loosescrew84

Hello all, I'm pulling my hair out with this issue and hoping you can help.
First, the background - car has 155k, general good condition. I've had it for about 3k miles with no issues until now. Driving down interstate at 70mph, car dies. Starts and dies repeatedly on side of road. Turns out to be a tooth off of timing. Dealership replaced belt 15k ago for prev owner and didn't replace tensioner, tensioner spring, or water pump. So I replace belt, crank sensor, crank seal, water pump, tensioner and spring, lower timing cover, all honda parts. Put it back together, starts up and sounds great. Take it down the road, car starts running like crap again, but this time doesn't die. Limp it back home, check timing, engine timing is good.
Check compression, 145-150psi on all four. New plugs are fouled already.
Symptoms - vibration at idle, sounds like firing through intake slightly, exhaust rattle (which didn't happen before first incident). If I rev it up, it sputters and dies. Can't rev past 2500rpm. Getting good spark on all 4. Hooked up Gopoint and dash command, no codes. I do see the short term injector trim is far negative, -12% to -14%. This backs up the fouled plugs. Anybody have any ideas? Thanks in advance

loosescrew84

Video of issue - you can hear the exhaust rattle and intake sound:
http://youtu.be/tgp3Kef0xTY

loosescrew84

loosescrew84

ezone

First guess is cam timing is still off by at least a tooth, or maybe the cam pulley bolt is loose and let the cam misalign from the pulley

Is the tensioner spring still intact? Is the tensioner bolt loose, did it pull threads out of the block?

loosescrew84

Thanks for your reply Ezone. I think I've figured it out - catalytic converter was toast. I noticed it was hissing at tailpipe so I separated the exhaust at the cat and found the core in several pieces. I removed them and fired it back up and runs great! The diagnostics look better also. MAP has decreased from 40kpa to 25kpa, ST injector trim is now positive. I plan to swap in a new cat by this weekend, any recommendations?

emich

Do you get Code - P0420 Catalyst System Efficiency Below Threshold?
If you do don't put new cat it's expensive and won't affect the driving. Seal the sensor with piece of soft copper tubing 1/4" leaving one or two holes exposed to the exhaust gases or modify the sensor installing resistor and capacitor. I'll post the diagram later. Did you replace the tensioner bolt with linger one as Honda recommends? I think is 1/4" longer but there is a space for even longer bolt to fit.

loosescrew84

Hi emich, I didn't get that code but thanks for the info. That's part of why I was so stumped - no engine codes. I didn't realize honda recommended a longer bolt for tensioner either - I bought a new honda tensioner which came with new bolt, I'm hoping that has it covered.
I've got a random technology catcon on order now, hopefully will have it in this weekend.

emich

Why you are replacing the cat if you don't have a code p0420?
Based on a Murphy's law you may get it with the new cat.
2001 – 2003 model years may require a longer fastening bolt!
https://www.techconnectcanada.com/do...20Bulletin.pdf
I used one of the long bolts from the bracket above which is 60mm instead of recommended 54mm and 23mm were protruding from the tensioner instead 15mm. I was surprised there was enough spase.

loosescrew84

Replacing cat since it's destroyed, see above pics. If I get a code I'll deal with it then, but what I had wasn't working.
I wonder why a longer bolt is needed for tensioner?

emich

You need longer bolt to prevent this.
I cought mine just before falling off only because it was making noise hitting the lower timing belt cover

ezone

The cat JUST broke apart and it has not been able to run long enough for the computer to run the self tests (drive cycles) that would check cat performance. You can't do a drive cycle if the engine won't stay running.

But if it was able to run, it would fail the cat monitor soon enough.

IMO it really isn't covered by Murphys' laws LOL
Or at least, Murphys isn't the reason cheap cats cause the P0420 code.

loosescrew84

Thanks ezone, I was hoping that was the case. My thought/hope is that new random technology cat + 2 new NTK oem O2 sensors will keep the PCM happy.

Reverb2005

The question I would ask is WHY did the cat melt and fall apart like that? It probably fell apart BECAUSE it melted..... the exhaust gasses are only hot enough near the engine to do that kind of damage so it isn't likely to happen in the muffler or down the pipe.

Was that the factory cat?

loosescrew84

That's a great question. It was the factory cat.

Here's my theory so far - during all this I noticed that the plugs look factory as well. They looked like the ignition conditions were good, but were REALLY worn out. I'm thinking inefficient ignition was sending unburnt fuel down the exhaust to ignite on the converter, thus raising converter temps & melting the catalyst core.

ezone

Has it recently had misfire codes or rich codes? These are the most common things that lead to a cat overheating and breaking.


If you never had misfires or problems with running excessively rich, then I might guess the cat may have suffered some sort of impact that caused the substrate to crack and break apart.....or had high mileage, but IDK. I'm only guessing why it did what it did.

Also, since the cat broke apart (assuming pieces went out the exit of the cat) you should check the rest of the exhaust system for chunks of cat debris that may cause clogging problems. Rubber mallet, bang on the pipes and mufflers and listen for rattles inside?

loosescrew84

No codes for misfire or rich conditions that I know of. It had a couple of old stored codes, p1298 and p1456 if I remember correctly. Hard to say, it has a new set of denso plugs now and I don't plan to give it an impact so hopefully my new cat will last another 12 years!
And thanks for the tip to check the cat-back for debris, I wouldn't have thought of that.