budmanv24

I recently installed a 99 carrera 996 engine into my 99 boxster. So far I've been having some issues with a large number of check engine codes. I've listed them below. Any suggestions for areas to check that might be causing these? By the way, my dme is still the boxster program as I wanted to get these issues settled before reflashing but that shouldn't be causing codes.

About to get fault codes
moduleType = MotronicDME78
DTC Count = 9
Fault Number:P0300
Description:Porsche fault code 507 - Misfire detection
Repair Infomationtotal)
DTC Count = 9
Fault Number:P0306
Description:Porsche fault code 509 - Misfire cylinder 6
DTC Count = 9
Fault Number:P0303
Description:Porsche fault code 512 - Misfire cylinder 3
DTC Count = 9
Fault Number:P1585
Description:Unknown DTC: 1585
DTC Count = 9
Fault Number:P0304
Description:Porsche fault code 511 - Misfire cylinder 4
DTC Count = 9
Fault Number:P1319
Description:Unknown DTC: 1319
DTC Count = 9
Fault Number:P1318
Description:Unknown DTC: 1318
DTC Count = 9
Fault Number:P1316
Description:Unknown DTC: 1316
DTC Count = 9
Fault Number:P1315
Description:Unknown DTC: 1315
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Pac996

Things to work with for diagnostics.
Is it always the same cylinders.
Have you combined boxer and 996 electronics control parts.
Old gas being used? Gotta have fresh gas since it does start going bad after a few to 6 months.

Try listing the swapped in parts and where did the engine come from since the engine might of been that way from the start.

budmanv24

Gas and oil are fresh. Gas in the tank was 18 months old so I pumped it all out and added 4 gallons of fresh premium. The oil is brand new mobil 0w-40. It is always the same cylinders. All the electronics came from the boxster. Motor came from another member on here.

budmanv24

Looks like all of the 1300 level codes are also misfire related. Could that be vacuum related? I'm gonna try swapping spark plug caps, and if that doesn't do anything then I'll try replacing the injector o-rings and manifold gaskets.

Pac996

18 months old as in the car sat drying fuel in the injectors and you need to clean the injectors with more than a fuel additive? Hint hint.

budmanv24

I'm using the fuel rails from the 911 motor which was sitting dry. You still think I should remove it and try cleaning it out with some carb cleaner or something?

Loren

Wrong DME type unless you changed the DME too.
Both of those engine should be using DME 5.2.2

budmanv24

The dme should be stock 99 boxster. Which should run the carrera motor just not to its full potential. So what would the DME78 even be for?

budmanv24

Ok, bottom left corner of the durametric screen lists Motronic 5.2.2

budmanv24

Turns out the number 3 spark plug was cracked. Swapped the plug and it runs like a completely different motor. I still get a misfire on cylinder 4 under real hard acceleration so I'm gonna buy a whole new set of plugs and drop them in. I also think the idle stabilizer may be bad bc sometimes the idle fluctuates around 500 rpms. And the valve makes weird buzzing noises after the car is off till you tap it and then it will stop.

redridge

try cleaning the ICV and the throttle body.... they are known to cause idle fluctuations....

budmanv24

Ok, I'll give that a try. Here's one of the codes it started throwing:

DTC Count = 5
Fault Number:P0506
Description:Porsche fault code 32 - Idle control at stop

So I'd say its safe to assume that is probably the culprit.

The other four codes that are showing up now are misfire on cylinder 4 and a couple other generic misfire related codes to that cylinder. So I'm definitely making progress.

budmanv24

In case anyone else runs into these same problems, here's what the causes were. Cylinder 3 had a cracked spark plug. Replacing that cleared up the misfires on cylinders 3 and 6. I then swapped the coil caps on cylinders 4 and 5 and sure enough the misfire moved to cylinder 5. Replaced the cap and all the misfire codes were gone. The erratic idle turned out to be a loose battery connection...oops. Now I'm getting an air bag code 48 which looks like the passenger seat belt buckle. So tomorrow I'll check that with an ohm meter to see if it's faulty.

Tacet-Conundrum

Sounds like a rewarding way to spend your time. Wish I had the free time to do the same. Might be back off to Lithuania again.

JR944

Hey Bud,

Really glad to read that the fixes were pretty straightforward! Can't wait to hear how you like the car once it's up and driving!
Joe