996 Stall / Startup Problems

I have a 2000 C2 manual with roughly 90k experiencing a stall / startup problem... First event was after a 30-minute drive, car stalled entering parking lot shortly after low fuel signal came on. At the time, assumed possible empty tank scenario. Luckily was next to gas station. Filled tank, would not start. Had my durametric with me, but unfortunately pc battery was dead. In the meantime, let car cool down, checked battery and other fluids... all good. Tried to restart, no go. Went home to charge durametric, and research troubleshooting. Learned about observing tachometer to rule out cam position sensor issue, and jumping relay to rule out issues with the relay, before assuming or troubleshooting the fuel pump. Returned to the car a few hours later, hooked up durametric and found P1137 (446, clutch switch signal implausible) and P0336 (110, Engine speed sensor open circuit). The former error is not new and mechanic previously confirmed related to clutch micro switch being loose. The latter I had never seen before. At this point, I cleared the codes, and upon attempting to start car, it immediately started without even a struggle. I assumed that clearing the open circuit code did the trick, felt too simple, which was later confirmed as I'll describe below. Drove it back to the house and everything was fine, until I got it in the driveway when it stalled and would not restart. This time however, the durametric did not detect any error codes. I left it outside overnight, and planned to do the prescribed troubleshooting, but it immediately turned on. I shut it down to see if it would turn over again, no problem. The consistent pattern is 30-minute drive ending in an inclined/bumped stop resulting in stall, and restart after x hours rest. Two other things to note: I historically have had the occasional struggle getting the car in the garage (entry has slight incline) with the engine having rough idle. As this was my first porsche and been a while before purchasing that I've driven manual, I just chalked it up to user error. No issues on hills up/down, but maybe 1st gear / low rev combination may be triggering something. And the only new thing I noticed because of this experience, which may be unrelated, is the dash oil sensor reads low. Dipstick reads full and I recently did service and no overheating issues. On background, this car has received an engine refresh a few months ago and has been running fine. Any thoughts?

Quotes source post: 19050582

what does "engine refresh" mean exactly..? What parts were changed and why? The Crankshaft position sensor is the one that causes the tachometer needle to jump (not cam position sensor or relay as you said above). And a bad CPS is the one that creates the problems exactly as you've described above. When it dies next check the tach needle. If its not moving try spraying/flooding the CPS with WD40 or brake clean to cool it down. This usually cools it down enough to start righ back up if the problem is the CPS... jmo

Quotes source posts: 19050653, 19050653

Mainly top-end refresh... timing chains, guides, tensioners, lifters, springs... while doing IMS, clutch, AOS...also fuel filter and some other bits like water pump, low temp thermostat, etc.. No sensors replaced. Good correction on crank, not cam! Presuming I experience this problem again, will follow your tip, though would not be able to get to it without a jack. Assuming the sensor intermittently fails by overheating, are there other symptoms or ways to monitor on durametric that would identify this as the source of the problem without waiting for it to fail again?

Quotes source post: 19050861

Yes. When the car won't start watch your tachometer (or hook up Durametric and read engine rpm). While the starter is turning the engine the tacho should jump a bit and Durametric should show about 150-200 rpm. If the tacho is stuck at 0 or Dueametric still reads 0 the crank pisition sensor needs to be replaced. You issue - no hot restarts - is a typical failure mode of the crank position sensor.

Code P0336 means there was a fault detected in the Crankshaft Position Sensor... This code rarely comes up even when many many crank position sensors fail to start or run..( ie. no codes) but when it DOES come up, YOU HAD BETTER BELIEVE IT........ or you will be guessing and chasing you tail..

Quotes source post: 19051049

Well I ordered a new CPS and installed this weekend... quick and easy. WOW. Not only did it fix my stall / start-up problem, I experienced an immediate difference in the engine as I traveled up the gears. Checking the durametric engine roughness, and confirmed improvement before/after on a couple of cylinders. I guess It's the kind of thing you don't notice with this apparently slow failing sensor... I wonder how long it was on its way out. Thanks for all the tips.

Question for OP�.When you stalled it and tried to restart, did it try to restart acting like a low battery or did nothing happen at all in engine bay and dash lights worked? Trying to draw correlation with your story to mine. Stalled my 2093 C4S at intersection (getting use to LWFW). Tried to recrank, but felt like low battery. Pushed out of intersection. Would not start even with a jump. This time starter did not even try to engage. Towed 1.5 blocks to house, after waiting 4hrs� After ruling out failing battery, went down the ignition switch path. Still nothing and now 4 codes come up and rear wing goes up and down erratically. Talked to Pedro at Pedro�s Garage, who happens to be local. Now leading suspect is bad immobilizer under drivers seat, But�..CPS sounds like it�s a possibility too�. Thoughts?

Its super easy to see if the starter is getting its start signal. U just need to probe the back side of the relay or the wire at the main engine harness plug on the right side of the engine bay. My bet is you have a start signal and the starter is bad? Plenty of simple dianostics to direct u to the issue without throwing money at it. If the carpets not wet i doubt its the imobilizer. I could also be a coroaded wye cable

Quotes source post: 19547732

IIRR, immobilizer will not let the starter crank slow, then not crank at all. It won't let it even try to start/crank if its bad. I'd go with what DJ said. Starter control voltage test, then if needed...Y cable, bad battery. You said the battery was ruled out... Did you load test the battery..? or just a voltage check..?

Thanks de jeeper and allcool. Back on battery first: First time I tried to restart after stall engine tried to crank but drug and wouldn�t start. Moved car with help of good samaritan, who gave me a ride home. Picked my battle wagon (LC200) after topping off a known good battery. Drove back to car with wife and put in battery. Same result, full dash and other items working doors, alarm, frunk. Since not new battery added jumper cables from LC200. Still nothing in engine bay. Don�t have ability or not smart enough to do load test of battery, but figured good on start power side with both batt and cables running. What is Y cable and if you have a pin-out diagram for rear connector that would be helpful? Also once home I replaced ignition switch with Pedro�s help, pulled CLU/immobilizer, ECU, and checked relays on shelf behind seats� no obvious issues when looking at connections or signs of water intrusion. In FL with humidity so Pedro idea was to crack open CLU and bath it in 99% isopropyl alcohol. Other considerations: after ignition switch replacement got up to 3 failure messages along with rear wing up and down erratically.

Car is new to me, successfully navigated Tail Of Dragon on my eighth rally up there. Worked flawlessly. Really bummed that it�s stone cold dead right now. Underrated whip for sure!

Yea like i said the starter is my guess without diagnostics. When mine would get hot it would really draw the battery down and bearly start the car. Eventually the motor fails and it wont spin. To test the battery remove it and take it to the parts store or sometimes they can test it in the car. A battery can fail so bad that even with a second one to jump ot still wont work. Strangely enough it will still power low power items. There is a yellow wire in the 24 or 25 position of the x59/1(right side large round plug in engine bay) plug. It connects to pin 87 of the starter relay on the back shelf. If u have power in that wire with the key turned the start is getting the start signal. Search for info on the wye cable. Its a common issue where coroasion creates an issue with the heavy gauge power wire. Oh yea the codes and wing issue may just be a function of a low bat power or a no start condition. What r the codes?. Do u have a multimeter? If so check the voltage and see if it drops below 9v when the key is turned.

Last night I looked for voltage at starter lock relay (position 7) behind seats on parcel shelf. Nothing although relays were warm. Wonder if I was on wrong terminals, ie switched vs switching�. Cleaned up CLU/immobilizer outside of casing last night and have fresh battery in for today�s checks�

U need to check pin 87 by pulling the bottom cover an back pinning. Or get a realy test modual. I use this kit for testing. https://www.fcpeuro.com/products/rel...xoCAcAQAvD_BwE

Changes from key on 0.01 v to 0.35v while key is in start position. Confirm relay, position 7 is correct?

Another tidbit: Just got back from Advance Auto. The battery that was in it when it died is at end of life and the big one in the picture is �really good�� I�ve been using the big one since I got home and trying to fix this bad boy�

Now u have to check the other terminals. Pin 30 is also yellow. It should ha e 12v when u turn the key to the start position. Pin 85 is ye/vt/bn goes to pin d33 in the dme. This should go to ground when the computer sends the signal to the starter (key in start position) Pin 86 rd/bu this should be 12v with the key on its power for many relay coils and sensors

Thx, but starting at the start…if I’m expecting 12v at pin 87 while ignition is in start position and don’t get it (showed 0.35v). Doesn’t that mean there is a problem upstream (no signal/current going to start relay)…? BTW you had asked about fault codes previously. Pro version of Durametric should show tomorrow and I’ll be then able to read fault codes… That said, not sure that Durametric can read or diagnose the immobilized/CLU at the component level. LR

If u look at the diagram of the relay posted earlier.... 30 is 12v power in 87 goes to the stater seliniod For 30 to connect to 87 the coil must energise. So one side of the coil needs 12v and the other is ground. The 12v is supplied when the key is on and the dme closes the ground. So u need to test each pin. No power to 87 means the relay is not closing. The results from the other pins will tell u why. 1. 12v to pin 30 means u have power to the relay 2. A continuity check between the small wire on the starter and 87 will tell u the wire is good to the starter 3. 12v on the coil tells u its ready to energise 4. Ground On the coil tells u the dme is telling the coil to close, thus allowing the stater to fire. This is the first step for diag. U can also go through every fuse up front and in back. There is also a fuse on the immobilizer. It may be as simple as a blown fuse. To check the immobilizer u have to pack it up and send it, your key and the dme to www.ecudoctors.com . What i can say is i have never seen an immobilizer fail like this. Learing how to diag electrical issues is worth the squeeze.

Got ya - Will go through in order you prescribe. Yes one of the fist things I checked was 15a mini-fuse on immobilized. All of the related fuses are good up front have not looked at fuses in rear yet. Thank you.

Several codes. Will go through the Start Lock relay (position7), but suspect all it will do is confirm that no switching voltage is even getting that far with the first image with �fault 33 DME-immobilizer, open circuit.� under Alarm I48 Durametric menu. Hope is someone has seen this before and knows what the fix is�.?

Quotes source post: 19555834

Should have 12v at term 30, try jumping terminal 87 & 30 together. That should spin over the starter motor if all is good there. This will tell you if its a control signal problem or starter system problem. Make sure car is in neutral when testing.

Update: now have 12v to pin 30 on position 7 (start lock) relay with key in ON position. AND relay 7 clicks�at same time. Is that normal behavior for that relay where it is unlocking the ABILTY to start�. Saw other posts talking to jumping pin 30 to 87 and engine (starter) should crank� when I jump those pins, nothing happens, other than the dash voltmeter moving slightly. So still not fully understanding the system. Makes me think it�s one of two things: I installed the ignition switch wrong if the start lock relay actually should not function (click) when key is turned to on, but only when turned to start position. Or�.the starter is bad� Is this logical?

Ok missed above msg. Sounds like the signal side is fine but the start side is not�again when I jumped pin 30 and 87, engine did not crank. OBTW I have the clutch safety switch jumped also�

I suppose I could just start the work to replace the starter. 94k miles on engine and not seen any PO notes on starter being replaced� Worst case I have a reliable starter for hopefully the remaining life of the car� There�s an FCP video on starter replacement. Well within my capabilities, just wish car was on lift to raise some to optimize reach vs bending down. Looks like starter is around the 11o�clock position of engine. In fact pulling it now before a replacement in hand will allow me to bench test it. And will also ensure there is no corrosion or bad grounds (?).

Quotes source post: 19555990

Yup, sounds like a bad starter. Powering up term 87 directly energizes the starter. You Seeing the voltage drop means its pulling current and not spinning. Only other thing could be is if Y cable is totally bad not letting hardly any current thru... By the way, jumping out 30 to 87 bypasses the clutch safety switch, directly feeding the starter solenoid. Would advise to check continuity of 87 small wire to starter, but you said you see a voltage drop when jumped so its probably good and starter windings are pulling current/shorted/bad. At this point its uneeded but could play around and clamp an amp-probe on big wire to starter or even on the battery either neg or positive and jump 30/87, should see amperage draw,,, or maybe smoke at starter (lol) if starter is trying to spin with shorted windings. Unless starter windings are now almost totally open. jmo

Not too bad pulling the starter. Think the engine had been dropped before cuz the band clamps were all clocked awkwardly on the two plenums�Fortunately was able to get really small box end wrench in there to start to loosen, then flexible 1/4 drive extension to speed things up� Starter INOP. First bench test try, bendix tried to come out but didn�t and nothing from the starter motor itself. Reasonable price for 100% new Bosch starter ordered on Amazon. Probably made in China, so will see how long this one lasts. One coming out didn�t have any manufacturing date visible, probably covered by the Bosch remanufactured sticker, so not the first time the starter has been replaced. This is third component (ignition coils, injectors, now starter) on this car that�s OEM and made in China. For a reasonably priced 996, have to put up with non German parts, but really that�s the only OEM option without paying Porsche labeled part prices which are 3-5 times the cost. I at least hope that if you buy Porsche parts they have a shred of pride left and have smaller runs of those parts made in Germany. If not and they�re still made in China, that�s insult to injury!!! Will update when starter installed. Thx, LR

Final update: C4S is back in business. It was the starter and now I have a buttery smooth ignition and newfound 996 knowledge as a bonus. Starter job was interesting. Like a country vet shoulder deep, delivering a calf. In this case, different liquids and smells. Broke off that pesky coolant line connector right behind the idler pulley and had to find fix for that. See pictures attached for my solution. Was able to use the existing plastic bracket. Drilled it out and it worked perfectly with metal connector. Thanks so much to those of you that took the time to provide advice! Rennlist is a great community and hope to pay it forward as able. Cheers, LR

Nice.... and yea everyone breaks that nipple.

Get this and solve that problem forever:

Great you got starter in and running..!!! My solution for broken connector... Used the old connectors drilled out base to secure this brass barb coupling. If I can make do with an economical replacement thats as good or better....

Even better if you don't live in the northern ice country is eliminate that coolant line all together.

All good ideas. Biased, but like my solution best. My barbed connector was perfect length and had a larger ID than the brass stuff. Used 1ea stock removable clamp that was beefy and two of the largest in this pack on other side.