Car is stuck in limp mode

[Zack Riley]

Hey all, New to the VL world and chasing a fault that popped up the other day.I recently picked up a Berlina that's been off the road since 2011. She's in pretty good nick for her age. 97000 on the clock, mechanic things its pretty close to accurate, minimal rust, factory tape deck, bla bla bla.
She's on club rego now, been having a good time with the car.
Long story short, the car is stuck in limp mode, (wont rev past 2k rpm in gear, looses power for about 5 seconds then comes back on and wont engage overdrive). I am cursing that is probably my own stupid fault and I am finding it difficult to find anything that links to the exact cause.

Okay, I'll get the "what I did," out of the way

I installed a Mongoose M60 immobiliser, cutting power to relays M and N.
Put an air filter into the car (as it was missing when I got it)
Replaced the crank case breather hose and a few belts.

I get codes 12,13,14,23,24 and 31.
I have followed the instructions posted by Bangers in the other thread and had a bit of a look.
My initial thoughts with this are it has something to do with the immobiliser on relay N I think knocking out all of those circuits, however there was no air filter in the car. Reading a few other threads, they suggests the AFM, whilst others suggest it could be gearbox oil.

I know a lot of the old links point to a few of the dead pages, and the Haynes Repair manual isn't really showing me much.

So, sorry in advance if this has come up a million times before, I've been hunting for an answer for a few days now and keep getting dead links. If possible, I would like to not pull the immobiliser circuits, but if I have to move them I will.

Any pointers on what would be the best course of action? I have a spare computer I can chuck in it also if need be.

 

[Not_An_Abba_Fan]

VL does not have "Limp Mode". There will be something else causing it. Relay N is the fuel pump relay? If it was cutting power to that it would just stall and not run at all. I'd be looking at the fuel pump itself, pretty common for them to fail. Or blocked fuel filter.

Check the connections to the AFM, make sure it's tight and not leaking.

 

[Zack Riley]

VL does not have "Limp Mode". There will be something else causing it. Relay N is the fuel pump relay? If it was cutting power to that it would just stall and not run at all. I'd be looking at the fuel pump itself, pretty common for them to fail. Or blocked fuel filter.

Check the connections to the AFM, make sure it's tight and not leaking.

Okay, so when this happens the motor doesn't die. I'll put up a video next time I drive the car.
Motor will run in gear up to 2000rpm then drop to idle for about 5 seconds. I'll have a look. Car revs normally when in park or neutral.

 

[Not_An_Abba_Fan]

When the fuel pump is starting to fail, it can supply enough fuel when stationary, but as soon as it's under load it won't keep up so the revs die out.

 

[Zack Riley]

Awesome, looks like I'm dropping the tank. Probably the original from the factory

When the fuel pump is starting to fail, it can supply enough fuel when stationary, but as soon as it's under load it won't keep up so the revs die out.

 

[losh1971]

Fuel pumps die in two ways. They die when they reach their usable mileage but they also die from not being used. This is why gas cars need to have the pumps run once or twice a week for 10 mins and not just the 30 seconds before they flick over.

 

[chrisp]

It’s a long time since I had a VL, but the crank angle sensor in the distributor was a known issue. I wonder if the crank angle sensor is on the way out and only working up to 2000rpm?

 

[losh1971]

When my CAS died in my VL it wouldn't restart it was just dead one morning.

 

[losh1971]

You can scan for codes with a paper clip AFAIK.

 

[Zack Riley]

It's been off the road since 2011 so that's fair.

Fuel pumps die in two ways. They die when they reach their usable mileage but they also die from not being used. This is why gas cars need to have the pumps run once or twice a week for 10 mins and not just the 30 seconds before they flick over.