Mechanic recommendations

[Ashton1911]

I have a grand marquis that had clogged cats and needed them removed. I welded in a muffler in its place to keep it quieter, but now I have a constant check engine light for the O2 sensor. Does anyone know a mechanic in the north Indianapolis area who they could recommend? Looking for an honest guy who does good work?

 

[phylodog]

We've had good service and experiences with Esler's in Westfield. They're one minute off of 31 so it's an easy drive from north Indy. Honest people and good service in our experience (my father just had a bunch of work done to his Jeep and was very pleased).

 

[Mr. Habib]

You do know that not having a catalytic converter is probably causing your O2 code right?

 

[indyblue]

You do know that not having a catalytic converter is probably causing your O2 code right?

Yup!
https://www.wheelsjoint.com/mercury-grand-marquis-bad-o2-sensor-symptoms-causes-and-diagnosis/

The downstream O2 sensor in Grand Marquis is located further down the exhaust system, after the catalytic converter, and is responsible for measuring the level of pollutants passing through the catalytic converter. The main purpose of downstream O2 sensor is to ensure that the catalytic converter is functioning properly. If this sensor goes bad, it does not have any affect on the engine performance, but the check engine light may illuminate and you may see error codes related to catalyst efficiency.

 

[Frosty]

What you need are some non-foulers to replace your O2 sensor bung.

https://www.355nation.net/threads/how-to-install-an-o2-sensor-non-fouler-to-eliminate-a-check-engine-light-with-pics.401/

Not for your specific vehicle at all but it will give you the gist of what I’m talking about. If you’re going to take it to a mechanic they have to replace the cats.

 

[Creedmoor]

Drill a hole in the dash right through the check engine light.

 

[thunderchicken]

Any honest shop will be required by federal law to simply replace the catalytic converters. A shop cannot legally bypass a catalytic converter on anything newer than 1979.

When people remove the catalytic converter, it causes oxygen sensor codes because it should be monitoring the exhaust before the converter and after the converter (upstream & downstream) so the computer can determine fuel needs. Removing the converter can cause the downstream oxygen sensors to read as rich. The computer sees this and actually dumps less fuel into the engine, thus actually creating an overly lean condition. Lean conditions can cause burnt pistons and valves. The oxygen sensor data is also used by the computer to determine catalyst efficiency.
Most likely you check engine light codes are P0420 bank 1 cat efficiency below threshold, P0430 bank 2 cat efficiency below threshold, bank 1 & bank 2 downstream (aka sensor 2) stuck rich.


Not bragging or beating my chest here, this comes from more than 20 yrs experience as an ASE certified technician

 

[wingrider1800]

Any honest shop will be required by federal law to simply replace the catalytic converters. A shop cannot legally bypass a catalytic converter on anything newer than 1979.

When people remove the catalytic converter, it causes oxygen sensor codes because it should be monitoring the exhaust before the converter and after the converter (upstream & downstream) so the computer can determine fuel needs. Removing the converter will cause the downstream oxygen sensors to read as rich. The computer sees this and actually dumps less fuel into the engine, thus actually creating an overly lean condition. Lean conditions can cause burnt pistons and valves. The oxygen sensor data is also used by the computer to determine catalyst efficiency.
Most likely you check engine light codes are P0420 bank 1 cat efficiency below threshold, P0430 bank 2 cat efficiency below threshold, bank 1 & bank 2 downstream (aka sensor 2) stuck rich.


Not bragging or beating my chest here, this comes from more than 20 yrs experience as an ASE certified technician

But welding in bungs and adding anti-foulers under the rear sensors will keep the light out.

 

[d.kaufman]

Not bragging or beating my chest here

 

[thunderchicken]

But welding in bungs and adding anti-foulers under the rear sensors will keep the light out.

Yes but an honest shop cannot install them as a means to bypass a catalytic converter. That violates Federal law

 

[thunderchicken]

View attachment 212691

Well played sir well played

 

[edporch]

In doing a quick search of how they work, it appears an oxygen sensor puts out a small varying DC voltage depending on the exhaust.
Maybe one could "fool" the system by feeding the voltage that represents the ideal exhaust into it?

 

[WebSnyper]

No idea on this specific brand, or about your specific vehicle, but I believe folks use O2 sensor spacers for just such a situation:

Oxygen Sensor Spacers & Isolators

 

[thunderchicken]

In doing a quick search of how they work, it appears an oxygen sensor puts out a small varying DC voltage depending on the exhaust.
Maybe one could "fool" the system by feeding the voltage that represents the ideal exhaust into it?

Actually the computer (PCM) adjusts voltage based on data the sensor sends back to the PCM. The only thing an oxygen sensor does is read oxygen content and reports it back to the pcm.

 

[churchmouse]

In doing a quick search of how they work, it appears an oxygen sensor puts out a small varying DC voltage depending on the exhaust.
Maybe one could "fool" the system by feeding the voltage that represents the ideal exhaust into it?

It’s a variable consistency with TPS and engine speed.
Way to hard.
My sister had fouled cats on her Camaro from cheap fuel and a bad tune up. I took the car out for a blast with some good pump fuel in it and stood on it.
1 of 2 things was gonna happen. The cats would burn off clean or the car would burn to the ground.
They cleaned up but it took. Multiple trips up and down the interstate.

 

[wingrider1800]

Yes but an honest shop cannot install them as a means to bypass a catalytic converter. That violates Federal law

Right. It's not even legal to remove the exhaust in order to do other work without installing converters if they have been removed. I hear all the time that since we no longer have emission testing that the converters car be removed. As Waylon says "wrong"

 

[bwframe]

Is Car Talk still on the air?

Those boys taught us how to fix those idiot lights with black electrical tape a long time ago.


.

 

[rem788]

What is it you want the shop to do? As others have stated a shop must replace the converters as this is the only legal repair they can perform. If you want then to turn the CEL light off, they can clear codes and the light will go off until the catalytic converter test is performed and the light will be turned on again. Installing spacers or whatever to alter the sensor signal seems iffy at best to me. You don't give the vehicle year but OBD II vehicles (after 1996) are technically sophisticated and difficult to fool. I agree with thunderchicken, there may be unintended consequences related to altering the signals to the engine computer not limited to just drivability/fuel economy problems. Also, I was never a fan of the black tape CEL resolution solution, much better to block the light with a picture of your girl friend.

 

[awames76]

if the cats are removed the downstream o2 [rear o2] are telling u the cats are not working. 2 cheep options. one i have used sparkplug non foulers and have worked. drill out the end and put the o2 inplace of the sparkplug in it then put the non fouler in the exhaust and it takes the o2 out of the exhaust and tricks it. works most of the time. option 2 not tryed but should work is buy new o2 sensors and plug in to plug and zip tie under body some where leaving sensor in the air. leaving old sensor in the exhaust but not electric pluged in.

dont know if this is the right one to fit your sensor

Dorman 42009 Spark Plug Non-Foulers - 18mm Gasket Seat NEW | eBay

Dorman 42009 Spark Plug Non-Fouler. Spark Plug Seat Style: Gasket. Spark Plug Seat Type: Gasket. All our Non-Foulers are constructed of high-quality steel for long-lasting durability. Spark Plug Non-Fouler.

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