I have a seriuos question about cel fixes. I need to know what people think of them. Are they bad , good. What does this actually do? Any advice. This is for the two cats in the turbo back.
Thanks in advance.

 

They are good, heh. All a celfix does it allow the ECU to see the proper voltage that simulates an existing sensor showing a reading within normal parameters.

For the cats in particular these are EGT sensors. They are to tell the ECU that exhaust temps are high enough to activate the cats. If you leave the circuit open (remove the sensor) the ECU assumes the temps are too low. You stick the resistor into the harness and the ECU signal returns to it at an expected voltage.

jason

 

Not exactly-
There are two separate issues and fixes related to modded exhausts.
The most commonly discussed is the fix for a catless downpipe. There is a rear 02 sensor located between the downpipe (2nd) cat and midpipe (3rd) cat. This sensor is used to measure the efficiency of the downpipe cat but is not aware of the midpipe cat since it's upstream of it. When the downpipe is replaced with a catless one, the catalyst efficiency test will fail and a P0420 catalyst inefficiency code will be set. The "fix" for this is installed inline with the rear 02 sensor circuit and alters the sensor readings so the ECU thinks there is still a properly functioning cat in place. This is the only fix needed for a turbo-back system since as I mentioned the third/midpipe cat is not monitored by the ECU.
As for the uppipe, replacing it with a catless one will generally not set a P0420 assuming the downpipe cat is still in place. The uppipe cat is small and is used to reduce cold-start emissions since it heats up very quickly. There is a factory EGT probe located in the uppipe that is used to monitor its temperature to warn the ECU of catalyst overheating. When a catless uppipe is installed it may or may not have the mount to reinstall the probe, but often the probe gets damaged during the install or later on due to the higher exhaust flow in the pipe, and sets a code (usually P0546, this code will also set if the sensor is left out and not reinstalled). The fix for this issue is to install a 2.2k ohm resistor in the connector in place of the probe, this will simulate an exhaust temperature in the proper range.

 

Thanks for the explanation. So is it ok to use these fixes(downpipe one especially)? Is there any possibility that by removing this o2 sensor that it will harm my engine? Give me an idea. Since i am removing this should i get ant egt gauge? If so what should it read?


Mulder, it seems to me after i read your post again that the ecu will still be able to monitor the egt with the uppipe sensor. For now i'm just doing the turbo back. The reason i'm doing the turbo back is to get the Cobb stage two. Also the sound!

thanks, any more input is welcome.

 

For the downpipe fix you don't remove the rear 02 sensor, just modify the signal to prevent the ECU from detecting the missing cat. Some people have also had success with a mechanical "fix" that consists of using spark plug anti-foul adapters to move the rear 02 away from the exhaust stream enough to make it produce normal readings.
If you install an uppipe that has a bung for the stock EGT probe (not all do) you can reinstall the probe in the new pipe. However with the cat no longer there, the probe has little use and they also are prone to failure in catless pipes. You'd be better off doing the resistor mod for the probe and plugging the hole with a bolt. If you want to monitor your EGTs with a gauge the proper procedure is to drill and tap the manifold and install the aftermarket probe there.

 

I am having my exhaust installed somewhere. Can i install the electrical cel fix after i get the car back. If the cel comes on can i reset it by removing the neg battery cable or do i need a code reader. I am also looking into the mechanical fix that is described in this forum. i spoke with the guy that is doing my exhaust and he said he would install the mechanical fix but would not do the electrical fix. He said that he does not want this kind of liability. He seems to think that either is fine though.Does anybody have any opinions as to which is better? thanks ahead. the info here is really good.

 

go to:

http://www.ponyexpressperformance.co...liminator.html

they sell the MIL (CEL) fix kits($20.95) easy install (20 minutes);
gets rid the annoying cat inefficiency cel....for good....just follow their directions...and you'll have no problems.