(T) ECU "timing correction"

Hello EveryBody,

I need some help.
So, we pluged the ECU to the Computer . We used the VISA program.
No error, but there is a field in the parameter list. This filed is the "timing correction". And this value ( I think ) not good. What is the correct value?
So my value is: 0 - ... deg. But sometimes this value goes to -23 deg. What is this? What is the error or has anybody solution?
Ps: The Engine is TD100 Marea 97'

Thank you

is this not for the Variable Valve Timing?

HI,
I don't think, But I do not know what do you think for.
There is not variable valve in the TD100 engine.

whity

ignition timing correction is just one of the many real time data values you can read. during engine load and use it should change almost continually as the ecu adjusts the ignition. on your car a major contributor to this is the EGR pressure transducer. when cold or at idle the value should be 0. if it stays at 0 when you rev the car (once its warmed up) i would suspect an EGR fault is most likely. next time you should let the car warm up while checking the correction value, then rev the car for a few seconds and see if it changes (it should).

Ok, Thanks the information but I do not understand that why is the value sometimes -23 deg. Have you any solution?
Yes, my EGR valve does not work because I unpluged the vacum cable from the EGR. What do you think about this?
Regards

-23 means the ignition is 23 degrees advanced at idle, but only occasionally because it is at 0 most of the time. thats not a problem, you would expect the ignition to advance when the ecu determines that ignition advance is needed to make sure all the fuel is burnt in time. it could also retard slightly depending on the conditions, but overall at idle you would expect to see 0 more often than anything else. if it was constantly at -23 i would possibly think overfueling was happening, and the advanced ignition was used to compensate for that, but on modern cars that kind of situation usually only happens if a sensor fails that affects the fuel injection (so ignition is used to compensate that lack of control on fueling), where as on older cars the carb set up would be suspected.

if you can repeat this test you should try accelerating the engine speed, this should show an increase in the ignition advance. this happens to make sure the air-fuel mix has enough time to burn at higher rpm. at higher rpm there will be more fuel and less time to burn it, so ignition advance is needed. if it was not advancing correctly you would notice a loss of power and high emissions (unburnt fuel).

lets assume you did notice a lack of ignition advance at higher engine speeds. traditionally advance was controlled by vacuum. although your car (all modern cars) now use electronic ignition systems, there is still an electronic method used to assess the vacuum. the EGR pressure transducer on your car sends a signal to the ecu, which lets it know the vacuum condition. if this was faulty the ecu would not recieve this information, which could cause the ignition advance to be incorrect (retarded in relation to engine speed). this isnt noticable at idle, but under load you would see power loss and high emissions.

if you have disconnected your EGR vacuum hose then obviously the EGR pressure transducer will be telling the ecu that there is no vacuum, which would retard your ignition.

hope this helps. i really should charge for this type of info, garages dont give it out so freely.

But you don't and thats why we LOVE you!

if you have disconnected your EGR vacuum hose then obviously the EGR pressure transducer will be telling the ecu that there is no vacuum, which would retard your ignition.


AHA, Ok I understand but more question:
I just unpluged the vacum cable from EGR valve, therfore just the EGR valve does not work, but the little vacum valve ( this valve controls the big EGR valve ) before the EGR is working.
Is it enough? Or not.

regards,

i'm not familiar enough with this engine to say exactly. however the basic principles of EGR systems mean the EGR vacuum solenoid (little vacuum valve) is controlled by the ECU and is turned on to allow vacuum to the pressure transducer (basically this swithes EGR on or off). The pressure transducer regulates the amount of vacuum to the EGR valve depending on engine load (exhaust back pressure). From your description it sounds as though the pipe which would allow the pressure transducer to regulate the amount of vacuum to the EGR valve has been disconnected. this alone should not cause the ignition to retard, however i would need to examine this particular set up more closely to be certain.

i just realised, i havent even asked you what the problem was that started all this in the first place. what exactly is wrong with your car?

TD100? Isnt that a turbo diesel??? If so then it does not have spark ignition??? Otherwise, yes high vacumn usually low engine load so weak mixture so burns slow so lots af advance to geat peak pressure just after TDC.

haha quite right! i was thinking its a 1.6 petrol (dont know why, maybe too many injector threads has started to get to me). i need a good shake sometimes.
i'm pleased someone is awake.

Ok, Ok I am trying to write the correct problem.
So the enginde is a 97' TD100 with Lucas injection system. So:
My problem is the revolutions per minute.
So, sometimes when I use the maximum engine rpm in 1st and 2nd and 3rd gear after the acceleration the engine is not working correctly. The RPM is rippling. Or I use the engin a fix rpm 2500 and i use the gas pedal fine sometimes the engine is rippling too. I hope you understand my problem. I changed the fuel filter and a lot of things but nothing. Fuel filter , MAF, Potentio meter on the gas pedal, ... .
No error in the ECu... . I do not know what is the problem. The injetion system is working everything looks like good.
But we have two thing what we did not change. the first injection point. There is a electronic system on this point.

Solution?

sounds like misfiring (if you can use that phrase for a diesel).

there are only 3 real possibilties:

1. fuel injection giving too much or too little fuel
2. lack of compression
3. turbo not giving enough boost

lets rule out the easy one first, do a compression test on all cylinders. if you have low compression it may be due to worn piston rings, dirty valves, inaccurate timing setup, worm camshafts. the compression test will give you a good idea of how healthy the engine is.

assuming the compression test shows all cylinders are getting good compression, you can be sure the problem is the fuel injection or turbo.

it would then be a good idea to try and determine if the fuel injection is overfueling or underfueling. if you see more black smoke than you would normally expect then it means overfueling is the problem. if the rpm wont go as high as it should it probably means underfueling is the problem. an emissions test will confirm more accurately which is happening.

fueling problems dont neccessarily mean the fuel injection is to blame. it can also be a turbo problem. i would check the 4 main causes of turbo problem, stuck EGR valve, stuck wastegate, faulty MAF, or post turbo leak (check piping).

if all that fails to find the fault at least you will know the following for certain:
1. compression is fine
2. turbo is providing correct boost
3. underfueling or overfueling is the problem.

once you know that you can start to go through all the possibilties of why the fuel injection is under or over fueling.

This field you are looking at sounds to me like the injection advance value, but I'm not sure which one you are looking at ?

the actual advance value is read by the ECU using the sensor injector (the first injector near front of engine with the green bit around it and cable coming out of it). The desired timing advance will be calculated by the ECU based on the other sensors inputs. The ECU then controls the injection advance solenoid to change the injection advance.

I would not expect to see it jumping around randomly, but it will change smoothly when the engine is driving the car.

What happens when you drive the car - does the engine lose power when it hits a certain rpm or do the RPM's just jump around (hunting) - really need a better description of the problem, and symptoms of it, e.g. black or white smoke etc..

there are several possibilities for timing faults, the most likely culprits being the injection advance solenoid or the first injector. Maybe a mechanical fault with the injection pump.

i agree, now that i know we're talking about a diesel it must be the injection advance angle that is been read. however both injection and ignition advance follows the same theory, its all about making sure the cylinder achieves maxiumum pressure from combustion, which is all about making sure combustion happens at the correct time in relation to the piston's stroke. with ignition you consider the time the fuel/air mix is ignited, with injection you consider the time the injector opens.