mileet

Hi guys,



I'm new to the site so please be patient with me? (Also grammar isn't my strong point)



So, I've owned my 2003 996 carrera for the past 2 years and for the most part its been trouble free. I got it with 110,000 miles its now got 130,000.



Maybe 5-6 times over the last year it's started misfiring as I come to a stop, it starts up after maybe 2 minutes and misfires for 30-40seconds, then runs fine.



The last two times this has happened the display has said low oil pressure as it's been misfiring, but then starts running normally with no message?



Any how just before Christmas I started the car as normal and left it ticking over but got held up,so it was probably idling for 40mins. I heard a loud misfiring sound and it cut out. I thought it had run out of fuel so I put a gallon in and it went up to a quarter. I tried starting it,but it turns over but won't start. I have since had it towed in to a garage and they have plugged the computer into it and no faults are showing. Can anyone help as the garage isn't to sure?

i'm based in doncaster UK i cant seem to find any specialists in my area.



Thanks in advance

Mileet



P.S. it's a triptronic

P.p.s Ive since snapped drilled replaced the crank position sensor?

Ahsai

If the engine turns over but doesn't start, you have to check for fuel and sparks. Has the shop checked those? Also, when cranking, do you see the tach needle bounced up for about 1/8"?
Have they plugged in a scanner to check for any error codes? DId you hear the pump priming for 1 second when you turn the key to the last position before crank?

mileet

The Speedo does move, and I can hear it prime, the shop recovered it and thought that they would plug it in and codes would appear. Their computer didn't show anything? I checked the fuse today and the fuel pump fuse was blown, I changed it but still no joy? Not sure why, if the relay is faulty would that cause fuse to blow? It hasn't blown since I changed it.

thanks
mileet

Ahsai

Not speedo, I was talking about the needle of the tach. It should bounce for about 1/8" when you crank. You need to watch closely to notice that.
If the fuel pump fuse was blown, you shouldn't hear it prime or you meant you hear it after you replaced the fuse?
The fuel pump circuit should be checked because the fuse is dedicated to the fuel pump. Should check the fuel pump relay and the fuel pump itself.

DBJoe996

^^Agree. And the fuel pump going bad or being blown entirely will not throw any codes. I would start by checking the fuel pump relay, or just replacing it with a new relay.

DBJoe996

mileet

Sorry guys,

it is the tacho,

when it was in the shop getting cps done we turned the ignition on and heard the pump prime (small buzzing sound from near the battery).

pulled it out of shop battery was flat so put a jumper pack on, and jump leads car cranked but no fire.

later after looking on the web I tried the fuse and it was blown, changed it not firing.

will change relay and try tapping fuel pump (in case it's stuck)

Is the relay a standard relay or a oem part?

thanks
mileet

Ahsai

If the tacho needle doesn't move at all when you crank, either the crank position sensor (or its circuit) is bad or the DME is not getting power. I know you said you're replaced it already. Maybe recheck its connectors?
Check fuses C1-C4 and E1.

mileet

Will check them, the tacho does move a tiny bit.

Ahsai

Ok, do an e-gas throttle body recalibration. Leave the key in the last position before crank for 60s. Foot off the gas pedel. Then turn key to OFF and leave it there for 10s. Then try to start it again.

Ahsai

It's an OEM part. Not the generic Bosch 4/5 pin relay.

mileet

Thanks so much Will try it tomorrow