955 turbo, starts fine, stalls and dies after 2-3 secs

boss11 · boss11's Garage

Guys, hope someone can help:

my 2004 CTT developed a jerk after a short boost, so I pulled up and it stalled, now when I start it, it starts fine but doesn't hold idle and struggles to rev, basically undriveable..

My first thought was fuel pump, however when I tried to isolate a faulty pump by removing fuse #13 and then #14 to see if it runs on one the result was the same.

When I hooked up durametric it showed P0011 which I believe is quite a common code, could potentially mean issue with camshaft sensor or adjuster, but would it cause the symptoms I am experiencing?

What should I check next?

boss11 · boss11's Garage

If anyone is interested, I checked intercooler pipes, they were all fine, so I started digging deeper with Durametric, noticed misfire in cyl 2, also voltages on MAF sensors did not seem right as one was reading constant 1V and the other oscillating between 0 and 1.

so to investigate the misfire I pulled out ignition coils and five of them were cracked.. Cyl 2 spark plug well had oil in it - explains misfire.

Ordering 8 x coil, 8 x spark plug and a valve cover gasket kit, going to try and clean the MAF sensor that is not showing constant voltage, hopefully that will get the pig going...

fintstone · fintstone's Garage

The coil pak problem is common.

island911 · 07:48 AM

Coil packs may show cracks, but... the cracks are not an indication of bad coils (it's just a thin cosmetic plastic shell over metal that cracks)

Wellwood · 04-03-2017, 03:21 AM

Ignition coils (they have been updated many times). V8 models.
The check engine light will come on, possibly blinking. Do not drive the vehicle if the check engine light is blinking.
The engine will run rough. Each coil is $61, and all eight should be replaced at the same time.

Driver-side fuel pump. All models.
The SUV will start and then die. It will run on full throttle, when cold, and when there’s less than a quarter tank of fuel — the secondary pump is operational during those conditions. The fix requires the pump and filter housing above the pump to be replaced. Expect to pay about $500 for parts.

island911 · 06:52 AM

^^^fuel pump^^^ It's odd that NO codes will be generated for a primary fuel pump failing. --and btw that is what causes such a weird start and stall situation.

It's strange that a side marker lights out throws a code, or say an unexpected signal from the oil-level sensor... But a seized fuel pump doesn't throw a code ? --seems wrong.

island911 · 03-13-2021, 07:52 AM

Quote:

Originally Posted by Wellwood

...
Driver-side fuel pump. All models.
The SUV will start and then die. It will run on full throttle, when cold, and when there’s less than a quarter tank of fuel — the secondary pump is operational during those conditions. The fix requires the pump and filter housing above the pump to be replaced. Expect to pay about $500 for parts.

Such a good post. ^

Having recently replaced another fuel pump let me add this (from an OT post I made)

The High Pressure fuel pump - The dealer charges ~400 for the part. This is the same as the Touareg pump (~$40) other than Porsche somewhere updated the design to have both low pressure lines detach (unclip) from the main (drivers-side) pump. (the older 955s and T-reg pump have one LP line perm attached and must be passed across to the secondary pump side) This is a PITA job. --I loath dealing with fluids. Make certain the tank is as close to empty as possible. And in a well ventilated area (outside with a box fan pointed.) Nitrile gloves... The pump assembly barely clears the hole. (fat fingers not accommodated.)

Oh, and the unclipping of the lines does not have a consistent theme. -some squeeze buttons, some slide clips. ..and the High pressure side is on an accumulator - it will fountain for a while (eye protection / face shield)

island911 · 03-15-2021, 07:49 AM

One other pro tip, on replacing the fuel pump: Make sure that the wires are well clear of the level float-arm. Knowing that with the pump out those wires fall back into the tank, and with the float low, it's easy to grab that wire and pull it over the float. ...which will keep the tank from reading "full" when full.

fintstone · fintstone's Garage

I diagnosed my issue (bad pump) and had both sides/pumps replaced by a pro. Afterward, it had that exact problem. At first, it never read above half full. Took it back and they worked on it and then it never read below half full. They told me that the problem was in the instrument panel and would cost me many thousands to fix...and I should just drive it and try to keep from running out of gas by tracking miles between fill up. They claimed it impossible that it had to do with their work...and sorta implied I was stupid and wasting their time. I took it home and drove it for about a week or two like that before I got fed up enough to take it apart and fix it myself. I have pretty much done my own work on it since then.