please help with throttle body!

[Guest Anonymous]

This throttle dilema is really starting to take its toll. To sum up the problems:

1. Its a TWM 2800 series, on a l28 turbo.

2. Took it apart (looking back, i shouldnt of )

3. Now the throttle closes perfectly when the car

is not running, but when running it seems that

the Throttle position sensor (from sds) seems

to put the shaft under tension therefore not

letting the plate close all the way. Its not

much (not even half a millimeter)

4. Is it the air rushing by the plate that is

causing the tension on the shaft and plate, or

does the tps put a load onto the shaft, or

do i simply have the idle screw set to low,

and i should let it rev higher,(its idling

at about 1400, too low???

please help!

thank you in advance,

franklin

[Guest HIGHRPM]

Originally posted by zpeedrazer:

This throttle dilema is really starting to take its toll. To sum up the problems:

1. Its a TWM 2800 series, on a l28 turbo.

2. Took it apart (looking back, i shouldnt of )

3. Now the throttle closes perfectly when the car

is not running, but when running it seems that

the Throttle position sensor (from sds) seems

to put the shaft under tension therefore not

letting the plate close all the way. Its not

much (not even half a millimeter)

4. Is it the air rushing by the plate that is

causing the tension on the shaft and plate, or

does the tps put a load onto the shaft, or

do i simply have the idle screw set to low,

and i should let it rev higher,(its idling

at about 1400, too low???

please help!

thank you in advance,

franklin

I don't know much about the datsun system, but most systems that i've worked on all have the same basic pricipal. the tps does not apply tension to the shaft!! The base clearence for the throttle plate and the bore should be about .001 to .0015 of a gap at closed throttle, which is controled by the set screw. Then the TPS is adjusted to show that the throttle is closed. Some TPS units are a switch type{ with an audible click when you work the throttle, some are set up to a certain resistance value.Whatever the design of the TPS, it is not a throttle stop.The Tps sends a signal to the computor which then sends a signal to an idle control circuit which controls your cold start idle and your fast decell speeds. So I would remove the TPS, set throttle plate clearance, lock set screw, reistall TPS and set to indicate closed value. And that should be that . Hope this helps.

[R0N]

Originally posted by zpeedrazer:

i should let it rev higher,(its idling

at about 1400, too low???

please help!

thank you in advance,

franklin

If you start it, does it die right away? I had this problem till I raised the idle screw (240sx tb)

 

1400 rpm, that's too high. My car is not tuned at all but idles at 750. I got some very good tips on how to tune it from Scottiegnz but I'm not going to attempting to tune my car until I get my wideband AFM with datalogging.

 

I was amazed on the instructions Scottygnz gave me, it was better then the SDS book.

 

Good Luck,