaking.
I tested injector harness with noid lights with all injectors unplugged. I get about 3 seconds of injector pulse then it stops. Turn of ignition and try again one bright flash from both banks at same time then nothing.
It will reset about every 2 hours with battery connected and will repeat same results.
Learned the hard way fuel pump cycling for a few seconds with each ignition on cycle. One bright flash on all injectors is cold start mode. Similar to pumping accelerator on carb. engine.
Repeating this cycle will flood engine.
I was trying to start my engine with water pump off. Temp sensor unplugged. I never did figure out why it would fire of for a few seconds and then die. I did discover having no water in engine, water pump off temp sensor unplugged was flooding the engine every time I tried to restart engine after it ran a few seconds and died.
The reason I was trying to start engine with water pump off was because I previously put it all together after I installed new Opti and it wouldn't start.
So tore it back down and installed second new opti.
Turned out fist new opti was ok.
I spent many days cleaning grounds, checking connectors and getting help here. Before I stumbled on to the right combination to bring her back to life.
Never did nail it down to just one issue.
I never figured out why engine would start and die I would lose injector pulse after a few attempts to restart engine. After I left it alone for a couple of hours or overnight injectors would pulse and engine would start and run about 3 seconds.
I did finally figure out repeated attempts to restart it was flooding it. Why it would die and why it would lose injector pulse is still a mystery to me.
Much later and many repeated attempts to get it started after it ran a few seconds and died. I figured out repeated attempts to start it was flooding it. I disconnected power to fuel pump turned engine over to burn off the flood it started shivered and shook and leveled out. I quickly restored power to pump. It kept running.
Last edited by drifter5674; 02-22-2016 at 12:41 AM.
02-21-2016, 07:34 PM
#31
That temp sensor controls a lot of things
02-22-2016, 12:31 AM
#33
After I got her all back together had some issue starting with engine warm.
Seemed flooded.
Turned out one leg on water pump sensor wasn't making contact. Digital temperature on dash was also not working.
Computer was keeping it in cold start mode.
So the pump cycled every time I turned the ignition on and all eight injectors got full pulse.
Flooding a warm engine.
Man what a learning experience this has been.
Hope to get the hesitation and coughing issue resolved soon.
It has to be in fuel delivery or fuel pressure.
Seemed flooded.
Turned out one leg on water pump sensor wasn't making contact. Digital temperature on dash was also not working.
Computer was keeping it in cold start mode.
So the pump cycled every time I turned the ignition on and all eight injectors got full pulse.
Flooding a warm engine.
Man what a learning experience this has been.
Hope to get the hesitation and coughing issue resolved soon.
It has to be in fuel delivery or fuel pressure.
03-08-2016, 10:53 AM
#34
Burning Brakes
your initial problem was likely more to do with not getting either the oil pressure signal or the opti-spark pulse. as long as those two are present, the injector drivers will be energized for 4ms periods until the engine catches. your not getting that should have pointed you to the start sequence in the service manual and saved a lot of headaches...you are right about the CTS and for closed loop, and I am having the opposite problem as you, mine will run and start great when hot, but when cold it pops and coughs until it gets to closed loop...wish I would have seen your thread last year and I would have posted the start sequence step-by-step for you to check...if you are still having temp display issues, there is another temp sensor in the head that drives the display, the one on the pump is strictly for the ECM...
glad you got it running though and good luck!
glad you got it running though and good luck!