Cranks won't start
#21
02-10-2018, 09:09 PM
This is a common problem across all GM lines. I even have a forklift with a tbi 4.3 chevy v-6 and a commercial/ marine pcm. I cannot scan this system with an automotive scanner however looking at symptoms I can diagnose and repair. I have replaced the coolant sensor for flooding when cold.
#23
02-19-2018, 07:13 AM
Replaced plugs yesterday. Same outcome at first. Can popped and backfired, cranked for about 2-3 minutes. Removed plugs, dry. Put them back in and cranked some more. Same thing spit and stuttered, but would not run/start. Removed and checked plugs, dry. Put them back in and cranked, but decided to press gas to floor and hold it. I got a little life it ran on for about 3 seconds. I could smell fuel. Pulled plugs, dry. Put them back in and cranked again, floored it, them let off and pumped the gas 3 times and it backfired, hiccups, I let go of the key and feathered the gas, as it came around from an extremely rough idle and a giant blue cloud out the exhaust it was idling. Drove it around the block, started and shut it off about 5 times and call it fixed.
So in about 7 years and this happening 4 times I still have no idea why it happens or what fixes it. This last go around I replaced the coolant temp sensor and connector, plugs, tested all fuses, disconnected the remote start with non of it really helping. After cranking on it yesterday for what would normally fry a starter, it finally started. I'm sure I will be back here in a year or so, frustrated when it happens again. Such a strange situation that seems to have no real answer. Thanks to those that offered help.
So in about 7 years and this happening 4 times I still have no idea why it happens or what fixes it. This last go around I replaced the coolant temp sensor and connector, plugs, tested all fuses, disconnected the remote start with non of it really helping. After cranking on it yesterday for what would normally fry a starter, it finally started. I'm sure I will be back here in a year or so, frustrated when it happens again. Such a strange situation that seems to have no real answer. Thanks to those that offered help.
#24
02-19-2018, 04:33 PM
cyclicly pump the pedal to the floor two or 3 times and then hold it down. I think it is a flooding issue. My S cars do this every once in a while,. If you don't get it running on the first or second try, too much gas accumulates and you have the equivalent of a flood. Holding the pedal down clears it. It''ll take like 8 seconds but if you torture your starter and hold the pedal down , it will sputter, spit, boom and rock, but when it starts, there will be a huge plume of fuel rich smoke out the tailpipe.
Doing what you did as I stated in my earlier post clears a flood -- the key being a flood of whatever happens to be in the cyls. In this case, now that I think about it more, I think it's more or less all oil, since the injectors have been shut down, possibly from trying to clear the flood last time you tried to do so as holding down the gas pedal shuts off the pulses to the injectors.
Once the flood is cleared the injectors open back up and when you finally get it to run roughly, a small amount of oil left in the cyl(s) burns with the air + fuel and you get the smoke plume.
The car is running rough due to the residual oil still left in the cyls mixed with what should be in there until the engine warms up enough that the oil burns more easily in the cyls like does in a typical oil burning Saturn.
That's the best I can come up with after 26 years of continuous s car ownership in one form or another. Pretty sad, but this is one I've never understood as it happens so infrequently and the behavior is just whack, since if the car has a true oil burning issue it should happen more consistently unless a valve guide seal temporarily gets out of position then goes back into place.
Andy?
Is the above plausible or do I need a new drawing board to start with?
Last edited by derf; 02-19-2018 at 04:36 PM.
#25
02-19-2018, 07:47 PM
The 2002 L series passlock system disables the injectors only. It really sounds like a security issue, maybe some corrosion on the bcm circuit board. Does your security light come on then go off when the car runs properly? If the light flashes for 4 seconds then stays on it is in short tamper mode. If the light continues to flash it is in long tamper mode and the injectors are disabled.
We have a remote start stop system in our trucks at work and corrosion on circuit boards is an issue from time to time.
We have a remote start stop system in our trucks at work and corrosion on circuit boards is an issue from time to time.
#26
02-19-2018, 10:53 PM
Andy,
I have had this occur on my 97 SC2, 95 SC2 and I remember at least once with my 92 SL2.
None of these vehicles had Passlock of any flavor, nor a BCM. Just a starter disable feature when you locked/armed the system with the fob.
It behaves exactly as Eksnolp and I have experienced. That's why I was able to describe to him what to do to remedy the situation just by his description.
My guess/explanation may be dead wrong, but it is not limited just to Passlock II equipped S cars, so although the injector behavior is consistent with Passlock II security being tripped (or thinking it's been tripped), I personally do not believe that to be the root cause of this behavior.
I had never been in a position to have the time to stop and check if the plugs were wet after a few failed crank attempts as I was always in a hurry to go somewhere and knew how to fight through the odd behavior. The fact that we know at least in this case they were not just deepens the mystery, because when you first try to start it, it will fire a few times but stall. If you don't get it running, on the second cranking , it just cranks and does not fire at all. No sputter no nothing. Just cranks. The fact that it ran on ether indicates the DIS system was functioning as advertised, leaving some of the only explanations to be that either no air/fuel mixture was entering the cylinders or something else was at the same time, preventing the mixture from burning.
I used to assume it was unburned fuel building up in the cyls, and the plume of smoke and the sickly rich smell of fuel were from built up unburned gas. But I forgot my smoke colors. Shame on me..
-----------------------
I now believe that somehow the injectors get into a shutdown state based on meeting some evil case set of parameters, possibly a flaw in the PCM programming, and they stay shut until you perform the "flood clear" with the pedal. The PCM likely sees the full range motions of the throttle via the TPS and re enables the injectors. In the meantime, oil has either snuck past the valve guide seals or been pushed up past worn oil control rings and enough has been accumulated in the cyls to screw up the firing of the cyl contents.
The other thing I forgot to mention is that, in my case, I learned I had to WAIT a short while after it failed to run after the 2nd cranking. I always assumed this again was a fuel flood condition clearing itself. I now think it may have been the oil slowly draining back down past the oil control rings.
So his overnight stays at the mechanic's basically served as wait times for drainage, and once clear enough the car would start, run roughly, and then smooth out.
I have recovered my S cars from this condition without ever changing a single part. On any of the cars.
Dunno and likely never will. But my identical experience with three non passlock non BCM S cars leads me to believe it is more than a security issue,
That's my take, anyway.
I have had this occur on my 97 SC2, 95 SC2 and I remember at least once with my 92 SL2.
None of these vehicles had Passlock of any flavor, nor a BCM. Just a starter disable feature when you locked/armed the system with the fob.
It behaves exactly as Eksnolp and I have experienced. That's why I was able to describe to him what to do to remedy the situation just by his description.
My guess/explanation may be dead wrong, but it is not limited just to Passlock II equipped S cars, so although the injector behavior is consistent with Passlock II security being tripped (or thinking it's been tripped), I personally do not believe that to be the root cause of this behavior.
I had never been in a position to have the time to stop and check if the plugs were wet after a few failed crank attempts as I was always in a hurry to go somewhere and knew how to fight through the odd behavior. The fact that we know at least in this case they were not just deepens the mystery, because when you first try to start it, it will fire a few times but stall. If you don't get it running, on the second cranking , it just cranks and does not fire at all. No sputter no nothing. Just cranks. The fact that it ran on ether indicates the DIS system was functioning as advertised, leaving some of the only explanations to be that either no air/fuel mixture was entering the cylinders or something else was at the same time, preventing the mixture from burning.
I used to assume it was unburned fuel building up in the cyls, and the plume of smoke and the sickly rich smell of fuel were from built up unburned gas. But I forgot my smoke colors. Shame on me..
-----------------------
I now believe that somehow the injectors get into a shutdown state based on meeting some evil case set of parameters, possibly a flaw in the PCM programming, and they stay shut until you perform the "flood clear" with the pedal. The PCM likely sees the full range motions of the throttle via the TPS and re enables the injectors. In the meantime, oil has either snuck past the valve guide seals or been pushed up past worn oil control rings and enough has been accumulated in the cyls to screw up the firing of the cyl contents.
The other thing I forgot to mention is that, in my case, I learned I had to WAIT a short while after it failed to run after the 2nd cranking. I always assumed this again was a fuel flood condition clearing itself. I now think it may have been the oil slowly draining back down past the oil control rings.
So his overnight stays at the mechanic's basically served as wait times for drainage, and once clear enough the car would start, run roughly, and then smooth out.
I have recovered my S cars from this condition without ever changing a single part. On any of the cars.
Dunno and likely never will. But my identical experience with three non passlock non BCM S cars leads me to believe it is more than a security issue,
That's my take, anyway.
Last edited by derf; 02-19-2018 at 10:59 PM.
#27
02-20-2018, 12:25 AM
So let’s think about what controls the injectors. Do S cars batch the injectors all the time or do they sequence them after initial batch start? If they sequence they need a cam sensor signal to determine #1. The crank sensor controls the spark if there is a coil pack and wires. I don’t think they have coil on plug.
It is pretty obvious that the injectors are not being driven since the cars run on ether. I would want to check the injector signal with a noid light when in the no start condition. I would also verify proper fuel pressure during cranking.
GM has had ignition switch failure issues over the years but it causes system failures not no fuel injectors. Unless there are two separate ignition feeds to the pcm, one for the ignition side and another for the fuel control side. Are there two pcm fuses on your cars? Like “A” and “B”?
This is just my thought processes on troubleshooting, I have no manuals for S cars. My L series cars are a completely different animal.
Andy
It is pretty obvious that the injectors are not being driven since the cars run on ether. I would want to check the injector signal with a noid light when in the no start condition. I would also verify proper fuel pressure during cranking.
GM has had ignition switch failure issues over the years but it causes system failures not no fuel injectors. Unless there are two separate ignition feeds to the pcm, one for the ignition side and another for the fuel control side. Are there two pcm fuses on your cars? Like “A” and “B”?
This is just my thought processes on troubleshooting, I have no manuals for S cars. My L series cars are a completely different animal.
Andy
#28
02-20-2018, 03:52 AM
Injectors: Mult-port fuel injection.(assume sequential)
Ignition timing: only a physical CKP, no physical cam position Sensor.
2 coil packs, 2 cyls/pack (1/4, 2/3) waste spark
(Eksnolp did verify fuel pressure at rail during troubleshooting.- ok )
There are indeed PCM 1 and PCM B fuses.
PCM B is fusing a 12V feed from the battery to the PCM at Pin D6 (1st Gen). This is the fuse everyone pulls to clear SES codes as it kills power to the PCM.
This appears to be the power source to the PCM itself.
PCM 1 is fusing a 12V feed from the battery to the PCM at IGNITION B+ @ Pin A7. So that is the ignition feed to which you refer.
This particular 12V feed provides current to the DIS, PCM 1, B/U lamp, EGR, and PCM B systems through their respective fuses
---------
There is an injector fuse (INJ) which has a battery feed to both ends, one end of which is the feed to the fuses for the systems above, the other end of which splits between a battery feed connection and the 4 injectors themselves.
I believe this to be an error since the fuse would never blow AND as drawn, it provides no fused protection to the injectors.
I believe it should be indicated as a split off of the same feed as the systems mentioned above. If so, it would provide fused protection to all 4 of the injectors.
--------
Assuming the correction is valid:
The 12V feed to the injectors splits into 4, which go to the injectors, respectively, and connect to the PCM at Pins D13, D14, D15, and D16. As configured, I am assuming that the PCM grounds the each of the mentioned pins as necessary to complete the circuit and open the injector for the required interval to meet fuel needs.
So it SEEMS, at 4:27 AM Eastern Time, that the ignition system has its own 12V feed into the PCM fused by PCM 1, whereas the "switching" power used to control the opening and closing of the injectors is likely coming from the 12V feed that powers the PCM itself, and when each injector circuit is completed, the injector sources its operating current from the battery feed.
If that is correct, then the only ways to shut down the injectors electrically are
---for the battery feed to the injectors to go open (possibly corrosion at the fuse/junction block)
---for the PCM, for whatever reason, to stop grounding the pins and opening the injectors
My reference to an "evil case" scenario above is my way of saying this seemingly illogical behavior is in fact completely logical once one understands the logic behind it. Or it's a programming flaw. Dunno.
Conclusions based on assumptions based on assumptions based on assumptions are rarely correct. I know that.
But you have to start somewhere with the wrong answer in order to find the right one.
If it's not clear, I'm more than willing to make a complete *** of myself on this site in the quest for knowledge I don't have and the improvement of my troubleshooting skills.
I welcome the opportunity to do so, and thank those who are willing to provide guidance.
Ignition timing: only a physical CKP, no physical cam position Sensor.
2 coil packs, 2 cyls/pack (1/4, 2/3) waste spark
(Eksnolp did verify fuel pressure at rail during troubleshooting.- ok )
There are indeed PCM 1 and PCM B fuses.
PCM B is fusing a 12V feed from the battery to the PCM at Pin D6 (1st Gen). This is the fuse everyone pulls to clear SES codes as it kills power to the PCM.
This appears to be the power source to the PCM itself.
PCM 1 is fusing a 12V feed from the battery to the PCM at IGNITION B+ @ Pin A7. So that is the ignition feed to which you refer.
This particular 12V feed provides current to the DIS, PCM 1, B/U lamp, EGR, and PCM B systems through their respective fuses
---------
There is an injector fuse (INJ) which has a battery feed to both ends, one end of which is the feed to the fuses for the systems above, the other end of which splits between a battery feed connection and the 4 injectors themselves.
I believe this to be an error since the fuse would never blow AND as drawn, it provides no fused protection to the injectors.
I believe it should be indicated as a split off of the same feed as the systems mentioned above. If so, it would provide fused protection to all 4 of the injectors.
--------
Assuming the correction is valid:
The 12V feed to the injectors splits into 4, which go to the injectors, respectively, and connect to the PCM at Pins D13, D14, D15, and D16. As configured, I am assuming that the PCM grounds the each of the mentioned pins as necessary to complete the circuit and open the injector for the required interval to meet fuel needs.
So it SEEMS, at 4:27 AM Eastern Time, that the ignition system has its own 12V feed into the PCM fused by PCM 1, whereas the "switching" power used to control the opening and closing of the injectors is likely coming from the 12V feed that powers the PCM itself, and when each injector circuit is completed, the injector sources its operating current from the battery feed.
If that is correct, then the only ways to shut down the injectors electrically are
---for the battery feed to the injectors to go open (possibly corrosion at the fuse/junction block)
---for the PCM, for whatever reason, to stop grounding the pins and opening the injectors
My reference to an "evil case" scenario above is my way of saying this seemingly illogical behavior is in fact completely logical once one understands the logic behind it. Or it's a programming flaw. Dunno.
Conclusions based on assumptions based on assumptions based on assumptions are rarely correct. I know that.
But you have to start somewhere with the wrong answer in order to find the right one.
If it's not clear, I'm more than willing to make a complete *** of myself on this site in the quest for knowledge I don't have and the improvement of my troubleshooting skills.
I welcome the opportunity to do so, and thank those who are willing to provide guidance.
#30
02-20-2018, 10:31 AM
Eksnolp
Are you sure it was blue smoke and not black (fuel)?
I have done a bit of random surfing, finding numerous other postings of the same issue. Many state black smoke, none state blue.
It seems like a situation where the injectors are simply not being re enabled at the next ignition cycle like they are supposed to (as they are shut down when the car is not running (when you turn it off).
It is not till you start pinning the pedal down and feathering it that the PCM re enables the injectors. Dunno
Are you sure it was blue smoke and not black (fuel)?
I have done a bit of random surfing, finding numerous other postings of the same issue. Many state black smoke, none state blue.
It seems like a situation where the injectors are simply not being re enabled at the next ignition cycle like they are supposed to (as they are shut down when the car is not running (when you turn it off).
It is not till you start pinning the pedal down and feathering it that the PCM re enables the injectors. Dunno