Cat Removal - CEL disabling

I don't endorse it, but the answer to your specific question is: http://www.o2simulator.com

 

You can use a spacer to pull the sensor out of the exhaust stream, usually that works. Otherwise the O2 sims work, and if you want to spend the money, get an ECU reflash.

 

Does anyone do a 355 5.2 ECU reflash?

 

Yep.

 

Where are the spacers sold? I was on a site that had those the other day but can't find it now. The spacers go in the post-cat O2 sensor holes, is that right?

 

They are just washers. They lift up the O2 sensor a bit...sometimes out of the main exhaust stream.

 

Spacers do not work. Been there......done that.

O2 sims are something I have not tried.........

Getting your ECU reflashed is the best option IMHO.

 

Yes, I understand that part about "feeding" it less sample gas. Well, the one I saw would be the equivalent of a whole bunch of washers! It would certainly be an easy install but based on Kds's post it seems they don't do the trick :-(

 

Did you have yours done? What happens when you have to have a smog test done? Will it fail or otherwise show up as having been modified?

 

We don't have smog tests where I live........and it is highly doubtful it will ever happen in my lifetime, so I cannot answer that.

Getting the ECU reflashed simply widens the parameters for the second O2 sensor, so no CEL gets turned on when the "dirtier" exhaust gas passes over it. It would fail a sniffer test though........but everything also looks stock when the exhaust system is looked at. You can buy test pipes that look like cats, so no one is the wiser. FWIW the OEM 348/355 cats take very little time to swap in your home garage, so put them on at test time, and take them off afterwards.

O2 sims would fail a sniffer test as well, as they merely trick the ECU into thinking the readings are within OEM parameters, plus you'd have all the funky non OEM wiring back there which may pose questions, depending on the regulations and diligence of your inspection station.

 

Spacers did not work for me either.

I did the po-man's fix... pulled the bulb. I kept it though, and the cats too, so that it can all go back with ease.

 

The rear O2 sensors on the 355 already have a shroud around them with just a little hole in the tip and so they behave just like the spacers and still turn on the CEL eventully.
Also, some ecu's sense the heater current draw of the sensor so maybe a resister has to be installed also. You could get a $120 code reader and just clear the code every other week.
Too bad there isn't some hardware/software out there that reflashes the Motronic...........that would be cool!

Jeff Pintler
89 348tb, 86tr

 

So what happens if there is another problem that would trigger a CEL light? How will you know?

 

which one to get for the 360?!

 

I just had test pipes installed and the guy put the spacers on the front o2 sensors. That works in that I no longer get codes 0422 and 0432, but I do get a pending code P1126 (LTFT bank2).

Could this long term fuel trim error on bank 2 (lean error) be caused by the FRONT o2s being spaced from the exhaust stream? Should I install the front o2s normally? Who does reflashing on the 5.2s?

Thanks,

Nick

 

Nick,

The front o2's are the only ones used in closed loop. The rears are only used to test catalyst efficiency.

I would not space out the front o2's, you want them to be in the direct path of the exhaust.

 

http://www.s2ki.com/forums/index.php?showtopic=229959

A simple spacer solution to the O2 sensor dilemma. I used 2 of these antifoulers per post-cat sensor (4 pcs. total), so it is really out of the exhaust stream. Do not place a spacer(s) at the pre-cat sensor!

I would still get a CEL occasionally, but it is seldom enough not to be a nuisance. I check and erase the code then with an OBDII checker, simple. I swap out the pipes with cats every other year for the smog check. A very reversible mod/workaround, and you get to keep the CE lightbulb.

All in all, works for me, but then again YMMV. For off road use only ;-). HTH.

Cheers

 

Hey.

I think now maybe no spacer was added to my primary o2s. I'm looking online at the Larini test that are on my car and it looks as if the primary o2 bungs are made taller than usual.

Look at this and tell me what you think:



See the taller, angled o2 bungs? One thing is for sure, I don't get codes p0422 and p0432 anymore (where I did with the Hyperflow cats). Perhaps my p1126 is another issue related to the engine-out service I just had performed (bank2 intake air leak, etc.)

By the way... when standing at the back of the car, which side is bank2? The right side?

--Nick

 

hmmmm.... I've never seen an o2 sensor angled downwards like that (not that I've seen that many o2 sensors). My understanding is they should always be at a right angle or angled upward so condensation does not collect at the sensor tip or "help" corrode the sensor threads.

 

You're speaking of the Larini test pipe pick that I posted, right? I really think this is a method used to eliminate the secondary o2 errors. I still have no catalyst below threshold errors.

--Nick

 

Is there anyone with experience with cat removal on a 95 with 2.7 ecu. Are the issues the same? Does anyone else know of issues that I should be aware of that are different than that discussed above?

 

My car is a 2.7 and I have removed the cats, no codes, no lights, no problems. Very simple conversion.

 

I just pull the codes periodically to be sure nothing else has tripped. And I pay very close attention to the way the car is running. Not as good as the immediate feedback on the CEL but like I said it's the low-brow way to go.

Personally I think not having the cats provides more benefit than not having the CEL.