Engine Changed Tfi Module Now Catalytic Convertors Smell

theYman · Aug 12, 2013

Well, tonight I changed the TFI module. I took the stock Motorcraft (e6sf-12a297-a1a) module off because it had 106,000 on it (probably shouldn't have)and figured it was about at the end of it's life. I replaced it with a BWD select module.
I drove the car around and it seemed to perform better but I notice now the catalytic convertors have the typical sulfur smell. Is this because the car is now "rich" and not burning all of the fuel? Maybe the BWD module isn't as good?

jAEded · Aug 13, 2013

You're probably fine.

The tfi module is what the ecm uses to make changes to the timing curve. It shouldn't have the effect of making the car run rich.

It makes the distributor really hot. I like the remote mount better. Did you use thermal paste between the tfi module and distributor?

theYman · Aug 13, 2013

jAEded said:
You're probably fine.

The tfi module is what the ecm uses to make changes to the timing curve. It shouldn't have the effect of making the car run rich.

It makes the distributor really hot. I like the remote mount better. Did you use thermal paste between the tfi module and distributor?

Yes my son builds computers so we had some commercial grade white thermal paste laying around. I'm going to test it some more tomorrow morning, Maybe the exhaust is hotter now that it runs better....

theYman · Aug 13, 2013

Well this morning the car idled terribly with the BWD TFI installed. I drove it and the car hesitates with any throttle applied. So, I reinstalled the old Motorcraft tfi. No more rotten egg smell and the car idles rock solid. Lesson learned. I will get another Motorcraft module for a back up.

jozsefsz · Aug 13, 2013

The replacement module may not have been the right match for yours (if it wasn't altogether faulty). Here's a really good post that talks about the differences. They'll plug right in and look the same, but will run terribly if the wrong part is listed.

http://forums.corral.net/forums/5-0-5-8-engine-tech/696387-difference-between-tfi-modules.html

Getting the same Motorcraft P/N that you removed is a pretty good way to ensure they match.

mikestang63 · Aug 13, 2013

put the old one back in. No sense fixing what ain't broke. When it comes time to replace the TFI only use a replacement FOMOCO unit and use the proper grease.

Did you check to see if the timing and base idle are correct?

theYman · Aug 13, 2013

mikestang63 said:
put the old one back in. No sense fixing what ain't broke. When it comes time to replace the TFI only use a replacement FOMOCO unit and use the proper grease.

Did you check to see if the timing and base idle are correct?

Yes, rechecked both after each module change.

jAEded · Aug 13, 2013

theYman said:
Well this morning the car idled terribly with the BWD TFI installed. I drove it and the car hesitates with any throttle applied. So, I reinstalled the old Motorcraft tfi. No more rotten egg smell and the car idles rock solid. Lesson learned. I will get another Motorcraft module for a back up.

Motorcraft part number on the one for manual trans is DY-425. Automatic trans is DY-504.

DY-425 is the black one. DY-504 is the grey one.

jAEded · Aug 13, 2013

Looks like dy-425 and dy-504 are obsolete. Around $175 where I can find it. Couple on Ebay from $80 - $100. Found dy-504 for around the same price.

DY-425 Interchanges with: E8FZ-12A297-A ; E5RF-12A297-BA ; E43ZP-12Z297-A ; E43Z-12A297-A

DY-504 Interchanges with: E6SF-12A297-A1A ; E6SZ-12A297-A ; E6SF-12A297-A2A

jAEded · Aug 13, 2013

I have a mallory tfi distributor and havent had any issues. I'm worried now though because the mallory came with a grey tfi module on it and my cars stick.

theYman · Aug 13, 2013

jozsefsz said:
The replacement module may not have been the right match for yours (if it wasn't altogether faulty). Here's a really good post that talks about the differences. They'll plug right in and look the same, but will run terribly if the wrong part is listed.

http://forums.corral.net/forums/5-0-5-8-engine-tech/696387-difference-between-tfi-modules.html

Getting the same Motorcraft P/N that you removed is a pretty good way to ensure they match.

Good point. I do remember a few posts where the part numbers were switched. I did cross reference the number on several parts sites including BWD's and it supposedly was correct.

mikestang63 · Aug 13, 2013

I buy most of my OEM replacement parts from Rock Auto.

MOTORCRAFT Part # DY1076 {Click Info Link for Alternate/OEM Part Numbers} View attachment 126023
Automatic trans.

$89.79

MOTORCRAFT Part # DY1074 {#5U2Z12A297A, DY425, E43Z12A297A}
Standard trans.; w/ Distributor Mounted Module $111.79

madspeed · Aug 14, 2013

any clue as to the differences? Not sure the aftermarket ones have you specify, so maybe that's some of the problem with the parts store ones not haing a good reputation

jozsefsz · Aug 14, 2013

madspeed said:
any clue as to the differences? Not sure the aftermarket ones have you specify, so maybe that's some of the problem with the parts store ones not haing a good reputation

The link I posted above has a really good, detailed explanation. The long story short is one supports CCD (computer-controlled dwell) and the other does not. One gets a start signal from the PIP, the other from the ignition feed, which tells the computer cranking is happening (and to fire the injectors accordingly). You're right, getting the right one from the aftermarket when two aren't listed is like flipping a coin (especially in transition model years). I'd imagine the wrong one could cause hard start problems and a general lack of power / poor running (similar to a weak coil since the dwell will be off.)

jka · Aug 14, 2013

Have you adjusted the timing after replacing the TFI module? Your timing may be the problem.

theYman · Aug 15, 2013

jka said:
Have you adjusted the timing after replacing the TFI module? Your timing may be the problem.

Yes, the timing was the same at 14 degrees BTDC, I returned the BWD unit for a refund.

7991LXnSHO · Aug 15, 2013

If you changed the module and had the problem, that or disturbed wiring was your most likely answer. Glad it is good to go. I just went through the same thing with a JEGS module. I changed it for one from NAPA since it was in stock and it runs fine. But the old Ford one is in the car just in case, just like I carry an HEI module in another car. I am surprised by the Borg problem. They used to be the best before buy outs.

theYman · Aug 16, 2013

For some reason the car runs even better now after this. I did disassemble the TFI plug and cleaned all the spade connectors. Yesterday, I got on the highway in traffic and accidentally did a crazy fishtail as I was merging..lol. Was fun and scary.

7991LXnSHO · Aug 16, 2013

Sounds like a little tune up was in order. Yah hoo!

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