Skunk2 Throttle Body Sticking?!
09-20-2018, 09:28 PM
#21
Senior Member
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Join Date: Mar 2006
Location: Indianapolis, IN
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Essentially everything except the bypass screw (you obviously need to be able to adjust this), and throttle plate bolts (never touch those). I use blue for all the loctiting.
I've installed a few lately that have had decent hardware, your results may vary. Just snug every throttle body to intake manifold bolt one at a time without the gasket. If you can still wiggle the throttle body, then the screw is too long. I have a drawer full of various lengths and sizes of SS metric allen bolts available to me, so unfortunately I can't tell you the exact length for all of this.
The only other problem spot besides the spring hole mentioned above, the loctiting, and the TB to IM bolt lengths is the IAC adapter bolts. For a while there was one with the NB adapter that wasn't even sticking out past the gasket, so I had to lengthen it. IIRC in one of the locations I could just reuse the stock screw, but again I would just grab the appropriate one from the hardware drawer and loctite it in.
Hope this helps, thanks everyone for the shout out. The amount of time I wasted trying to tune the sporadic idle before I found this issue was insane, so good to now know what it was.
I've installed a few lately that have had decent hardware, your results may vary. Just snug every throttle body to intake manifold bolt one at a time without the gasket. If you can still wiggle the throttle body, then the screw is too long. I have a drawer full of various lengths and sizes of SS metric allen bolts available to me, so unfortunately I can't tell you the exact length for all of this.
The only other problem spot besides the spring hole mentioned above, the loctiting, and the TB to IM bolt lengths is the IAC adapter bolts. For a while there was one with the NB adapter that wasn't even sticking out past the gasket, so I had to lengthen it. IIRC in one of the locations I could just reuse the stock screw, but again I would just grab the appropriate one from the hardware drawer and loctite it in.
Hope this helps, thanks everyone for the shout out. The amount of time I wasted trying to tune the sporadic idle before I found this issue was insane, so good to now know what it was.
This needs to be a sticky
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11-07-2018, 06:26 PM
#23
Junior Member
Join Date: Jul 2017
Location: Sussex, England
Posts: 224
Total Cats: 47
Has anyone had the throttle sticking closed after running through the mods on here? There seems to be a fair bit of stiction on the very initial bit of travel. It gets tiresome in the 50mph average speed zones that keep cropping up around here :(
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11-10-2018, 10:12 AM
#24
Cpt. Slow
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Join Date: Oct 2005
Location: Oregon City, OR
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Have you tried screwing in the throttle stop, and decreasing the bypass? My first guess, without seeing the throttle body, is that the throttle valve is closing too much and jamming in the bore.
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11-13-2018, 06:02 PM
#25
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Join Date: Jul 2017
Location: Sussex, England
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I thought it may be side loading on the cable (the throttle cable mounting now looks to be a touch offset from the throttle cable axis? - but I didn't pay much attention to this with the OE TB) but lubing the cable didn't help.
I also did a trackday and on the return journey the sticking was even worse than before, it was both sticking closed and open. This could be from everything getting heat soaked or just a pure function of run time (I doubled the number of hours on the throttle body). I'll take it apart and have a look.
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11-18-2018, 05:36 PM
#26
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Join Date: Jul 2017
Location: Sussex, England
Posts: 224
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I took the throttle apart this weekend. I couldn't find anything obvious binding, so I redrilled by 6 o'clock return spring hole at 5 o'clock.
This seems to have resolved the sticking open issue, but the sticking closed issue is still somewhat there. I wonder if now perhaps I have a lot more preload compared to what I am used to, so it feels quite unnatural. I can't really see any easy way to solve this.
I'm tempted to have a go at designing a cable cam with a variable motion ratio which would be much slower around the throttle closed position. This would help reduce the efforts at the throttle closed position and enable finer control (at least get it back to OEM) at small throttle openings. It's just very frustrating to pay solid money for such a crappy aftermarket part, but here we are.
This seems to have resolved the sticking open issue, but the sticking closed issue is still somewhat there. I wonder if now perhaps I have a lot more preload compared to what I am used to, so it feels quite unnatural. I can't really see any easy way to solve this.
I'm tempted to have a go at designing a cable cam with a variable motion ratio which would be much slower around the throttle closed position. This would help reduce the efforts at the throttle closed position and enable finer control (at least get it back to OEM) at small throttle openings. It's just very frustrating to pay solid money for such a crappy aftermarket part, but here we are.
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04-05-2023, 09:00 AM
#28
Thank you for this thread! I was recently having an issue with my Junk2 TB sticking open, found this fix, drilled it out and extended the spring yesterday and not only does it appear to have fixed the issue with the plate sticking open, but it has also fixed a few other drivability issues I was dealing with that I assumed were unrelated!
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04-05-2023, 10:12 AM
#29
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Join Date: Aug 2014
Location: North Carolina
Posts: 486
Total Cats: 148
Here are two posts I made on the changes I made as part of installing a Skunk2 TB. I'll try to make a separate thread later.
https://www.miataturbo.net/build-thr...5/#post1617029
https://www.miataturbo.net/build-thr...5/#post1617472
I've got over a year and 10k miles on it, including two track days. The only issue I have had during that time is that I get occasional stalls when the engine returns to idle while warming up in colder temps (40f and below). I think this is because the IAC is not as responsive due to the tiny and convoluted air passages in the Skunk2.
Otherwise, once up to temp it drives and performs like stock in all conditions.
https://www.miataturbo.net/build-thr...5/#post1617029
https://www.miataturbo.net/build-thr...5/#post1617472
I've got over a year and 10k miles on it, including two track days. The only issue I have had during that time is that I get occasional stalls when the engine returns to idle while warming up in colder temps (40f and below). I think this is because the IAC is not as responsive due to the tiny and convoluted air passages in the Skunk2.
Otherwise, once up to temp it drives and performs like stock in all conditions.
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