Took 2001 Tribute DX in for oil change and was told oil pan gasket and valve cover gaskets were leaking. Didnt want to pay their price, so I changed them myself.
When I was done there was a slight hesitation in idle and initial take-off. Next day daughter is driving car and starts to shake and squeal(like a slipping belt). On investigation, discovered that the innards of small cat convert closest to radiator had come loose and plugged the big cat downstream(must have knocked loose some of them when I took part of exhaust pipe off for the oil pan gasket). Vacuumed out debris-no more squeal and shaking/vibration almost gone. BUT poor idle and loss-of-power still present.
Checked vacuum hoses and replaced some that looked in bad shape. Sprayed throttle body cleaner around to test for vacuum leaks-nothing. I admit I might not have gotten everywhere-first time trying. Changed PCV valve. After this-no change to idle.
I tested the TPS-voltages were within spec. COPs are sparking-checked them. Cleaned ICV.
I'm wondering if old plenum gaskets can cause this, or if the bad cat caused damage, or if I am just missing something. It ran fine till I took it apart.

Tyler

 

yes, old gaskets could cause vacuum leaks and rough idle. Using an enrichment tool should pin point it.

I doubt that the you were able to remove all the "cat litter" with a vacuum. Besides there may be more stuff braking loose fromt he precat and clogging up the main cat.
Also the data from the O2 sensors won't make much sense to the computer , so the computer is trying to adjust the fuel trim.

But still I have the gut feeling it is a mostly caused by a vacuum leak that you missed. You know you can use a cigar and the brake booster hose to make a smoke test. Seal the air filter with a plastic bag.

 

Hope you replaced big cat downstream. If those little bits from pre-cat get back in engine through EGR system your engine may need serious rebuilding, as you may get rod knock. Clean your EGR valve or by-pass it (working on a new solution that will not allow bits to go back in engine---see next post: EGR re-route bypass))..
To get possibly a cheaper pre-cat with exhaust manifold click after the colon: The Official Site of MagnaFlow Exhaust Products - Exhaust Systems For Trucks, Suv's, American Muscle, Diesel, & Sport Compact Vehicles
I had mine replaced, needed new studs as well: https://www.mazdaforum.com/forum/maz...-3-0-v6-29854/
If you get one from magnaflow i'd appreciate feedback with pics of old one and new one.

Yes, old plenum gaskets should have been changed as well as throttle body to plenum. They get hard and crack.

Mileage?

 

EGR RE-Route, Bypass

The following is cut and pasted from various pages on DIY: EGR Re-Route (Re-routed properly pics page 5) for the EGR re-route. First page is not great. Good pics later by Zoomer on Page 15 for CAI and Edward1982 for Stock air box on Page 19. It is 21 pages. I spent over 1 hour reading and pasting stuff below. My pics won't paste on here.
Page 1 is good until step 5 (wrong penny year may not work). Go to page 5 for the rest of that install.

My shortened explanation:
Basically with this MOD you are cutting the tube that goes from exhaust to the EGR valve.
You block off or cap off the exhaust where the nut attaches the bottom part of tube @ exhaust.
The upper part of tube is attached with 5/8" heater hose and routed to the air box after the air filter on a stock box but before the MAF sensor.

Stuff copied and pasted from that thread:

As far as a visual inspection goes when the EGR mod is concerned, it may be seen on certain models (it is on my 2006 V6).
NOTE: when done the EGR TUBE will not be hot.
As far as passing an emissions sniffer test.... if you have free flow cats, just make sure you drove around for a good half hour before the test, that way the whole system is primed and heated. Someone had test pipes on both my NA Miata Roadsters, 96 Eclipse GSX, and my 88 RX7 T-II S4 FC, and passed emission inspections (visual and sniffer) in Nevada, S.C., and VA., with flying colors.
yes it would pass, so long as you dont have a cel.
Nope, the EGR still performs its duties as it normally would, it just doesn't compute that it is flowing fresh air instead of CO2. The amount of air is not enough to learn out the car as we have a pig rich tune anyway and it runs like a dream.
I've been sporting this mod for well over 7K with no issues whatsoever.

i've had the setup on my car since august 1st of 2009. and also did it on my escort which i ran that way for 3 years and would still be running it like that had i not crashed it. neither one of the cars showed/show any issues. i wouldn’t look for gains. the ultimate gain is a cleaner intake tract.

Remember what I said. The EGR only monitors flow. It doesn't matter what is flowing. Whether it be clean air, hot exhaust..burps or farts. It doesn't care. It just wants to have something flowing thru it to stay happy

Intake air must be filtered first and before the MAF sensor.

Just slapping a breather filter on will cause a cell due to the EGR drawing in/expelling air/exhaust gases.
Hence by connecting it to the air box or cone of a SRI or CAI, you're providing the EGR with what it needs.
If you setup the EGR with a cut tube and breather you essentially are causing a deviation in the flow that its used to. Once the ECU sees the deviation it will trip one of two CELs..
1. Egr insufficient flow
2. Egr too much flow ( I can't remember the exact wording but its pertaining to too much flow)

What happens is with out a vacumm/scavenging source on both ends. When the egr is commanded open, at a certain percentage where the exhaust flow vacumm may overcome the intake mani vacumm to create a certain amount of flow or vice versa...the flow will either be toomuch or too little for that programming percentage. Once the ECU sees this a couple times it will illuminate the CEL

Now, when you reroute it to the intake like I have been telling people, you essentially are setting it up like factory with two vacuum sources on either end. This in turn will keep the flow values in the proper range and you won't get a CEL.

I always put it closer to air filter so the vac isn't as strong as it would be closer to the TB and get the too much flow code.

I'm guessing it could work either way, but always stuck with what I never had issues with. That being before the MAF. I did it after MAF on two cars by request of the owner and kept getting EGR malfunction codes. This was some years ago ,but have been doing it pre MAF since and before then and never once threw a code.

 

Thanks for the responses!

When I inspected exhaust and discovered precat material in the main cat I checked both precats. The precat next to firewall looked complete from what I could see from pipe opening. The precat next to radiator had the insides loose and moving around. I broke-out and removed everything I could of that, so I think its just a metal can now with an O2 on either end.

Will definitely check vacuum again.

Mileage is 116597. It is a V-6 if you havent guessed. Forgot to mention that.

So the EGR takes exhaust gas after the precat and puts it back into the intake? And it measures CO2 output from exhaust with the sensor? I'm not sure I understand what the mod will do other than protect the motor from debris.

Thanks again for your replies!

 

Yes the EGR gets recycled exhaust from after the pre-cat. There should be an exhaust tube on 1 side of the engine going back up to egr valve.
The O2 sesnsor after the pre-cat measures the efficiency of the pre-cat. Without pre-cat insides you MAY throw a cel, you may get lucky.
This sensor measures the pollutants making it through the converter and out of the tailpipe. The data from this sensor is compared to that of the upstream sensor. If the data between the two sensors becomes more similar, the vehicle's computer may trigger a catalyst inefficiency check engine code, which turns on the Check Engine light.

With the guts gone from pre-cat you may get a popping sound in exhaust along with a hesitation as the harmonics from the shape of the pre-cat come in to play.

Yes the mod protects your engine from damage from the cat bits from re-entering your engine. That's what it is mainly intended to do. This is for people that don't get e-tested.

 

Super job, Noggin!

 

OK. Although there were a couple of small vacuum leaks, that wasn't the main problem. I put the #4COP on the #6cylinder and the #6COP on the #4cylinder when I put it back together the first time.

As soon as I discovered that and put the wires where they really go it ran like expected. How embarrassing! I didn't look to see if the wires had a label on them. I just put it back according to length of wires.

This is the first car I have worked on with COPs. Didn't even think it would mess with the timing.

 

Ah, tracing back the steps is an important way to find one's errors. No need to be embarraassed.
Hey, I once -it was late late night- was looking for that one srewdriver that will reach the bolt. Twenty minutes later I found it. It was in my right hand's fist!