Clogged Converter?

Topic: Clogged Converter? (Read 1561 times) previous topic - next topic

Clogged Converter?

June 28, 2006, 08:37:09 AM

Here are the details on the car:

'86 XR7 turbo 2.3
137k miles

This car doesn't run very well. There have been a few days where it can barely move under its own power.
I need to do a tune-up with Ford parts, as most of the ignition components seem to be some cheap aftermarket brand. Hell, the plug wires aren't even separated... they're just bunched together with cable ties.
Once that's done I may have a better idea of what's wrong with the car.
Anyway, here is why I think the cat may be clogged.
The car gets atrocious gas mileage. Last time I checked, it got just under 14mpg in the city.... on premium fuel. Yeah, that's gotta change.
Sometimes the car runs like total butt. It misses, coughs, sputters, farts, you name it. Giving it more/less gas on the throttle seems to have no effect at all; like something is clogged. I'll get done driving it and when I open the door, I get the strong smell of fireworks coming up from under the car. I've never had a car that would emit that smell, and I've never had issues with a cat before... any thoughts?
While money is certainly an issue, I'm considering just changing out ALL of the exhaust to something less restrictive for performance, plus I would have all new exhaust and not have to worry about it. My state does NOT test emissions, so I suppose I could "gut" the cat.
Any ideas?

Clogged Converter?

Reply #1 – June 28, 2006, 09:53:43 AM

Before you gut the cat why not just pull the exhaust off temporarily and do a test run to see if there is any difference? I realize it may be a pain to unbolt some of the rusty bits, but at least it'll give you an idea of what the issue actually is.

Clogged Converter?

Reply #2 – June 28, 2006, 09:56:09 AM

LOTS of plans!
I would bet that the cat is on its last legs. Either replace it, gut it or put in a straight pipe before you do any other mods. That alone should help your performance. Had asimilar issue once upon a time - pulled the cat and I swear it weighed 25 lbs! It's amazing how much better things ran after that.

Clogged Converter?

Reply #3 – June 28, 2006, 10:00:02 AM

Quote from: Paul Flockhart

Before you gut the cat why not just pull the exhaust off temporarily and do a test run to see if there is any difference?

How much backpressure is needed on that motor to perform properly? I only ask because I ran a 360 with only headers last weekend and the motor ran like . Hooked the Flowmasters back up and WOW! Didn't realize the backpressure would make that much difference.

Clogged Converter?

Reply #4 – June 28, 2006, 10:01:47 AM

I recently took the cats off my Vic' and they were clogged. After that she ran much better and felt like the car lost 50 lbs. It had more guts and power then before and it sounded better too. But to follow the law I gutted a pair and put them back on.

Clogged Converter?

Reply #5 – June 28, 2006, 10:02:19 AM

Get behind the car and smell the exhaust coming out, if it smells like rotten eggs it's probably the cats. If not, it may just be the o2 sensors.

Clogged Converter?

Reply #6 – June 28, 2006, 10:19:43 AM

Quote from: Paul Flockhart

Before you gut the cat why not just pull the exhaust off temporarily and do a test run to see if there is any difference? I realize it may be a pain to unbolt some of the rusty bits, but at least it'll give you an idea of what the issue actually is.

yes, id try this first....

Clogged Converter?

Reply #7 – June 28, 2006, 10:38:07 AM

I was thinking about cobleing up a device to measure backpressure. I simple air guage on a fitting the size of an 02 sensor. I know I've seen them before but you cannot find them anywere.

Clogged Converter?

Reply #8 – June 28, 2006, 10:16:48 PM

Quote from: nirvanagod

Get behind the car and smell the exhaust coming out, if it smells like rotten eggs it's probably the cats. If not, it may just be the o2 sensors.

No, the exhaust smells normal. It may be a little on the rich side. Could it still be the cat?

Thanks for the replies, everyone. I really appreciate it.
I just bought new (Motorcraft) plugs wires, plugs, cap and rotor. I'll see how she runs after the tune-up and reply to this thread. The only way to disconnect the exhaust before the cat would be at the manifold. Wouldn't it run like butt with zero backpressure anyway? Am I missing another exhaust coupling somewhere?
This is my first 2.3 turbo car, so I'm learning something new every day.
I've been running 93 octane and it doesn't seem like there's much of a difference from 87, aside from the lighter wallet.

Clogged Converter?

Reply #9 – June 28, 2006, 10:27:38 PM

Make sure you set the base ignition timing correctly (SPOUT out) when you do the tune-up.....

Also, on a turbo..you want as freeflowing of an exhaust as possible....don't think like you would for an N/A motor.....do disconnecting the exhaust will be a good thing, esp if the cat is clogged.

Might as well toss a new O2 sensor in there as well. Should be a single wire one, and they aren't that expensive.

Clogged Converter?

Reply #10 – June 29, 2006, 10:03:39 AM

I had a plugged up cat on my 84 turbo coupe and I replaced everything and it would still run like . It would bearly get out of its own way. I finnaly took it to a shop they took out the o2 sensor and noticed that lots of exhust was coming out of the hole. So they put a pressure gauge on there and I had 18psi of back pressure. I took it to the exhust shop they pulled the cat and you couldn't see through it even when looking at the sun. They put on a new cat and it was a whole new car. I would drop that exhust and take her for a run. If anything if it is the cat you could poke it out and then put it back together.

Clogged Converter?

Reply #11 – June 29, 2006, 01:13:53 PM

isnt it that you can check if acat is cloged by pulling a vacume test. i thought i remembered reading something about that in the haynes manual. mybe turbos are different. im not sure i'll look and see what i come up with

yep check to see if it's pluged threw vacume. the manual says. check threw intake vacume.

1.open the throttle to about 2000 rpm
2. release quickly
3.if no restriction the gauge will quickly drop to not more than 2 in Hg or more than it's normal reading
4. if the gauge does not show 5 in Hg or more above it's normal reading,or seems to momentarily hover around it's highest moment before it returns the exhaust system or converter is pluged.

good luck

Clogged Converter?

Reply #12 – June 29, 2006, 09:48:26 PM

Thanks for all of the help, folks. I really appreciate it.

Here's the latest:
Shawn once told me to use only Motorcraft plug wires on these engines, so this is what I purchased.
When I pulled out the old plug wires, they were totally rotten at the ends of the boots. I suppose oil, heat and missed sparks will do that. Oh yeah, they were some cheapo aftermarket brand.
I put all new Autolite plugs in, Motorcraft wires, and a brand-new cap and rotor.
Holy bacon! It feels like I have a new engine! I can actually wind it past 4,000 RPM without it falling flat on its face. It is by far the most incredible difference I have ever witnessed from just a basic tune-up.
In any event, this was definately part of the problem before. The contacts on both the cap and rotor were actually rusty. This thing purrs now.
I hope I can keep my foot out of it... :)

Quote from: Chuck W

Also, on a turbo..you want as freeflowing of an exhaust as possible....don't think like you would for an N/A motor.....do disconnecting the exhaust will be a good thing, esp if the cat is clogged.

I was not aware of that. I suppose some custom exhaust will be in the works in a few months.

Thanks again for the help!