Exhaust PACKED THERMACTOR HEAD PORTS?

R82148V · Dec 15, 2021

Hello Everyone!

I hope all is well!

I have an 87 vert that is throwing codes 94 & 44. I do have stock mid-pipe running original 4-cats. I narrowed it down to packed ports in the heads. Everything else checked out ok. I was able to clean out about 3 inches in the head but that is all I can reach from the back. I attempted to take out the front thermactor plugs but no luck. I really dont want to open a can of worms by destroying the plug threads and such. I had the headers off and I can see the cat honeycomes. They dont looked clogged to me.

I know you are supposed to have pumped air into the heads at warm up which helps the pre cats heat up and if you dont, you risk the pre cats clogging.
What do I do since I cant clean the head ports? Do I just continue to run with the OE 4-cats, run an aftermarket high-flow 2 cat set up or one of those regular WALKER set ups like on Rockauto?

I definitely want to keep all emissions equipment on there... Would a high flow 2 cat set up be wrong for a vert!

Thanks again and Happy Holidays!

Dan02gt · Dec 18, 2021

I would just run it like it is for now. LMR makes a factory style replacement H pipe you could get if your factory cats fail.
I’m not sure how you would fix the issue with the clogged ports in the heads without removing them.

7991LXnSHO · Dec 18, 2021

My Mustang 5.0 has the thermactor plugs installed front and rear, and the back ones will not come out with the heads on. I wanted to add the thermactor parts back for looks, so the cows could breathe fresher air, keeping the computer happy, and mostly sound control. So, I used a t in the vac lines from the solenoids to make sure the new high flow cats get air directly during warm up. It will be fine until I upgrade the heads.
After warm up, the smog air pump piping goes directly to the cats, not through the crossover pipe.

Mustang5L5 · Dec 18, 2021

It’s really only an issue during initial warmup. After that the cats aren’t fed O2 so as long as you arent pig rich, you should be fine.

One side of my engine was plugged up and I ran a stock 4-cat hpipe fpr the last 20 years knowing it was plugged. Maybe 10-30k miles like that? Didn’t really see any signs of cat fouling when I finally removed the pipe last year. They looked very clean.

I pulled the heads and that pipe off the car and the left one was just plugged solid. It would be difficult to clear it off the car, let along do it on an assembled engine. I’d probably have to remove the rear pipe and front thermactor plugs and find some sort of Rod that I can mount to a drill and send on through. Maybe grind a paddle at the end and go in and out. Sounds like a pita

Dan02gt · Dec 18, 2021

Mustang5L5 said:
It’s really only an issue during initial warmup. After that the cats aren’t fed O2 so as long as you arent pig rich, you should be fine.

One side of my engine was plugged up and I ran a stock 4-cat hpipe fpr the last 20 years knowing it was plugged. Maybe 10-30k miles like that? Didn’t really see any signs of cat fouling when I finally removed the pipe last year. They looked very clean.

I pulled the heads and that pipe off the car and the left one was just plugged solid. It would be difficult to clear it off the car, let along do it on an assembled engine. I’d probably have to remove the rear pipe and front thermactor plugs and find some sort of Rod that I can mount to a drill and send on through. Maybe grind a paddle at the end and go in and out. Sounds like a pita

If the main passage is that clogged I bet the small ones that go to each of the exhaust ports would be clogged too. They would be almost impossible to clean out without soaking the head in a cleaning solution.

Mustang5L5 · Dec 19, 2021

I agree. I bet if I inspected my head I’d probably find this is true.

Sounds like a huge pita

TIGGER · Dec 19, 2021

When I bought my saleen 12 years ago I had the same issue. The car would not pass smog. The heads and cross over pipe were completely plugged. I went down the same path. Only way to clean it out without removing the heads is to pull the front plugs and clean it front to back. I was able to get my pass side front plug out with no problems but the drivers was stuck. I had to drill it and use an easy out with some heat. If I remember correctly they have thread locker on them from the factory so the heat really helped. It was a lot of work but I got it out without damaging anything.

I then used a coat hanger, a cut down drier vent cleaner, compressed air, mineral sprints, and a ton of brake clean to get it cleaned out. The floor had a ton of crap on it when I was done. I had my headers off as well which made it easy to clean the side ports. It was a lot of work but it worked out for the better for me. And the car ran much better after the clean out and more importantly passed smog. I have over 45k since all that work and it is still running good.

I do not think the codes will go away unless you clean the crud out of the heads, in my opinion.

I am running a BBK 2 cat xpipe on my saleen with no issues as my original h-pipe was hacked by a previous owner. If your cats are bad, an after market 2 cat pipe would be fine on your vert.

Good luck to you.

7991LXnSHO · Dec 19, 2021

Major Edit. I checked the wrong tread for verification! Fixed to delete poor info on codes 94 and 44.

https://www.stangnet.com/mustang-forums/threads/bad-codes.848261/#post-8530080

@Mustang5L5

Mustang5L5 · Dec 19, 2021

Code 80/81 are the codes for the TAD/TAB if you unplug them. A 75ohm resistor will “fool” the ECU into thinking they are working and you won’t get these codes during the KOEO test.

Code 91/41 are KOER codes that are detected when the engine is running. The smog pump diverts air to the heads and the o2 sensors will detect the change.

You can have the code 91/41 or only one without getting the corresponding 80/81. In other words one tests the solenoids, and the other is a passive test by detecting a subtle change in sensor performance.

I’m currently using resistors to get rid of my 80/81, but I’ll forever have the 91/41. Considering most states aren’t doing a code check, or sniffer test. It’s strictly a visual and you shouldn’t have an issue. As for killing the cats, like I said this only functions during warmup. You probably spend 99% of your time driving with the system disabled anyway. Just ensure a good state of tune and keep the smog pump flowing to the primary cats. get your car nice and hot on your drives and it shouldn’t be an issue.

evintho · Dec 19, 2021

Mine were plugged solid too. The only way to clean them thoroughly is to hot tank the heads. Are you needing a valve job anytime soon?

R82148V · Dec 20, 2021

So I took everyone's advice and used a piece of coat hanger.. I sharpened the end to a point and grinded in some barbs. I bent the metal on a 45degree bend to get around the corner a little more and deeper in. The passenger side engine port was a hard dry solid. I was able to clean out about 3 inches before, but wanted to see if this new life hack tool made a difference. As I was attempting to clean it out further, I broke through! about 4 inches in and it became totally clear!
On to the Driver side was the same deal except is was more of a wetter carbon consistency. This side too, I was able to clean out about 3 inches earlier and with this tool, at about 4 inches in, I was able to poke though! You can feel it release. The barbs helped with the cleanout, pulling out the crud. I'm going to run it without the crossover tube on just to help blow out the rest of the stuff. I also have that one way valve that is on the crossover tube on order. Should be here tomorrow. The one that is on there now is original. you can blow trough it but its hard to do. I took it off and its shot. all carboned up in there.. I tried brake Kleen but it just made it worse The valve started to whistle if you blew through it. So fingers crossed, with both head ports and a new valve, it will be it!

I am running the original h-pipe.. They seem to be ok. I always do try to keep the car tuned as best can be.

TIGGER · Dec 20, 2021

Nice work, you are lucky. My heads were totally plugged, from the front to back. It took me a while to break thru all the crud initially. After, I cleared a path, I started breaking off more and more so I could get the pipe cleaner in to scrub the walls better. I used compressed air to blow all the loose crud out the back of the heads.

General karthief · Dec 20, 2021

That has got to be a crappy mess

R82148V · Dec 21, 2021

TIGGER said:
Nice work, you are lucky. My heads were totally plugged, from the front to back. It took me a while to break thru all the crud initially. After, I cleared a path, I started breaking off more and more so I could get the pipe cleaner in to scrub the walls better. I used compressed air to blow all the loose crud out the back of the heads.

What you did sounds like a pita but overall the best method to clean them out. I wanted to do the same but I didn't have any luck on removing the front plugs. That is where You are lucky!
I tried PB blaster, a large flat head and even the Loctite hack but they wouldn't budge. Figured I'd stop while I was ahead before I destroyed something I wish I didn't. I was about to deal with the blockage and either run the OEM h-pipe always worrying of a possible pre cat blockage or pickup a high flow cat h-pipe. You guys helped me decide to keep the original on there.
I have annoying OCD ways when it comes to working on this vert. Everything has to be perfect or close to it. Even one code, either KOEO or KOER, will drive me nuts and I wont stop trying to figure it out. Even if the code is nothing more than emissions. hahaha..

You guys have been so informative and I thank you for lending me your ear, time and knowledge. Doing a ton of internet research, it does become confusing since everyone has a different opinion or trick.

I'll let everyone know how it does once the crossover tube valve arrives.

R82148V · Jan 3, 2022

SUCCESS!!

Broke through the 4 inches of crud from the back thermactor ports. Made sure the crossover pipe was clear. Replacing the crossover pipe backfire valve. Ran the car and Codes 94 & 44 no longer exists and the engine runs great!
KOEO - Code 11
KOER - Code 11
Cyl Balance test - 9

Thank you everyone for working on this and giving amazing expertise information to make this happen.

Happy New Year!!

Exhaust PACKED THERMACTOR HEAD PORTS?

R82148V

Active Member

Dan02gt

mazing how much gas smell came from that tiny hole

7991LXnSHO

wanna catch the space herp

Mustang5L5

That is…until I whipped out my Bissell

Dan02gt

mazing how much gas smell came from that tiny hole

Mustang5L5

That is…until I whipped out my Bissell

TIGGER

7991LXnSHO

wanna catch the space herp

Mustang5L5

That is…until I whipped out my Bissell

evintho

R82148V

Active Member

TIGGER

General karthief

wonder how much it would cost to ship you a pair

R82148V

Active Member

R82148V

Active Member

Similar threads

Exhaust PACKED THERMACTOR HEAD PORTS?

Active Member

mazing how much gas smell came from that tiny hole

wanna catch the space herp

That is…until I whipped out my Bissell

mazing how much gas smell came from that tiny hole

That is…until I whipped out my Bissell

wanna catch the space herp

That is…until I whipped out my Bissell

Active Member

wonder how much it would cost to ship you a pair

Active Member

Active Member

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