Engine Code 41 again

Creomod · Tuesday at 8:13 PM

This is related to my issue that I’ve had for 3-4 months. Car running ragged. Swapped everything. I keep getting the code 41 just replaced the o2 sensor so question , I’ve heard the thermactor crossover can get “carbon blocked” what if your not running the crossover and just put in the thermactor plug. Can that area behind the plug get filled with carbon? The one I have in the pic is one I have lying around. I’m having an issue trying to remove them with a quarter it’s a tight spot and they are stuck. When I installed them I didn’t add antisize(not sure if your supposed to)

AeroCoupe · Tuesday at 8:17 PM

Had mine blocked off in iron heads for years with zero issues and I did use copper anti seize on mine but never removed them do I cannot say if it would have helped.

Creomod · Tuesday at 8:43 PM

AeroCoupe said:
Had mine blocked off in iron heads for years with zero issues and I did use copper anti seize on mine but never removed them do I cannot say if it would have helped.

Yes I have the gt40s . I did notice the 1 or 2 bolts on my passanger side header loose as well. Haven’t started it up after tightening but I dought it was that. I redid the lower intake gaskets,bought new everything even sent the ecu back to ecu exchange and it tested good 2 times on their car is what they said. Removed injectors cleaned them new filters,pvc screen valve ignition switch fp,fp filter regulator spark plug wires just to make it look nicer cleaned wiring . Next I’m gonna spray the male 10 pin I cleaned them with electrical cleaner but want to spead them just in case . Air filer,new battery lol my wife’s getting pissed . I haven’t ran compression test cuz I do not drive hard at all so and I’m good at swapping oil. I vacuum lines and plugs to.

Mustang5L5 · Wednesday at 9:08 AM

When i pulled my E7's, i did find one side was completely blocked up and I did run my smog pump/pipe. I don't recall having a code for it though.

AeroCoupe · Wednesday at 9:50 AM

Good trouble shooting advice from jrichker here:

Post in thread 'Code 41 and 91'
https://stangnet.com/mustang-forums/threads/code-41-and-91.762521/post-7631720

Creomod · Wednesday at 2:52 PM

Mustang5L5 said:
When i pulled my E7's, i did find one side was completely blocked up and I did run my smog pump/pipe. I don't recall having a code for it though.

When you said it was completely blocked up , when you removed the pipe the end was carbon blocked? Was the hole in the head blocked up with carbon as well? If so did you poke it out of the head or was the carbon barley built up a little?if it was clogged I’m assuming it was like a peeice of charcoal even in the head am I right?

Creomod · Wednesday at 2:57 PM

Any way to get these tgermactor plugs off ? Quarter didn’t work, debating to use a bolt with jb weld bad idea? Any ideas?

gkomo · Wednesday at 3:05 PM

Interesting, I had Code 44 that replacing the crossover tube behind the heads with a new one, and cleaning out the holes in the back of the heads with a pick fixed. Maybe i'm thinking of a different issue than what you have. Mine were completely clogged with carbon.

Once the tube was replaced and the head holes picked out as best i could get them, my Code 44 went away. But it wasn't Code 41 like you have.

Creomod · Wednesday at 3:19 PM

AeroCoupe said:
Good trouble shooting advice from jrichker here:

Post in thread 'Code 41 and 91'
https://stangnet.com/mustang-forums/threads/code-41-and-91.762521/post-7631720

I did look through that (appreciate that) I am getting code 41 but I replaced and secured vacuum lines/hoses fittings and redid that but when it comes to the crossover tube head ports does this mean I have to remove both thermactor plugs on both heads even though I’m getting just a code 41? It’s weird I think when I force my car to drive longer I get the code 91 as well. I and I know the cars running lean I can’t smell gas and almost feels like it’s in limp mode

Creomod · Wednesday at 3:22 PM

gkomo said:
Interesting, I had Code 44 that replacing the crossover tube behind the heads with a new one, and cleaning out the holes in the back of the heads with a pick fixed. Maybe i'm thinking of a different issue than what you have. Mine were completely clogged with carbon.

Once the tube was replaced and the head holes picked out as best i could get them, my Code 44 went away. But it wasn't Code 41 like you have.

So can you remember the holes in the block were they really like blocked off inside ? I mean not that far but was there a lot of carbon in there like alot?

Creomod · Wednesday at 3:28 PM

Nickle didn’t work and it’s thicker

Mustang5L5 · Wednesday at 7:39 PM

Creomod said:
When you said it was completely blocked up , when you removed the pipe the end was carbon blocked? Was the hole in the head blocked up with carbon as well? If so did you poke it out of the head or was the carbon barley built up a little?if it was clogged I’m assuming it was like a peeice of charcoal even in the head am I right?

Yes. Removed pipe and the port was full. Totally blocked

I didn’t investigate any further however. Heads went to the scrapper

gkomo · Wednesday at 8:50 PM

Creomod said:
So can you remember the holes in the block were they really like blocked off inside ? I mean not that far but was there a lot of carbon in there like alot?

Ya completely clogged. I have the process and some photos (as best you can back there) in my progress thread.

What i was trying to say though is those clogged ports caused a code 44 for me, not 41. And wouldn’t the thermactor plugs basically be the same as clogged with carbon ports? No air can get through.

General karthief · 2026-07-09T13:31:38-0500

If the heads have the air passages plugged then that area is likely not your issue, check the spark plugs on the right bank for difference in color/condition, I'm leaning on a vacuum issue, head to intake sealing issue?

AeroCoupe · 2026-07-09T15:12:37-0500

The smog system is literally there to push hot air into the combustion chambers during startup so the efficiency is higher. Hotter motor burns cleaner hence why modern cars run in the 205 to 220 deg range now.

You have a lean condition or so the ECU perceives which is causing it to try and put more fuel to the mixture. You have ruled out the O2's, you have fixed leaks, checked vacuum lines, etc. Have you made sure you have the correct fuel pressure? Do you know if the plugs in the back of the heads are sealing and the right bank is not allowing fresh air to be pulled into the motor?

The only way I know to remove those plugs is with a large flat head or standard screw driver like blade. I would make one from a hex wrench so I could use a 1/2" rachet wrench to remove them. Crap thing is you will need to move the motor forward to get access to them or figure some other means of turning the tool.

Creomod · 2026-07-09T16:46:42-0500

General karthief said:
If the heads have the air passages plugged then that area is likely not your issue, check the spark plugs on the right bank for difference in color/condition, I'm leaning on a vacuum issue, head to intake sealing issue?

I don’t think it be the lower, I just redid that 2 weeks ago and cars still not running had it down for 3 months so far. It seems like 2&3 plugs are a little black but they don’t smell like gas. And yes I put thermactor plugs on the heads just assuming that there might be carbon built up behind them causing my car to run horribly but having a hard time removing them

Creomod · 2026-07-09T16:55:44-0500

AeroCoupe said:
The smog system is literally there to push hot air into the combustion chambers during startup so the efficiency is higher. Hotter motor burns cleaner hence why modern cars run in the 205 to 220 deg range now.

You have a lean condition or so the ECU perceives which is causing it to try and put more fuel to the mixture. You have ruled out the O2's, you have fixed leaks, checked vacuum lines, etc. Have you made sure you have the correct fuel pressure? Do you know if the plugs in the back of the heads are sealing and the right bank is not allowing fresh air to be pulled into the motor?

The only way I know to remove those plugs is with a large flat head or standard screw driver like blade. I would make one from a hex wrench so I could use a 1/2" rachet wrench to remove them. Crap thing is you will need to move the motor forward to get access to them or figure some other means of turning the tool.

Yes I have the correct fuel pressure. Fueled out o2s I just replaced them few days ago along with vacuum lines and I redid the lower intake as far as leaks I don’t have any that I’m aware of unless it’s a vacuum leak and I have no idea about the plugs in the heads are sealing and not allowing fresh air to be pulled into the motor how do I know that?

AeroCoupe · 2026-07-09T20:37:18-0500

Safest thing would be to have some kind of smoke machine and just see if it sucks the smoke in. The smoke machine would also help with locating any vacuum leaks.

Engine Post in thread 'Need help with slowww start'

Nov 17, 2023

Did you replace the fuel filter when you did the tank and pump? Pull codes and then like the General said look for vacuum leaks. I would suggest you build a smoke machine and use that as well.

Engine Code 41 again

Creomod

Attachments

AeroCoupe

lube between the nut and the face. I know my lubes

Creomod

Mustang5L5

That is…until I whipped out my Bissell

AeroCoupe

lube between the nut and the face. I know my lubes

Creomod

Creomod

Attachments

gkomo

now i can hopefully expect to receive the shaft

Creomod

Creomod

Creomod

Attachments

Mustang5L5

That is…until I whipped out my Bissell

gkomo

now i can hopefully expect to receive the shaft

General karthief

wonder how much it would cost to ship you a pair

AeroCoupe

lube between the nut and the face. I know my lubes

Creomod

Creomod

AeroCoupe

lube between the nut and the face. I know my lubes

Engine Post in thread 'Need help with slowww start'

Similar threads

Engine Code 41 again

Attachments

lube between the nut and the face. I know my lubes

That is…until I whipped out my Bissell

lube between the nut and the face. I know my lubes

Attachments

now i can hopefully expect to receive the shaft

Attachments

That is…until I whipped out my Bissell

now i can hopefully expect to receive the shaft

wonder how much it would cost to ship you a pair

lube between the nut and the face. I know my lubes

lube between the nut and the face. I know my lubes

Engine Post in thread 'Need help with slowww start'

Similar threads

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