***No start/No Spark Ran Fine last Night***
03-31-2017, 03:35 PM
#47
Addict
Rennlist Member
Rennlist Member
I had the exact same issue when I resurrected the S4. It turned out to be the ignition switch. It was only passing 8 to 10 volts on one of the busses. It would get very weak spark, or none at all. Sometimes it would stumble and die. New ignition switch cleared it right up.
04-01-2017, 02:17 PM
#48
Rennlist Member
Thread Starter
OK guys. We are getting a lot of voltage drop with the key in the on position and the ignition amplifiers/modules get so hot that you will burn your fingers even mounted to the heat sinks. Bad ignition modules or should we be looking for something else causing the hot modules???
04-01-2017, 10:43 PM
#49
Three Wheelin'
OK guys. We are getting a lot of voltage drop with the key in the on position and the ignition amplifiers/modules get so hot that you will burn your fingers even mounted to the heat sinks. Bad ignition modules or should we be looking for something else causing the hot modules???
Seriously, Anyone else got any ideas. We're running out of ideas. Thanks in advance!
Joel, Mike & Randy..
04-01-2017, 10:55 PM
#50
Rennlist Member
Stupid idea: feel the modules on one of your running 85+ 928's. See how hot they are.
I know ignition modules are supposed to get hot, that is why they are mounted to heat sinks. However, I don't know how hot.
I know ignition modules are supposed to get hot, that is why they are mounted to heat sinks. However, I don't know how hot.
04-01-2017, 11:44 PM
#51
Three Wheelin'
Good idea... I'm sure they get warm, but they were practically burning my fingers with just the key in the "ON" position (not cranking the engine) - something is definitely not correct. Another symptom, the coils were getting warm with the key in the "ON" position (not cranking)... weird?? Mike is going to use the ignition amps from his 86 to see if the current amps ARE the problem or if they are REACTING to another problem. Other than that, were kinda stumped...
Thanks brother!!
Thanks brother!!
04-01-2017, 11:59 PM
#52
Team Owner
I would go back to the CE panel and verify that every relay is correctly plugged into the correct slot,
also that the empty slots are indeed empty ,
NOTE please have someone else do this CE inspection other than the person thats been working on the car.
From the report something is crossed did you ever swap out the ignition switch ?
what was the last thing that was fixed prior to the failure?
what did the car do prior to the failure>?
was the defroster switch turned CW? not pushed?
if no joy on any of this testing then your going to have to perform a trigger ring inspection to verify that the ring has not turned on the flywheel this has happened a few times and will result in poor running or no running
https://rennlist.com/forums/928-foru...er+ring+pinned
use an IR gun to verify the amp temps on a running car,
the coils will get warm during normal operation this takes some time
also that the empty slots are indeed empty ,
NOTE please have someone else do this CE inspection other than the person thats been working on the car.
From the report something is crossed did you ever swap out the ignition switch ?
what was the last thing that was fixed prior to the failure?
what did the car do prior to the failure>?
was the defroster switch turned CW? not pushed?
if no joy on any of this testing then your going to have to perform a trigger ring inspection to verify that the ring has not turned on the flywheel this has happened a few times and will result in poor running or no running
https://rennlist.com/forums/928-foru...er+ring+pinned
use an IR gun to verify the amp temps on a running car,
the coils will get warm during normal operation this takes some time
Last edited by Mrmerlin; 04-02-2017 at 12:33 AM.
04-02-2017, 06:12 AM
#54
Rennlist Member
If you check out Vol 1A of the WSM, page 28-63 it shows how to unplug the drive signals to the final amplifiers. Disconnect that and see if the high current drain/heat problem goes.
04-02-2017, 08:57 AM
#55
Team Owner
Please go through my post and answer the suggested items to inspect.
just suggesting things to do without any responses on what troubleshooting your doing/finding is not how to fix an issue
just suggesting things to do without any responses on what troubleshooting your doing/finding is not how to fix an issue
04-03-2017, 12:06 AM
#56
Rennlist Member
- From the report something is crossed did you ever swap out the ignition switch ? No. This has not been done yet.
- what was the last thing that was fixed prior to the failure? Nothing. Car was running just fine. Went out earlier in the evening and parked it. Went to start and nothing.
- what did the car do prior to the failure>? See above answer.
- was the defroster switch turned CW? not pushed? - Can't answer that one yet..
04-03-2017, 08:24 PM
#59
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
Taking a few days off from a big project effort. Sorry I didn't respond earlier. Reading the electrical diagrams:
You can test for ignition switch ignition-circuit problems by measuring bus 15 voltage. Fuses 11 and 12 connect directly to bus 15. 11 Is for the rear wiper motor, 12 is for mirrors. You can test through the little probe hole in the back of the fuse, or take one out and probe the socket. With key in engine-run position, you should see battery voltage on both sides of the fuse, or in one side of the fuseholder with fuse removed. Use your DMM in DC volts mode, referenced to chassis ground. The voltage there will droop some when the starter motor is engaged, but no less than maybe 10.5 Volts when cranking. If the voltage stay up while cranking, look beyond the ignition switch.
The ignition switch feeds voltage to bus 15, which triggers both the LH and EZF relays. If you can feel those relays engaging with key in run and start positions, the ignition switch is doing its job.
Those relays supply power to the fuel injection and ignition systems, respectively. Source for voltage for the EZF relay is through CE panel connection U11, via one of the smaller red feeders that connect directly at the battery positive terminal. EZF power exits from the relay at W14, black wires, one to pin 25 on the EZF connector and the other connects to pin 18 on the LH connector. Voltage at W14 should be the same as battery voltage with key on. Voltage at U11 should be the same as battery voltage with key on. If U11 is good and W14 is low, look at the relay and the realy socket. If both go low with key in Run, look at the connections at battery positive.
In my experience, starting with the battery positive connections is really the best first step. The fuel pump, injection and ignition relays all get power via those minor feeders that connect to battery positive right at the battery. Those need to be clean, shiny, and tight. A good main battery cable connection and ground connections are critical too, as shared by others. The "minor" positive connections are critical to getting the engine to actually run, after it's cranking on the starter motor.
You can test for ignition switch ignition-circuit problems by measuring bus 15 voltage. Fuses 11 and 12 connect directly to bus 15. 11 Is for the rear wiper motor, 12 is for mirrors. You can test through the little probe hole in the back of the fuse, or take one out and probe the socket. With key in engine-run position, you should see battery voltage on both sides of the fuse, or in one side of the fuseholder with fuse removed. Use your DMM in DC volts mode, referenced to chassis ground. The voltage there will droop some when the starter motor is engaged, but no less than maybe 10.5 Volts when cranking. If the voltage stay up while cranking, look beyond the ignition switch.
The ignition switch feeds voltage to bus 15, which triggers both the LH and EZF relays. If you can feel those relays engaging with key in run and start positions, the ignition switch is doing its job.
Those relays supply power to the fuel injection and ignition systems, respectively. Source for voltage for the EZF relay is through CE panel connection U11, via one of the smaller red feeders that connect directly at the battery positive terminal. EZF power exits from the relay at W14, black wires, one to pin 25 on the EZF connector and the other connects to pin 18 on the LH connector. Voltage at W14 should be the same as battery voltage with key on. Voltage at U11 should be the same as battery voltage with key on. If U11 is good and W14 is low, look at the relay and the realy socket. If both go low with key in Run, look at the connections at battery positive.
In my experience, starting with the battery positive connections is really the best first step. The fuel pump, injection and ignition relays all get power via those minor feeders that connect to battery positive right at the battery. Those need to be clean, shiny, and tight. A good main battery cable connection and ground connections are critical too, as shared by others. The "minor" positive connections are critical to getting the engine to actually run, after it's cranking on the starter motor.
04-03-2017, 10:51 PM
#60
Three Wheelin'
We probably won't get back to the car till next weekend. We'll check on Stan's, Dr. Bob's, John's and everyone else's suggestions then... Thank you ALL immensely! We'll be sure to report back any findings.
One thing noted was a significant voltage drop with the ignition amplifiers plugged in with the key "ON" (not cranking). They also heated up QUICKLY with the key in the "ON" position... again, not cranking. When we unplugged the ignition amplifiers, the voltage immediately went back up to over 12 volts. It's a significant finding... but I'll be damned if I know WHY it's significant as in what's the root cause. Could the cause be something upstream in the fuse / relay / CE panel ?? Or could the ignition amplifiers themselves be THE problem? Resisting the urge to just throw parts at the problem...
Like I said, we'll report back after we test the circuits recommended above. In the meantime, if anyone has an epiphany on possible causes, please post it on here. Thanks again for all the assistance & suggestions!
Joel
One thing noted was a significant voltage drop with the ignition amplifiers plugged in with the key "ON" (not cranking). They also heated up QUICKLY with the key in the "ON" position... again, not cranking. When we unplugged the ignition amplifiers, the voltage immediately went back up to over 12 volts. It's a significant finding... but I'll be damned if I know WHY it's significant as in what's the root cause. Could the cause be something upstream in the fuse / relay / CE panel ?? Or could the ignition amplifiers themselves be THE problem? Resisting the urge to just throw parts at the problem...
Like I said, we'll report back after we test the circuits recommended above. In the meantime, if anyone has an epiphany on possible causes, please post it on here. Thanks again for all the assistance & suggestions!
Joel