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2001 XJ P0432 code with freeeze frame data

tufdog71

NAXJA Forum User
Location
PA
This is the third time I've gotten this code after replacing all 4 O2s (205,000 miles....overdue! and poor MPG). I finally got myself an Actron scanner with datastream/record/ freeze frame capability.

So here's what it said (I know, it doesn't talk!):

P0432.............O2S 2/1 Catalyst Efficiency
RPM 640
Calc load 5.1%
MAP ("HG) 12.7
Coolant 201degF
STFT1 -2.3%
LTFT1 1.6%
STFT2 -3.9%
LTFT2 0.8%
VEH speed 0MPH
Fuel sys1 CLSD
Fuel Sys2 CLSD

Any help is greatly appreciated. i have learned a lot from this forum and can only hope to learn more.

CEL came on while i was stopped at a red light.
 
does your scanner show you the output wave from the O2 sensors? You can test the cat with an IR heat gun or other temp probe. Run the engine at 2000 RPM for a minute or 2. IIRC the output should be 10% higher than the input. Also, the 12.7" HG is low, I would verify with a vac gauge. That and the negative fuel trims may indicate something.
 
Subscribing... sounds like you're experiencing very similar data to me in my '01 XJ.

Have you had any 0331 Cylinder Head problems on yours?

I've got a code scanner that reads the same things you posted, I believe... I need to pull mine again and see what they are.
 
Talyn, I tested temp pre- and post-minicat. Both banks were 100+degrees hotter after the mini-cat. I did not record actual temp and I checked at HOT idle. I will recheck at 2000RPM.

I think my scanner will record O2 data/waves. What should I be looking for?

With low MAP pressure should I check (again) for vac leaks?
Where would I connect the vac gauge to test vac pressure?

Redsnake, I have not had any overheating or loss of coolant. I replaced valve cover gasket a few weeks ago and did not see any coolant or signs of a cracked head. I will keep my fingers crossed on the 0331 issue.
 
At idle the rear should match the O2 sensor wave form, but slower. At 2000 RPM the front should be a wave and the rear should be flat, but I can't remember what voltage. I want to say around .4v.

For the MAP pressure you want to check it at idle with a vacuum gauge. Connect it to where the brake booster is hooked to on the manifold. You can also do other checks with a vacuum gauge to determine the health of your engine. The MAP reading could be just how the scanner is interpreting the numbers.
 
you need to replace the cat.

Your fuel trims are perfectly fine. You have new o2 sensors, and they are basically not seeing the change in exhaust gas that should occur after it goes through the cat. Unless you have a massive leak between the sensors, your cat is not doing its job. The only time before/after temp readings really matter is if you cat hollowed out, which normally doesn't occur.

99 times out of 100 a cat efficiency code is the cat itself.
 
Thanks for the input. I will check vac pressure and look closely for an exhaust leak in/near the manifold.

I hate to spend over $1000 for minicats if something else could be the cause.

Eastern Catalytic Convertors (very close to me geographically) makes an aftermarket dual mini cat for the 2001 for 1/3 the cost from a dealer. Anyone ever used their product?
 
I agree with teknicsrx7 about the cat. The code you ae getting is pretty specific and, generally speaking indicates that the cat in question is no longet functioning properly.

You have replaced the pre/post cat O2s so that eliminates those variables.

As for the 12.7"Hg reading, you need to verify that. Any of the ports on the manifold will do to take a reading. That reading would be bad here at my place (6,500' altitude) where we normally see mid to high 14sHg. Rule of Thumb is that you loose 1"Hg for every 1,000' of altitude due to ambient air pressure drop. Keep in mind that an Inch-Mercury reading is a relative pressure reading. It represents the pressure differential between the current atmospheric pressure (Bar) and the pressure in the vessel being tested.

Assuming the best case and the manifold pressure is where it should be, the MAP sensor would be suspect. Also MAP really is Manifold Absolute Pressure. Not Vacuum... The PCM converts the psia to a "vacuum" reading for ease of reference as most folks do not deal in absolute air pressures...

Here is a handy dandy test proceedure for you:
(1) Inspect rubber L-shaped fiting from MAP sensor to Throttle Body. Replace as neessary.
(2) Test MAP sensor output voltage at MAP sensor connector between terminals A and B. With ignition ON and engine OFF, output voltage should be 4-to-5 volts. The voltage should drop to 1.5-to-2.1 volts with a hot neutral idle speed condition.
(3) Test Powertrain Control Module (PCM) cavity A-27 for the same voltage described above to verify wire harness condition. Repair as necessary.
(4) Test MAP sensor supply voltage at sensor connectorbetween terminals A and C with ignition ON. The voltage should be approximately 5 volts (+/-0.5V). Five volts (+/-0.5V) should also be at cavity A-14 of the PCM wire harness connector. Repair or replace wire harness as necessary.
(5) Test the MAP sensor ground circuit at sensor connector terminal A and PCM connector A-4. Repair wire harness if necessary.

And here is the pinout on the MAP sensor:
MAPConnector002.jpg


So, if the voltages are wrong and if the Vacuum gauge reads where it should (In the neighborhood of 20"Hg if you are at an altitude of 1,000' or less) the MAP sensor is shot.

In theory, a perfect engine, at sea level, in a 1 bar atmosphere will develop 21"Hg. It is a rare day that happens. Most days, you will see 17"-20"Hg. Depends on what leaks are present and what the current barometric pressure is and the condition of the engine. If the day is stormy and the barometer is down, so will the vacuum be.

If the volatges are bad and the vacuum reading is bad, you need to start hunting for leaks. Absolute worst case would be that there are engine problems such as intake valves that no longer are seating properly or the rings are well on their way out and the engine can not pull the vacuum.

Hope this helps!
 
Wow! Thanks for the info/test procedure. I will check tomorrow (raining today). This is quite the learning experience.
 
I know you don't want to spend the money on cats, and so you're hoping its ANYTHING other than those, but don't fool yourself. You'll wind up spending more money in time, diagnostics, and parts you don't need, and still wind up replacing your cats. Just saying....
 
I will keep my fingers crossed on the 0331 issue.

Not sure I would worry about the head. I have a 2001 with the 0331 and did a lot of reading on it and by in large the majority of the head cracks due to casting happened before 100,000 miles. If your head cracks with the kind of mileage that you have I would suspect outside circumstances.
 
Ok. I tested the voltages at the MAP connector. 5.2 VDC between A/B and A/C with key ON/engine OFF.

Also hooked up my mighty-vac (brake bleed tool) to the vac line between brake booster and intake and started the Jeep. Needle bounced between 16-18 "Hg at idle and about 20"hg when I opened up the throttle a little.

So I deduce that the PCM is NOT recording proper vacuum (if the mighty-vac gauge can be trusted!!!!) since it only indicates about 12"Hg during a scan at hot idle. Would this mean that the MAP sensor is going?

I'm gonna go get a propane torch to check again for any vac leaks.

A graph of the post cat O2s at 2000RPM is NOT steady, they both oscillate between .3 and .8 VDC.

Thanks again to everyone for their input.
 
If you're talking about the 'pre-cats' then it shouldn't cost $1K for a replacement... I see them online and the local parts stores for ~ $220. It looks like that's the route I'm going to have to take on my '01 w/the P0432 code.

Reason I asked about the 0331 Cylinder head is I just had to replace mine about 6K miles back (~ 118K total miles) and mine had been apparently cracked for a while. Several thousand miles of burning coolant thru the exhaust. From what I've read and been told burning coolant thru the exhaust can ruin the catalytic converters and I'm pretty sure it at the very least helped burn out mine. I also had a lot of other issues w/my '01 when I bought it used that likely helped w/the cracked cylinder head, but just wanted to throw that potential issue out there for you.
 
OEM replacement lists for around $700 plus core. I found aftermarket for about $300. I'm curious if anyone has installed an aftermarket and gotten good results (emission test and no repeat of codes).

I have no symptoms of a cracked head. I'm the original owner (205,000). And I have maintained the cooling system and have never overheated.
 
Needle bounced between 16-18 "Hg at idle and about 20"hg when I opened up the throttle a little.
Depending on how much the needle is bouncing it could indicate some other issue, but you were also using a tool that isn't meant for what you were doing. However it is same to say that the engine vacuum is fine.
So I deduce that the PCM is NOT recording proper vacuum (if the mighty-vac gauge can be trusted!!!!) since it only indicates about 12"Hg during a scan at hot idle. Would this mean that the MAP sensor is going?
What we know is that the scanner may have reported the incorrect value. It may just be the way the scanner interprets the MAP signal, or a certain set of conditions that made that freeze frame data. Can the scanner show you a live reading of the MAP sensor? Check the MAP sensor with a volt meter while the engine is at an idle and then rev the engine. It should change. Record the idle value.
A graph of the post cat O2s at 2000RPM is NOT steady, they both oscillate between .3 and .8 VDC.
That tells you that the cat is faulty. While you could have believed the code and replaced the cat it is good that you did proper diagnostics instead of being a parts replacer.
 
Thanks Talyn. I will borrow a proper vacuum gauge and check vacuum. I will also test MAP voltage with engine idling then rev it and record the changes.

I expect that I will have to replace the cats. I just dont want to right now (my work van is costing me a small fortune!!!!!) and I'd like to eliminate any other possibilities as well.
 
There is also a test you can do with the vacuum gauge to show bad cats. I can't remember the exact procedure, but google may help you.

I'd like to know this as well since I do have a nice (usable) vacuum gauge and would like to double check my pre-cats to make sure they're the source of my issues as well.
 
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