Does anyone have info on code p1397

pulled from a boxster with DME 7.8 . i would not expect these to be that much different. Hey Guys I was just wondering if any of you have any info on P1397 ( cam sensor bank 2 ) . I am trying to help a buddy T/S this code after rebuilding his 996 3.4 engine. He hung a scope on the sensor output and we can definitely see the Hall effect sensor activating and deactivating as the cam goes through the field. But the scope is capturing an overlay of both left and right bank Sensors. ( this is how Porsche does it and sends it to the DME on one line ) We were able to find a diagram of what a boxster is supposed to look like but it is way off from our profile. Was wondering if any of you tech guys have a picture of a profile of what the motronic (5.2.2 I believe as its a 99 3.4 ) looks like for this signal that the DME is expecting . I will also ask on the 996 forum but I know we have a few technical guys on this forum also Thanks

the two pics we have what a boxster looks like what we have ( the hall effect profile is above the crank profile ) . As you can see it lookes like something is not right . So we were looking for if anyone has a profile of a M96 7.2 cam sensor profile we can check against

Try posting in the 996 section may have better luck there, or 996outpost

you've got a 996 3.4 engine (ie, 7.2 dme) in a later boxster with a 7.8? if so, then you will get cam issues - the variocam systems are different.

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no no no , it was just the only pic we could find on line was one for a boxster with 7.8. I know there are a couple of tech guys on here so just wondered if someone local had a picture like the one I posted of the boxster so we could compare. People at large don't go to this level of troubleshooting I think , they just swap out the sensor and take it to someone if that does not fix it . I thought there may have just been one or two interested parties that wanted to discuss it . Besides that I would expect the engines at idle to post pretty well the same , as vario cam kicks in off idle. personally I think its an incompatible replacement or a wiring harness issue . I will move to plan B , wake up the rennlister with a black/black 99 3.4 in Burlington and get him over here for a comparison. I'll probably need to bribe him with food though.

Since my heads are still sitting on a bench, I can pull one and bring it over to see if that makes a difference. Or I can ask my buddy with a 99, to drive over and see what his sensors show on the scope.

i have wiring diagrams for most iterations of 996, so if you can get me part # for the harness being used, and year of the car it is in, i can do some looking. if it is a mismatched harness then it is probably just a matter of moving some pins in the connector.

Thanks Guys He ordered a sensor off amazon rather than pay the Porsche tax so I am thinking they are incompatible. That's what I meant by mismatched Imre, Ed might take you up on that, if you can pop it off let me know and ill take it over to Eds. ( Mark it though so we don't get confused. ) .. just pop it in and se if it fixes it . In our troubleshooting we have established the harness is fine . So its either the sensor of we are off slightly in the timing. We are borrowing a Durametric on the weekend for further investigative work if we cant get to the bottom of it so yeah we might have to call in your buddy to see what good looks like . I asked Colin to and he offered to help. .

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Ok, I'll give it a go and see if the sensor comes out of the head.

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Thanks Imre I might go see Ed tonight..

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Send me a text if you do and I'll pull the sensor and go see him as too. I'll bring my little guy, he has small hands, comes handy working on tight spaces.

'99 3.4 is a 5.2.2 DME. Only four possibilities for that error, open circuit, short to +, short to ground, or faulty sensor. Here is the oscilloscope output for the 5.2.2 DME And here is the wiring diagram for the '99 as well For comparison I've added the output for the 7.2 and 7.8 below The factory diagnosis manuals are quite comprehensive and make backyard maintenance on these cars quite simple; contrary to popular opinion. Todd

Sorry, the 7.2 didn't post. Here is the 7.2

Todd that is fantastic , exactly what Ed and I have been looking for, thank you so much. . I borrowed a Porsche durametric analysis tool from a buddy and am heading to Eds this afternoon to check it out . here is my follow up question . We have been scoping pin 21 which is an overlay signal of both cam sensors as your schematic indicates. But your scope picture is of pin 20 and looks more like a crank pules !! are you sure that's the cam pulse signal you indicated in your last pic ?? Thanks

Last pic is for a 7.2 DME just for comparison of all three types of signals on the 996 . If you have a '99 C2 3.4 it is a 5.2.2 DME you have a throttle cable and not egas and the DME has one large black connector. In '99 only the C4 used a 7.2 DME and had egas and there are 5 small plastic connectors to the DME. Therefore you are probing the correct signal ( pin 21) as indicated in the first picture in the first post I made if you are looking at a '99 C2. One reason why the 7.2 and 7.8 cam sensor profiles look different than the 5.2.2 signal is that there is a separate signal for each cam sensor with the later DME versions Crank sensor on a 5.2.2 looks like this and is pin 78 Todd

Thanks Tod This is a really interesting one to troubleshoot Aa you can see the image on the scope is exactly as you describe( second pic ) . My scope picked up exactly what we were supposed to. We overlayed the crank signal on it and that looked fine too. We even disconnected the sensors one at a time And saw the cam pulses drop out. You can see the pic where we disconnected cmp on 1-3 and the pulse disappeared.( first pic ) Durametric showed no pulses for cmp one or two and the code came back Immediately after we cleared it. ( I am beginning to understand DME does not have a scope function , you actually need both for a good analysis, the Durametric will tell you the values over time but you need the scope to see the picture. At this point i am suspecting bad dme as we see a perfect pulse at the sensors . Will confirm by swapping shortly I hope all this helps someone in the future and I will continue to update. PS does anyone know how to cross post these things or do I have to copy and paste the whole thing ? I think 996 forum may be interested.

This is what I have surmised by our testing and Todd's excellent info . 1. Both Cam sensors are working and reporting a plausible waveform to the DME from the signal wire of the hall effect sensor illustrated by the two pulses. 2. On the second 360 degree rotation of the crank the engine sees no pulses from the sensors which agrees with the manual but which I find VERY odd. One thing I am unsure of is on the scope it shows one full cycle of the crank about 70ms. In Todds data it shows 35 ms , but the illustration may be used to show the different pulses and is not representative of one full crank cycle. interesting stuff ( to me anyway )

The crank to cam ratio is 2:1 so there shouldn't be any cam sensor signal on the 2nd 360 or am I wrong?

I wish this thread was in English..... just kidding.... good work guys.

Okay Ed Imre and myself have been working this problem for weeks and we have learned a lot ... mostly that it is really hard to steal a Porsche unless you have a tow truck . The next attempt is to try and get the car running with another key head ( crypto chip ) immobilizer module, and ECU all from the same car.. if the car then starts we can see if the problem follows , but looking over the weekend data I may have seen something in the data .. look at the scope output below ... you can see where CMP one and two go low for a few milli seconds as the sensor see the flags pass through on each cam .. sort of what we expect , but look closer , look at the time between the pulses ( between the purple arrows )... it is about the same thickness as one of the pulses... roughly I would say about 20ms. Now look at the pic below , this is out of the manual ... it is not very high resolution but it looks like the pulses are a lot closer together. This would indicate the software is seeing sensor two too late. Which would lead us back to a mechanical issue. If what I am seeing is correct ( and that is a massive assumption) it would indicate we could be off one tooth on our cam sprocket. it is likely enough not to cause any other issues beyond a code and maybe a rough idle. More to come ...

If I had to bet my right nut, I would say the left intake cam is advanced by at least 1 tooth but we'll graft on my ECU, immobilizer and key onto this car and see if it finally starts with it.

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Imre wouldn't you say its retarded one tooth ? if it were advanced would it not be overlapped on to the other sensor ?

LoL Sorry to interupt the Nerd Fest but did you guys read this thread , similar circumstance. Start at Post #23.

Thanks Mark I have read over those posts before. I reached out to Doug for his timing procedure so we will see what happens. Since this comes up often after a rebuild , it has to be in the mechanical timing somewhere. Imre how much variation do you think we have on the slots in the cam ? do you think about a link or so ? I think the slot is to vary timing with the crank, you still have to have the two cams on the right links. I'm sure Todd will know. This is an interesting one to be sure.

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Yes, you are probably right. It looks like the 4-6 bank intake is at least 1 tooth off. I'm thinking it's closes too soon and doesn't fill the cylinders with enough air to make it run well.

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Don't know but I can look at my cams since they are still on a cardboard box.

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next year will be the year.. I can feel it

We think we have it !!!!!! Data showed cam pulse for 4-6 coming too late as mentioned. We checked a cadaver engine and with Imre's car which showed 15 teeth between cams. We calculated if it was off one tooth the cam would be off about 17 degrees. We took pics of the cam sensor flag. On both engines at tdc and sure enough it looked like about the 17 degrees as suspected. That was enough for us and the work started to take that side off to inspect. About half an hour later we had the exhaust and cam cover off and oil drained. Then we did the count. And sure enough 16 teeth. It must have jumped during assembly. Bingo !!!!! Another half hour releasing the tensioner and intake cam, popped the front pad off the tensioner and that was enough to move it a link. That was enough for the night but we are pretty sure we got it. Next is the clean up reinstall of covers. Oil back in and testing

Car all put back together and running great. no codes, pulls strong and his been running great. A good diagnostic exercise to be sure.

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Awesome!

Sorry to revive an older thread, I believe I have the same issue where the Bank 2 exhaust and intake cams were timed incorrectly. @theiceman were you able to correct this with engine in the car dropped as far as it would go? My symptoms were P1397 and misfires on all bank 2 cylinders. Idle was slightly rough, exhaust pressure from bank 2 was less than bank 1. Interesting when driving I would clear codes and as long as I was above 1500 rpm I only got the P1397 and not the misfires. I also took some more oscilloscope images. I am seeing that same 20ms delay between pulses indicating timing is off one tooth. Without VarioCam engaged With VarioCam engaged