VT 5 litre check engine code 0048

[falcodore]

I'm just gonna keep driving it the way it is, I'll let my mechanic deal with it at the next service. This one seems a little too challenging.

 

[RR99]

Here you are, attachment is from the Holden VT/VX Service manual.

By sheer coincidence, I came across the article below in the last hour as I was looking for instructions on how to repair a VS V8 ignition module. May help you with your problem. Although it specifically references code 48, 49 is not that much different.

Kalmaker
17 April 2015 ·
Are you having problems with your 5L VT with misfiring and / or trouble code 49 for cam sensor????
Replacing the distributor with chinese replacements makes it worse????
Have you ever wondered why the VS Series 3 with the same sequential rollercam engine doesnt suffer from the same problem? ??
Here is the answer
The Holden electrical engineering department stuffed up with the wiring harness design on the V8 VT by moving the ignition module even further away from the distributor and also mounting it to the plastic air cleaner box, whereas previously it was mounted to the metal engine bay.
The module doesnt need grounding to function but without a proper earth it's asking alot to pull all the signals back to ground within milliseconds. ..
The main problem with the harness is, they have all the wiring from the distributor, the coil, and from the module back to the ecu all wrapped in one, and that causes lots of electrical noise.
On some cars, just moving this around causes or fixes the problem.
To fix it properly the best bet is to relocate the most offending signal wire, which is the brown wire from the module to the negative side of the coil.
This circuit also has the tacho wire spliced in, so by removing it you will lose your tacho signal, so there are 2 ways to fix it.
The way I prefer, although it probably makes no difference, is to cut the brown wire at the module end approx 50ml from module, and cut a little hole in the rubber boot and poke it through.
Then splice, solder and heat shrink a suitable guage wire of at least 15amp and run this wire up around the shock tower to the coil.
You can either join this near the coil or if you happen to have correct terminals like I do, replace it.
You will notice that on the main harness on the passenger side of firewall there is a little white service tacho plug taped to the thick harness which also has brown wire.
If you join to this as well, you get your tacho back.
Although this will still send a weak signal all the way back down to where you cut it near the module, it wont create enough noise to upset things.
I guess in reality its the same as splicing in near the module instead of cutting the brown wire, and the main noisy load will go direct to the coil
This combined with grounding the module will have your chinese distributor working like it is supposed to with no more code 49.
Also make sure the noise suppressor is still connected to the positive side of the coil.
Most people think its supposedly there for "the" radio interference, but its there for all radio interference including ignition interference.
I tuned a very low km VT Senator recently with only 42k on it and it had a slight misfire and it was still using the original Bosch distributor and although the standard harness was being pushed to the limit, it wasn't setting a code. I guarantee that any simple mod like relocating and fitting a better coil would upset things, so I recommend any one with a 5L VT to upgrade this before the problem begins.
I would also recommend this mod to all 5L V8's from VN through to VT. You will improve ignition performance better than upgrading to aftermarket coils/dizzys, MSD's etc.
Phew... long post..... hope this helps all you and your beloved 5L's

Is there a better ignition system ? I just had a look at my VT C91 and it appears that the coil is directly attached to the distributor cap ? I am trying to solve a miss under load but other than that the car runs well.