87 S4 with an odd issue
#17
Three Wheelin'
I remember a thread like this a ways back that exhibited similar symptoms that turned out to be a cracked CPS connector. Once things got warm, moved around etc, the signal would get "lost" and engine died. Airbox off, MAF off and you should be able to see it well enough. Pain to remove with intake in but doable.
#18
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Checked the coils for wandering spark travel night in the dark and didn't see any obvious issues...will be changing the CPS tonight after work. It'll be a joy I'm sure... Cranked her again this morning and of course, she started and ran beautifully. Will post again later tonight with an update...
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928S4forme,
I bring my S4 up to the NC Mountains frequently to run the BRP from Maggie to AVL. Where are you located? Will be up again in a few weeks.
I do know where all the ground connections are!
I can bring up the relevant tech manual elect diagrams if needed.
Seems like electrical issues to me also, as Greg said, can be really elusive. Connectors crumble to dust!
Dave
Dave
I bring my S4 up to the NC Mountains frequently to run the BRP from Maggie to AVL. Where are you located? Will be up again in a few weeks.
I do know where all the ground connections are!
I can bring up the relevant tech manual elect diagrams if needed.
Seems like electrical issues to me also, as Greg said, can be really elusive. Connectors crumble to dust!
Dave
Dave
#21
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928S4forme,
I bring my S4 up to the NC Mountains frequently to run the BRP from Maggie to AVL. Where are you located? Will be up again in a few weeks.
I do know where all the ground connections are!
I can bring up the relevant tech manual elect diagrams if needed.
Seems like electrical issues to me also, as Greg said, can be really elusive. Connectors crumble to dust!
Dave
Dave
I bring my S4 up to the NC Mountains frequently to run the BRP from Maggie to AVL. Where are you located? Will be up again in a few weeks.
I do know where all the ground connections are!
I can bring up the relevant tech manual elect diagrams if needed.
Seems like electrical issues to me also, as Greg said, can be really elusive. Connectors crumble to dust!
Dave
Dave
#22
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Ok everyone here is the latest...
The CPS is fine...
Replaced original starter
Changed plugs...
Verified alternator is good
Verified battery is good
Checked relays and found issue with the cooling flaps (wrong relay)...
Verified correct relays for each position on ce panel...
Injectors are firing correctly...
Swapped battery ground with new strap...
Cleaned ground points...
All that and I still have the same problem
When she is cold she starts and runs perfect. After she gets hot, she begins to hi/low idle and when throttled she dies. After she is dead, you try to crank her and she acts as if the battery is dead and won't turn over. The starter acts as if it's been heat soaked. Let her cool down an hour or so and she starts right up and runs.
Any suggestions?
The CPS is fine...
Replaced original starter
Changed plugs...
Verified alternator is good
Verified battery is good
Checked relays and found issue with the cooling flaps (wrong relay)...
Verified correct relays for each position on ce panel...
Injectors are firing correctly...
Swapped battery ground with new strap...
Cleaned ground points...
All that and I still have the same problem
When she is cold she starts and runs perfect. After she gets hot, she begins to hi/low idle and when throttled she dies. After she is dead, you try to crank her and she acts as if the battery is dead and won't turn over. The starter acts as if it's been heat soaked. Let her cool down an hour or so and she starts right up and runs.
Any suggestions?
#23
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Are there 12+ volts at the jump post, also, at the CE panel --- when the car is hot and starter won't engage? Did you say the starter wouldn't engage in the hot, stall, can't restart mode --- or won't turn engine over?
Are you certain you got the critical ground points?
How were the valley ground ring terminal solder joints?
Did you indeed swap CPS out? I've damaged a new one on installation because the metal end wasn't well bonded to the plastic.
Am wondering now about your 14 pin connector. Did you unplug, then snap the backs off the two halves to inspect the solder joints. I've seen many of them broken, making intermittent contact. This is where the signal passes to engage the starter. This is probably where I'd put the next bit of effort if you haven't already addressed it.
Did you replace temp II? Are its threads clean so it grounds to the water bridge?
We used to live in Elkin during summer.
Are you certain you got the critical ground points?
How were the valley ground ring terminal solder joints?
Did you indeed swap CPS out? I've damaged a new one on installation because the metal end wasn't well bonded to the plastic.
Am wondering now about your 14 pin connector. Did you unplug, then snap the backs off the two halves to inspect the solder joints. I've seen many of them broken, making intermittent contact. This is where the signal passes to engage the starter. This is probably where I'd put the next bit of effort if you haven't already addressed it.
Did you replace temp II? Are its threads clean so it grounds to the water bridge?
We used to live in Elkin during summer.
#24
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After she is dead, you try to crank her and she acts as if the battery is dead and won't turn over. The starter acts as if it's been heat soaked. Let her cool down an hour or so and she starts right up and runs.
I will say, on a possible positive note, that the couple of 928s with TBF that I have seen would still crank, just very slowly, as if the battery was down but not stone dead. Do you hear the solenoid click? Let's say there is an issue with the starter. That still doesn't explain the stalling. TBF would explain that as well as (slow) cranking.
You should check crank endplay regardless of "clean" oil.
#25
Nordschleife Master
You say CPS is fine.
How do you know this, have you tested the signal and the brain with an oscilliscope WHEN the car will not start? Or swapped in a known good one?
How do you know this, have you tested the signal and the brain with an oscilliscope WHEN the car will not start? Or swapped in a known good one?
#27
Team Owner
OK do this next,
check the crank end play first.
then replace the CPS, put in a new part.
Replace the 4 running relays,
Ignition,
LH,
EZK .
and fuel pump once it dies,
then replace these one at a time , and try to start the engine,
use 53 relays Roger sells em
check the crank end play first.
then replace the CPS, put in a new part.
Replace the 4 running relays,
Ignition,
LH,
EZK .
and fuel pump once it dies,
then replace these one at a time , and try to start the engine,
use 53 relays Roger sells em
#28
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Will do. I will order new 53 relays tomorrow from Roger and swap out the CPS. Will let you know what comes of it.
#29
Team Owner
do the crank end play first as if its grinding up you wont need the other parts
#30
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Colin: Of course, you know the CPS does not interfere with the starter. Just pointing out it may explain the car stalling, but it still should crank. It's hard for me to come up with anything that would cause the car to stall when warm and make the starter not crank over the motor but TBF. Doesn't quite fit that either if the starter is completely dead.