Just wanted to ask if my broken water temp sensor on the back of my water pump housing is causing my rough idle in my fd. My power fc is tuned if that matters. i dont have anything to judge it against since I just got the car running today after a semi rebuild. I just want to make sure Im not wasting time not troubleshooting elsewhere. The power fc isnt getting any water temp reading right now. I have a new sensor on order.

 

A broken thermal circuit = infinite resistance = very cold false reading = add a lot of fuel = rich = bad idle.

You need to learn to use the manuals.

 

well i replaced the sensor and my idle, although slightly better is still crap. it idles as though its bridge ported and revs super rough with a lot of engine vibration but as soon as i create a vacuum leak it idles perfect and revs smooth. the vibrations go away as well. by creating a vacuum leak, i mean removing the vacuum cap from the other nipple on the side of the uim. while i was troubleshooting another issue, i noticed the tps was way out of calibration and the throttle cable was tight to the point that it was pulling the throttle plates open. im starting to think this is the reason why.

im guessing the po or whoever worked on the car did this as a fix and couldnt find the actual issue. i am going to make a separate thread for it if i cant find any information on this.

 

problem solved...

this little thing here has a super small and tight sweet spot. i found it and perfection was achieved. along with adjusting it, i recalibrated the tps to different parameters withing spec.

 

The picture shows two throttle adjustments.
The one on the bottom that is rusty is the main physical throttle idle adjustment just like all TBs and carbs have. It is the main physical idle adjustment. The ISC is the electrical idle control, and the air bleed screw/air adjusting screw is the fine tune physical idle control.

The one in the middle of the photo is the mechanical stop for the secondary throttle. It is used to prevent the throttle plates from digging into the TB bore when closed all the way.
You loosen it so it does not work, open the secondary throttle and let it softly close all the way so that it is 100% closed. Then turn the screw in just until it touches the level but does not ever open from it.

 

i didnt know you were chuck westbrook. this whole time..... you were right here lol

anyway, i dont have an isc or any other idle controls. long story short, i reset the stop for the secondary throttle so that it was just touching like you described. then i compensated with the funny looking rusty screw on the bottom of the picture. the po had overtightened the throttle cable and adjusted the tps accordingly. so to undo that, i loosened the throttle cable and adjusted the screw to supplement what his intentions were and adjusted the tps accordingly. my idle afr is in the low-mid 11s

my issue now is that im having a really bad ignition break up issue when trying to get into boost. so i cant boost at all. i can drive out of boost just fine but as soon i try and put that load on, i get nasty break up and my afr gauge pegs out at 10 since thats the lowest it will read. a friend of mine is helping me troubleshoot and were to the point of messing with the tune itself. i am a little skeptical since i havent changed anything and i dont understand how a great tune could go sour just from nothing it seems like. i just took everything apart and put it back together. i didnt change anything =\

 

The setup of the throttle body is the first thing to do on all unknown cars.
(1) Secondary throttle alignment.
(2) Hot wax rod/cold start idle disengages when hot.
(3) Cable setup so that there is slack in it at idle but also fully opens TB when floored.
(4) Get airflow for proper warmed up idle then adjust TPS for correct voltages.