What is a PCM reset?

[cev]

I have searched the forums on the PCM reset and find it extremely interesting. Just wondering however, can someone simply tell me what it exactly is and why you should or shouldnt do it?

I have also heard that on a VX LS1 models, whether it be a SS or a Berlina, that the PCM reset is not exactly how its written?

Just curious as am getting a cat back exhaust soon on my auto VX SS and am looking for ways to improve fuel consumption.

[dominik]

I have searched the forums on the PCM reset and find it extremely interesting. Just wondering however, can someone simply tell me what it exactly is and why you should or shouldnt do it?

I have also heard that on a VX LS1 models, whether it be a SS or a Berlina, that the PCM reset is not exactly how its written?

Just curious as am getting a cat back exhaust soon on my auto VX SS and am looking for ways to improve fuel consumption.The thread you're after is only a few doors down. Gotta use that Search feature more often buddy :)

Go here (http://www.ls1.com.au/forum/showthread.php?t=35266) and click on the links in the first post.

[xshore]

I will be doing the same. At the moment I'm driving 120kms / day and any help I get with fuel consumption will be cash in my wallet, then prolly out into my gf's hands.

[cev]

Thanks mate.

However im curious those people with a VX whether they have had any issues? Some people have said that instead of 3 beeps they hear like a little sound tune?

[BLACK 346]

Thanks mate.

However im curious those people with a VX whether they have had any issues? Some people have said that instead of 3 beeps they hear like a little sound tune?

They may be referring to what it actually sounds like.
The sound the car makes is actually more of a chime
than a beep. Like when you leave your handbrake
on an try to take off, it chimes to warn you that you
are a dumb **** trying to drive with the park brake
on.

[cev]

Question: Can you do this PCM reset on a standard VN Commodore? Because my old VN idles like crap.

Also someone tells me that instead of letting the car idle for 5 mins that you should put the lights on, put the air con on and drive the car very very hard so the car re-learns? He says dont be scared if the car dies out when slowing down for the first time or if the brake fails the first time???

[BLACK 346]

Question: Can you do this PCM reset on a standard VN Commodore? Because my old VN idles like crap.

Also someone tells me that instead of letting the car idle for 5 mins that you should put the lights on, put the air con on and drive the car very very hard so the car re-learns? He says dont be scared if the car dies out when slowing down for the first time or if the brake fails the first time???

This is all correct, except you must also be totally naked
and beep your horn every 10 seconds :rolleyes:

[bobg]

This is all correct, except you must also be totally naked
and beep your horn every 10 seconds :rolleyes:
And wave to passers by who see you and admire you display!!!! :D :D

Regards

Bob G

[Deano T]

Street Tuna says that resetting the PCM gives no performance gains.

[Smitty]

They may be referring to what it actually sounds like. The sound the car makes is actually more of a chime than a beep....

correct
its a chime...
You may remember a thread I started with mine losing power in the heat (still unresolved) and I saw this thread
so
I did a reset last night
3 chimes is the order of the day on a VX...

oh
and I will let youse know how it goes over the next few days

cheers

[xshore]

I'm going to do this today, couldnt yesterday. But when start car holding mode and up in, I flick through the options and it says F 10.1 L/hr. Where is the L/100Km ?

[myles]

Street Tuna says that resetting the PCM gives no performance gains.

It might not give a performance gain over the original specs, but mate, I can bet my life it has improved the performance of how my car was 'currently' running.

Improved performance beyond its original performance? No.
Improved it's performance compared to how it was running? Yes. Compared to a friend's later model SS, my now feels as if I've driven it only a few thousand ks.

I guess it depends on the car. Every car is different.

[clixanup]

I'm going to do this today, couldnt yesterday. But when start car holding mode and up in, I flick through the options and it says F 10.1 L/hr. Where is the L/100Km ?

I assume you're referring to the instant fuel use as opposed to the average. If so, it changes to a litres per hour reading while the car is travelling at less than 10km/h or stationary. 10.1 l/hr is pretty high. Mine is usually around 2.1 when stopped at traffic lights - V8/auto.

[XLR8 V8]

I'm going to do this today, couldnt yesterday. But when start car holding mode and up in, I flick through the options and it says F 10.1 L/hr. Where is the L/100Km ?


The display shows L/hr while your car isn't moving. Once you reach more than 10km/h (I think) the display goes back to L/100km.


Edit: Beat me to it by one minute! :p

[Airzoom]

Pulled the red 10A fuse number 29 on the VY yesterday, turned on the ignition and three beeps later the engine management said check engine.
Replaced the fuse and started up let it idle for five minutes. Took it for a drive and I can't say I've noticed much difference driving just idles better.

[xshore]

Mine doesn't change, It stays on L/hr even at 110km/hr. I'm lost how to get it to L/100km.

At the lights in neutral mine sits on 3.4 L/ hr and 3.7 with a/c on. Anyone have a list of what all the readouts mean ? I couldn't find it using a search on here.

[BLACK 346]

Mine doesn't change, It stays on L/hr even at 110km/hr. I'm lost how to get it to L/100km.

At the lights in neutral mine sits on 3.4 L/ hr and 3.7 with a/c on. Anyone have a list of what all the readouts mean ? I couldn't find it using a search on here.

Is yours a VY. Pretty sure VT/VX don't have the
L/100KM feature. Happy to be corrected though.

[xshore]

hmm mines a VT2 :confused:

[pah]

My VY key would not talk to the car computers.

The NRMA popped out and disconnected the battery lead for about 10 - 15 seconds. That resulted in some form of reset for the computers to the extent that they once again recognised my car key. Most handy as I was in Canberra and it's a long walk back to Sydney.




PAH

[JezzaB]

hmm mines a VT2 :confused:

My VU cant do it either. If you want to work out the current L/100Km just check the L/h when you are @ 100Km/h and that will be your L/100Km (or if your @ 50Km/h multiply it by 2)

oh and for all the dash MODE-UP setting check out http://www.dd.id.au/3_Window_Cluster_Mode_UP.html

Jez

[Smitty]

I did a reset last night
3 chimes is the order of the day on a VX...
oh
and I will let youse know how it goes over the next few days

cheers

well
can i say what an improvement, after the reset last night!

it was raining this morning going to work' so I thought the 3rd gear wheel spin (at 60) was 'coz of the rain
tonite...? dry
and whoa......does it go...like it should
leaving work I was a little...ummm enthusiastic
which resulted in 2 black lines up the main road
...pwwhharrrrrk does it go, like new

now, does it stay like this???
I have had a problem with hot weather performance
(see my other post on the site)
so i want a hot day to see if it retains its increased performance
but for now...?
the extra go is showing up my clutch....
my new(ish) clutch is slipping a full noise in 2nd

oh well
get one thing right...and stuff sumfing else.... :lol:

cheers

[One tonner]

Here is a strange thing that was happening to the volume controls on the steering wheel of the Tonner. :confused:
The volume would go up pressing either the up or the down buttons on the steering wheel.
Did a PCM reset and appears to have corrected the problem.
I did replace the speakers in the doors a while ago but this is a more recent development, who knows. :rolleyes:

[myles]

well
can i say what an improvement, after the reset last night!

it was raining this morning going to work' so I thought the 3rd gear wheel spin (at 60) was 'coz of the rain
tonite...? dry
and whoa......does it go...like it should
leaving work I was a little...ummm enthusiastic
which resulted in 2 black lines up the main road
...pwwhharrrrrk does it go, like new

now, does it stay like this???
I have had a problem with hot weather performance
(see my other post on the site)
so i want a hot day to see if it retains its increased performance
but for now...?
the extra go is showing up my clutch....
my new(ish) clutch is slipping a full noise in 2nd

oh well
get one thing right...and stuff sumfing else.... :lol:

cheers

Smitty, you made my day! You put my thoughts and experience of what it did to my SS into words. The car rips along!

Glad you posted, now I know I wasn't daydreaming. :)

[Smitty]

Smitty, you made my day! You put my thoughts and experience of what it did to my SS into words. The car rips along!

Glad you posted, now I know I wasn't daydreaming. :)

the drive into work this morning...only confirms my post from last night
the PCM reset gave me an extra ??? kw
it goes...just like new one :cool:

cheers

[xshore]

Well I did the pcm reset too. I didn't hear no chime, probably because I was under the bonet not inside the car.

Before PCM reset at idle: 3.4 L/hr
After PCM reset ad idle: 2.4 L/hr

As for cruising I can't tell as I don't get any averages. I don't know how long it will last.

[Smitty]

Well I did the pcm reset too. I didn't hear no chime, probably because I was under the bonet not inside the car.

ummm
how did you manage to turn the ignition on
while the fuse was out...???
3 metre arms....? :lol:

[VX2VESS]

Is yours a VY. Pretty sure VT/VX don't have the
L/100KM feature. Happy to be corrected though.

mine does l/hr stationary and l/100 moving instant readout window, its a berlina however.

[BLACK 346]

mine does l/hr stationary and l/100 moving instant readout window, its a berlina however.

Does it change by itself? I will check again this
arvo, but pretty sure mine stays at L/HR, wish
it was L/100

[myles]

Like jezzab said, just hit the freeway and travel 100 k and it will give you a good indication.

Smitty, your VX SS sounds like its performance has improved like it did with mine!

It's making me even more envious of the guys with edit. :lol:

[Smitty]

Smitty, your VX SS sounds like its performance has improved like it did with mine!

maaaaaate, is the pope a catholic...or what....... :lol:
goes like a new one

now
all i gotta do is save for the Edit :)

[VX2VESS]

Does it change by itself? I will check again this
arvo, but pretty sure mine stays at L/HR, wish
it was L/100

yes as soon as the car moves...

[xshore]

ummm
how did you manage to turn the ignition on
while the fuse was out...???
3 metre arms....? :lol:

Are you meant to turn ignition on ? The instructions I read didn't say this

1. Ensure Engine Coolant Temperature is more than 80 degrees.
This information is relatively easy to find. While the car
is turned off, hold down the MODE and UP Buttons on your trip computer, and turn the car on.
2. Turn Ignition OFF * VERY IMPORTANT *
3. Remove PCM/BCM Fuse
For starters, grab the Fuse Tool from the main Fuse compartment. (Pull down the panel below the steering wheel, the fuses are on the right hand side, and the tool highlighted below. (Look up 'Fuse' in the owners manual.) Next, pop the bonnet and open up the Engine Compartment fuse/relay panel) - just above the battery. The fuse diagram should be under the lid of the engine compartment fuse box. You are after F31 - the "ENG. CONT/BCM" Fuse. It is a 10A on my car - but I believe can be different on later models. Use the Fuse tool above, and carefully remove the PCM Fuse. If the fuses are Brittle (as they can get if older), I suggests picking up a few backup fuses before you do this... just in case.
4. Wait 20 Seconds
5. Replace the PCM/BCM Fuse
6. Perform the Idle Learn Procedure
For Automatic Transmissions:
a. Ensure Ignition off and PCM Fuse is back in place
b. Set the park brake on and block the drive wheels
c. Turn the Air Con / Climate Control OFF
d. Start the Engine (Coolant temps should still be >80 deg.)
e. Shift transmission into Drive
f. Allow engine to idle for 5 minutes
g. Shift transmission into Park
h. Allow engine to idle for 5 minutes
i. Turn the engine off for 30 seconds
For Manual Transmissions:
a. Ensure Ignition off and PCM Fuse is back in place
b. Set the park brake on and block the drive wheels
c. Turn the Air Con / Climate Control OFF
d. Place transmission in Neutral
e. Start the Engine (Coolant temps should still be >80 deg.)
f. Allow engine to idle for 5 minutes
g. Turn the engine off for 30 seconds

[Smitty]

mate
the most important bit is missing.......
you have to do this-
4a. turn ignition on (do not try to start engine) and wait until 3 chimes sound..
turn ignition off

hth

cheers

[racketsports]

mate
the most important bit is missing.......
you have to do this-
4a. turn ignition on (do not try to start engine) and wait until 3 chimes sound..
turn ignition off

hth

cheers
Do you do this section whilst the fuse is still out?

[XLR8 V8]

Do you do this section whilst the fuse is still out?

Yes .... insert step 4a. in between step 4 and step 5.

[Smitty]

Yes .... insert step 4a. in between step 4 and step 5.

yep, thanks mate
4a usually goes between 4 and 5
thats why i numbered it 4a.... :D
and yes
to be done with the power OFF (fuse out) to the PCM
but ignition on...
the three chimes..indicate the reset has occurred

seems contrary but thats the way it works...

and the ignition MUST be OFF before you reinsert fuse
otherwise you will fry the PCM
which is verrry expensive...

[xshore]

I tried again after work yesterday. This time when i turned ignition on it chimed in ~ 10 sec. Then i went through the rest of the procedure. Instant results. The drive home was nice. The engine was a lot quieter at idle and while driving. the accelerater pedol was very firm and the power increase was awesome. it was a lot firmer when i was changing gears. i can agree with others it makes if feel new again. I'm pretty sure it didn't change the fuel consumption by much. about 2 weeks again ever since i was desperate and filled up with some shitty petrol from a not so popular petrol station my accelerater pedol felt slushy.

[Smitty]

I tried again after work yesterday. This time when i turned ignition on it chimed in ~ 10 sec. Then i went through the rest of the procedure. Instant results. The drive home was nice.

yeah...nice
an instant horsepower pick me up..... :cool:

[2inch]

It's like giving your LS1 a can of redbull! My question is, does a custom edit remove the need for regular PCM resets?

[BLACK 346]

It's like giving your LS1 a can of redbull! My question is, does a custom edit remove the need for regular PCM resets?

Apparently so :yup:
Mine never feels like it needs one anyway.

[xshore]

fuel economy has improved. no more guzzling 1/4 tank to work. no more mad spikes in the L/hr when i touch the accelerator.... and the note out of the exhaust, very nice.

[PepeLePew]

Tuna did say a reset makes no difference. But to clarify what he said it makes no difference when your tune is 'right'

My car recently has been responding favourably to a reset...concerns me something is no longer quite right with plugs, cats, O2 whatever...

Far as I can see though, even if it does make a difference it'll slowly head back to where it was as it learns, yes?

[xshore]

yep it will. but i think my fill up with really shit petrol had something to do with it too, so aslong as i stick with optimax or ultimate i should be better off.

[Smitty]

fuel economy has improved. no more guzzling 1/4 tank to work.


ain't that the truth....
after my reset, I have been checking
from 270 ks to a tank to ...450k's a tank
I am amazed what a simple thing can do.... :confused:

[MNR-0]

A PCM reset is only short lived if your VCM is not properly tuned. Within a few hours of drive time it will revert back to its prior state. There is never a need to reset your PCM if you have a good tune.

To my knowledge nothing changes with a PCM reset apart from memorised fuel trimming in closed loop. If you already have stable and optimum fuel trimming this is not required and can take you backwards as your car has to re-establish its optimum fuel curves.

I liken this to the difference between a cheap whore and a marriage of love. :rolleyes: Untuned the reset will give you quick cheap one-off gains but you have to keep going back for more. Tuned the fun lasts all year round (well, for some people anyway - bad marriages are also quite common (aka. bad tunes))

[Smitty]

A PCM reset is only short lived if your VCM is not properly tuned.
and after sampling what a reset can, i am looking at an Edit....
saving right now...

[pah]

Hi MNR-O,

I agree - steer clear of cheap whores. The trouble is that a bad marriage is a LOT more expensive . . . when it ends. A marriage of love is the way to go.

Am I correct in my belief that the PCM monitors driving style and alters the engine's tune to suit driving styles and throttle openings? If so, perhaps a reset takes the computer back to a default setting that is running a little less rich?



PAH

[MNR-0]

It depends on what the stock tune is like. Odds on its pig rich in PE mode regardless and its just the closed loop learning. Usually you can nail it straight after a reset and it will lean off the first few times in PE due to the LTRIMS learning just how farkin lean your car runs in closed loop. Once they realise your are lean, they will add fuel to your WOT charges and you are back to square one. You only get 1-3 WOT runs before it all goes south again.

[karter42]

Well curiosity got the better of me, so on Saturday did a PCM reboot. Gotta say, Mid-range/Top-end, no real difference at all but bugger me, bottom end a lot of difference, very smooth and responsive.

Don’t know about the 3 WOT and back to normal theory though, Did more than that over a couple of laps of Mt Panorama and still the same as when the re-boot was done. A little better on fuel as well as burning light grey in the exhaust again.

[Thumper]

burning light grey in the exhaust again.
What! are you using leaded fuel? If it were my R8 and it had a light grey exhaust, I would be :eek: :eek:

[karter42]

What! are you using leaded fuel? If it were my R8 and it had a light grey exhaust, I would be :eek: :eek:

BP Ultimate, has got me buggered. For months it was grey, lately dark but not black, back to grey now