hrcslam

See the video below. Is this clogged cats?

A Little history. Car was burning a lot of oil. It came to me with a misalignment between the heads (previously rebuilt and installed by someone else) and the intake manifold. That caused crankcase oil to get sucked into the CC and burn it. I had the intake machined and the leaking stopped. Car ran great. I went out about a week later to work on some other things and the car would idle fine, but instantly bog down with any throttle input. I figured out how to get it to rev up (by bouncing the throttle up and down slowly as I increased throttle). By revving it up it would eventually get better, but it comes with a rattling sound. When the rattling sound stops the symptoms would return. I'm thinking clogged cats from oil coking. All this can be seen in the video. It bogs down hard in the beginning, but after I get it to rev up, it rattles and revs up much better. No great, but a lot better.

Anyone care to confirm or give me different ideas of things to check?

I've already checked the opti (new MSD) and the spark plug wire routing, and plugs. Good compression check. Good fuel pressure. No bad grounds or sensors. No codes. All injectors are working too. No fuel leaks.

Thanks in advance!

Yes, I know it's got a wicked exhaust leak on the passenger side at the AIR pipe. That'll get fixed too. But that's not the cause of this issue.


My Camaro did something similar when I first got it, it didn't run this bad though. I removed the cat and it ran damn near perfect. I just want more confirmation before I tell my buddy to order two new cats. Also, if anyone knows of a better option (like LT headers with cats (that still have the EGR) for about the same cost as two factory replacement cats.....).

SOLVED: Bad Optispark and clogged Fuel injectors. Fixed the Opti (MSD rebuilt it) and cleaned the injectors. Been running good for about a year now.

hrcslam

This is what it ran like before I fixed the intake manifold to head leak, notice the oil. I got this car and it wouldn't even run. I had it running great after I fixed that intake manifold leak. Now this. Arg.

BTC

I'm listening on my phone in a restaurant, so it's kinda hard for me to hear. If your cat is plugged, it probably won't rev very well, and would likely be blowing metal flakes or dust out of the exhaust. The manifolds might also be glowing. Those have been the symptoms I experienced on my 1994 Camaro when my cats have collapsed

I thought I heard some metal on metal in that video, but again it's hard for me to hear.

BALLSS

well that exhaust leak pre 02 would cause/contribute to a clogged CAT as the 02 would read lean and PCM would command more fuel on that bank and that more fuel would, over time, clog that CAT

Back pressure exhaust test also can identify a clogged CAT or use a IR temp gun. If the front on the CAT is quite a bit hotter than the back...clogged

You can just buy generic Catco CATS the pipe size you need and have them welded in vs buying factory bolt ons

In the video there was a moment where there was a heavy knocking sound...hopefully that was just exhaust hitting something and not.....internal motor knock

hrcslam

Good idea with the IR gun, I'll do that.

That knock is the rattle I was talking about. It runs better when it rattles. It sounds like it's coming from the passenger side cat. It goes away after a while and it runs worse again.

JC316

iTrader: (1)

Sounds like bottom end to me, but I've heard a bad cat sound like that too. Get under there with a mallet and give that cat a whack, if it rattles, you found your problem.

hrcslam

I thought the same thing. But it goes away for no reason. Rod knock doesn't do that, it gets worse under load.

KW Baraka

iTrader: (7)

Clogged cat should glow red.

Run it a few minutes to get the engine warm and then take a look......

KW

hrcslam

I'll check it out, but they don't always glow red hot. My Camaros didn't.

BALLSS

FWIW my clogged CAT didn't glow red also.

BTC

After listening to it on my computer, I think it could potentially be clogged/collapsed cats. I also still hear what sounds like metal on metal towards the end of your video and that doesn't really sound cat related to me.

The cat on my Camaro has collapsed probably 2-3 times. My symptoms were always a very sudden, dramatic loss of power, the car would not rev freely, the manifolds would get red and very fine metal shavings would blow out of the exhaust.

SS RRR

iTrader: (2)

Take the y-pipe off and see what happens.

KW Baraka

iTrader: (7)

I said it "should" glow red; that is......if it's actually clogged.

"Clogged" does not equal broken/crumbling. If the substrate material is broken/crumbling, then exhaust will still flow (slowly/barely) through the cat and the substrate will blow out the cat, through your pipes and muffler, and eventually out of the tailpipe. It may glow red, but because the cat's not truly clogged, it may not.

"Clogged" almost always means that the substrate has melted due to excessive heat and is no longer porous.

When this happens, exhaust will not flow through the cat; it will retain the heat from the exhaust, get excessively hot and styart to glow red.

KW

hrcslam

Clogged , yup I used the word right.....

Clogged doesn't only mean flow is completely stopped, hindered flow is caused by clogging too....

Also, I've personally seen cats glow red that aren't clogged either. So glowing cats doesn't mean there's clogged cats, and clogged cats don't always glow red.

Thanks for the input though.

atlantadan

Best idea here, so far.

bufmatmuslepants

iTrader: (3)

When mine was clogged if I put my hand by the exhaust idling you feel it was not nearly the normal amount of air coming out, and it would stop revving around 5000rpm, it just fell on its face. Beat on the cat with a hammer and listen for rattling, my honeycomb broke and was sitting like a diamond with the tip sticking out the end of the cat.

hrcslam

I disconnected the AIR ports to the Exhaust manifolds at the check valves (to open up the exhaust) and it made no difference. So, it's not the cats.

What's weird though, is when I was trying to get my ALDL cable to connect to Tuner Pro RT I had the engine idling and the condition improved as the engine warmed up. Still no codes. But, occasionally the condition will completely go away. I can rip the tires loose one minute, then the very next pull it'll bog and die off the line. If it doesn't die it'll stutter and have a drastic loss of power. If I let it idle again for a minute or two, it'll work for a minute then go back to bogging.

It's got a new MSD opti, new wires, new Coil and AC Delco ICM. All things needed to get it running at all. Fuel pressure is still good. I did a compression check when I first got the car not running, but haven't done one again since this issue started as I don't think that the problem. And the metal clanking sound that was heard in the first video I posed is gone. Weird.

If I disconnect the MAP while the engine is cold it idles much better, but still bogs down with any throttle input (which is expected with the MAP disconnected, non-MAF car). I tried swapping the MAP from my Camaro, but it didn't help at all.

I was leaning towards the Coolant temp sensor, but the fans are kicking on when they are supposed to. So that doesn't make any sense. Unless, for some weird reason, the Dash coolant temp sensor has an effect of AFR for Corvettes?? IIRC it is just like the F-Body's and uses only the Coolant Temp sensor on the WP.

I tried to get my stupid cable to connect to the 12pin OBD1 port, but it just will not communicate. It doesn't seem to work on any car (1995 Suburban, 1995 Silverado, 1994 GMC Box Van). I think I got a bad cable from OBD Diagnostics (OBD2AllinOne.com). But before I rule that as fact, maybe I'm doing something wrong with it. My 16 Pin works perfect on my 1995 Camaro, so I know it's not the laptop I'm using.

Any other suggestions? I'm waiting for the engine to cool down. Then I'll re-install the AIR Check Valves and pull the spark plugs and see if they are fouled (good possibility considering all the oil it was burning).

Thanks in advance!

atlantadan

Did you try the latest drivers for the cables? FTDI drivers are here.

hrcslam

I tried a bunch, I'll try that one too. Thanks!

hrcslam

I did try those, I re-installed them again to no avail. Really wish I could data log this.

Now it starts sputters and dies within seconds.

I disconnected the MAP again and it'll idle nice and smooth, but still bog hard with any throttle input. Lightly feathering the throttle up will get me to about 2500 rpms though. It'll bog with throttle input, then rev up when released. But if I catch it just right I can bog it at a higher RPM and let off the throttle and it'll gain more RPM, repeat until I get to 2500 ish RPM. It's starting to smoke again too. Argh!

Turns out the PCM for less chip had fallen out (likely while running), so I'm thinking the chip is bad now.

I wonder if it's worth removing the Opti again though. Maybe it's clocked wrong? I had one opti spin between the cam drive and the rotor when the roll pin popped out, maybe that happened here? I may just remove the Opti again to check it out. If all looks good there, I'll have to get that chip replaced.