Does anyone have Ideas of ways to tell if it is time to change you cat?[8D]

 

DRO:

When it stops using the litter box, and starts eating your dinner off of the table......

Sorry about that, just had to do it.....

I assume you are thinking that your cat convertor is bad. What symptoms are youhaving??? The two ways they die that I know of are the catalyst material becomes poisoned somehow, or the insides breakdown and plug up so it will not pass any exhaust.

If the cat is bad, you should be getting a CE light.Unless the cat is 100% plugged, you would notice the engine not wanting to rev up into the higher rpm ranges, but it could still idle and drive at low speeds just fine.

Don

 

Cats are rarely an issue. They don't go bad without problems upstream of them for long periods of time ie running rich.

 

Well My "D" used to have alot more more power when I floored it. It may be that I have sinced then changed to 87 octanewhen I was originally using 93 octane. 87 octanewith a mixture of xylene has given me a little more power /gas mileage, but I still want it back to were it used to be. Considering that I have 20's and 30x9.5 when not using 20's I still feel a hesitationwhen I floor it at 40 to 60 mph. Not the shift then go like it used to be. I have changed the spark plugs back to champion resistors and gapped them my selfto fac .044. I have noticed a difference in power between 87 and 93 octane gas, but I still know I used to floor it and go. I all so changed my oil from synthetic blen to full synthetic, Q power. Yes that did give me more power, but still not close. I do keep upwith regular maintence plugs, oxygen sensors, and such.I read in the threads timing maybe an issuse.[sm=confused06.gif]

 

THIS IS SOMETHING i MAY TRY[align=left]TPS Modification:
(Applies to '92 -Current models)[/align][align=left]Have you ever noticed that slight stumble right off idle when you mash the pedal to the floor? Here's an easy fix for the sluggish response of the throttle (which is related to the TPS Sensor).[/align][align=left]Check your TPS voltage before doing this modification as none of the factory sensors are calibrated the same. We've seen ranges from .3v-.7v...from the factory. Connect a Digital Volt Meter to the middle terminal on the TPS sensor (with the harness connected and the Key-ON/Engine-OFF). If it's close to .7v...leave it alone.[/align][align=left](1) Remove your TPS Sensor from the vehicle (Located on the drivers side of the throttle body - 3-Wire Connector)
(2) Put the TPS into a vice and drill the two brass inserts out of the casing with a 1/4" or 7/32" drill bit (drill from the back of the sensor...not the front). You'll need to push on the drill as it will only spin the inserts...once they're heated up enough, they'll pop right out.
(3) Clean up the holes with either the drill or (preferred) a small round file.
(4) Reinstall the TPS Sensor on the throttle body. You'll need two small washers on the screws as the holes are now bigger than the screw head. Leave it slightly loose as you're going to have to set the initial Key ON/Engine OFF Voltage before starting the engine.
(5) Reconnect the TPS sensor harness and connect a Digital Volt Meter to the middle terminal on the TPS Sensor (you can poke through the weather-proof connector).
(6) Turn the ignition key ON but do NOT start the engine.
(7) Set the initial voltage (by turning it with your fingers) on the TPS at about .7 volts. (Optimum range is from .7 - .75 volts)
(8) Tighten down the TPS screws and check the voltage one more time (yes...it can move slightly when tightening it down)
(9) Start the engine but do NOT step on the accelerator pedal...let the computer learn the new initial voltage setting.
(10) Turn the engine off and close the hood...drive away of you want...your throttle response should be much more precise now.[/align][align=left]Here are some pictures for the various steps:[/align][align=left]




Factory TPS Sensor w/Brass Inserts

TPS Sensor in the vice (ready to drill)


Modified TPS Sensor Holes

TPS Sensor reinstalled with washers[/align][align=left]Some have claimed that the TPS Sensor is adjustable on the actual throttle body without any modifications...this is completely false. There is no room for adjustment unless you drill the inserts out.[/align]

 

The tbs was the problem. back to normal

 

I have seen this write up before and I have measured the voltage being suppliedto the TPS at 5.0volts.Return was .7 volts. So my question is this:

The book saysreturn voltage should be between 0.2 and 1.4 with an average of 0.9. The WOT should only be no more than 5.0 volts returned because the supply is regulated at 5.0 volts.

So if you do this fix:

WillWOT bereached pre-mature or could it never be reached? And if so is there a fix for this.

 

Oh,

To test a Catalytic Converter most shops will do a back pressure test to confirm over pressurization. Anything over 2.5 lbs back pressure I would change out the Cat to a high flow one.

Most shops will do this for free. They drill a hole into the pipe before and after the cat to confirm the back pressure.

 

Ok Hydra you have to understand I had a problem with my "D" hesitating when I floored it. This modification fixed it so... It is back to where it used to be I changed My TBS because it was bad. You know the high rev prob it haswhen you usecrusie control.If you read the thread it states that every TBS ishas a diff voltage reading.Thanks for the info on the cat.[sm=icon_cheers.gif]

 

True.

Mine is set on .7 when I tested it after reading the write up a long time ago so I didn't worry about it.

It might be a good idea to have the back pressure tested just to see what it is.

But, what is the reading on WOT and does the mod reach voltage prematurely???