Hi guys,

I guess I made the mistake of my life when I sold my XJ and got myself a 1999 4.7 WJ....

So here's what’s happening...
Recently I was getting the P0432 Code (Main Catalyst Efficiency below Threshold Bank 2) and I was ignoring it for a while, until my car suddenly loss power while driving on the highway... I was going around 60Mph and tried to pass another car, when it started to make some weird noises and loss power completely (Luckily it was midnight and not so busy)... I pulled over and tried to figure out what it is, there was a weird burning like smell and when I started the car one more time, it cranked, moved couple of feet and loss power again, the car is not stalling, but the RPM is climbing up to 3000RPM and then falling to 500-700RPM and even if I floor the pedal, it is not climbing back again....
If I shut the car down for like 5 minutes, it works again normal but it stops back, after around 5-10 minutes...

My check engine light was on for P0432 but after this, I started to get the following codes P0432 - P0174 - P0206 - P0407 – P0417... and maybe couple more...

My mechanic thought that it was the fuel pump, then he checked the fuel pressure which was around 58Psi and he eliminated that factor (Maybe it was running normal when he checked that I don’t know) , and he said that it sounded like exhaust back-firing and suggested to change the catalytic converters... There were 3 of them, 2 on Y pipe and one before the muffler... So we got 2 universal cats, welded them on the Y pipe and eliminated the one before the muffler (they all looked clogged by the way) the check engine light went off, everything was normal for an hour of driving and then started to do the same thing again...

I'm desperate now, I'm afraid to get the fuel-pump and get stuck with it again...

Please.....Anybody faced the same problem? Any solutions or advices?
and thanks for the reading the thread...

Best Regards
Leon

 

Sound electrical. Start by reseaching symptoms. I will look up what codes refer too but multiple causes can set off the same code. Google various combinnations of your symptoms and see if anything fits.

Also maybe start checking ground cables (multiple grounds on this motor) and electrical connections. Check fuses and relays too.

 

My advise is to find another mechanic, the one you have is just fixing the symptom not the cause. Catalytic converters don't just clog up, you have too much raw fuel in the exhaust and that is what will cause a converter to melt down. A fuel pump is most likely not the cause of the catalytic converters to fail.

 

Find another mechanic. I can't diagnose this over the internet but your mechanic obviously can't do it in person.

 

I'll try to change the O2 sensors and maybe a tune-up and check the grounds and see what's gonna happen.... do you think that the main cause is the fuel pump? (I'm not having any problems to crank it anytime)

 

an O2 sensor can kill a cat, once the cat is gone it can restrict exhaust flow enough to kill power. on my ZJ I rock docked on the cat,crushing the catalyst inside, my truck would cut out and stall all the time. I replaced the cat and it solved my problems. unless your cat is just really old though, you need to determine what killed it first.

 

Can a bad O2 sensor kill a brand new cat in couple of hours of driving?? But again, the car is not stalling, it's just losing power and the rpm ia dropping to 500-700 rpm and not responding, even if I floor the pedal.... could it be the TPS? Or kick down cable??

 

Thank you guys for your kind efforts, I just replaced one of the O2 sensors (bank 1 sensor 2) downstream and it's running like a champ for now (knock on wood) ....

 

If anyone needs cat-convertors or exhaust related parts, I found this great site and they ship very fast, www.performance-curve.com their prices are really cheap compared to my local suppliers, I got 2 cats + muffler for only 156$ shipped to my door and it took only 2 days... you can call them too, the guys are really experienced and they help you a lot.... tx again everyone