97 5ltr VT code 49

[Jayme]

not all of the dash just check engine light and a few other things.... tach and speedo arent data driven, still got their own inputs and can be made to work.

[vn5000]

An easier option may be to ask vl400 to mod the vt v8 bin code so that it doesnt use the cam sensor or sequential injection.I dont think it wouldbe that hard to do ,not for vl400 anyway.
If you put a vr ecu in you would have to change / mod the wiring harness and you may also have problems on the bcm side of things as well.
I think you are best following cougars advice as he seems to have found a fix for the problem and buy a good genuine bosch dizzy.

[GTS308]

Ok Ill try another dizzy first...I dont mind spending another couple of hundred as I can always resell it if it does not fix the problem..Ok Im off to Ebay....Stay tuned!

Well Im back..lol and have just purchased the New Genuine Holden Distributor from Ebay...Give my a week or so to have it delivered and finding the time to fit it.
Local Holden mechanic will bring the Holden Tech2 around and check it when its in..."FINGERS CROSSED PEOPLE"


Cheers Mark

[GTS308]

WHOOOOOOOOOOOHOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Im pleased to announce that fitting the new distributor I bought from Ebay fixed the problem. Big thanks to "thecougar" for the tip you saved the day..
Although have not clocked up anymore than 50ks on the test run she is pulling like a rocket and even managed a bit of tire smoke (Not on purpose..ha ha)
All the other times the code was thrown within a couple of K's or hitting a bump..So am feeling confident the problem has gone...

Although now Im wondering why 2 5ltr VT's have such a dislike to reconditioned distributors as well as new sensor plates?
Now remember my original Bosch Distributor was fitted with a genuine old stock Bosch sensor plate and it still failed..
Surely their must have been many VT 5ltr Commodores that suffered cam or crank sensor faults and replacing the sensor plate fix them so why are these two different?

Would have loved to put the new and old side by side and disected them to find the difference but " I aint taking it out now lol "
So it must come down to something that happens when the distributors are pulled apart..I dont know..

I would like to thank all the people that have posted on here and tried to sort this problem out, you guys are really on the ball and have a wealth of knowledge and I really appreciate you sharing
that with us less edumicated..lol. I must also add that this forum page is fantastic and is the first place I look when I have problems..Well done!

So I thought I would bore you with some pictures of a very dusty (Nine months without a wash) 1997 5ltr VT Holden by Design....Cheers again everyone..Mark!

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[vn5000]

Good to here .
The aftermarket sensors must be susceptable to electro magnetic radiation.

[VL400]

Well done on the fix, now get out there and start driving it

[Neil0264]

How to fix those Fault Code #49's.....

Hi All!
Sorry to say this for the people who have been spending $thousand$ changing
parts in order to fix the dreaded fault code #49 and its associated misfires,
but most of them have been fixed simply by moving one wire. Two, however,
were not so lucky and have required more of the full 5 steps involved
in solving this problem.

ALL of the 5.0 cars from VN thru to early VT have a wiring problem which can
produce ECU fault code #49.
Note: it was found that some cars have this exact problem and hence misfire
or hiccup, but never produce an ECU fault code. Never-the-less, they still
have the same problem and hence the same solution.

I was forced to solve this problem since people were buying my rebuilt
ignition modules only to find they misfired or plain didn't work in THEIR
cars. It left me scratching my head for a year wondering what was going
on since the very same modules worked fine in mine and other's cars.

The problem stems from electrical interference of the hall-effect (crank)
sensor signal (the main timing signal) coming from the distributor.
This is a low-level "computer" type signal that is easily prone to noise
interference.

The wire for this signal goes into the module on one of the pins of the
6-pin connector on the ignition module.

Take a look at the wiring to that connector..... What do you notice?

Holden have bundled ALL of those 6 wires together!!!! (along with the 4
wires from the 4-pin connector).

Now just think of what wires are sitting together there....
You have a high-power coil drive wire going out of the module to the coil,
with 7 Amp pulses on it to energize the coil, and high-voltage kick-back
voltage spikes on it when the coil fires, AND IT'S SITTING RIGHT NEXT TO a
low-voltage low-drive strength signal from the hall-sensor which is easily
interfered with.

It's like having a radio/TV antenna transmitting in the wiring loom of your
engine bay! The interference on the hall-sensor signal is very short so
requires a good/fast oscilloscope in order to see it, however it has quite
a bit of kick behind it and imparts a way over-voltage spike on the
hall-effect signal and simply blasts right through the modest signal filters.
The earth wire to the module on the 6-pin connector also has those same
7 Amp pulses running down it as the coil-drive wire; another problem.

So far most of cars giving fault code #49 have been solved just by moving the
coil drive wire out of the loom. This is the brown wire on one of the fat
end pins of the 6-pin connector; it goes to the -ve terminal of the coil.
(Brown on the VR - Check on your car's wiring diagrams!)
The wiring loom is hard to pull apart so this is easiest achieved by leaving
it in there but disconnecting it at the coil so that no high current flows
down it, wrapping it up and insulating it (snip off the connector if you need
to re-use it on the new wire), and running a new wire away from the wiring
loom.

Tap another (15Amp rated) wire into that wire as close to the car-side of
the 6-pin module connector as you can get and run it separately to the coil.
At least 10mm away from the loom. The more the merrier.

Why is this problem almost exclusively the domain of the VT Commodore?
Well the VT was especially bad since Holden moved the ignition module
forward in the car to the air box hence increased the length of the wiring
loom. They also mounted the module on the plastic air box instead of metal.
Not good for pulling noise out of the earth of the system.

These 5.0's are barely running at all. Some suddenly get this problem after
something is changed. One of the people who had a huge problem with #49
could get his engine to stop just by touching the wiring loom.
Another got this problem only after changing the alternator.

Some people have managed to "fix" this problem by changing the distributor.
It it can also be "fixed" by changing the module, (to a lower power module
that doesn't get as much energy to the coil) however this is mostly
unnecessary.
People who have achieved this "think" they have fixed it but what they've
done is changed things just enough to push the problem back up the cliff to
just hanging on the edge of the cliff ready to fall off it again if anything
is changed in future.

This is a lesson on wiring that really APPLIES TO ALL CARS but they get away
with it in most, however the single-coil V8s are really pushing the limits.
The ignition module has to hit the coil hard to build up a sufficient
electric field in order to generate a spark (since there is less time
between sparks as say in a 4-cyl engine), so the high current pulses
radiate a lot of interference noise in these 5.0 cars.

The ignition systems in cars are very noisy. They should never be have been
wired with all those wires simply bundled together like that.
Whether you get this problem or not, and how bad you have it, stems solely
on the luck of how the wires fall in the loom.
If the coil-drive wire happens to be sitting right next to the hall-effect
sensor wire then you are in big trouble and you might not be able to solve
this problem simply by moving the wire(s) out of the loom (as in two people's
case). You will require a special ignition module with some serious signal
filtering in it.

In two modules I had to:
-increase the signal filter on the Base timing signal path.
-increase the filter on the EST signal path.
-add a filter to the power feed going out to the hall-effect sensor; (which
already came standard in my 2 enhanced performance re-built modules).
-add a filter to the Base timing signal as it was passed through the module
to the ECU. Supposedly the ECU will have a filter for this signal but I also
added a little one at the module end of the wire to make sure.


The FULL list of things to do to fix the dreaded VT Fault Code #49 problem are:


1. Run alternate brown coil-drive wire to the coil to remove the electrical
noise from the wiring loom.
2. Ensure module is earthing properly through the case and then, if the
module is not mounted on metal (chassis earth), like in the VT, then wire
the case to a good solid chunk of metal to remove electrical noise
(from module earth wire) from the loom.
Alternative: Can also tap another wire into the black earth wire and
wire it to the nearest good earth, as in the brown coil-drive re-wire
above.
(Don't disconnect the original black wire though).
The alternate above is needed on most Bosch modules since they seldom
earth out through the case.
3. Renew (or add, if not there) the 0.5uF coil suppression capacitor
(from +ve coil terminal to nearest chassis earth).
4. Check and cleanup all engine earthing straps.
5. Get an ignition module with improved signal-noise filters (which we
now have!)

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