sgjii

I recently purchased 2001 XJ 4.0L 154Kmiles which has the dual pre-cat exhaust setup. I have done several rehab projects over the last two months to the base mechanicals, fluids, etc. I have not made an exhaust change and I have checked for exhaust leaks. Rear muffler has a small hole but is well after the cats. The truck is now throwing P0432 CEL code for Bank2 Catalytic Converter Inefficiency. I drove the truck approximately 400 miles before starting the major rehab work. I am now looking for advice and help regarding my next course of action and if I should consider replacing the dual pre-cat unit. Below is the history to this point.

Within minutes of buying the truck, I received a Cyl 3 Misfire code. At about 200 miles, I replaced spark plug plugs and reset the code, as I did not know about heat soak yet. I also learned how these engines do not like platinum plugs. I had installed Champion Platinum plugs and the truck ran terrible and threw various cylinder misfire codes, which is when I first found the Cherokee Forum. I read/researched and quickly learned I needed NGK coppers and about heat soak being my original problem. Before my forum education and before I changed to the NGK plugs, I also cleaned the butterfly and visible throttle body areas with Carb Cleaner and the engine not running but Carb Cleaner obviously ran down into the intake manifold. I also used a bottle of Seafoam dibbled directly through the throttle body, while running, as a cleaning attempt. It was after this industrial sized smoke cloud Seafoam process that I first got a P0432 code. I received my forum education, cleared codes and installed NGK and it ran great for the next 200miles but threw the P0432 code shortly before I parked it to start the heavy lifting of my rehab.

The work I have done in the engine bay is as follows:

1) new NGK copper spark plugs

2) installed the foil like heat shield on top of the intake manifold by the fuel injectors, per a TSB regarding heat soak.

3) installed the injector #3 heat wrap, per another TSB regarding the heat soak

4) modified the electric cooling fan circuit by adding a Derale temperature triggered fan control for electric fan "after run" when the engine was shut off. again another heat soak counter measure

5) removed & properly cleaned the throttle body & IAC on the bench

6) installed an aluminum throttle body spacer with new gaskets

7) valve cover rehab including repaint, new Fel-Pro gasket, new PCV grommets, PCV elbows and PCV hoses

8) oil filter housing O-ring replacement w/Oil Change including a quart of Rislone for cleaning

9) cooling system refresh with coolant flush, all new hoses, thermostat, water pump, belt, idler and fresh coolant including Bars Leak original formula, for water pump lubrication and preventative measures

10) checked and cleaned all grounds, including new battery terminals and new battery

11) cleaned small debris and dirt from air box and checked air filter which was new from previous owner

All my other work has been suspension, brakes, tires and detailing, which have been countless hours and a major process in their own right.

After putting the truck back on the road, the P0432 code returned at the 75mile mark and has remained since with 300miles of driving. With the battery disconnected for a few weeks during rehab, I am thinking it took the first 75miles for the ECU to run enough data to determine and throw the P0432 code.

The thing I am asking myself is if I caused a Cat problem with the Platinum Plugs running problem, the Carb Cleaner, the Seafoam or other. I am also thinking I might have an O2 sensor issue and not a Cat issue at all. Again, maybe O2 sensor damage from the Carb Cleaner, Seafoam or other...

I apologize for the small novel chronicling the details but thought the history was important.

Suggestions on how to proceed???

sgjii

Been a week, 38 views and not a single reply...

Bueller, Bueller, Bueller....

98XJ40K

"Catalytic converters contain precious metals like platinum, palladium, rhodium among others. Basically, the cheaper the cat, the less precious metals used. It should be noted that there are some automobile makes that are very finicky when it comes to catalytic converters and the logic that the PCM uses to monitor them. Just because the parts guy says it will work doesn't mean that it will. The reason is that the engineering of the vehicle was done with a high quality catalyst in mind and it can't be replaced with a low cost catalyst. There are also different kinds of catalysts. Some makes will allow for a cheaper catalyst while others simply will not. Toyotas & Subarus are the most notorious for this. Subarus require CARB certified catalysts to keep the check engine light off and won't tolerate an aftermarket catalyst, no matter how expensive. So basically if you have a recurrence of this code after replacing the catalyst with an aftermarket catalyst, this may be your problem. If you have this code and haven't replaced the cat, there's basically two likely causes: The catalyst is no good, or the engine is running out of optimal air:fuel ratio. A tune up or engine repair may correct it. Otherwise you'll need to replace the catalyst. Read more at: http://www.obd-codes.com/p0432 Copyright © OBD-Codes.com"

From what I found workin the old google machine, either wait it out after the ecu reset and see if the computer corrects your rich/lean condition, or replace the cat. I believe it takes about 50 cycles to completely normalize after a reset. Hope that helps.

Turbo X_J

I can tell you for sure it's not the platinum plugs, I have an '01 with 22k on those, every time the engine starts after like the 3rd revolution and it purrs like a cat.

evan00xj

I will say a have an undying hatred for the 2000-2001 exhaust configuration. Ive replaced my header and pre cats. Runs great using the ngk plugs.

sgjii

How much, where and what brand pre-cat did you end up getting? Locally they are huge money but Rockauto shows a couple of options for under $200. Walker is a name I recognize at $228 w/$40 rebate and the other option is Eastern Catalytic at $185.

My further research has indicated that this code can come with only a 5% decrease in Catalyst efficiency. That is a pretty small window of operating parameters...

I did get a piece of local advice regarding O2 sensors. It was suggested that I replace O2 sensors with a new catalytic converter and further more, if I had a "lazy" or out of spec Oxygen Sensor it could be what is throwing the code in the first place. I have no idea how old the O2 sensors are and based on the fluids in the truck the previous owner was "gas n' go", so I am guessing they were never replaced as maintenance, just if they had failed and created a symptom.

Since I don't believe I have an engine problem of oil burning, cracked head or other combustion contaminant, I think I will try the path of least resistance, both cost and difficulty, and start with replacing the four O2 sensors and see how it goes. If the code comes back then I think I have no choice but a catalytic converter and move the new O2 sensors to the new cat assembly.

CCKen

Before blaming the Cat I would consider changing the upstream and downstream O2S's on that bank...if not all the O2S's if they have been installed for a long time, or have been subjected to Seapuke.

There have been reports of Seapuke contaminating Oxygen Sensors. It happened to me on a non-Jeep engine.

Also, a new Downstream O2 Sensor along with an aging Upstream O2 Sensor may cause this trouble code to set (per 2001 diagnostics guide).



Here's a pic that shows the NTK O2S's for your system.

evan00xj

Here's my story:
I have a magnificent running 4.6L stroker in my xj. Runs like a champ. Pulls like a freight train. The only oil i have ever run is brad penn. The reason is bc it has high levels of zinc and phosphorus to protect aggressive flat tappet cams. Unbeknownst to me they do not recommend for vehicles with catalytic converters. Those high level concentrations will clog the cats.

I had used sea foam just as you did just me being the "preventative maintenance " guy i am. The result was the catalyst efficiency below threshold code. P0432 (i think) . What i did was change the spark plugs and coil pack for starters. Still had.the catalyst code. (Jeep still ran great) I purchased replacement pre cats from performance curve. They were very affordable compared to all the other brands. I haven't had any issues with the 02 sensors. After the new pre cats I've been golden. Our year jeeps do have four of them. 2 upstream and 2 downstream. To be honest i would have just bought a 99 style header and gone back in time, but i had JUST installed a Banks torquetube header that fits the 00+ with pre cats. Its an awful design man. Those darn pre cats really contribute to heat soak. I will attach some pics if they could help you. This is a difficult topic. Trust me ive been so frustrated with this darn configuration. Ive spent countless hrs searching for more in depth info on this. But theres really not alot out there.

sgjii

An update on the P0432 code.

I went the route of replacing the O2 sensors first. After the last CEL reset, it took another 430 miles to set the code again. Upon inspection, it appeared that the O2 sensors were the originals and were NTK branded.

I may catch a little guff on this one but I bought 4 after market O2 sensors. They are from a parts company called Prime Choice http://www.primechoiceautoparts.com

They were half the best price I could find on NTK or Walker and I am pretty confident they are Chinese. In researching the brand, they are a parts distributor primarily in Canada and they seem to have a good reputation. For about $2 more per sensor, I ordered the Lifetime Warranty ones. They sell on eBay and their own website. Phone customer service was very good to work with and shipping was prompt.

I finally have the sensors installed but almost no miles logged yet as I am still trying to get the nerf bars installed and fighting the rear leaf spring mounting bolts to get them loose.

I hope to be daily driving the truck again this week and we will see how the new sensors work out. I am gambling around $90 for four O2 sensors. If they work out, great. If they have a shorter than desired life, they are lifetime warrantied and I will get replacements. If they don't work out at all, I will ask for a refund. I have wasted more money on worse ideas in the past...

I was also hesitant to spend larger money on the sensors since I am technically replacing them as a "possibility" to contributing to the inefficient catalyst code, heck I may end up with a new pre-cat assembly as the ultimate fix or I could have a yet un-diagnosed problem that is contaminating the cat and sensors.

sgjii

Monday update. I have now logged 500miles on the new O2 sensors and it appears CCKen is right again. I think I will put CCKen in the same category as E.F. Hutton; "When CCKen talks, I will listen."

Fuel economy is around 18MPG with a mix of in town and Freeway 70MPH+. I tend to have a heavy right foot and like the "loud pedal" the best, so I am sure that contributes to lower fuel economy. I may take a road trip in Nov and will see how "good boy driving" along with cruise control and sustained reduced speed works out.

So far, no CEL or P0432 code has returned, idle is smooth, truck runs great and fuel economy increased slightly by about 1.5MPG. After the first 500 miles, I would report that I am happy with my decision to replace O2 sensors first and I am happy with my aftermarket sensors.

Time will tell. I will update again with more miles or if a problem surfaces.

CCKen

LOL

Even a blind squirrel can find a nut once in awhile.

~~~~~~~

When I was a young aircraft mechanic (long ago) I worked under the direction of an old redneck mechanic that used to tell me "Listen..If I tell you a chicken can haul a freight train, you better start hitch'n him up". Nine times out of ten he was right.

sgjii

Been a few weeks and a few thousand miles.

Update: Non-NTK O2 Sensors are crap. Had failures, warranty replacements, codes for heater circuits, etc. etc., sent back the Prime Choice units for a refund and ordered 4 new NTK O2 senors.

Installed them, drove usual commute for 250miles with no incident. Then drove to Florida for vacation last week and 900miles down, no incident.

Once I was at my destination, within a day if in town driving, CEL light returned. I still had my code reader in the armrest and it all comes back to P0432 Inefficient Catalyst. Reset the code before my drive home and P0432 code has returned 2 more times. Seems to like highway driving better than in town. The good news was 17/18MPG loaded and 75MPH+ on the freeway.

NOW, anybody have a good write up or instruction set for replacing the Dual Pre-cat unit? I wasn't sure if the intake & exhaust manifolds had to come off or if it could be taken off from below.

The best deal I have found is an Eastern Catalytic brand unit and research indicates they are quality parts. The other unit I found was made by walker, also comes with a decent reputation. I am leaning towards the Eastern Catalytic unit as it is direct fit where the Walker indicates the need for an additional pipe and greater cost. The price range is $195 shipped for the Eastern & about $290 for the Walker and extra pipe.

I have had little luck with the aftermarket parts sites for what I need regarding hardware and gaskets. I can't see the top mounts where the assembly connects to the exhaust manifold but the bolt flange where it connects to the rest of the exhaust, well I can't even make out bolt heads, just rusty bumps where the fasteners should be. I was going to see what hardware came with the cat and then visit the dealer for the remaining pieces.

Any input or experiences would be appreciated, thanks guys.

mtulett1

hey sorry to resurect this thread but what size were the bolts you used to put that Cat on with? I'm doing mine next week/ thanks

jdwilliams

I started rehabbing my 2001 xj 5 years ago. It was a basket-case that came with wife #3. I have R/R'ed everything imaginable. I did the 0432 problem last year at about 155k miles.

You should know:

* Use only OEM parts on this model. I have found out the hard way that everything else is junk these days. This goes doubly for emissions parts.

* Use only NTK o2 sensors. You get what you pay for.

* The 3-way catalyst in the 2001 model is unique. Designed for rigid CA emission standards, it was installed into every 2001 XJ sold. The PCM expects an OEM catalyst system, and the algorithms used to determine efficiency depend on OEM cats and OEM NTK O2 sensors being present. Use nothing else or you will see an 0432 return again.

* Seafoam killed the cats. I used Techron to 'clean out' the engine. It worked well, and all the carbon went downstream to clog the cats. Your upstream precats are now coated in this stuff, and they won't ever work properly again, and must be replaced. If you install aftermarket non-3-way units, you will continue to get codes, and in CA, you won't pass smog checks. Only install engine cleaners if your cats are young and healthy, and can burn off the massive amount of carbon that will hit them square in the face.

I installed an entire new exhaust system with OEM precats, OEM main cat, and aluminized-stainless tubing and muffler from Walker. Money well spent in my opinion. Also replaced the O2 sensors with NTK's and they work great.

The cost nearly gave me a heart attack. I sucked it up for the wife's sake. Wise men keep their woman happy.

* Champion 438's are spec'd on this model/year, per the emissions sticker underhood on mine. I stick with OEM equipment, and this is no exception.

I had a dealership replace the exhaust system because I am old and cannot do this with the tools I own. Also, a welder was needed, a skill I do not possess. I was told that the old precats were removed/installed from below, without removing the manifolds.

I wish you well on your journey. I know this is an old thread, but perhaps it can help others who face similar dragons.

mtulett1

thanks bud do you know what size the bolts were on the manifold end of the pre cat?