Boxter Newbe with massive problems.... - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Hi guys, I've bought a Boxter 986 from 1998 (really cheap) which didn't start. Because I'm technican (electronic and mechanic) I had no concerns about not getting the problem under control But now after more than 50 hours of unsuccessful troubleshooting, I've got a little nervous. Here the wohle story: The previous owner of the vehicle parked it in winter 2014 (Garage). In the spring of 2015 the engine did not start. The car came to a free workshop for checking and changing the battery For reasons that are no longer comprehensible, the vehicle has been parked there outdoors, not overcahted, for almost half a year. During this time, the rear window apparently cracked and water penetrated into the interior of the vehicle. Inevitably, this destroyed the control unit for alarm, convenience and immobilizer, under the driver's seat. This control unit was renewed by a Porsche workshop and adapted to the vehicle key. Nevertheless the engine still did not start. Porsche workshop says engine ECU must be defective. For this (new) ECU, Porsche wants to see €6.000,- on there bank account. In words: SIXTHOUSEND, no joke. Since 2015 the engine has not been running. In this 5 years the car was in several free workshops, but no one could solve the problem. Therefore the previous owner decided to sell the vehicle, and that's how I came to this game. I bought a used ECU at local car reclaimer for €500,- and cloned the immobilizer data from the original ECU to the spare ECU. But the symptome is still the same. When turning key, ignition is on, all lights in dashboard are lit, but no reaction (and no noise) of the startermotor. The starter itself is 100% ok, because when I bridge the "startenable-relay" in trunk, starter runs but engine still doesn't start. What I've found out: "Main-relay" is correctly activated by the engine control unit. 5V Output Voltage of the ECU (for some sensors) is present. "Startenable-relay" is not activated by the engine control unit I've checked all fuses, all relevant cable connections (I have original circuit diagrams) but no abnormalities. Faultmemory of Motor-ECU and Alarm-Immobilzer-ECU says 0 Errors !!! All supplyvoltages (30, 15, 86s and 31) on both involved ECU's is checked and seems to be good. Signal of "engine-speed-sensor" and "hall-sensor" is checked (with scope) and is present in plausible amplitude and frequency too. But there is no measurable signal from the ECU to the ignition stages AND injectors. I'm really confused now. To me it seems as if the engine control unit is missing any "start release" So I have a question to you 986 owners: Is there any status which can prevent engine start ? With status I mean position of the convertible top, engine cover, trunk lid, driver/passenger doors, and so on. It's all open because of troubleshooting. Is it necessary to press brake and/or clutch while starting ? Or does anyone have hint for me where to search for the problem ? b.r. Spinokovits

Are you sure that the ECU, immobilizer, and the key fob transmitter are all programmed with the same code?

Sounds like the key/dme/immobilizer aren't matched up. 1 thing would be to find someone close to you that you can take the combo from your car and put in theirs to see if it still starts, or do the opposite. Other thing would be to send it off to someone like ecu doctors for testing/fixing. next would be to get a durametric that can scan the immbolizer and look at all of the codes, a standard reader can't do this. Of course, the dealer should be able to do this also. Not sure how you (or if you had someone do it) "cloned" things over. This isn't a simple thing to do with these cars.

Yes, it is necessary to depress the clutch to start the car. The door, trunk lids and top position don't effect starting.

Thanks for first ideas. @Stl-986 This was my first idea also. To check this, I removed the transponder from the key. Then immobilizer throws error "wrong key or key not matched" and cant be cleared When puting transponder back into the key, error is gone, respectively can be cleared. So I hope this should be OK, but not fur sure of course. Would be a great idea if I had someone with the same car nearby. But unfortunately I haven't. That's my daily business. ;-) Not for Porsche´s, but for VAG group (VW, Audi, Seat and Skoda) and you're right, Porsche seems to be a little different. I have all the tools (and 20 years experience) to extract and read/write the memorychips of most ECU's. @thstone Not 100% for sure, but because no error is stored in immobilizer (except I remove the transponder from the key) I think (hope) this should be OK. Any other ideas ? b.r. Spinokovits

If this is a manual transmission, are you certain that the clutch interlock switch is not faulty? A manual transmission Boxster will act as you describe if this switch is not functioning properly or the clutch pedal is not depressed all the way to the floor (and I mean buried in the carpet).

There's a fuse on row B or C that will keep the vehicle from starting if it's blown. Same with the fuse on the immobilizer and if you have a bad starter relay located in the trunk. I believe only north america has to press in the clutch to start. Everywhere else has the ROW tune and you can start without your foot on the clutch

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Good approach. I've checked it an found out the following: According to the original circuit diagram, it looks as if the clutch monitoring is only installed (and active) in (manual) vehicles in North America and Canada, while this is not the case here in Europe. (Really no idea why) In any case, a clutch pedal switch is not installed in my vehicle and the corresponding cables are not present at this point. Is there any other known fact that can prevent the engine from start ? b.r. Spinokovits

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Hmmmm I've checked all the fuses, but I will do it again just to be sure that I've nothing overlooked. ;-) The starter relay is not bad. If it is supplied with power when it is removed, it switches as normal as it should. The problem is apparently that it is not activated by the engine control unit. The question is why? I only bridged it on a trial basis to rule out the starter motor as faulty. I think the reason why the starter relay is not activated by the ECU is the same why there came no signal to the injectors and spark stages. b.r. Spinokovits

Doublepost sorry.

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So is it a tiptronic or manual?

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Manual, WITH clutch of course, but without clutch monitoring switch.

Ok. Yes ROW cars didn't have the clutch safety switch that US cars have so you can eliminate testing for that. My gut still tells me it's an immobilizer issue. Now, if you are lucky you might have a breaker yard that has a matched set that would allow you to borrow or return them if you bought one. Not sure exactly where you are but you could check with the guys over in Boxa.net, they are mainly in the UK. Might also want to check with any Porsche clubs to see about reaching out to any members.

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When I first got mine there was an odd relay with a fuse jack at E6 (telephone/terminal 30). Removing the jack or fuse caused the car to behave as described. However, I recently re-tuned to ROW version and this is no longer the case. If you're in Europe and have an ROW tune then this won't be your issue. The part about the clutch depression is also true. On US tunes, the clutch must be fully depressed and if it is not or the actuator switch is bad then the car will behave as described. Again though, with an ROW, this feature is not active and clutch depression does not affect starting. Sorry I've got nothing good to add.

Wonder if the spare ecu is a ROW or US spec.

Interesting point! If the OP installed a US tuned DME in a ROW setup vehicle, that girls not going anywhere. Sent from my POCOPHONE F1 using Tapatalk

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I feel very similar, unfortunately I have not yet found any tangible evidence that would point to it. (No error entries) This seems a good idea. I'm searching for a complete set. But some guys where you can buy such sets are really very strange. The last one I asked, offered a set of immobilizer, key and "airbag control unit". When I asked about the engine control unit, he said that the engine control unit doesnt have immobilizer. Austria, east of Swizzerland, south of Germany. Ohh thats a good tip. Maybe they are selling those kits I need. There are already two of us. I really dont have any idea how to find out that. The car is definitifely a german car, no US-reimport. The spare ECU I bought is from germany too. They both have exactly the same Bosch.- and sparepartnumbers. (see pic attached) I think without a 100% good set of key, ECU, and immobilzer it is impossible to go on and exclude this as cause of failure. b.r. Spinokovits

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I would try to get ahold of a piwis and flush the 986 row tune to your dme. Sent from my POCOPHONE F1 using Tapatalk

Hi, I just fixed one with this exact issue. You need a new key. If you have the ability(I used PIWIS III), you can go to transponder key programming and look at all the currently programmed immobilizer ID's. Mine had none stored, but would give me a "key already programmed" with my old key. New key programmed immediately and started up.