1994 stalls, no codes and restarts no problem
07-10-2015, 04:07 PM
#21
Le Mans Master
Thread Starter
Update for what it is worth.
Hooked up the fuel pressure gauge. Prime....40 psi. Idle....40 psi. Running on the road....drops to about 36 and up to 40. But never below 36. Ran the car for about 1.3++ hours and that sucker NEVER DIED!!
And for you that tell me to slap the computer....after driving it that long and no failure.....slapped the computer 4 times and nothing....still ran well.
There were times when stopped at a stop light or sign it would run a little rough....but not really noticeable.....not something you would point out to a mechanic or point out to anyone....because if you didn't drive it all the time you would never notice it.
By the way, it is not my car so the owner was driving. So driving style was the same. I was just the passenger watching the fuel gauge and the other gauges. Hottest it ran was it blipped to 208 for a second and then back to 207 and down to 205. Most of the time it was running 204-205.
Hooked up the fuel pressure gauge. Prime....40 psi. Idle....40 psi. Running on the road....drops to about 36 and up to 40. But never below 36. Ran the car for about 1.3++ hours and that sucker NEVER DIED!!
And for you that tell me to slap the computer....after driving it that long and no failure.....slapped the computer 4 times and nothing....still ran well.
There were times when stopped at a stop light or sign it would run a little rough....but not really noticeable.....not something you would point out to a mechanic or point out to anyone....because if you didn't drive it all the time you would never notice it.
By the way, it is not my car so the owner was driving. So driving style was the same. I was just the passenger watching the fuel gauge and the other gauges. Hottest it ran was it blipped to 208 for a second and then back to 207 and down to 205. Most of the time it was running 204-205.
07-10-2015, 04:26 PM
#22
Update for what it is worth.
Hooked up the fuel pressure gauge. Prime....40 psi. Idle....40 psi. Running on the road....drops to about 36 and up to 40. But never below 36. Ran the car for about 1.3++ hours and that sucker NEVER DIED!!
And for you that tell me to slap the computer....after driving it that long and no failure.....slapped the computer 4 times and nothing....still ran well.
There were times when stopped at a stop light or sign it would run a little rough....but not really noticeable.....not something you would point out to a mechanic or point out to anyone....because if you didn't drive it all the time you would never notice it.
By the way, it is not my car so the owner was driving. So driving style was the same. I was just the passenger watching the fuel gauge and the other gauges. Hottest it ran was it blipped to 208 for a second and then back to 207 and down to 205. Most of the time it was running 204-205.
Hooked up the fuel pressure gauge. Prime....40 psi. Idle....40 psi. Running on the road....drops to about 36 and up to 40. But never below 36. Ran the car for about 1.3++ hours and that sucker NEVER DIED!!
And for you that tell me to slap the computer....after driving it that long and no failure.....slapped the computer 4 times and nothing....still ran well.
There were times when stopped at a stop light or sign it would run a little rough....but not really noticeable.....not something you would point out to a mechanic or point out to anyone....because if you didn't drive it all the time you would never notice it.
By the way, it is not my car so the owner was driving. So driving style was the same. I was just the passenger watching the fuel gauge and the other gauges. Hottest it ran was it blipped to 208 for a second and then back to 207 and down to 205. Most of the time it was running 204-205.
Still thinking computer did you give it a little slap or a good smack?
Last edited by antfarmer2; 07-10-2015 at 04:44 PM.
07-10-2015, 04:40 PM
#23
Le Mans Master
Thread Starter
No I didn't pull off the vacuum line. It should increase 6-8 psi. But the important part is that with the vacuum line attached to the FPR and running down the road the pressure held like I would expect it to. I was looking for it to suddenly cut off and drop to 10 psi or less so the injectors would not spray and therefore have the car die. But it did not and didn't show any sign of dropping off at any point. If the car had an adjustable FPR and I was going to change the pressure setting, I would have disconnected the line and plugged it.
I did get a reply to my PM to rickcarol where he indicated that his problem was the TPS. He had symptoms that included sputtering and cutting out on acceleration when he ran it thru the gears pushing it. Sometimes it would die, but usually accompanied what the sputtering and fuel starvation symptom. When accelerating at a normal rate there was no issue. Not the same as what we are experiencing here.
I did get a reply to my PM to rickcarol where he indicated that his problem was the TPS. He had symptoms that included sputtering and cutting out on acceleration when he ran it thru the gears pushing it. Sometimes it would die, but usually accompanied what the sputtering and fuel starvation symptom. When accelerating at a normal rate there was no issue. Not the same as what we are experiencing here.
07-12-2015, 01:35 PM
#24
Le Mans Master
Thread Starter
Yes, I did slap the computer 4 times....and nothing.
Without codes to point in some direction it is difficult to try and nail this down.
Without codes to point in some direction it is difficult to try and nail this down.
Last edited by John A. Marker; 07-27-2015 at 10:53 AM.
07-12-2015, 02:27 PM
#25
I understand frustating
07-18-2015, 10:43 PM
#26
Le Mans Master
Thread Starter
Update 7/18/2015
We don't know if the issue has really been solved. But she has driven the 94 all last week and today about a 30 mile round trip and not an issue with stalling.
Solution---(don't know for sure)----- but a friend who is a mechanic suggested that it might be the chip in the key starting to fail. So since last Saturday she has used a new key she had made last year with a new chip. She had the key made as a spare. We are still not comfortable that this is the solution and the idea that it could stall at any point in time is still lingering in the back of our minds. I guess time will tell......
Solution---(don't know for sure)----- but a friend who is a mechanic suggested that it might be the chip in the key starting to fail. So since last Saturday she has used a new key she had made last year with a new chip. She had the key made as a spare. We are still not comfortable that this is the solution and the idea that it could stall at any point in time is still lingering in the back of our minds. I guess time will tell......
07-19-2015, 08:50 AM
#27
I would keep a eye on the computer as the OP said smacking it would either fix it or kill it good luck
07-21-2015, 03:55 PM
#28
Le Mans Master
Thread Starter
Well, we can now tell you that the chip/key solution was not the solution. It stalled today on the freeway....11 days of driving without a problem.
Tomorrow when she brings in the car I will check for codes again. This time it took three times to start...not immediate like prior times.
Tomorrow when she brings in the car I will check for codes again. This time it took three times to start...not immediate like prior times.
07-22-2015, 02:18 PM
#29
Le Mans Master
Thread Starter
Time to go out and pound some sand....
Pulled the codes a few minutes ago and not ONE F'n code. When she drove it in this morning it stalled once. She stopped to get or mail something and took three times to get it started and had to keep feeding it gas to keep it going just sitting there. It started up and ran fine after I checked for codes.
Really starting to lean again toward the OPTI.
Pulled the codes a few minutes ago and not ONE F'n code. When she drove it in this morning it stalled once. She stopped to get or mail something and took three times to get it started and had to keep feeding it gas to keep it going just sitting there. It started up and ran fine after I checked for codes.
Really starting to lean again toward the OPTI.
07-27-2015, 10:52 AM
#30
Le Mans Master
Thread Starter
Doing some more research lead me to a Corvette repair shop/parts supplier. I fired off a email to them (keeping their name out of this so they are not flooded with email asking for help) described the problem. Asked a couple of questions about their part, return policy and warranty. They replied indicating in their experience this issue was probably related to a bad connection to the fuel pump and not the part I was going to purchase from them. Stand up people.
So now another area to check....we might have been on the right track with the fuel pressure gauge.....just not lucky enough to have the engine die!
So now another area to check....we might have been on the right track with the fuel pressure gauge.....just not lucky enough to have the engine die!
07-27-2015, 11:08 AM
#31
Doing some more research lead me to a Corvette repair shop/parts supplier. I fired off a email to them (keeping their name out of this so they are not flooded with email asking for help) described the problem. Asked a couple of questions about their part, return policy and warranty. They replied indicating in their experience this issue was probably related to a bad connection to the fuel pump and not the part I was going to purchase from them. Stand up people.
So now another area to check....we might have been on the right track with the fuel pressure gauge.....just not lucky enough to have the engine die!
So now another area to check....we might have been on the right track with the fuel pressure gauge.....just not lucky enough to have the engine die!
I thought you did this.
Leave it on just becareful how you do it not to crack the windshield.
07-27-2015, 12:49 PM
#32
Le Mans Master
Thread Starter
Yes, we ran the car for 1.3 hours and then more with the FP gauge on the rail and pressure was good all that time. Without the problem showing itself, all you have is a guess. And we can guess and throw parts at this car all day long and have the problem still there. It ran fine for 11 days and we were thinking it was the chip in the key and thought it was solved. Can't drive around town for another 10-12 days with the gauge taped to the windshield.
The person that directed me back indicated that the symptoms were more than likely a pump related issue with perhaps a short on the connection on the connector outside the filler neck. He confirmed our initial thoughts that Opti seemed to always be a no start issue after the stall.
We will be looking at these connections this week.
The person that directed me back indicated that the symptoms were more than likely a pump related issue with perhaps a short on the connection on the connector outside the filler neck. He confirmed our initial thoughts that Opti seemed to always be a no start issue after the stall.
We will be looking at these connections this week.
Last edited by John A. Marker; 07-27-2015 at 01:45 PM.
07-28-2015, 02:01 PM
#33
Le Mans Master
Thread Starter
I checked the connections on the outside of the filler neck and all looked good. We decided to change the fuel pump and check the connections on the inside of the tank.
The pass through plug was not fully seated on the three pins, but should have mad a good connection. Took the plug off and wire brushed the pins and also sprayed with electrical contact cleaner. Cleaned the female part of the plug in with the same spray. Replaced the pump and filter sock. Old sock was black and hard.
Cleaned the weatherpak connection to the pump and filler neck with the same electrical contact cleaner. They all looked good before cleaning, but you never know.
Then started the car...it started which is a good sign. Then played with all the wires...pushing....and pulling.....all of them that go into the ECM while the car was running. No issues there.
So she will run the car and see what happens.
The pass through plug was not fully seated on the three pins, but should have mad a good connection. Took the plug off and wire brushed the pins and also sprayed with electrical contact cleaner. Cleaned the female part of the plug in with the same spray. Replaced the pump and filter sock. Old sock was black and hard.
Cleaned the weatherpak connection to the pump and filler neck with the same electrical contact cleaner. They all looked good before cleaning, but you never know.
Then started the car...it started which is a good sign. Then played with all the wires...pushing....and pulling.....all of them that go into the ECM while the car was running. No issues there.
So she will run the car and see what happens.
07-28-2015, 03:35 PM
#34
Le Mans Master
Member Since: Oct 2002
Location: Las Vegas - Just stop perpetuating myths please.
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Thats how the first opti on '94 Z28 died. Stopped me on the freeway but was able to pull to the side. Once it cooled off it got me home. Sometimes the opti wil flat out die but my first opti was interment and would quit with greater frequency.
Hope this helps even if its a little late.
Hope this helps even if its a little late.
07-28-2015, 03:47 PM
#35
Le Mans Master
Thread Starter
Everything I have read about the Opti indicates that it will die and will not start immediately. Has to cool off or may never start. This was not the case...car started right away.
Person that I emailed above, also said not characteristic of the Opti. He put me back onto the fuel pump and wires to same.
And her Opti was changed last year with a AC Delco unit.
Person that I emailed above, also said not characteristic of the Opti. He put me back onto the fuel pump and wires to same.
And her Opti was changed last year with a AC Delco unit.
Last edited by John A. Marker; 07-29-2015 at 09:31 PM.
07-29-2015, 05:56 AM
#37
Hello gentlemen. Everyone here seems to be talking about fuel pump or opti issues, and with good reason as those can be common failure points, but I believe the problem for both of you is fuel related, but more on the fuel injector end of things.
If both of your vehicles have the original fuel injectors, I would suspect them to be the culprit. They are sneaky. They are clever. They are infuriating, and under the right circumstances, they can be almost impossible to spot as a problem.
Bear with me while I ramble here.
A few years ago, a shop I worked at had a customer come in with a '94. Random stalling problem. Car would immediately restart most of the time, sometimes would not. Sometimes would run, sometimes would die again immediately. The stalling was as if someone had turned the key off. Very abrupt and no warning.
Most ignition components and fuel supply related electronics (oil pressure switch, pump relay, etc) had been replaced in a futile effort to solve the problem, all with no luck, and this was after visiting three different shops. The owner of the shop could not isolate the issue either and was prepared to send the car to the dealer.
Before sending it off, I convinced them to let me have a look at it, and so began the arduous process of testing, testing, and more testing. Everything I tested seemed fine. Fuel pump, ignition components, spark plugs and wires had the correct gap and resistance. Pump was flowing the proper gallons per minute. Sensors all functioned smoothly without any hiccups, no codes, you get the idea.
At this point I plugged in my meter to the fuel injector leads to see if the PCM was doing its job, and it was. Even as the car stalled, my voltmeter displayed gradually increasing duty cycle, all the way up to 100% as the PCM was trying to keep the engine running! (For those not familiar, increasing duty cycle here would be the PCM lengthening the injector pulse width trying to dump more fuel into the cylinders. 100% cycle means it was trying to keep the injector wide open.)
So now I could see that the vehicle had plenty of fuel on the supply side (regulator, pump functioning perfectly), and yet little to no fuel on the metering side (fuel injector).
At this point, I pulled the connectors off the injectors and measured the resistance across the two terminals on each injector. It's been a while since I wrenched on vehicles for a living, but if memory serves the resistance should be in the 14-16 Ohm area. Measuring the injectors, I looked for a greater than 10% difference in resistance between all of them. (This is where the injectors can be deceptive. A failed injector can still show acceptable resistance value, especially when cold, but will short out and read out of spec when at operating temperature. Even this is not a guarantee because if the coil wiring is still solid, but the solenoid body is failing or sticking, the injector can still read the appropriate electrical value)
I found two that fit the >10% difference criteria.
Now, as I mentioned, these injectors can be sneaky, and a failed one can hide quite easily among its healthy counterparts, which is why I pulled all the injectors for cleaning and further testing. My mentality was that if two of them were bad enough to show, then there were probably more faulty ones that were still able to hide. Side note: before completely removing the injectors, I removed them from the manifold base while leaving them attached to the fuel rail. Doing so allowed me to place a piece of cardboard underneath them and monitor them while I turned the key on. As fuel pressure increases, any injector that can no longer seal fully will start to leak (I've seen some gushers, and tiny drip leaks). This test did confirm that I had at least one failed and leaking injector.
I took them to a friend's place that happened to have an injector pulse width tester, and this is where they really showed their true colors. Connecting each one individually, I found there were FOUR injectors that were total junk. Not going bad, not on their way out. Total and pure junk. They would sometimes pulse, or not at all. The car being able to immediately restart came from the fact that fuel was able to leak past the injectors, and puddle into the cylinder head intake runner, which supplied plenty of fuel for initial startup, but the seized body inside the injector could not keep it supplied, starving multiple cylinders for fuel and causing the engine to shut down. Injectors can get expensive, and to keep already expensive costs down I kept the good ones in service, and only replaced the garbage ones. Ideally, all of them should have been replaced in my opinion. After replacement, the car started, and ran. And ran. And ran some more. And ran very smoothly. And the problem was solved.
I'm not guaranteeing this is your issue, but it sounds so strikingly similar to what I encountered here that I think it's worth your time and effort to investigate. I'm sorry for the mini novel, but really hope this helps you out. Good luck!
TL;DR
Had similar issue with a '94, half the fuel injectors were junk.
If both of your vehicles have the original fuel injectors, I would suspect them to be the culprit. They are sneaky. They are clever. They are infuriating, and under the right circumstances, they can be almost impossible to spot as a problem.
Bear with me while I ramble here.
A few years ago, a shop I worked at had a customer come in with a '94. Random stalling problem. Car would immediately restart most of the time, sometimes would not. Sometimes would run, sometimes would die again immediately. The stalling was as if someone had turned the key off. Very abrupt and no warning.
Most ignition components and fuel supply related electronics (oil pressure switch, pump relay, etc) had been replaced in a futile effort to solve the problem, all with no luck, and this was after visiting three different shops. The owner of the shop could not isolate the issue either and was prepared to send the car to the dealer.
Before sending it off, I convinced them to let me have a look at it, and so began the arduous process of testing, testing, and more testing. Everything I tested seemed fine. Fuel pump, ignition components, spark plugs and wires had the correct gap and resistance. Pump was flowing the proper gallons per minute. Sensors all functioned smoothly without any hiccups, no codes, you get the idea.
At this point I plugged in my meter to the fuel injector leads to see if the PCM was doing its job, and it was. Even as the car stalled, my voltmeter displayed gradually increasing duty cycle, all the way up to 100% as the PCM was trying to keep the engine running! (For those not familiar, increasing duty cycle here would be the PCM lengthening the injector pulse width trying to dump more fuel into the cylinders. 100% cycle means it was trying to keep the injector wide open.)
So now I could see that the vehicle had plenty of fuel on the supply side (regulator, pump functioning perfectly), and yet little to no fuel on the metering side (fuel injector).
At this point, I pulled the connectors off the injectors and measured the resistance across the two terminals on each injector. It's been a while since I wrenched on vehicles for a living, but if memory serves the resistance should be in the 14-16 Ohm area. Measuring the injectors, I looked for a greater than 10% difference in resistance between all of them. (This is where the injectors can be deceptive. A failed injector can still show acceptable resistance value, especially when cold, but will short out and read out of spec when at operating temperature. Even this is not a guarantee because if the coil wiring is still solid, but the solenoid body is failing or sticking, the injector can still read the appropriate electrical value)
I found two that fit the >10% difference criteria.
Now, as I mentioned, these injectors can be sneaky, and a failed one can hide quite easily among its healthy counterparts, which is why I pulled all the injectors for cleaning and further testing. My mentality was that if two of them were bad enough to show, then there were probably more faulty ones that were still able to hide. Side note: before completely removing the injectors, I removed them from the manifold base while leaving them attached to the fuel rail. Doing so allowed me to place a piece of cardboard underneath them and monitor them while I turned the key on. As fuel pressure increases, any injector that can no longer seal fully will start to leak (I've seen some gushers, and tiny drip leaks). This test did confirm that I had at least one failed and leaking injector.
I took them to a friend's place that happened to have an injector pulse width tester, and this is where they really showed their true colors. Connecting each one individually, I found there were FOUR injectors that were total junk. Not going bad, not on their way out. Total and pure junk. They would sometimes pulse, or not at all. The car being able to immediately restart came from the fact that fuel was able to leak past the injectors, and puddle into the cylinder head intake runner, which supplied plenty of fuel for initial startup, but the seized body inside the injector could not keep it supplied, starving multiple cylinders for fuel and causing the engine to shut down. Injectors can get expensive, and to keep already expensive costs down I kept the good ones in service, and only replaced the garbage ones. Ideally, all of them should have been replaced in my opinion. After replacement, the car started, and ran. And ran. And ran some more. And ran very smoothly. And the problem was solved.
I'm not guaranteeing this is your issue, but it sounds so strikingly similar to what I encountered here that I think it's worth your time and effort to investigate. I'm sorry for the mini novel, but really hope this helps you out. Good luck!
TL;DR
Had similar issue with a '94, half the fuel injectors were junk.
Last edited by Solderhead; 07-29-2015 at 05:58 AM. Reason: Formatting
07-29-2015, 06:10 AM
#38
Instructor
Thanks for the novel
As soon as I get back from this trip I am going to try the test you described since I have NOID lights and all the other equipment I need to do the testing. Just have not had time to get to much lately.
07-29-2015, 07:50 AM
#39
Let us know what you find. If your injectors check out ok, then the next step (for me anyway) would be to check the alignment and condition of the ignition switch actuator rod, followed by the ignition switch itself to make sure it's not losing its connection due to faulty contacts or slipping out of position.
07-29-2015, 10:30 AM
#40
Le Mans Master
Thread Starter
Solderhead, very interesting. Maybe it is my old mind and all the days with carburetors, but if you had four bad injectors wouldn't the car run rough most of the time? Wouldn't you set a lean code at some point? And if the injectors were going up to 100% duty cycle, wouldn't you stall more frequently at higher speeds where more fuel was required. I am not doubting what your saying, just having a difficult time understanding the logic. But then again sometimes the C4 defies all logic.
Her car only has 89,000 on it. I changed my injectors just because on my 95 with over 160,000 and they were the originals. I just went out and checked each injector. They all read 12.78 +/- .01. Granted this is the duty cycle you have referred to in you post.
I REALLY appreciate your writeup. When your trying to solve a problem it helps to have options to explore. Can you explain to me in detail how you tested the duty cycle of each injector? You indicated you tested the injectors and the car stalled with your test showing an increasing duty cycle. We can't get the damn car to stall on any consistent basis, if we could that would point us in a direction.
Her car only has 89,000 on it. I changed my injectors just because on my 95 with over 160,000 and they were the originals. I just went out and checked each injector. They all read 12.78 +/- .01. Granted this is the duty cycle you have referred to in you post.
I REALLY appreciate your writeup. When your trying to solve a problem it helps to have options to explore. Can you explain to me in detail how you tested the duty cycle of each injector? You indicated you tested the injectors and the car stalled with your test showing an increasing duty cycle. We can't get the damn car to stall on any consistent basis, if we could that would point us in a direction.
Last edited by John A. Marker; 07-29-2015 at 02:05 PM. Reason: Ohmed injectors