Problems with 4-throttles !!!

[levin818]

Problems adjusting the 4-throttles !!!

Hello friends, sifu, master, datuk, kawan-kawan sekalian,
I just had my SVT ITB removed, cleaned up, adjusted those lock nuts at individual throttle (to synconize the 4-butterfly) according to BT service manual, etc. Everything go smoothly but now i have a poblem. Since i have adjusted those lock nuts position, i need to re-adjust the 4 idling bypass screws in order to have a balance air flow. This is because the current position of the idling bypass screw is set for previous setting (before i adj the individual throttle). If it is a BT ITB, i can easily remove the surge tank and plug in a carb balancer at each throttle to read the air flow. But now mine is SVT, i CANNOT run the engine without closing the surge tank. So, how to measure the airflow at each throttle?
Currently the distance of 4 bypass screws measure from the screws surface to the top end position are as follow:

throttle no. 1 = 3.6mm
throttle no. 2 = 3.6mm
throttle no. 3 = 3.7mm
throttle no. 4 = 3.5mm

Engine idling at 1000rpm min, slightly on the high side.

Please advice if you have came across any solution before, or you have an idea on it. Tks!

 

[Acoustic]

just stick something at the afm to forrce the flap open and do yourr job.

 

[rollakid]

wanna ask, itb also have their own individual idle screw? where? wan learn.. cuz now i just adjust at the afm there only...

 

[cuscostrutbrace]

Yup..acoustics right...remove the intake surge tank and stick a wrench or what ever to hold the flap slightly opened,as it is in idle,i have tried this many times before,the engine can rev also,but not too high,i also try unplugging the afm connector and start,also can idle but not really smooth,but make sure to bypass the fuel pump pins or engine cannot start at all. :-)

 

[LevinTE27]

yea.. remove ur air flow. get something to stuck the air flow flap to keep it open. then engine can idle without air flow, start to do ur job then..

just stick something at the afm to forrce the flap open and do yourr job.

 

[Acoustic]

wanna ask, itb also have their own individual idle screw? where? wan learn.. cuz now i just adjust at the afm there only...

http://www.my-acoustic.com/Car/engine_overall/engine_tuning/part_1/engine_tuning.htm

http://www.my-acoustic.com/Car/vacuum/4_throttles'_vacuum/4_throttles'_vacuum.htm

 

[levin818]

Hey guys,
Thanks for the great idea! I will try it out when i get the Carb Balancer (still have no idea where i can borrow this stuff).
Just for your info, 1st gen ITB is damn lousy. When pulling the throttle's cable, i can see that the 1st and 2nd butterfly is leading 3rd butterfly, and the 3rd is leading the 4th.... they aren't syncronize at all... with all lock nuts seal with original yellow paint from factory. Moreover the 4th is opened wider at resting position. This explained why i always have a different burning colour at the 4 spark plugs' tips.
I just had a looked at my spare 1st gen ITB (already striped into pieces, so don't know how is the butterfly scyncronization status) 4 bypass screw's position, suprisingly all are at same position, that is 4.2mm from the top end position. It explain why my engine is running at 1000rpm idling with 3.5mm ~ 3.7mm position (may be my mech has adjusted these 4 screws due to previous idling problem). So before i get a Carb Balancer, I will first try to move all screws to 4.2mm and see if i can bring down the idling to 800rpm.
Perhaps, i will have better FC after syncronize the 4-throttles.

Will update later.

 

[Acoustic]

i think cuscostrutbrace has carb balancer, else pay power zone to do it

 

[levin818]

Aduiiih... 4.2mm give me idling at 1300rpm.
Pening liao...

 

[QiW]

eehhhh sifoo ... go gemok place in kajang laa ... he got the balancer ... but how much he charges to balance your vacuums i dunno laaa .. coz gua tarak 4ITB maaa .. huahahaahahahahaha ... :p

 

[levin818]

Hi Alan,
Your 4 ignition coils is much more powerful thats why you don't need 4-throttle ma...
Btw, tks for the info, i will pay him a visit this week end.

 

[levin818]

This morning the idling drops to 1200rpm at cold starts, ~850rpm at working temp. Could be the ECU starts to compensate the errors (that causing 1200rpm idling).
Note that I did not replace the gasket eventhough BT service manual recomended to replace some. And i forgot to apply instant gasket at each old gasket during installation.
Could it be the minor vacuum leak (at the old gasket) that causing high idling?

 

[Acoustic]

Levin wong sifu, I used to do like this ........

find flap voltage when engine idle at 900 rpm, i.e. mine was 3.15V DC

reset ecu, take off plenum, force open AFM at 3.15V, start, write down rpm together with water temp and air temp, start duration.



screw them all down max, it will either idle too high or too low, we write down rpm, listen to the sound

then screw them all up max, again write down rpm and listen

then screw all 4 one round until desired rpm

like that lor ............ but once put back plenum, can hear engine sound different

 

[levin818]

Hi Chin,
Tks for the great tips.
I will try following steps on tomorrow:

1) disconnect the AFM connector
2) jump FP to B+ (to run the fuel pump)
3) disconnect the ISCV (to avoid it kacau the rpm. Its default position is 50% open).
4) Turn all 4 screws to the bottom position (totally close)
5) Strat the engine and search for the highest air flow cylinder with the Carb balancer (i hope i can start the engine at this situation).
6) Adjust the rest of the 3 screw to be the same air flow as the first one.
7) put back everything & reset the ECU. Check for the idling rpm.

By the way, the FC remain bad until today (half tank made <200km). The Vf at the diagnosis connector give me 0.04V (meaning that the ECU is running the injectors at the lowest duty cycle. Highest duty cycle will give ~4.5V reading. Ideal reading is ~2.5V). Something went wrong with my fuel system...

 

[Acoustic]

hahahahahahaa, i think your method cannot work lah

the key point is manually force the flap open to 3.15v - this also you never do, i don't know you can maintain engine idle or not.

like that still don't understand i don't know how to explain further.

some more you want to disconnect ISCV, more difficult to maintain idle.

you sure you understand afm and iscv or not???

when you open afm, no need to jump wire for fuel pump anymore. it is connected when afm gate open. don't know why you always do not necessary thing ????? really shake head


haih i no eye see, you do lah, then let us knnow tthe outcome


btw i also try all 4 screws down max, then 1 cylinder up max and can hear engine sound change very different. after listen more, can understand engine idle bettter than sometimes "tune tune" by listen......

 

[cuscostrutbrace]

Hi..I have tried both method before,

1.Disconnecting afm socket and jumping fuel pump,ISCV connected
2.Force open flap,afm socket connected,ISCV connected

Both method i can start my engine and idle,and last time i have a friend transplanting SVT with one throttle(cylinder no 4) taken out from a donor ITB,directly he put into his SVT,the idle goes wild,1200 rpm to 1500 rpm up and down,when he changed back to the original throttle that comes with the engine,idle goes normal,that what he told me lor... :-)

 

[levin818]

hahahahahahaa, i think your method cannot work lah

the key point is manually force the flap open to 3.15v - this also you never do, i don't know you can maintain engine idle or not.

like that still don't understand i don't know how to explain further.

some more you want to disconnect ISCV, more difficult to maintain idle.

you sure you understand afm and iscv or not???

when you open afm, no need to jump wire for fuel pump anymore. it is connected when afm gate open. don't know why you always do not necessary thing ????? really shake head


haih i no eye see, you do lah, then let us knnow tthe outcome


btw i also try all 4 screws down max, then 1 cylinder up max and can hear engine sound change very different. after listen more, can understand engine idle bettter than sometimes "tune tune" by listen......

Are you sure Mr. Chin?
If i tell you that i just managed to idle my engine at 1000rpm with AFM and ISCV's socket DISCONNECTED, and with Fp jump to B+, what will you think?
Just tell you again if you still not aware of, i will never try out something without a reason.
It idle at 1000rpm very stable, with temp needle pointed at 1/5 scale.
I even can ramp the rpm to ~2000rpm (never try more than that).

Tks cuscostrutbrace for your great info!

 

[cuscostrutbrace]

Yes..i agree with Mr Levin818,last time i also got the engine to idle at around 1000rpm and very stable,also can rev,with both method,engine can be revved till 2k+ rpm...

 

[Acoustic]

wah, like that also can????? what is the logic?

no afm signal, voltage= open circuit or 0v, fuel map selection would be ???? from where ???

not logical, but since two of you proof can means can.

force fuel pump on is easy, no iscv at most i tiinnk idle eratic, but no afm voltage i really don't understand

see what logic you all give ???

 

[levin818]

Disconnected the AFM socket ==> It simply because Bill has shown it to me when he was in KL. You were there also lah... but keep tok kok around and never pay attention. Theory behind? ECU running in limp mode when one of the sensor's signal is absent (may be...)

Disconnected the ISCV ==> without any voltage applying to the ISCV, its opening is 50%. This is more than enough for the engine to idle.

I disconnected the ISCV because i don't want the ECU to interrupt the idling rpm when i measure the airflow of the individual throttle. Imagine if you let the ISCV connected and when half way tuning the throttle bypass screw, suddenly the ECU gatal go change the ISCV's duty cycle, then airflow also change.... die lor have to redo all again.