Unable to set Throttle body and TPS

Post here for mechanical and engine topics such as fuel issues, transmission problems, rough idle, exhaust, electrical issues, etc

Moderators: GRNSHRK, ron, bfons

Post Reply
User avatar
smtguy
Posts: 159
Joined: Sat Apr 29, 2017 3:38 pm
Location: Southern California

Unable to set Throttle body and TPS

Post by smtguy »

I have long suspected that my '83 633CSi (US Version with 02 sensor) had incorrect settings on the TB and TPS. I have spent a good deal of time on Bigcoupe researching what needed to be done to correct these settings, and read the admonishments from Brucey and others; all of which made sense to me.

Over the weekend I decided I had enough time to methodically tackle these adjustments, and to check for vacuum leaks. I found 3 leaks and managed to seal them. When it came to the TB and TPS adjustment though I found I was unable to set the required .020" butterfly to bore gap to any more than about .008" due to the constraint of the mechanical adjustment. I also found that even when I set it to .008" I was unable to adjust the TPS to click when the throttle fully closed. Getting the settings as close as possible to the recommended ones, upon starting the car, it would idle high at 1100-1200 RPM - a little high I would say.

Does anyone have any idea what I could be doing wrong?
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

Scott
User avatar
Jono B good
Posts: 188
Joined: Mon Jun 04, 2018 10:33 pm
Location: Victoria, B.C., Canada

Re: Unable to set Throttle body and TPS

Post by Jono B good »

Make sure the throttle body is damned well clean, use a toothbrush and rags clean it out especially where the plate meets the intake potion of the TB. While in there and you can lube the hinge points of the plate and other moving parts just don't drench it out. It could possibly be a jammed Idle Air Control Valve, easy enough to clean though, use MAF cleaner not throttle body cleaner as it's too harsh, spray inside the IACV and shake, shake, shake. Rinse and repeat, with fingers keeping cleaner inside, the metal valve should be able to freely move once dried, if it doens't help, then try to do a reset to the ECU by disconnecting both battery terminals and wait an hour. Then drive as normal after about a 30 minute using various equipment AC, Radio etc. she should be back to normal. I'm quite sure Brucey will have better anecdotal evidence that points in a completely other avenue though. \:D/

P.S. the TPS could be pooched as well, you may need to replace the unit, if test results don't jive.
Image
~Cirrusblau-Metallic~
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: Unable to set Throttle body and TPS

Post by Brucey »

it is possible that your throttle linkage is simply too worn; the butterfly is sprung shut directly and the linkage that constrains it (and has the throttle stop on it) is connected via a linkage that has two bushings in it. Commonly these bushings wear (they ought to be lubricated at every service and they usually aren't) and the more they wear the more the throttle closes itself. Eventually you run out of adjustment. The throttle stop itself can wear too.

With reference to this illustration

Image

if you have run out of adjustment you can

- replace part #5
- bend the wire link in part #5 to shorten it
- elongate the slot in #6 so that it moves further
-bend the tang on #6 so that the range of adjustment is changed

since the TB rarely wears out it is easy enough to source a good used replacement

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
smtguy
Posts: 159
Joined: Sat Apr 29, 2017 3:38 pm
Location: Southern California

Re: Unable to set Throttle body and TPS

Post by smtguy »

Thank you both for your help. The other part of the problem would then be the TPS clicking where it should after setting the gap on the TB.

The other thing I don't understand is if I get the gap set at .020" what keeps the car from idling high? The ICV? WHere should the screw be set on that?

Thanks again.
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

Scott
User avatar
Brucey
6 Series Guru
6 Series Guru
Posts: 10077
Joined: Fri Apr 09, 2004 7:17 am
Location: Cambridge, UK

Re: Unable to set Throttle body and TPS

Post by Brucey »

you set the TPS after the TB is set correctly. A 0.020" gap (or smaller) should (by itself) only let in enough air to let the engine idle very slowly, even when hot.

If the engine will only idle quickly, there is a fault with the ICV (jammed open or something) and/or there is air bypassing the TB somehow (i.e. effectively an air leak of some kind, either metered or unmetered air).

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
User avatar
smtguy
Posts: 159
Joined: Sat Apr 29, 2017 3:38 pm
Location: Southern California

Re: Unable to set Throttle body and TPS

Post by smtguy »

Thank you Brucey - I will give it another try.
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

Scott
User avatar
hornhospital
Platinum Member
Platinum Member
Posts: 2929
Joined: Sun Jul 11, 2010 6:46 pm
Location: Silverhill, AL
Contact:

Re: Unable to set Throttle body and TPS

Post by hornhospital »

Scott, what are you using for the 0.020" gauge? If you're using a flat feeler gauge, accurate setting will be difficult. It's best to use a #76 drill bit (0.020") or piece of drill rod that diameter. A feeler gauge won't readily bend at that thickness, and the gauge flat will bridge rather than laying tucked down against the radius of the throttle bore, resulting in a bigger-than-0.020" gap.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
User avatar
smtguy
Posts: 159
Joined: Sat Apr 29, 2017 3:38 pm
Location: Southern California

Re: Unable to set Throttle body and TPS

Post by smtguy »

Hi Ken - Yes, I was using a .020" pin gauge.
1983 Bronzit 633CSi 5 speed
2004 Audi TT Quattro 6 speed

Scott
Post Reply