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Catalytic Converts

stangg

Well-Known Member
My understanding is that with 24# injectors, that you either need the cobra EEC, or a MAF sensor that is calibrated for 24# injectors.
If it continues to smell like raw fuel, maybe try some stock 5.0 19# injectors. You might also want to check to see if the O2 sensor harness is properly routed to the left / right O2 sensors. I could be wrong, but think the left bank injectors are controlled by the left O2 sensor, and the right O2 for the right bank of injectors.
 

CUAviator

"I wanna go fast..."
My understanding is that with 24# injectors, that you either need the cobra EEC, or a MAF sensor that is calibrated for 24# injectors.
If it continues to smell like raw fuel, maybe try some stock 5.0 19# injectors. You might also want to check to see if the O2 sensor harness is properly routed to the left / right O2 sensors. I could be wrong, but think the left bank injectors are controlled by the left O2 sensor, and the right O2 for the right bank of injectors.
Thanks for the info. I’ll look into that.
 

CUAviator

"I wanna go fast..."
My understanding is that with 24# injectors, that you either need the cobra EEC, or a MAF sensor that is calibrated for 24# injectors.
If it continues to smell like raw fuel, maybe try some stock 5.0 19# injectors. You might also want to check to see if the O2 sensor harness is properly routed to the left / right O2 sensors. I could be wrong, but think the left bank injectors are controlled by the left O2 sensor, and the right O2 for the right bank of injectors.
Here is the MAF part number I’ve got for the MAF (ford maf f1zf-12b579-aa afh55-03b). Can you verify that’s capable of 24# injectors? As for the computer, it’s the EEC IV A9L.
 

stangg

Well-Known Member
I no longer have the MAF that came with my A9L and donor engine, but in my stash of parts I purchased a ford original speed density to MAF conversion kit which includes an A9M EEC and the same MAF you listed F1ZF-12B579-AA AFH55-03B. That kit utilizes the stock 5.0 HO 19# injectors.
I would try swapping to the smaller 19# injectors, or the easier swap would be to try the bigger MAF meter.

Summit shows different MAFs for different injectors ...
Link to MAF options

Just thinking out loud here --- Years ago I had a 94 T-Bird. Driveability was deteriorating and I was slow to look into it. Finally it got so bad I could barely drive it. Called my BIL and he said to unplug the MAF and see how it drives. That made a huge difference and was at least able to drive the car 50 miles to home. I'm curious if you simply unplugged the existing MAF to see if it makes any difference in odor. If it reduces it, could be an indicator that the MAF is giving bad signals to the EEC. This is just a guess, but something to try before spending any money.
 

CUAviator

"I wanna go fast..."
I no longer have the MAF that came with my A9L and donor engine, but in my stash of parts I purchased a ford original speed density to MAF conversion kit which includes an A9M EEC and the same MAF you listed F1ZF-12B579-AA AFH55-03B. That kit utilizes the stock 5.0 HO 19# injectors.
I would try swapping to the smaller 19# injectors, or the easier swap would be to try the bigger MAF meter.

Summit shows different MAFs for different injectors ...
Link to MAF options

Just thinking out loud here --- Years ago I had a 94 T-Bird. Driveability was deteriorating and I was slow to look into it. Finally it got so bad I could barely drive it. Called my BIL and he said to unplug the MAF and see how it drives. That made a huge difference and was at least able to drive the car 50 miles to home. I'm curious if you simply unplugged the existing MAF to see if it makes any difference in odor. If it reduces it, could be an indicator that the MAF is giving bad signals to the EEC. This is just a guess, but something to try before spending any money.
I’ll give it a try. Is this one of those “disconnect the MAF, disconnect the battery for 30 min deal”?
 

CUAviator

"I wanna go fast..."
no, just disconnect the MAF, then start it right up. It should run, just not optimally.
Great, thanks. One more question; I want to do a vacuum test, check the PCV, and charcoal canister - if you look at the pictures attached, are you able to see where I’d do that (my engine is so modded, I can’t tell what’s what compared to standard 5.0 motors)
 

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stangg

Well-Known Member
On a stock ford manifold there are ports on the bottom side of the upper manifold where some of the vacuum lines plug into. In picture # 5, you have two larger vac hoses that look like they are running to the underside of the top manifold. One looks like it is connected to your brake booster, the other should go to the rear of the lower manifold where you will find the PCV valve. The only other line (smaller 1/4") looks to be tied to the fuel pressure regulator. If I remember right, there may be some small ports under the top manifold for the TAB / TAD and EGR that I don't think you have. If your manifold has those ports, check to see if the plugs are still sealing them up.
 

CUAviator

"I wanna go fast..."
On a stock ford manifold there are ports on the bottom side of the upper manifold where some of the vacuum lines plug into. In picture # 5, you have two larger vac hoses that look like they are running to the underside of the top manifold. One looks like it is connected to your brake booster, the other should go to the rear of the lower manifold where you will find the PCV valve. The only other line (smaller 1/4") looks to be tied to the fuel pressure regulator. If I remember right, there may be some small ports under the top manifold for the TAB / TAD and EGR that I don't think you have. If your manifold has those ports, check to see if the plugs are still sealing them up.
Yep, thanks - I’ll have to dig into that!
now back to the MAF - I disconnected it and boy was that crap. It started ok but then the idle dropped to 350-400. Took it for a little spin - sputtering, hesitating, backfiring all over the place. Still some gas smell, but I didn’t have it running too long to really get it pungent.
so with those symptoms without the MAF, what are the thoughts on that?
 

stangg

Well-Known Member
Well, not an expert on this but given its still rich with the MAF disconnected, could very well mean the EEC is telling what it thinks are 19# injectors to open for a set period of time, but given they are 24# injectors, spraying a greater volume of fuel.

If your going to throw parts at the problem, I'd probably start with installing a MAF that is compatible with 24# injectors.
 

CUAviator

"I wanna go fast..."
Well, not an expert on this but given its still rich with the MAF disconnected, could very well mean the EEC is telling what it thinks are 19# injectors to open for a set period of time, but given they are 24# injectors, spraying a greater volume of fuel.

If your going to throw parts at the problem, I'd probably start with installing a MAF that is compatible with 24# injectors.
Thanks. I’ll be checking that out. I am going to try and get a copy of the tune (tuned before I bought it).
 

stangg

Well-Known Member
What? The original EEC was tuned!!! That's a pretty important detail that you left out. All bets are off as in respect to injectors / MAF if the tune is unknown.
 

CUAviator

"I wanna go fast..."
Start with the basics and make sure your engine is tuned and running properly. Just because it starts and drives doesn't mean it is. Verify the O2 sensor function AND location. An improperly placed but functioning sensor can cause it to run rich. I love the idea of incorporating an A/F gauge. It doesn't have to be a permanent fixture just use it to aid in tuning.

Have you pulled the plugs and "read" them to see how things are going? Be interesting to see pics of them. They can typically tell you the story of where you are at better than anything else.

All that said, some engines are going to be less effective at burning fuel than others. As mentioned earlier, if you've got a pretty aggressive cam featuring lots of overlap...get used to unburned fuel. I think in this case a pair of cats might help initially but they are going to get used up quickly with all that raw fuel coming into them consistently.

This wouldn't even be an issue if they went back to making the gas of yesteryear. That stuff smelled awesome!
Here’s what the drivers side bank of plugs looks like
 

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CUAviator

"I wanna go fast..."
What? The original EEC was tuned!!! That's a pretty important detail that you left out. All bets are off as in respect to injectors / MAF if the tune is unknown.
Yep, probably my bad. This started off as a “what are good cats?” As we progressed down the 5.0 rabbit hole, and as I’ve been in a million discussions with everybody and their mother about this situation, I went back and looked and sure enough, no mention of a tune (while I mentioned it in just about every other post I have on the internet).

a few bits of info:
- I was able to run a KOER test with the only code being Failed ECT sensor (makes sense, hard starts esp when warm). I replaced it yesterday but the weather had been too bad to try and drive the car (after I had to recharge the battery)

- ran a cylinder balance test -‘did all three levels with a code of 90 (good)

- I called the shop in CA that did the tune and talked to the guy that did it. He said the MAF is tuned for 24# injectors but couldn’t remember anything else other than “get rid of that POS Ford computer and replace it with a Holley.” So that’s where I’m at.
 

Horseplay

I Don't Care. Do you?
Hard to ever trust a computer monitors color but those plugs look like all it running just fine. You want the insulator to be just this side of almond color or so. Personally, I think you are chasing a ghost. If I recall this was all about gas smell not about a poorly performing engine. How about forgetting about the "tune" and simply making sure you don't have another cause for the fumes. Did they set it up with a rubber hose for the fuel return vs a hard line, for example? Soft lines age and can allow odors to escape without leaking fluid.
Dropping over a grand plus technician costs to swap out the controller on an otherwise perfectly running set-up seems stupid. Not to mention, the factory box probably out performs the Holley anyway.
 

CUAviator

"I wanna go fast..."
Hard to ever trust a computer monitors color but those plugs look like all it running just fine. You want the insulator to be just this side of almond color or so. Personally, I think you are chasing a ghost. If I recall this was all about gas smell not about a poorly performing engine. How about forgetting about the "tune" and simply making sure you don't have another cause for the fumes. Did they set it up with a rubber hose for the fuel return vs a hard line, for example? Soft lines age and can allow odors to escape without leaking fluid.
Dropping over a grand plus technician costs to swap out the controller on an otherwise perfectly running set-up seems stupid. Not to mention, the factory box probably out performs the Holley anyway.
Haha, no way am I swapping computers and you are correct - in general the engine runs very well. I was just trying to find out (from the shop) if it was specifically tuned to be rich or verify the MAF/injector combo.
still working on trying to do a vacuum leak test.
 

kb3

Well-Known Member
I agree with Terry. Those plugs do not show that it is running rich by any means, especially to the point of creating the gas smell you are detecting. The Ford computers are really good about changing the parameters to make it run well if all the parts are installed and working correctly. The mass air computers typically don't require any extra tuning as you change up the engine makeup, cams, etc. so I think you are back to square one. Follow Terry's advice and start chasing the fuel lines. I am running a 306 with 30lb injectors a 85 mm MAF and 75 mm throttle body and I never smell anything out of the ordinary.
 

Midlife

Well-Known Member
Staff member
Moderator
Aren't there hydrocarbon sniffers mechanics use to find fuel leaks? Why not go that route?
 
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