chevygirl

iTrader: (69)

How can you tell if you have a plugged cat verses a torque converter problem? Vehicle runs fine until 3rd gear at cruising speed when you want to increase the load slightly. It shakes and shimmys and has no power unless you give it alot of load and then it changes gear and stops.

RPM WS6

iTrader: (3)

Getting any codes (SES light)?

Is the condition worse with the engine hot vs cold, or is it the same?

chevygirl

iTrader: (69)

no engine codes. It is the same hot or cold. i have a rough idle bad is the only other problem.

jkichline

iTrader: (1)

Sounds like you are having random misses. What year make and model? Sometimes misses are not caught by the computer. I had this issue when I had a leaky injector. Its very tought to diagnose without a code.

thunderstruck

iTrader: (15)

i wouldnt rule out an ignition problem either... coil pack or spark plug or wire

PunkerPontiac

iTrader: (1)

easy way to check for clogged cat (assuming you have a vaccum gauge)... hook up vaccum guage to manifold vaccum. run engine at 2500 rpms. If vaccum drops to zero after a few seconds, you have a restricted exhaust.

chevygirl

iTrader: (69)

I thought since the problem was at 3rd gear it would have to be the torque converter. I have checked for a leaking injector and that is not happening. Everything ignition has been replaced by factory parts.

jkichline

iTrader: (1)

But you said that you also have a rough idle. That tells me you have an ignition problem. I could be wrong but thats my guess. Do you have any problems at all in 1st or 2nd? Do you have an EGR valve? If so, you might want to decarbonize that. Have you cleaned your MAF Sensor lately?

If I am wrong, your TCC could be freaking out from a bad electrical connection or something. Check all grounds, especially.

chevygirl

iTrader: (69)

The egr valve has been replaced several times and all the sensors have been replaced. No problems in 1st and 2nd gears. It runs rough at idle sometimes worse than others like it is going to go dead. This shaking in 3rd gear is a new problem since the engine was taken out at the dealer it started doing this. Since then they have put in another new engine (because it might have had an internal coolant leak) and still have the rough idle and the shaking like it is missing in 3rd gear. If you give it alot of gas and it goes into 2nd it does not do it. I have been trying to get the rough idle fixed for almost 2 years but this 3rd gear thing is a new problem started about 5 months ago. With the 2nd new engine there was no change in the idle or the shaking. The mechanic said he checked all the ground wires and there was no change. It runs rougher some times more than others at idle. My trans. fluid is also not draining back after the engine cools down. It is way high on the stick cold and comes down where it is suppose to when it is running.

jkichline

iTrader: (1)

It seems that a ton of work has been done to your car. I would make a list of EVERY Part that was replaced with the new engine in. Then, post it here. Everytime I think of an idea for you, I realize that you probably replaced it by now.

By the way, how did you check for a leaky injector? I'd like to find out how to do it on my Durango. My T/A, I assumed I had a leaky injector because when I replaced them, it ran MUCH better. Also, it ran MUCH better with injector cleaner in the gas tank.

Have you tried running injector cleaner in the gas? If so, did it run any different?

chevygirl

iTrader: (69)

I haven't tried the injector cleaner. The dealer didn't think it would change anything. You can smell a leaky injector when you open up the hood or inside the car when you cut it off. I will make a list of things I have had done and post it here.

RPM WS6

iTrader: (3)

Not necessarily.

I'd use a digital mulit-meter and ohm test the injectors just to be sure. They should be somewhere in the 12 ohm range.

chevygirl

iTrader: (69)

I do have a plugged cat. Temp is colder coming out the back of the cat then the front. Now I have to figure out what is causing it.

BLKWS.6

just replace it It should be under warrenty

chevygirl

iTrader: (69)

Does anyone know if a bad cat or clogged cat can make a vehicle idle bad?

Pewterpower

I'll let you know Tuesday. I'm going in for a new cat (I'm at 78,500 miles ) and my idle has been stange ever since I started throwing codes.

2002 SS #476

iTrader: (2)

One way to check for a clogged cat is to use a thermometer. It should be around a couple hundred degrees cooler before that cat, it’ll be hotter after the cat due to the burning of fuel. A clogged cat can cause a rough idle due to the exhaust gases getting back up into the cylinder, which there an inert and will not burn.

If your TCC clutch is locking up, it would stall when you stop. It would be like leaving a manual in gear and trying to stop.

chevygirl

iTrader: (69)

Mine is alot hotter in the front like 350 with the infared thermometer and 160 in behind the cat. I am going with the cat being the problem. I have a weird idle that acts like it is gasping every once in a while. I hope this cat solves it all. It has been a long road to figure out the idle issue. I wish I had bought the infared a long time ago. I still don't know why in 2 years the cat is clogged so I got to figure that one out.

Thanks for the info!!!!!

Pewterpower

Got my car back, with a new pass side cat, and the idle is fine now.

KameleonTransAm

iTrader: (1)

^Out of curiousity did they charge you anything at the dealership or just replace it for free and be done with it? Because im throwing PO430 code so my passenger side cat needs replacing but I'm worried they'll try and charge me for something useless. Oh and I'm in FL (if that makes a difference)