3.0 liter Ford 24V V-6 in Mazda Tribute

[Bolted to Floor]

I could use some help and know that some of you guys may be familiar with this thing.

It’s a 2002 with 180,000 miles. It’s a spare that gets driven on my off days every other Friday. The main catalytic converters are made into the exhaust manifolds and it’s melted down the second catalytic converter on the back side (cylinders 1, 2, & 3) in less than 10,000 miles. There is a third converter under the car that gets clogged by the upstream melt down.

Generally, the check engine light is off. When it has come on, it’s usually a code for misfire on a cylinder. It was #3 one time and #5 more recently. It has been having a stumble or dead miss for the last few months. You can see the needle on the Tach drop about 200 RPM at idle when it happens. I’ve changed the fuel filter several times and it helps for a little while, but goes back to acting the same. Fuel filters have not been changed on a regular basis for years. Some of the first few I did change has small black looking specks in them. The most recent did not. I have also been adding Seafoam to every other tank. Up to this point, I’ve been thinking its clogged fuel injectors. The only cleaning they’ve ever had was from pouring a can of something in the tank.

Pulled the plugs for a compression test today. Cylinder 4 was the lowest at 150 PSI. All others were in the 170 to 180 range. Added some WD-40 to each and retested. All shot up another 20 PSI. The plugs on 1 and 2 are the most suspect, and seems wetter than any of the others, but not oily. Coloring looked decent on the porcelain.

Its in need of valve cover gaskets. Could oil leaking into the area with the spark plug cause issues with its ability to fire? It’s from something I read…..You guys are a more trusted source to verify or call BS.

Could it still be clogged injectors? Are they worth cleaning or just replacing?

Until the compression test, I was thinking it could be a burnt valve. Not so sure though.

Any thoughts on what else could it be??

When I did this the last time, it was the factory unit that melted down. It was replaced with a middle priced unit from Rockauto with good reviews along with the Cat underneath the car, oil change, and a fresh set of plugs.

Considering the last 2 years recent, it’s also received new drums, rotors, pads, shoes, soft brake hoses, radiator, hoses, and a battery.

Thanks for any help you can offer.

[My427stang]

I'd look for codes first and fix anything you find.  Burning front cats is generally from retarded timing or too much fuel.  Would seem to me that the car should tell you something. 

[Stangman]

So what are the codes that you are getting, besides the PO420-1 for the cats. You say it’s usually a code for a particular cylinder misfire. Do you get random cylinder misfire or any oxygen sensor codes. So many things can make a catalytic converter go bad. Bad or dirty MAF sensor, vacuum leak (intake leak, PCV hoses, dirty throttle assembly Upstream 02 sensor and more). The valve covers leaking in the plug holes could be a culprit. When you take the coils off the cylinder that is misfiring are they dripping with oil. When the C.E.L comes on is it flashing that’s when you are doing the damage. I’m not sure if that the same motor as 2005 but the valve seats drop on those motors. 180,000 miles has the timing chain been replaced. If you have a friend to put a computer on it you can look at long ans short term fuel trim, especially upon cold start up till it get warmed up. Last thing aftermarket coils especially standard coils on the Fords are commonly not that great. So don’t be afraid to double check that you didn’t get a bad coil. DONT drive with the light flashing. That should keep you busy keep us informed.

[shady]

replace all the intake gaskets (o rings) on the upper & lower intake runners. While you have it off it may be a good time to replace the rear plugs & coils. Also check the egr & pcv lines.  Only thing I ever did to mine.

[machoneman]

A well-worn timing chain will retard cam timing and could also cause your overheat condition. Heck, with that many miles and the recurring issues, I'd also pull the heads for a valve job, spring replacement, valve seals, etc. But, I'd also check/inspect the cylinder bores for wear.

A leakdown test now would be quite helpful. Some E-Bayers sell same for $50 or so. 'Course one must also have a air compressor too. 

[shady]

I had 190k on mine & ran perfect. 3.0s don't have timing chain issues like the 4.0s.  probably one of the best engines ford built sans FE.
You have to remove the upper intake to get to the back plugs & coils soooo, I would shot gun it & replace all plugs & coils.  You don't need any gaskets for the intake just the o rings. Mine had an intermittent miss when cold & turned out to be the lower intake o rings, so be sure to also replace those. Coils are a common failure, just replace them all or at least the back three as you have to pull the intake to get to them. I don't know why but 3.0s cats are real sensitive to misfires, you never want to drive your car if it isn't running 100%. You will ruin them in just a few miles.

[Bolted to Floor]

So what are the codes that you are getting, besides the PO420-1 for the cats. You say it’s usually a code for a particular cylinder misfire. Do you get random cylinder misfire or any oxygen sensor codes. So many things can make a catalytic converter go bad. Bad or dirty MAF sensor, vacuum leak (intake leak, PCV hoses, dirty throttle assembly Upstream 02 sensor and more). The valve covers leaking in the plug holes could be a culprit. When you take the coils off the cylinder that is misfiring are they dripping with oil. When the C.E.L comes on is it flashing that’s when you are doing the damage. I’m not sure if that the same motor as 2005 but the valve seats drop on those motors. 180,000 miles has the timing chain been replaced. 

Codes are P0305 for misfire on cylinder 5 and P0457 for Evaporative emission system leak detected. No other codes present. No O2 sensor codes. The oil does not leak bad enough to get on the coil boots. Just some oil settling on the plug where the socket grabs. No on a timing chain replacement.

If you have a friend to put a computer on it you can look at long ans short term fuel trim, especially upon cold start up till it get warmed up.

What type of programs are out there to se the info you are talking about. I do have a scan tool, but it won't do that.

 

DONT drive with the light flashing.

Too Late!!! It was flashing on me the last time I drove it.

 

Last thing aftermarket coils especially standard coils on the Fords are commonly not that great. So don’t be afraid to double check that you didn’t get a bad coil. That should keep you busy keep us informed.

Over the years, it still has 3 Ford coils and 3 have been replaced with something from O'reilly's, I don't remember the brand. Other than Standard, is there any more brand to stay away from?? Looking at Rockauto, Denso is about the price point I want to be in.

Thanks for the comments

[Bolted to Floor]

This is the scan tool I have.

 

[url=https://flic.kr/p/RBcSLc] 

Spark plugs 4-6 on front side of engine.

[url=https://flic.kr/p/RBd5p2] 
 

Spark plugs 1-3 on back side.

   


Throttlebody

[url=https://flic.kr/p/2fhVWz5]     


Inside of throttle body, kinda!!

[url=https://flic.kr/p/24L2VsF]   


Map Sensor from filter side

[url=https://flic.kr/p/24L2VUH]   


Map from intake side

[url=https://flic.kr/p/24L2W9k]   


Front O2 Sensor

[url=https://flic.kr/p/TemUa3]   


Back O2 Sensor

[url=https://flic.kr/p/2dYHr1i]   


And what’s left of the Cat!!

[url=https://flic.kr/p/2dYHqYV] 

[Bolted to Floor]

A well-worn timing chain will retard cam timing and could also cause your overheat condition. Heck, with that many miles and the recurring issues, I'd also pull the heads for a valve job, spring replacement, valve seals, etc. But, I'd also check/inspect the cylinder bores for wear.

A leakdown test now would be quite helpful. Some E-Bayers sell same for $50 or so. 'Course one must also have a air compressor too.

I will it a lot of thought before pulling the motor apart for a valve job or rebuild. Just not sure the car will be worth it. I will look into the leak down test and I do have a good air compressor.

Thanks for the comments.

[Bolted to Floor]

I had 190k on mine & ran perfect. 3.0s don't have timing chain issues like the 4.0s.  probably one of the best engines ford built sans FE.
You have to remove the upper intake to get to the back plugs & coils soooo, I would shot gun it & replace all plugs & coils.  You don't need any gaskets for the intake just the o rings. Mine had an intermittent miss when cold & turned out to be the lower intake o rings, so be sure to also replace those. Coils are a common failure, just replace them all or at least the back three as you have to pull the intake to get to them. I don't know why but 3.0s cats are real sensitive to misfires, you never want to drive your car if it isn't running 100%. You will ruin them in just a few miles.

This thing has been a great little car. The wife drove it for years, then all the kids did too.

I'm looking at the Denso coils. I will at least do the three on the back and a new set of Autolite plugs. The last time I went through all of this, I replaced the upper and lower intake manifold O-rings then. I will have another set coming. Maybe the sensitivity is caused by the location right there on the exhaust manifold. The gases don't have much of a chance to evaporate in the exhaust stream......I don't know, just spit balling.

Thanks for the comments

Gotta $600 shopping cart siting at Rockauto. Ouch!! Rather spend it on the Mustang!!

[Bolted to Floor]

I'd look for codes first and fix anything you find.  Burning front cats is generally from retarded timing or too much fuel.  Would seem to me that the car should tell you something.

It's probably telling me something Ross......I don't know that I'm smart enough to understand what it's saying though!!!

Thanks for the comments.

[Stangman]

Well your in there. Like someone said change the back plugs autolite/ac Delco and change the intake o rings don’t overtighten. With the cat looking like it is that’s definetly hurting flow could be backing up as it heats up. MAF sensor looks clean but maybe you should take it out and at least look at it closely, had one kick my ass once had a small piece of a feather from a bird and it would run good then I guess it would flip up and block off the filament. One thing I didn’t say earlier that someone brought up check EGR isn’t stuck open and check the port for it. The cat is bothering me gonna de hard to tune with that cat. Wondering if you should hollow that out till you get it to run right and when you nip it in the bud put a new cat in. As far as coils you can get motorcraft the densos aren’t bad. As far as looking at data that scan tool isn’t going to give you the data that you need to see. Something like a snap on Solus or Modis. While you have it apart look at all the plastic vacuum hoses and plastic breather tubes. Throttle don’t look that bad but might as well clean it. Carb spray and rag. Make sure you do the little things like gapping the plugs right. Don’t overtighten plugs or crack them, don’t just drop them in hole you don’t want one of the gaps to close. I think I would hollow out that cat. Just took a better look and the top filament on the MAF sensor is dirty, a quick spray of carb cleaner and while it’s wet blow it ou with air. You can see one is white the other has a coating or film of dirt. You can get a paper towel and wipe it but be careful. Twist the tip of the paper towel and spray some cleaner on towel and wipe gently till it looks like the white one.

[Katz427]

 I think you need a code reader that can give you "live" data from the 02 sensors. The O2 sensor is the "check" for the ECM to see if it is providing the correct fuel. Then you can zero in on the problem. First thing I learned, check the fuel pressure on the rail. Happy hunting, you will find it.

[e philpott]

Cylinder 5 miss fire caused the Converter to melt down , the unburned fuel reignites in the Cat , Fix the miss fire and you will fix the car

[TripleJ]

Re: 3.0 liter Ford 24V V-6 in Mazda Tribute
« Reply #13 on: Today at 10:16:50 AM »
Quote
Cylinder 5 miss fire caused the Converter to melt down , the unburned fuel reignites in the Cat , Fix the miss fire and you will fix the car

X2

[Russ67Scode]

I had a 2002 Mazda Tribute with 230000 miles on it.  Changed the fuel filter every other oil change
Did have a PVC hose go soft on me. And one coil go bad (dead miss)
I also cleaned out the IAC about every 4 th oil change  I can’t remember what the fuel injectors look like but if they are EV1 type there is a small (bucket) screen at the inlet that’s easy to change

[Bolted to Floor]

Oh yea, Stangman, I am in there. Went through most of my life with the tear it apart and see if I can fix it attitude. It’s already broke, how much worse can I make it!!

Hadn’t thought about hollowing out the Cats. That takes 2/3 of the dollars out of the Rockauto cart and gets it back on the road. Tags and inspection are good through December, so that buys me some time on replacing the cats. I know the CEL will stay on for now!!

I will go through with cleaning the MAF and throttle body. The EGR was a casualty of the back pressure, I think, and will be replaced. It has a extra hole that wasn’t there when I left the house that morning.

Those scan tools are nice and thanks for the suggestions. I will have a hard time justifying that to the my better half, seeing how the one I got only gets used about twice a year.

Thanks for the comments. I will walk away from the Mazda for a few days. The money that would have bought parts for this thing bought parts to rebuild the third member in the Mustang the week before!!! Time to get that back together.