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Bumping the thread as I'm still struggling with this issue ...
I've already replaced the alt-to-starter cable, the starter motor, a new battery and I just did this swap over the weekend to replace the power distribution post & battery positive cable with a clean 996 version. My original part had some corrosion, but wasn't terrible. Anyway, no improvement with any of the parts.
Car cranks OK in the morning when cold, but stop to fill up for gas or drop into a store ... and you're lucky if it cranks over. I don't suspect the alternator is the problem as the car starts fine in the mornings and battery voltage at rest is ~ 12.7V when I checked on the weekend before swapping the distribution post.
I'm at a loss as to what to try next - the only thing I can think of is the ground strap cable in the engine bay passenger side??
What a coincidence, my car just died on the road this weekend due to what initially seems like a bad alternator (12.x Volts at battery terminals when running). The problem lies with the fact that there are just so many small issues that I suspect might have lead to my alternator being over-worked the past several thousand kms.... I have a bit of diagnosis to do over the next few days.
Wow that sucks. It seems like you have covered all the usual suspects. A couple recommendations:
1. I see you are in Ontario. I would imagine you have some corrosion on the underside. I would start there. Corrosion on a cable or junction box = resistance. Resistance = hot start issue.
2. So, I would inspect the cable from the battery all the way to the alternator for any signs of corrosion. I assume you already checked the junction box on the tranny when replacing the starter+alternator cable. I've read where that was corroded and caused hot start issues.
Maybe some of the other guys on here have a wiring diagram, but I would take off the center underside panels from the *** to the tip to inspect every inch of that cable. I actually have never seen where it goes forward of the tranny.
3. If you have a multimeter I would also check at every point in the system to isolate where its coming from.
- at the alternator
- at the junction box
- at the battery
-etc
4. A simple one, but maybe shouldn't be overlooked, have you tested the cold crank on the new battery?
Electricity is voodoo magic to me, so sorry I can't be more help here. Hopefully some of the other guys can jump in.
Thanks Bruce.
I agree ... electricity is voodoo magic! As a mechanical engineer, give me something tangible to work with - electricity drives me crazy.
I am in Ontario, but the car is only summer driven and was originally a Florida car. Underside is actually very clean. You're right, the junction for the alt+starter cable on the transmission was clean when I replaced the cable last year. But I just recently ordered a set of QuickJacks so I'll take an opportunity to get the car up and look all along that other cable to the battery.
I'll check the voltages at those locations too - both hot and cold to see if / where there's a difference.
Haven't had the battery tested, bought it in October last year pretty much just before it was stored for the winter where it was hooked up with a CTEK trickle charger. If it was weak, wouldn't that be noticeable at a cold start? Car fires up nice and strong when its cold after sitting over night.
What a coincidence, my car just died on the road this weekend due to what initially seems like a bad alternator (12.x Volts at battery terminals when running). The problem lies with the fact that there are just so many small issues that I suspect might have lead to my alternator being over-worked the past several thousand kms.... I have a bit of diagnosis to do over the next few days.
I just picked up a MY 2008 997 with 32K miles on it. It had the problem with the delayed start. I went ahead and purchased a used power distribution box from a 996 turbo and positive battery cable on eBay. Cost me $55 including shipping. I just finished replacing the bolt and cable as described by WhipE350. Took about an hour to complete. It started right up without any delays/hesitation. Beats me why Porsche would change from a well tested bolt-on positive lead to the distribution box with a push-on. Thanks for the write-up on this WhipE350.
"I just recently ordered a set of QuickJacks so I'll take an opportunity to get the car up and look all along that other cable to the battery. "
Your going to love the quickjacks.....I picked some up this spring to tackle this same problem and they made doing everything soooo much easier. You'll do all sorts of maintenance with your new easy access.
It's been a couple days since the car got towed home with a failed alternator and before just throwing a new one at it I wanted to poke around to see if there was more than one problem. Here's a quick rundown of what i did and found.
Battery charged up and was functioning well. tested at the local parts store.
Inspected and cleaned the junction box b+ connection. the tip and base of the post were corroded, so i cleaned the them up and reassembled. the main area of shaft where the connection was looked very clean and tidy. still appeared like it was a good conductor in that sense.
cleaned and inspected b+ connection at gearbox. looked good.
I then did a few voltage drop tests on the b+ side and also ground circuit of the starter during steady cranking (all cold, not heat-soaked)
b+ voltage drop from battery post to firewall junction box:0.07V
b+ voltage drop from battery post to gearbox junction 0.37V
b+ voltage drop from battery post to starter 0.53V
battery negative terminal to engine ground strap on body 0.15V
All this seemed ok, so I inspected the alternator and was going to replace just the voltage regulator, but some of the resistance readings did not match what the local YouTube stars had seen. When I cracked open the housing and pulled the rotor out, it and the stator looked terrible. There was quite a bit of corrosion on the internal components so it seems full replacement makes sense. It looks as though a PO might have had the engine bay detailed or there was a lot of moisture in the area. The bearings were also pretty ****ty.
Yes Voltage drop at the alternator should have been your first test. I think it was understood you had done that. Make sure you check the difference in v drop from alternator to battery. That's where the problem usually exists. You list a lot of points but it is generally a problem from B+starter/alternator back through the transmission junction to the firewall power distribution panel.If you have tested cleaned and replaced anything faulty then it's a ground or power supply problem.
I at first suspected my alternator so I removed it and had it tested. It tested 110%....literally. And it looks like crap because aluminum doesn't like anything.
If you haven't yet replaced your B+ alt/starter harness.....you'll be back. Just replace it. done fixed..and if you have aready....do it again. mines been done twice.
Oh yea.... saved $350. Retrofitted for $33. I actually utilized the capturing nuts off the firewall for the battery stud. I hit them with a wire wheel and tapped them so the coating came out of the threads too- they let you have a nice wide perch for the cable ends. I picked up two nuts and washers for the firewall studs from ace.
I agree ... electricity is voodoo magic! As a mechanical engineer, give me something tangible to work with - electricity drives me crazy.
I am in Ontario, but the car is only summer driven and was originally a Florida car. Underside is actually very clean. You're right, the junction for the alt+starter cable on the transmission was clean when I replaced the cable last year. But I just recently ordered a set of QuickJacks so I'll take an opportunity to get the car up and look all along that other cable to the battery.
I'll check the voltages at those locations too - both hot and cold to see if / where there's a difference.
Haven't had the battery tested, bought it in October last year pretty much just before it was stored for the winter where it was hooked up with a CTEK trickle charger. If it was weak, wouldn't that be noticeable at a cold start? Car fires up nice and strong when its cold after sitting over night.
I’ve read elsewhere that the crankshaft position sensor can also play a role in this symptom. Maybe a thought?
I’ve read elsewhere that the crankshaft position sensor can also play a role in this symptom. Maybe a thought?
I think with a bad crankshaft sensor it will still turn over well and strong but would either result in a crank and no start, or maybe just a long crank. Would unlikely lead to a "slow" crank as mentioned here. ECM looks for both crank and cam signals to send the spark signal.
Also to update my post above, checked the voltage drop at the alternator to be sure, it was fine. got nearly the same values as to the starter, which i documented above. Also confirmed the voltage drop from starter to alternator during cranking was about 0.3V while cranking (if memory serves me correctly).
So to summarize, cleaned and inspected all connections from front of car to back. The actual cable seems good to go and with a new Bosch alternator the car is running well. Over the winter I plan to rebuild the starter as previously outlined by another RL'er.
Just as an FYI I had to replace my two idler pulleys. The bearings were pretty dry and old. I saw the price of the OE replacement parts and they were about $80 each. I snooped about the internet with the measurements of the OE idlers and I was able to reverse engineer a set of generic Dayco pulleys @ Rock Auto that would do the trick.. Picked them both up for less than $25 but had to make 2 new aluminum bushings to mount onto the block with the original bolts. Made them on my mini-lathe and they work like a charm.
Well. Just got done with mine. I didn’t think this was the issue because the pin looked brand new. Sure enough, no difference Ran it, stopped for 2 minutes and it wouldn’t fire back up.
I miss my BRZ lol
Well. Just got done with mine. I didn’t think this was the issue because the pin looked brand new. Sure enough, no difference Ran it, stopped for 2 minutes and it wouldn’t fire back up.
I miss my BRZ lol
did it at least turn over for you? if so, it's likely not the battery topic.
did it at least turn over for you? if so, it's likely not the battery topic.
Yessir.
What happens is that after, I'd say more that 15 minutes of driving and if it doesn't sit for at least 3-5 minutes after being turned off, then it won't fire up first time. It will turn over very slowly and then stop turning over, then all the indicator lights come on. Turn car all the way off, scroll the internets for a few minutes. Start it up and go.
The battery has been testing fine but I took it in to get the CCA tested and it's down to 578. So, not great, but probably not the problem. After more browsing on hear it sounds like alternator cable or starter but I'm leaning towards starter. I've order my torx bits and 24" extension and will tear into it starting this weekend. With the hemorrhaging shock, she's just gonna sit anyways!
08-15-2019, 04:13 PM
