Terrym2010

So I recently purchased a 1999 3.4 996 as abit of a project. the car I purchased had a running issue and I was wondering if anyone has had this issue themselves.

basically the car turns over fires up and runs very rough after about 30seconds it dies in this time it smells like very strong fuel.
so far I have changed ( coil packs / spark plugs / maf sensor / crank sensor)

I have also done a few tests and I have worked out the misfire is across both banks.
when plugged in I get fault code p0336 but I have changed the crank sensor.

Anyone have any ideas ??

next on the list is compression test

hardtailer

Coolant temperature sensor (cts) and/or associated wiring.
It starts because no cts signal is equivalent to an engine at Arctic winter temperature at night which obviously starts the engine when it is cold albeit very rich (hence the smell) but when it starts to warm up the amount of fuel is far too much to keep it running so it dies.

Terrym2010

Would this make it misfire though ?

good idea either way cheers

De Jeeper

U need to buy r borrow a good scanner and start graphing the telemetry. This is the how u start to diagnose a driveabilty issue through diagnostics. Anything less then this is just a guess and without this u r wasting time and money.


We need to see fueling #s, sensor values and variocam functions.

168Sierra

Maybe you could try disconnecting BOTH battery leads, remove the battery, then connect the positive and negative cables toether to drain any capacitors. After that, reinstall the battery and reconnect the leads. This should reset everything to factory default settings. having the negative cable come off with the engine running can cause numerous issues.

996-CAB

I'm an electrical engineer and find it hard to believe there is enough stored energy in the tiny capacitors to matter, but you shouldn't have to touch the positive and negative cables together to discharge them. But do not jump them on the battery or you will have a fire. Let us know how it goes.

Terrym2010

Update the cylinders that aren’t firing are across both banks. Coil packs and maf changed. And still flagging code p0336 even after a crank sensor change.

jumpy chunky

Do you have access to a DVOM?

Terrym2010

yes mate

allcool

I might have missed it,,, did you test fuel pressure..?

Terrym2010

no haven’t tested yet all I know is it’s definitely over fueling as it stinks like petrol when it turns over and the plugs when changed we’re wet

allcool

Testing fuel pressure will also test the regulator, at least partially. I've seen a return line get blocked causing way to high fuel pressure doing exactly what you''re saying.

Not saying this is your problem, just it should be tested to rule it out.

jumpy chunky

Since you’ve got trouble code P0336 might make sense to track that by checking for continuity.

The speed sensor has a couple of leads encased in a shielded cable.

You might have already done the visual inspection which could rule out damage to the cable. Checking for continuity with a digital meter would be a next step. Also X 59/2 connector could have corrosion.

Hope some of this might help.