Probably Catalytic Converter Problems -- Questions Before Proceeding

I have a second Insight (2000 MT), that my son is the primary driver. I purchased it last spring for $1000. We have done a lot of work on it to get it back into shape, as it was highly neglected by the previous owner(s). By early fall of 2021, I had it in OK shape, not perfect but definitely improved over how it was when I bought it.

My son informed me a few months ago that the car was having problems getting up to speed. I took it for a drive and sure enough, we had trouble getting up to 55mph. This was "pedal to the floor and not gaining speed" type problems. At this point, I felt pretty confident that we either had poor engine compression or a clogged catalytic converter.

My son disconnected the second cat from the first and it has made a huge improvement in power. Now, we are trying to determine how to proceed. As I see it, we can either gut the second cat; or we can replace the second cat with a used OEM one or something new from Rock Auto.

But here are my questions:

1. If the second cat is clogged does that mean that the first cat is losing its honeycomb interior? Is the first cat about to go bad? We have no CELs currently lit on this car. If we have no CEL on the first cat, should I assume that the first cat is still OK? I replaced the LAF sensor last fall and the honeycomb looked OK in the first cat at that time.

2. Is it possible that the clog is not in the second cat, but in the exhaust system farther back toward the tailpipe? Or do clogs only happen in the cats?

 

thanks in advance for any help

 

Hi! You'll likely get a lot more responses in an Insight forum. This forum is usually a lot more Ferrari centric. Thanks!

 

Just replace it if you’re sure it’s the issue. You sure it couldn’t be the fuel pump or fuel filter? I’ve seen similar symptoms from that.

 

Ok, I'm a little confused...when you say "second cat" are you referring to the main catalytic converter and the first one is a precat? I'm assuming that there is only an upstream and downstream o2 sensor that would throw a CEL and you have to determine whether the downstream is after the precat or main cat...

 

insightcentral.net

Frankly it comes down to where you live. Pulling the cats is not okay in Virginia ......at all. It will fail the visible part of the Safety Inspection if they are not on the car.

That said if State compliance is not an issue .......and you spent $1,000 on the car.......punch them out. Besides the check engine lights.....the gas mileage will probably get worse since the O2 sensors will be out of whack.

 

@RedNeck thank you so much for your suggestion

 

Anyone else find it odd, this person posts technical questions for an Insight and a BMW 3 series on a Ferrari forum?
His profile says he is 27 years old, but he has a son that drives his Insight?

 

The squirrel population around here is out of control.

 

@f355spider also thank you for your suggestion

 

Maybe the thought process is that if we can work on Ferraris we can work on anything?

Obviously it isn't remotely true, but I can see it being a thing...

 

I think he has failed to understand that most people on this forum are rich guys, not car guys

 

The cats can break down and so can the muffler, etc. It just depends on the state of the exhaust system and age. Also, and I'm no expert on Insights, most stock cars have rather tiny exhaust systems to begin with.

Did you try putting your hand near the back of the tail pipe opening and see if exhaust is free flowing out of the system? It should come out the back with a fair amount of pressure. Try revving the motor up also, while holding your hand back there, to see if the force increases as the motor speed increases.

 

Think 55 is top speed for that car!
Kidding aside, if it's better without one of the cats you seem to be onto something.

 

Incorrect exhaust flow can really do a number on top end

I remember when I was a kid (maybe 8 or 9 years old), my Dad drove us all over to Sears in his 1966 mustang to have a muffler put on. When we left the garage area and got on the highway, the car would not accelerate past about 40 MPH, no matter what you did. My Dad turned around, drove back to Sears (right as they were closing the shop up) and told them they did something wrong. Of course the kids at Sears started some nonsense about "no sir, it's nothing we did, blah, blah, blah". Finally after arguing back and forth, my Dad insisted they call a manager or something. He came out, told the kids to put the car back on the lift and then sent over one of the older repair guys (real nice guy, must have been late 60's). The guy walked over under the car, took one look and said, "You idiots welded the muffler on backwards..."

They had to cut the muffler off, flip it around, weld it back on and then off we went home at 75 MPH+

So definitely check your muffler. They can sometimes rust internally (depending on design) and then all the baffles can pile up at the end of the muffler and basically block most of the flow.

When I bought my 1990 Toyota pickup, it had this crazy old exhaust can that was like 4 feet long under there. The inlet pipe - I kid you not - was something nuts like 1.25 inches in diameter. As soon as I could, I climbed under there with a hacksaw and cut that silly thing off and kicked it over by the wood pile. I think I must have gained 25 HP just by doing that haha.

Ray

 

thank you so much for your suggestion

 

Or power to an electric fuel pump.
One friend had juuust enough power to run his, but to really hammer the pedal and make demands
on the fuel pump for more fuel - it didn't have the current to do that.
Simply rewired it, new contacts - fixed it.

Another friend, his truck ran off one batter, but the fuel pump was running off his second
battery, and that battery was dying/not being charged, but provided just enough current
to run the fuel pump at idle or low RPM's, but the truck would stall out over X RPM's.
That one took awhile to diagnose.