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-   -   Found it!!!! (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/found-1171205/)

matty Sep 10, 2025 08:25 PM

Found it!!!!
 
FOUND it!!! I am thrilled. Ty for everyone’s help. This community is the only car club worth anything.

A cap got destroyed under the UIM where the throttle cable bolts to the uim. In person I can see that it is “mostly” intact. Hopefully nothing was sucked in.

I was spraying carb cleaner around at the advice of a few club members. I tested and cleaned other things in my journey.

I don’t know what this is for. I’ll look at diagram tomorrow. Hopefully I can get to it without taking UIM off. Never done that.

I think it was destroyed over time and finally fully gave out.

Now I gotta work on some other details with the car. I think it’s setup for simplified sequential but the power fc is “locked”. So it feels like parallel. It builds boost insanely slow. But I won’t tackle that. I’ll bring it to a friend/pro.

Also I have enough fuel for 650 hp but seeing 85% inj duty with only 400ishhp. I think maybe fuel pressure too low. I have no idea. But I won’t tackle that at either. And some other small details. Haven’t really touched the car in 10 years. So it’s time to have a pro work it over a bit.

Let’s see what happens when this thing is capped.

Thanks again.https://cimg4.ibsrv.net/gimg/www.rx7...cbddf0d04.jpeg
https://cimg3.ibsrv.net/gimg/www.rx7...1e94dea379.png

matty Sep 10, 2025 08:32 PM

Better pic
 
Better pic
https://cimg5.ibsrv.net/gimg/www.rx7...fcf4a0cd2.jpeg
now the question is. Where to buy high quality silicone caps?

FDAUTO Sep 10, 2025 11:51 PM

Autobahn88

DaveW Sep 11, 2025 07:21 AM


Originally Posted by matty (Post 12639242)
Better pic

now the question is. Where to buy high quality silicone caps?

99% of caps like the one that died are not made to withstand heat and anything more than a couple of psi internal pressure. If it were me, I'd cap that with a piece of hose, an aluminum plug, and a couple of hose clamps.

boostin13b Sep 11, 2025 07:40 AM

That probably used to be the PCV hose that goes to the oil filler neck. Those thin silicone caps don't last long under pressure, they are made for vacuum. Most likely was not rated for fuel or oil as well. I would get a rubber fuel hose and a plug like mentioned above, or get the factory hoses with PCV and hook it back up to the filler neck.

matty Sep 11, 2025 09:08 AM


Originally Posted by boostin13b (Post 12639281)
That probably used to be the PCV hose that goes to the oil filler neck. Those thin silicone caps don't last long under pressure, they are made for vacuum. Most likely was not rated for fuel or oil as well. I would get a rubber fuel hose and a plug like mentioned above, or get the factory hoses with PCV and hook it back up to the filler neck.

@boostin13b You are right. Rubber would be best. i was going to get 3ply silicone. But i guess rubber is better in this application. I will look around and compare silicone vs rubber

DaleClark Sep 11, 2025 09:23 AM

I just responded to your PM, glad you found it! In the words of a good buddy of mine that taught me how to work on cars - "that may not be it, but it sure as hell ain't helping".

Use EPDM rubber vacuum caps, McMaster-Carr has them. Anything else will fail, period, hard stop. I've never found a silicone cap that works. Hose and a bolt with hose clamps also works, doesn't look pretty but will work long term. A little RTV and a hose clamp on the cap isn't a bad idea either.

Dale

Cgotto6 Sep 11, 2025 12:48 PM

I recently found some very heavy duty reinforced silicone caps. They were off amazon of all places. I have had bad luck with any sort of rubber or silicone cap, especially on coolant lines. These new caps are super tough construction. I have a few of them on my car with no issues. They make different sizes.
https://cimg9.ibsrv.net/gimg/www.rx7...461a3e79e1.png

GtiKyle Sep 11, 2025 12:54 PM

Throw the worm clamp in the garbage, those will dig in and damage the caps.

boostin13b Sep 11, 2025 01:13 PM

Just grab the EPDM rubber cap like Dale mentioned and be done with it.

Cgotto6 Sep 11, 2025 03:12 PM


Originally Posted by GtiKyle (Post 12639309)
Throw the worm clamp in the garbage, those will dig in and damage the caps.

The clamps that came with them were cheap and did go into the trash. I use quality gator clamps and they are doing well on a few coolant nipples that are plugged. These caps are very stout, a wormclamp could not cut into them before stripping. I was shocked at how durable they were when they arrived.

matty Sep 11, 2025 08:02 PM

I saw those. I am debating them for sure. I put a cheap autozone rubber plug in tonight. Just to make sure it solved my problem. It did.


Originally Posted by Cgotto6 (Post 12639308)
I recently found some very heavy duty reinforced silicone caps. They were off amazon of all places. I have had bad luck with any sort of rubber or silicone cap, especially on coolant lines. These new caps are super tough construction. I have a few of them on my car with no issues. They make different sizes.
https://cimg9.ibsrv.net/gimg/www.rx7...461a3e79e1.png


matty Sep 11, 2025 08:06 PM


Originally Posted by boostin13b (Post 12639315)
Just grab the EPDM rubber cap like Dale mentioned and be done with it.

Yes. A few people suggest those. I’ll decide between the epdm and the three ply silicone above. They look very beefy!

Cgotto6 Sep 12, 2025 12:59 PM

Glad to hear the problem is resolved with fixing the vacuum leak. Sometimes its just the simple wear and tear items.

matty Sep 12, 2025 10:23 PM


Originally Posted by Cgotto6 (Post 12639411)
Glad to hear the problem is resolved with fixing the vacuum leak. Sometimes it’s just the simple wear and tear items.

Thanks.
I think the take away is that the best bet is to spray carb cleaner around. Finds the leak easily.

CREEPENJEEPEN Sep 15, 2025 06:11 PM

https://www.mcmaster.com/84735K91/

This is the exact size you need for the EGR port that is leaking on your FD. I would suggest the cap without the clamp since it's easier to install without taking off the UIM.

CREEPENJEEPEN Sep 15, 2025 06:17 PM

I have no clue why the link keeps going to the wrong page, it's this one, ignore the top link.

https://www.mcmaster.com/84735K91/



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