catalytic converter woes

**Gary** · 01-01-2009, 02:21 PM

i gotta drama

my UCF11 seems to enjoy munting the RHS cat, i dunno why

the previous owner had an exhaust fitted - nothing amazing, pressbent, deleted a few mufflers though. after he had it fitted (im going by reciepts i got with the car) he also had the RHS cat replaced with a cheap hiflow cat, the other side was left stock. then i got the car, the replaced cat was all rattly and annoying so i replaced it and the other side with some nice metalcats. they were doing really well until last night.

i was driving about all day, no dramas, got to a mates house and the car sat there for a couple hours, when i jumped back in the car started fine then struggled with its idle. it held it, didnt stall but it was running really rough and really didnt like me revving it. i drove for 50m or so, still happening. had a look under the bonnet, everything looked fine, no warning lights, fluids were fine, no smoke from the exhaust, radiator fluid wasnt all jumpy, no weird clacking noises etc so as far as i summised, the UZ was happy

id gathered its probably something to do with exhaust, but kinda ruled out cats as id very recently replaced the bloody things. i decided to tuff it out and get it home where i could fix the shit, during the limp home the cat warning light pops up. i was blowing smoke at low revs under load, looked brown (hard to tell at night)

ive just pulled em out, one side looks real nasty, the other side is loose but still largely together, both are munted though. so im assuming (dangerous) during its history, the car has gone through the factory cat, the replacement cheap hiflow cat, and my new metalcat all on the same side (the metalcat on the other side probably only blew because it was running crazy rich cos the other side was backing things up heaps)

so, what could be causing it? would it be possible that theres a blockage of sorts on one side of the exhaust thatd contribute to it? (its an independent twin system from cats to tip) going by reciepts it looks like the cat dramas have only started since the new exhaust has been fitted. i dunno how to test flow accurately
i cant think of anything else thatd affect only one side, not the dizzy on that side surely cos that goes over to the other side also... leads perhaps? spark plugs were fine when i swapped em out a while ago though... i'll pull the plugs now see if theyre much different left bank to right

**Dieseltrain** · 02-01-2009, 09:57 AM

Faulty igniters or Coil packs can do this. Unburnt fuel gets thrown down the exhaust and ignites in the cat and melts it . Normally once it does it though, it will continue doing it, its not normally an intermittent thing.

Check the Igniter, coil pack and also the O2 sensor on that side.

**Gary** · 02-01-2009, 11:32 AM

i dont have an ignitor or coils

but i will check o2 sensor

**Dieseltrain** · 02-01-2009, 02:49 PM

No igniter or coils? Whats running the ignition ?

**Gary** · 02-01-2009, 02:51 PM

distributors to leads, ive got one on each bank

they dont operate each side independently though, otherwise itd probably just be that

**Gavatron** · 02-01-2009, 02:54 PM

There is still at least 1 coil and 1 igniter regardless, probably 2 of each is it has 2 dizzys

**Gary** · 02-01-2009, 03:56 PM

coolio, but considering they act on each dizzy, and each dizzy operates cylinders on both banks, i dont think thats the problem is all

i have a look anywho

**Gary** · 02-01-2009, 05:17 PM

found the drama

the left side coilpack was sorta not connected to anything, the lead had been pinched (leads look factory) then i guess had burnt out thereby making itself into 2 leads

so maybe that had happened, making the car run on 4 cylinders, dumping all that lovely fuel into my cats, ruining them, cats munted and got nice and blocked, i got that warning light on the dash saying that was the problem

so curiosity didnt kill the cats, I DID! haha. that said though, i had to drive 60 odd k's home on 4 cylinders, and despite running rough the faithful UZ hauled 1.8tonne up to 100k's an hour reasonably! crazy

thanks for suggestions, you were right i dunno what i was thinking

**Dieseltrain** · 02-01-2009, 06:18 PM

All good mate

Least its problem solved aye !

I knew their should be 1 igniter and 1 coil pack on each side as well as the distributor, on a stock ignition system on a 1uz that is why i asked