M42 318iS TURBO INJECTORS CHANGE PROBLEM

[vatos_p]

HELLO EVERYBODY...I would like the help of everyone here...
I have recently changed my injectors for stock m42 to bosch 310cc ford racing injectors...

I use Perfect Power Smt-7 piggyback for recalibration , i am running in 0,5 bar pressure , and everything is fine.....

the problem is at idle and in the rpm form idle to 2000 rpm... after 2000 rpm the car runs exelent... below 2000 rpm it runs rich ( and i cannot lower the fuel anymore from the piggyback ) , and at idle the car goes from 500 rpm(ready to stall )  to 1230 rpm all the time , sometimes it idles like that , and sometimes it stays in 1120 - 1230 ...is there any way to recalibrate the stock ECU to accept the 310cc injectos so it can control correctly the fuel and the idle ?
is there any other way to fix it ? is there anything else should i look for ?

I have heart that motronic M1.7 Ecu can read any change in injectors or fuel and adjust itself ( learning mode )...
Does anyone knows about that? has anyonde did a change like that ?
waiting for your help....

[ose30]

I have heart that motronic M1.7 Ecu can read any change in injectors or fuel and adjust itself ( learning mode )...
Does anyone knows about that? has anyonde did a change like that ?

You are way too optimistic Motronic does not know what injectors you are using. Of course it runs rich when it is under low rpm's. You should remove fuel from idle and part throttle cels from fuel map under 2000rpm. That should be possible with SMT7. If not, then you need to have a rewrite chips program. Check out also those Ford injectors resistance is the same as the orginal ones have, otherwise you will burn your Motronic sooner or later. You can also add resistors to injector wireing harness to fix possible resistance problem.

[vatos_p]

You are way too optimistic Motronic does not know what injectors you are using. Of course it runs rich when it is under low rpm's. You should remove fuel from idle and part throttle cels from fuel map under 2000rpm. That should be possible with SMT7. If not, then you need to have a rewrite chips program. Check out also those Ford injectors resistance is the same as the orginal ones have, otherwise you will burn your Motronic sooner or later. You can also add resistors to injector wireing harness to fix possible resistance problem.

the injectors have the same resistance as the stock ones , it just have more cc than the stock ones..
the smt-7 can remove fuel , but the depends on stock ecu , because smt-7 cuts fuel by altering signals coming from afm , but in idle the afm is fully closed , so smt-7 cannot do anything about it because afm does not read air coming in...

could an ecu ( factory ecu ) recalibration fix this ?

[nuvolarossa]

the injectors have the same resistance as the stock ones , it just have more cc than the stock ones..
the smt-7 can remove fuel , but the depends on stock ecu , because smt-7 cuts fuel by altering signals coming from afm , but in idle the afm is fully closed , so smt-7 cannot do anything about it because afm does not read air coming in...
 
could an ecu ( factory ecu ) recalibration fix this ?

Can SMT7 be wired to a MAP instead of AFM? If so I think you'll solve all problems:rolleyes:

[Alibi]

SMT6 can be wired to MAP...and can fully control the injectors.

[ose30]

Can SMT7 be wired to a MAP instead of AFM? If so I think you'll solve all problems

How can MAP solve this problem? Injectors inject as much fuel with MAP or AFM when ideling. Motronic does not know if there is MAP or AFM. SMT7 converts MAP signal to such a way Motronic understands it, nothing else. Then ofcourse you have a possiblity to intercept fuel and ignitition maps.
I suppose the only possibilty to solve the problem is to rewrite chips program, if SMT7 cannot alter the amount of used fuel with low rpm's.

because smt-7 cuts fuel by altering signals coming from afm , but in idle the afm is fully closed , so smt-7 cannot do anything about it because afm does not read air coming in...

Now i do not know what you are meaning. Closed AFM does not have nothing to do with this. When your car is ideling, the Motronic reads the fuel map, you should be able to intercept the AFM signal with your piggy pack. At least it can be done several other piggy pack boxes like AFM Link and Intercept Link without difficulties. If i understood you correctly you can intercept AFM signal only when it is open. I suppose SMT7 is not designed to work that way.

[WARLOCKM42]

Hi do you have your idle control valve still on? If yes that is making the problem you see when the engine is idling it takes air from the idle control valve and from the small hole on the afm flaper. You run reach because you have added fuel via the larger ingectors but the afm flaprer door hole is too small to add the little extra air nedded for yopur engine to idle...engine stalls ecu raises the revs through the idle control valve instantly the flaper is moved and the engine is about to idle but it will never idle because ecu says at the same time to the idle control valve to stop and this procedure strars all over again.Theres a risky way to fix this ... try to open the hole on the afm a little, its located on the flaper.Since idling is your problem i thing it will be fixed this way maybe idle is a little higher after this 1000rpm or so but then you can adjust the thorttle body a little bit.The idea is to reduse vaccum becide afm flapper as not to open so fast when the idle valve opens and the engine revs make work a little smother.An other way is to open the afm reach to the potentiometer spring and adjust it with the engine working this will alow the potentiometer to move more difficult and motronic will understand that the amount of air coming to the engine is low so it will cut fuel too.You have to do it at working temerature and be very sensitive it is more dificult and more risky than the previous procedure but if you are desperate enough try this too.I wish i could do it for you but im 1000 miles away...

[ose30]

AFM calibration might work, but it is not the right way to fix this problem. The only right way is to change fuel maps first cels

[vatos_p]

1. yes , i have still the idle control valve on..
2. yes i have tried to alter the afm tensioner
3. exept the idle , from 850 ( idle ) to 2000 rpm i am running rich...because the injectors are large...i am thinking of putting a rising rate fuel pressure regulator , and lower the fuel pressure in low rpm , and when boost comes on rise the fuel pressure again...if i do that i think that with lower pressure in low rpm the larger injector will flow less fuel , and the problem is gone... and when  all the flow capacity of the injectors is needed in boost the fuel pressure regulator will rise the pressure...
do you think it will work ?

[ose30]

With that kind of pressure regulator you can change few % the amount of used fuel.

[vatos_p]

With that kind of pressure regulator you can change few % the amount of used fuel.

i only need a small amount of pressure drop , because the injectors are only 50% larger than the stock , and i have already cut 25% of fuel injected with the SMT-7 piggyback , so a 25-30% of pressure drop will do the job i guess..