Porsche Boxster 986 - engine swap project
Discussion
Moved onto the fuel pump. Went for the DeatschWerks DW300 (340LPH). On the Boxster the fuel pump basket has tabs on the bottom that lock it into the tank. That meant I couldn't use the pick up that came with the DW300. I was scratching my head trying to work out the best way of fitting it, I decided to hack up the old fuel pump so I could use the top and bottom sections of it. Turned out better than I thought.
I've turned my attention to the wiring. It took me ages working it out, both the Porsche and Audi wiring diagrams are a different style to each other which made comparisons difficult. Neither manufacturer has pin-outs for their wiring plugs and they aren't shown in one place, they are spread out throughout the various wiring diagrams which is time consuming to find. Other manufacturers list pin-outs for their various plugs, not sure why the Germans need to be so difficult? I've not retained the AC and I didn't have cruise control on my car so that's saved me some work. I've enjoyed every stage of this build except for working out the wiring, it's been a tough slog.
It's done now and i've started doing the soldering. Luckily, like I expected at the start of the project, as both cars use Bosch ECU's from the same era, lots of it is similar so there aren't really any major conflicts (famous last words). The Porsche ECU controlled the fans and the Audi one had a separate fan controller (which I didn't keep) so I need to go aftermarket but that's straightforward. Hopefully I might be able to fire it up soon.
It's done now and i've started doing the soldering. Luckily, like I expected at the start of the project, as both cars use Bosch ECU's from the same era, lots of it is similar so there aren't really any major conflicts (famous last words). The Porsche ECU controlled the fans and the Audi one had a separate fan controller (which I didn't keep) so I need to go aftermarket but that's straightforward. Hopefully I might be able to fire it up soon.
It's been ages since the last update. I've been really busy doing things but not lots of progress worth taking photos of.
The engine as it currently sits no i've connected everything up. I still need to sort out the breathers. You can see a neighbor's cat quite likes sitting on it during the rain.
I've fitted the turbo oil feed and return lines, that was a load of hassle. Also made a heat shield for the return pump as it's a bit close to the exhaust.
Progress is quite slow with the wiring. I worked out how to get around the Porsche immobiliser, the alarm control unit talks to the engine ECU and needs a signal back before it'll power up the various relays to run the engine.
The Audi ECU had an immobiliser also so I needed to get that removed. Luckily my mate Adam knows his onions with computers and electronics. We had to open up the ECU, short a pin on a chip to ground and connect the battery so the ECU went into boot mode. Then we could wipe the immobiliser chip which was done using a program that required command prompt. It was all past my comfort zone so i'm lucky Adam sorted it all for me. We were running out of time but we quickly coded in the 750cc injectors and the 4 inch maf housing so at least I could have a crack at getting it running.
I spent lots of time scratching my head wondering why I couldn't get the fuel pump to prime, turned out to be a poor connection on the plug inside the tank. With that sorted I was able to try and start it up. I was turning it over and it hydraulic locked on the starter motor. Pulled the plugs and found a cylinder full of petrol. One of the (new) Bosch injectors was stuck open. The fix was to take it off and give it a love tap with the hammer.
Once that was sorted I could finally start it up. It started up but I couldn't run it for long as the revs were high and climbing. I should be happy but the fault codes logged on VAGcom will keep me busy. The serious one is the throttle isn't happy, i've worked on the assumption that as the Bosch ECU's, throttles and pedal sensors are similar and from the same generation of car that they will all work together. The wires and their functions match. I'm getting these codes
18039 - Accelerator Position Sensor (G79)
P1631 - 35-00 - Signal too High
18042 - Accelerator Position Sensor 2 (G185)
P1634 - 35-00 - Signal too High
Looking around google, these commonly seem to be linked to earthed out lambda sensor wires. If that is the case it sounds like the damaged caused to the ECU is terminal.
I've also got
17834 - EVAP Purge Valve (N80)
P1426 - 35-10 - Open Circuit - Intermittent
17938 - Camshaft Timing Adjustment
P1530 - 35-10 - Short to Ground - Intermittent
17955 - Boost Pressure Regulation Valve (N75)
P1547 - 35-10 - Short to Ground - Intermittent
17695 - Boost Pressure Control Valve (N249)
P1287 - 35-10 - Open Circuit - Intermittent
I've also seen these described as terminal to the ECU. I know what's caused them, I am trying to keep the wiring nice and tidy and logical so trying to re-use the original Porsche relays. There is a relay that controls the O2 sensors, Injectors and coils on the Porsche, i've used this feed to power up the powerbus circuit on the Audi which powers these sensors. It turns out, it's 12v with the ignition on but switches to earth when the engine is cranking. So that's how everything has ended up shorted out. I've changed the power feed but the codes come back every time the engine is cranked. I'll have to crack open the ECU and check for signs of damage.
I'm going to forget about trying to get it done before the summer is over and just take my time with it and spend more time with the family. The wiring is grinding my enthusiasm down.
The engine as it currently sits no i've connected everything up. I still need to sort out the breathers. You can see a neighbor's cat quite likes sitting on it during the rain.
I've fitted the turbo oil feed and return lines, that was a load of hassle. Also made a heat shield for the return pump as it's a bit close to the exhaust.
Progress is quite slow with the wiring. I worked out how to get around the Porsche immobiliser, the alarm control unit talks to the engine ECU and needs a signal back before it'll power up the various relays to run the engine.
The Audi ECU had an immobiliser also so I needed to get that removed. Luckily my mate Adam knows his onions with computers and electronics. We had to open up the ECU, short a pin on a chip to ground and connect the battery so the ECU went into boot mode. Then we could wipe the immobiliser chip which was done using a program that required command prompt. It was all past my comfort zone so i'm lucky Adam sorted it all for me. We were running out of time but we quickly coded in the 750cc injectors and the 4 inch maf housing so at least I could have a crack at getting it running.
I spent lots of time scratching my head wondering why I couldn't get the fuel pump to prime, turned out to be a poor connection on the plug inside the tank. With that sorted I was able to try and start it up. I was turning it over and it hydraulic locked on the starter motor. Pulled the plugs and found a cylinder full of petrol. One of the (new) Bosch injectors was stuck open. The fix was to take it off and give it a love tap with the hammer.
Once that was sorted I could finally start it up. It started up but I couldn't run it for long as the revs were high and climbing. I should be happy but the fault codes logged on VAGcom will keep me busy. The serious one is the throttle isn't happy, i've worked on the assumption that as the Bosch ECU's, throttles and pedal sensors are similar and from the same generation of car that they will all work together. The wires and their functions match. I'm getting these codes
18039 - Accelerator Position Sensor (G79)
P1631 - 35-00 - Signal too High
18042 - Accelerator Position Sensor 2 (G185)
P1634 - 35-00 - Signal too High
Looking around google, these commonly seem to be linked to earthed out lambda sensor wires. If that is the case it sounds like the damaged caused to the ECU is terminal.
I've also got
17834 - EVAP Purge Valve (N80)
P1426 - 35-10 - Open Circuit - Intermittent
17938 - Camshaft Timing Adjustment
P1530 - 35-10 - Short to Ground - Intermittent
17955 - Boost Pressure Regulation Valve (N75)
P1547 - 35-10 - Short to Ground - Intermittent
17695 - Boost Pressure Control Valve (N249)
P1287 - 35-10 - Open Circuit - Intermittent
I've also seen these described as terminal to the ECU. I know what's caused them, I am trying to keep the wiring nice and tidy and logical so trying to re-use the original Porsche relays. There is a relay that controls the O2 sensors, Injectors and coils on the Porsche, i've used this feed to power up the powerbus circuit on the Audi which powers these sensors. It turns out, it's 12v with the ignition on but switches to earth when the engine is cranking. So that's how everything has ended up shorted out. I've changed the power feed but the codes come back every time the engine is cranked. I'll have to crack open the ECU and check for signs of damage.
I'm going to forget about trying to get it done before the summer is over and just take my time with it and spend more time with the family. The wiring is grinding my enthusiasm down.
Edited by Escy on Tuesday 16th August 01:47
I'm not stuck on the wiring, just not enjoying it as much as other parts of the build. I've got around the immobilisers, it starts and runs so all the hard work has been done plus i've identified a highly possible cause for all the error codes.
It's the realisation that it won't be seeing the road this summer that's pissed on my chips.
It's the realisation that it won't be seeing the road this summer that's pissed on my chips.
I'm leaning that way, I've done some tests the ECU isn't damaged. I've got VCDS which is the popular VAG diagnostic software, it can log all the sensors, the ECU can read the pedal sensor which is good news but the values are way off. I need to compare the values with my mates S4. Hopefully it'll be something that I can adjust on the software.
I'm chuffed to see this build has made it to the front page of Pistonheads, seeing that was a nice surprise. Thanks for that. 
superkarl said:
Pretty sure pedal values should just be 0-100.
I had a look at my mates S4 tonight and the values are 15% off the throttle and 80% full throttle. I've got a plan on to get this working. benillsley said:
Any reason you decided not to go for an after market ECU to run it? Cost? Or just because the standard kit is more than up to it?
The development done on the standard ECU is impressive so I don't see much of a benefit in going standalone at this point when you factor in the additional costs, although it isn't something i've completely rule out.Thank you all for the positive comments, I appreciate them, they are good for morale while i'm grinding away doing the boring jobs. 
I recruited some help on the wiring.
The Audi fuel pump relay also provides the power supply for the lambda sensors and injectors, I had these circuits wired up on separate relays but i'm getting a fault code on the fuel pump relay as well as all the other fault codes so have decided it best to re-do it. My mate picked this up for me from the scrappy as I didn't have the foresight to remove it from my A6.
I recruited some help on the wiring.
The Audi fuel pump relay also provides the power supply for the lambda sensors and injectors, I had these circuits wired up on separate relays but i'm getting a fault code on the fuel pump relay as well as all the other fault codes so have decided it best to re-do it. My mate picked this up for me from the scrappy as I didn't have the foresight to remove it from my A6.
She's the master tech, i'm just the labour.
The Audi fuel pump relay/distribution block fitted a treat on the Porsche relay holder which has helped keep it all neat and tidy. Everything has been wired up.
I got it started. Lots of the fault codes have gone. I've still got a temperature sensor code and the throttle pedal ones but otherwise i'm just left with the ones I expected now that will be coded out. I took a little video of it running. There is an exhaust blow on the v-band from the turbo plus it's in the car port so hopefully it won't be too loud once that's all sorted.
https://youtu.be/32okgq_I2Bg
It made a bit of a mess.
The Audi fuel pump relay/distribution block fitted a treat on the Porsche relay holder which has helped keep it all neat and tidy. Everything has been wired up.
I got it started. Lots of the fault codes have gone. I've still got a temperature sensor code and the throttle pedal ones but otherwise i'm just left with the ones I expected now that will be coded out. I took a little video of it running. There is an exhaust blow on the v-band from the turbo plus it's in the car port so hopefully it won't be too loud once that's all sorted.
https://youtu.be/32okgq_I2Bg
It made a bit of a mess.
Thanks for the positive comments.
I'm lucky the wife puts up with me.
Both the Boxster and Audi are pre canbus, they are both 2000 model years. That was part of the reasoning for using the cars I did, wanted to try and keep it relatively simple.
Getting the dash to function correctly will take some time, the rev counter isn't working, the fuel gauge might not work correctly as it seems like the last 1/4 of the tank is calculated by the Porsche ecu rather than from the sender in the tank, the oil level gauge doesn't work, some of the warning lights don't match. Plenty still to be done.
I'm lucky the wife puts up with me.
Both the Boxster and Audi are pre canbus, they are both 2000 model years. That was part of the reasoning for using the cars I did, wanted to try and keep it relatively simple.
Getting the dash to function correctly will take some time, the rev counter isn't working, the fuel gauge might not work correctly as it seems like the last 1/4 of the tank is calculated by the Porsche ecu rather than from the sender in the tank, the oil level gauge doesn't work, some of the warning lights don't match. Plenty still to be done.
Edited by Escy on Tuesday 23 August 09:01
I've spent some more time fighting the drive-by-wire fault codes. I noticed the Audi TT uses a similar pedal sensor to the Porsche so I thought i'd try one as it also runs a Bosch ME7 ECU so there is a good chance it could work. Porsche on the left, Audi on the right.
It didn't work so I decided to get an original Audi A6 pedal, that didn't work either.
At this point, i'm stuck, the pedal sensor values are perfect, the wiring is fine, VCDS reads it no problem. Possibly a hardware fault on the ECU (i'll try it on my mates car since the immobiliser has been removed)
Although it's running i've decided i'm going to take a couple of steps back and go for standalone engine management instead of waste more time and money on this. I originally wanted to keep the Audi ECU as I thought it would be the simpler option, I had hoped that the integration into the Porsche dashboard would have been seamless since they are both on Bosch systems and built in the same year, that was naive, nothing works on the Porsche dash.
Cost was another factor in keeping the Audi ECU but since I spent £400 on a wideband datalogger, needed a separate fan controller, and other bits and pieces it was a bit of a false economy. Mapping will be easier on a standalone and I won't have to rely on my mate to do all the coding on the Audi ECU (it's a lot of work as i've changed so much around). I've wasted a load of time pissing about with the Audi ecu which is a shame but you live and learn.
I don't suppose a standalone will be plain sailing either. I need to make a decision if I try drive-by-wire throttle again or go cable.
Here is my Zeitronix datalogger installed. That's now been removed as I won't need it anymore as the ECU's i'm looking at run widebands.
It didn't work so I decided to get an original Audi A6 pedal, that didn't work either.
At this point, i'm stuck, the pedal sensor values are perfect, the wiring is fine, VCDS reads it no problem. Possibly a hardware fault on the ECU (i'll try it on my mates car since the immobiliser has been removed)
Although it's running i've decided i'm going to take a couple of steps back and go for standalone engine management instead of waste more time and money on this. I originally wanted to keep the Audi ECU as I thought it would be the simpler option, I had hoped that the integration into the Porsche dashboard would have been seamless since they are both on Bosch systems and built in the same year, that was naive, nothing works on the Porsche dash.
Cost was another factor in keeping the Audi ECU but since I spent £400 on a wideband datalogger, needed a separate fan controller, and other bits and pieces it was a bit of a false economy. Mapping will be easier on a standalone and I won't have to rely on my mate to do all the coding on the Audi ECU (it's a lot of work as i've changed so much around). I've wasted a load of time pissing about with the Audi ecu which is a shame but you live and learn.
I don't suppose a standalone will be plain sailing either. I need to make a decision if I try drive-by-wire throttle again or go cable.
Here is my Zeitronix datalogger installed. That's now been removed as I won't need it anymore as the ECU's i'm looking at run widebands.
Thanks Pete.
Before condemning my Audi ECU to the scrap pile I flashed the standard map back on it. My friend had changed the injector and MAF housing sizes in the parameters so we could get it started but it turns out this had caused problems with some other code in the ECU as once the standard map file was back on, all the error codes I had previously been pulling my hair out over are now gone. The drive-by-wire throttle is working perfectly. It' a relief to see it working.
I could keep the Audi ECU since it's all wired up but the decision has been made to go standalone. I've gone for an EcuMaster EMU, it's got plenty of features and it is very good value for money compared to other similar ECU's. I've bought the additional drive-by-wire unit and a Bluetooth adaptor which can display all the data on my phone/tablet, this will definitely come in handy as it means I can start mapping without needing to worry about getting the Boxster gauges working straight away.
The wiring loom was too long before and it was all coiled up in the boot as it seemed like too much hassle to shorted it when using the Audi ECU but now I have an excuse to take a huge section out of it when wiring the new ECU in. It sounds easier than it is as there are loads of splice points inside the loom which I'll need to re-do. It shouldn't take me long to wire up as I've spent so long looking at wiring schematics in the last month they are practically burnt into my vision like arc-eye.
Before condemning my Audi ECU to the scrap pile I flashed the standard map back on it. My friend had changed the injector and MAF housing sizes in the parameters so we could get it started but it turns out this had caused problems with some other code in the ECU as once the standard map file was back on, all the error codes I had previously been pulling my hair out over are now gone. The drive-by-wire throttle is working perfectly. It' a relief to see it working.
I could keep the Audi ECU since it's all wired up but the decision has been made to go standalone. I've gone for an EcuMaster EMU, it's got plenty of features and it is very good value for money compared to other similar ECU's. I've bought the additional drive-by-wire unit and a Bluetooth adaptor which can display all the data on my phone/tablet, this will definitely come in handy as it means I can start mapping without needing to worry about getting the Boxster gauges working straight away.
The wiring loom was too long before and it was all coiled up in the boot as it seemed like too much hassle to shorted it when using the Audi ECU but now I have an excuse to take a huge section out of it when wiring the new ECU in. It sounds easier than it is as there are loads of splice points inside the loom which I'll need to re-do. It shouldn't take me long to wire up as I've spent so long looking at wiring schematics in the last month they are practically burnt into my vision like arc-eye.
Edited by Escy on Friday 9th September 19:40
I've finished up wiring in the new ECU but I've got a region lock problem with my laptop which is stopping me flashing a basemap. Hopefully I'll have a decent update soon.
KTF, i'm just using the EcuMaster EMU to control the engine. It's very configurable, I can invert outputs, adjust signals, etc. There isn't much I need it to integrate with, basically the Rev counter, engine management light, fan control and speedo, things like the oil light, low coolant etc are wired directly to the dash.
KTF, i'm just using the EcuMaster EMU to control the engine. It's very configurable, I can invert outputs, adjust signals, etc. There isn't much I need it to integrate with, basically the Rev counter, engine management light, fan control and speedo, things like the oil light, low coolant etc are wired directly to the dash.
I've got the new ECU wired up. I was lucky enough to pick up an RS4 basemap from a guy called Michele who works for Dutter Racing in Austria. First thing was to get the DBW throttle set-up correctly, i'm using the original Porsche pedal sensor rather than an Audi one. I've not used any software like this before and it's quite a steep learning curve, I was having problems with the throttle plate working the wrong direction (closed with the pedal depressed). Michele who sorted out the map helped me out massively, he logged onto my laptop remotely and set it all up for me, it took a while as I had the wrong firmware on the ECU causing some problems. Technology is awesome when someone in Austria can fix your car through the internet.
Here is a little video of the DBW throttle working. Not really that impressive but it feels like a triumph after all the troubles i've had in the past.
https://youtu.be/XzDL8D5ptCw
I should be able to try and start it up soon. I've noticed an oil leak in the middle of the Vee of the engine so i'm going to take the inlet manifold off to investigate before I start it up.
Here is a little video of the DBW throttle working. Not really that impressive but it feels like a triumph after all the troubles i've had in the past.
https://youtu.be/XzDL8D5ptCw
I should be able to try and start it up soon. I've noticed an oil leak in the middle of the Vee of the engine so i'm going to take the inlet manifold off to investigate before I start it up.
Gassing Station | Readers' Cars | Top of Page | What's New | My Stuff