TOTALLY BAFFLED! Does anyone have a poss. solution?

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kfisher777

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I have an 03' LS V8

Ok, I have posted various threads attempting to resolve this problem. It started with a few bad coils. I didn't get around to address the issue until my engine lost over half it's power and couldn't get up to highway speed. Plus really loud noise coming from intake under load.

I replaced the bad coils but that didn't fix the other power and noise symtoms. So, after extensive research and postings on this site, I determined I must have killed the catalytic conv's. A tip I was given to confirm the cats are bad. The test was to remove the two top O2 sensors to see if that frees up power. Wa-la! I regained a significant amount of power and the excessive intake noise was gone. The cats must be clogged up.

Due to a lack of funds I had to hollow out the catalytic converters until I can afford to purchase new ones. Well, after working on that all day today, I expected to fire the engine up and have regained all engine power with no abnormal intake noise....threre was no change. So clogged cats must not have been the source of the reduced performance.

The next thing I tried was to unplug the two O2 sensors but leave them screwed into the cats....no change/improvement.

The last thing I did was go ahead and remove the O2 sensors I disconnected to see if that replicates the successful regained engine power and no more excessive intake noise!

So, what does this mean? Could there be an obstruction further down the exhaust system? Don't see how there could be. I just can't figure this out. The CEL codes don't give me anything to do on either except something about the MAP sensor. Any ideas or suggestions would really help! Thanks
 
If you hollow out the cats and don't clear all the catalyst out of it then it is possible to clog your muffler. I've heard of that happening.
 
Chain of events: This is everything to the last detail

1- Strarted out with one coil starting to misfire and over a period of 3-4 weeks, 2 more coils dropped off and I neglected to replace them because I couldn't afford it at the time. Then rather suddenly, I lost over 50% engine power and my CAI intake was extremly loud when the engine was under load.

2- So, I figured that I dropped another coil or two and this was the result of having half the coils operating. As a result, I replaced the faulty coils (3 total) and assumed that was a sure fix. Not the case.

3- Although, I did regain some engine power back with a smooth idle, the intake noise was unchanged and very loud. I then unpluged the MAF to force the system into Failsafe Mode. That did even out the engine power some but, it eliminated the really loud engine noise coming out of the intake. I drove it like that for a few days while I was researching for a solution. BTW, the PCM never gave me any codes indicating any leads on the problem.

4- After the few days driving in Failsafe Mode I realized that I was averaging only about 7-8mpg! Mostly highway driving. By now I've been posting threads on here looking for answers was convinced I fried my cats from the long period of time misfiring. To confirm this, you recommended I disconnect and remove both upper O2 sensors. I took the LS for a spin and WA-LA! Full engine power and no intake noise along w/ 23mpg hwy!

5- Next I decided to hollow out the cats until I can afford aftermarket replacements. I pulled down the entire exhaust sys and cut the pipes around 5 inchs from the bottom of the cats. That way I could efficiently get those hollowed out and all the debris removed so none of it could go down the rest of the exhaust sys.

6- I got the pipes clamped back together and rehung the total exhaust sys. Put the O2 sensors back in and attached the connectors. I had the batt. unhooked to clear all codes, ect. Unfortunatly, I start the engine up and NO change at all from before I put it in Failsafe Mode. How could that be? It took me six hours to complete and being two hours late to my sister's B-Day party. What a bummer.

7- I tried the two last things I could think of. First, I disconnected the two upper O2 sensors but did not remove them. No change. Lastly, I went ahead and removed the two O2 sensors and WA-LA! Full engine power again with no intake noise. What in the world could cause this? I don't see how there would be any debris obstructing the resonators or mufflers.

Please help me if you can!!! Thank you for taking the time to read this lengthy message but I wanted as detailed as possible as not to miss anything.

Ken
2003 Lincoln LS V8 119k miles
 
What about the pre-cats?

You can re-install the upstream O2s and remove the downstream 02s to see if it is the mufflers. If you get full power this way, then it is the mufflers. If you don't, then my vote is the pre-cats, or you didn't hollow out the cats as well as you thought.

BTW, keep driving like this and you may get internal engine damage too.
 
The pre-cats? I thought there were only two primary cats that bolt right up to the manifold and housed the o2 sensors...one on top and one on the bottom.

I definatly removed all of the debris when I hollowed them out, so there's no obstruction there.
 
Three cats? That doesn't make much sense, but maybe it's a 2nd get thing.

Hey if you need some cats I have a set from an '01 V8.
 
Hmm I checked my LS DVD and for 2003 V8's it shows 3 cats one each side up front and further back a large precat where the two pipes meet. I have V6 and checked that parts pic and it shows no 3rd cat. Do you guys not have 3rd cat?
 
Just rechecked my Ford DVD and it shows a precat right in between the front cat and the long skinny round resonators. Right where both pipes come together leading back. ??
 
Some of the 2nd Gen LSes (at least the V8s) have a "third cat" that also acts as a crossover. IIRC, my '04 had it, but my '06 does not; it has a regular H-pipe crossover.
 
SoonerLS said:
Some of the 2nd Gen LSes (at least the V8s) have a "third cat" that also acts as a crossover. IIRC, my '04 had it, but my '06 does not; it has a regular H-pipe crossover.
Click to expand...

The assumption is that was a cat; it wasn't. It was a crossover of sorts.
 
Hmmmm,

Are you sure some delinquent didn't shove a banana up your tail pipe?
 
LS4me have you looked into the 3rd unit to see whats inside it?? I have not seen V8 exhaust so no idea. It looks like a precat. I don't think Ford would make that shell just to join 2 pipes together when single crossover would do.Someone with v8 exhaust off look in there.
 
Right on the Mark said:
LS4me have you looked into the 3rd unit to see whats inside it?? I have not seen V8 exhaust so no idea. It looks like a precat. I don't think Ford would make that shell just to join 2 pipes together when single crossover would do.Someone with v8 exhaust off look in there.
Click to expand...

We asked one of the Lincoln guys. We thought it was some kind of post-cat. He said it was a type of crossover. That said, this shows it as part of the catalytic system:

getimage.php


Rock Auto says this is not for CA, however Tman had it on his '03. As was said earlier, the '06 has the gen 1 design.
 
It must be a 3rd cat. I hollowed out the first two coming off the engine and didn't touch the crossover area. I still have a major exhaust obstruction. I'm gonna have to drop the whole system again and hollow it out.

I tried a test; started the engine and let it run for just a few moments...then I checked the temp of different areas of the exhaust. The pipes right before the crossover and was pretty warm. The crossover was HOT...but the area directly passed it unusually cool. Therefore, I'm assuming the crossover must be a cat and obstructed. Does this make sense? I guess I'll know for sure after a drop the system back down and attempt to hollow it out.
 
It's not necessarily a cat (although RockAuto and AllDataDIY seem to think it is--then again, AllDataDIY's info seems to be a bit, umm, generic), but it does sound like it's plugged.
 
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