Question about Error Codes - Engine Light

[wiseman]

I read threads about how you guys check for error codes by shorting out the pins with a bent paper clip.
My question is, if your engine is producing errors while driving, does the engine light come on at that time? To let you know there is an error, the engine light should come on, true or false?
I was told by a mechanic, that whenever there is an error, the engine light comes on, and stays on till the error is fixed, or the log reset by disconecting the battery.
If not, when does the engine light come on? My VS has had an intermitant miss in it for a long time, and the only time the engine light has ever came on, was when the fuel pump stopped working.

Also was told that a diagnostic check, will not pick up faults or errors with, coils playing up intermitantly, or show up a partially blocked injector, or injector problems. ( mabey unless it missfires while hooked up to the diagnostic).
I did my own error test with the paper clip, and came up with nothing (12), no errors.

My engine still has a intermitant misfire in it, i have changed all the usual things on it, spent heaps of $$, and still no luck. I am at a total loss as to what it is, it happens regularly, engine cold or hot.

[_R_J_K_]

Also was told that a diagnostic check, will not pick up faults or errors with, coils playing up intermitantly, or show up a partially blocked injector, or injector problems. ( mabey unless it missfires while hooked up to the diagnostic).
I did my own error test with the paper clip, and came up with nothing (12), no errors.

Code 12 will flash 3 times before any other codes are displayed.

There is only so much that the ECU can log codes for, otherwise you would have a million sensors for really not much gain. Have a look at the code list, they are all things which directly interact with the ECU in some way, and if the ECU "sees" something strange about them, it will log it. There is no way for the ECU to determine if an injector is blocked as opposed to completely stuffed, or if there is a cut lead as opposed to a dead coil. The ECU is not meant to be some all knowing black box that will pick up every fault, that is not what it was primarily designed for. Yes it was designed to pick up errors, but it's primary use is to control the engine.

Think of the fault logging as a troubleshooting tool as opposed to an all knowing system that will tell you exactly what's wrong with your car.

The search tool is good too for your miss-firing problem (if you haven't used it yet).

[ephect]

as _R_J_K_ said, it does log, the paperclip is a basic tool to check your codes, but it wont tell you everything, if you really wanna check if there is more wrong, get it plugged in at holden or midas on a tech (2) it will give you a heap more info, and im sure they can run your car and diagnose on the fly.

but yes there are a few threads on miss-fires, have a search and see if anything looks similar, if not post up more on your issue.

[Brett_jjj]

Some engine management problems will turn the engine light on depending on the error that has occured.Others will just log an error code that can be flashed up with a paper clip or read with a scantool.The Tech1 scantool holden uses for VS models and earlier can check all the sensors,and show their readings and voltages etc, It can also bring up the error code history to see what,(if any) errors have been logged and cleared over time.These can all be reset with a Tech1.Whereas if you just disconnect the battery it will clear any logged errors, but not the error code history.

[wiseman]

Yeah thanks for the info. Found out what i wanted to know. Besides ripping out all my hair, and puting a match to the car, i guess the next thing im gunna do is take it to my local mechanic to have the scan tool put on it. (he has one) I'm just fed up with replacing parts on it, and getting no where.
I have searched and read all the threads on here about VS misfire, and replaced all the usual stuff, no luck.
Brettjjj, i kept up with your thread about misfire, canister purge solinoid? Sounds like you got it sorted anyway.
Thanks for the help, and i will let you all know what the cause is or was, when i find out. I having it scanned in a couple of weeks when i get a rego check.
Cheers

[ephect]

while the weeks pass by before the scan, might as well post up whats happening and what you've replaced, you never know, something else might spring to mind

nothing to lose

[moff_man]

there is only really 3 or 4 tings that can cause a base miss. air - restricted flow or air leak, fuel, pressure and flow ie fuel pump fuel filter, and injectors, thats delivery of fuel, than spark. coils and leads also crank sensor for when to spark. there are other factors that can not be interment like compression, either you have it or you don't.

with the scan tools yeah they are a good tool but like any tool needs to be used in conjunction with good diagnostics. also a code doesn't necessarily mean a component is faulty, other things like wiring and such also comes to play.

[wiseman]

So today after getting my rego inspection, i also had a diagnostic check, it cost $15, and came up with one error code, Code 31 - Theft Deterrent Signal missing
Anyone know what this means? Dosent seem to have much to do with my engine miss.

[delcowizzid]

just means youve turned the key and tried to start the car and the key hasnt made proper contact with the surround ring of the ignition to turn of the security nothing at all to worry about

[wiseman]

just means youve turned the key and tried to start the car and the key hasnt made proper contact with the surround ring of the ignition to turn of the security nothing at all to worry about

Yeah thanks for that. The mechanic did say he bent out the tabs on the ignition barrel a bit to make better contact with the key. Still dosnt do much for my intermitant misfire problem.

[wiseman]

Hey all, just an update on my intermitant missfire. I swaped over the DFI/coil pack with a use one, and my car didnt miss a beat, well, for about 500km anyway, now its doing the same sh#*
This is the second DFI/coil pack i have replaced, last time was the same thing happened, it lasted about a week, then started missing again.
I have checked and cleaned the male plug that goes into the DFI, all the connectors look fine, however, i did notice one hole was blank in the plug, but forgot to notice if it had a wire going to the back of it.
I remember a thread on here somewhere called, 'why is my vs eating DFI's? Any ideas ?