Exhaust Changes

[sean_co]

Good evening guys,

i have recently taken delivery of a 2010 IS-F, have posted some photos and a short intro in the new to forum section.

i have a question about the exhaust and a modification the previous owner has done. I believe the previous owner had the Catalytic convert / converters removed (not sure how many it is) and the Lexus dealership says i will get a check engine light because of this. that makes sense as there are sensors before and after the cats (if they were there still). after now going for a long drive i eventually got that check engine light, as well as a traction control light and gearbox will not select 1st even at a dead stop. can this all be because of the Cats that have been removed and should i get them reinstalled?

aside from the obvious error codes its putting out is there any damage that can be caused by them being removed? usually in the turbo cars i have owned before the cats were removed but software was done to not give errors. is there a software tweak that can be done to not monitor the sensors after the cats on this ECU?

Regards,

[is200 Newbie]

Isn't removing the cats on a petrol engine after 2003 an MOT failure?

[scudney]

Yes it is and the cats will need to be put back on before it's next mot.

[sean_co]

in South Africa we dont have those tests for emissions, unlike you guys that would need the cats to pass those test. as soon as those laws hit South Africa most of our cars would fail.

so besides the MOT tests and the error lights is there possibility of damage? and can i go to a normal exhaust place to have Cats put back in or are there specific Lexus ones that i need?

[Stuno1]

May get corrected but I'm pretty sure the American lot remove secondary cats with no issue. I believe it's the primary cats that have the sensor in.

No issues with removing the secondary cats, will free up a few ponies and will be louder. Not sure how loud though. May get noise ingress in to the car.

Stu

[sean_co]

May get corrected but I'm pretty sure the American lot remove secondary cats with no issue. I believe it's the primary cats that have the sensor in.

No issues with removing the secondary cats, will free up a few ponies and will be louder. Not sure how loud though. May get noise ingress in to the car.

Stu

it is a bit more loud then a normal one. how close is the primary cat to the header? under the car you can see the straight pipe that was made up, i guess thats the secondary cat location.

im not 100% on how the exhaust system is suppose to look on the vehicle. will probably put in on the ramps on the weekend and have a better look. does someone on this forum perhaps have a photo of how the exhaust is suppose to look with cats and O2 sensors in place?

[Stuno1]

I don't but have a clip from the 2nd cats back. I believe the primary cats are after the headers...

[Stuno1]

If you google 'Lexus isf exhaust' and select images you can see a comparison of the stock system against and aftermarket one laid out on the floor. Looks like primary cats are indeed after headers.

[sean_co]

I don't but have a clip from the 2nd cats back. I believe the primary cats are after the headers...

this look like my exhaust. i assume then that my primary cats are still in place and that i should in fact not be getting any error code on the dash?

will have a look in day light to make sure the primary ones are still there. perhaps a faulty 02 sensor then

[Stuno1]

If it's the same system they yes. It will have a 'Hayward and scott' brand on the system when you look. If it is then happy days! I was first to get the system fitted and love it. It has smaller back boxes than stock, also removes rear resonator and is a true dual system.

Stu

[sean_co]

If it's the same system they yes. It will have a 'Hayward and scott' brand on the system when you look. If it is then happy days! I was first to get the system fitted and love it. It has smaller back boxes than stock, also removes rear resonator and is a true dual system.

Stu

i will look out for that branding. im taking it to the agent for OBD scanning just to confirm the error and then going to another generic place also. just to make sure i dont get conflicting info. when its on the ramps ill take some pictures

[Peter P18]

Hi Sean.

As Stu has already mentioned, removal of the secondary cat's should NOT cause any CEL issues. The O2 sensors that monitor levels and can cause CEL's are fitted to the headers/inlet manifolds. There are 4 O2 sensors in total two upstream, two downstream of the primary cat's. The primaries are part of the inlet manifolds/headers.

Depending on the outcome of your OBD 2 scan, it may be a simple case of replacing some of the O2 sensors. You could also try an O2 conditioner from the likes of SIKKY or PPE who sell replacement headers without the primary cat's? The conditioner tricks the system into believing all is well with the signals to the O2 sensors.

A replacement exhaust from the headers back should not be causing you any issues with CEL's (Check Engine Lights).

Hopefully you get it sorted mate.

Please let us know how you get on, and what they say. :)

Cheers.

Peter

[sean_co]

so a quick update for now.

first stop was a generic car shop, they kind of do anything and everything. plugged in the diag tool and got 2 codes, i dont remember the code now but its basically the last 2 o2 sensors. both of them were not reading anything. they guy at the shop put the car on a lift, we found what they call mini cats attached to the o2 sensors. to me it looked like a short extension. the wires on the o2 sensors would up extremely tight for some reason also. for those IT guys out there it looked like an ethernet cable, that tightly twisted.

o2 sensors were re installed without the so called mini cats and apparently the back sensors are now giving a reading. possibly the lack of reading was producing the CEL? all errors have been reset and tonight i will go for a bit of a drive to test. will upload photos of the mini cats so you guys can see what they are.

and the primary cats are still original. honestly whoever did this decat did a rushed job, welding looks horrible.

[Peter P18]

Thanks for the update Sean.

Be interested to know if this is a Hayward & Scott system.

I am under the belief no one has had the secondary cats removed as part of an H&S system thus far.

I only know that as I am planning to be the first! ;)

Hopefully it's all sorted. :)

[CharlieC]

Hi Sean, I had my secondary cats removed and so far have no issues at all.

[sean_co]

Thanks for the update Sean.

Be interested to know if this is a Hayward & Scott system.

I am under the belief no one has had the secondary cats removed as part of an H&S system thus far.

I only know that as I am planning to be the first! ;)

Hopefully it's all sorted. :)

this is the typical work of a local shop here. i thought it was all neatly done but while on the lifts i could have a much better look and its just a simple cut out old part and weld in a piece of pipe. its just horrible, should have take photos for your guys but the shop guys didnt really want me in the work area as it was so didnt try push my luck with a camera in hand.

as promised, here are the photos of the "mini cats" that were removed today. and i have been on on a 30km +- drive with no error :) much happiness! drove in normal mode, pushed it a bit, then switched to S and pushed it hard for 2 gears. so it seems to be ok so far.

[Stuno1]

Thanks for the update Sean.

Be interested to know if this is a Hayward & Scott system.

I am under the belief no one has had the secondary cats removed as part of an H&S system thus far.

I only know that as I am planning to be the first! ;)

Hopefully it's all sorted. :)

This, can't be h&s as branding is clear and not sure anyone has 2nd cats removed.

Be interested to know if it is h&s.

Stu

[Peter P18]

Thanks for the update Sean.

Be interested to know if this is a Hayward & Scott system.

I am under the belief no one has had the secondary cats removed as part of an H&S system thus far.

I only know that as I am planning to be the first! ;)

Hopefully it's all sorted. :)

This, can't be h&s as branding is clear and not sure anyone has 2nd cats removed.

Be interested to know if it is h&s.

Stu

Having taken the time to find Sean's newbie post, I noticed he's based in South Africa! ;)

Very, very, unlikely this is an H&S system.

Glad to hear it's done the trick though. :)

[sean_co]

Thanks for the update Sean.

Be interested to know if this is a Hayward & Scott system.

I am under the belief no one has had the secondary cats removed as part of an H&S system thus far.

I only know that as I am planning to be the first! ;)

Hopefully it's all sorted. :)

This, can't be h&s as branding is clear and not sure anyone has 2nd cats removed.

Be interested to know if it is h&s.

Stu

Having taken the time to find Sean's newbie post, I noticed he's based in South Africa! ;)

Very, very, unlikely this is an H&S system.

Glad to hear it's done the trick though. :)

this is defiantly not H&S, there was no branding at all. this looks like the typical cheap work from a local shop somewhere here. this is also why i usually ask to go into the workshop while techs are working on my vehicles. im currently waiting for a quote on a full system, when it comes through i will check with you guys if that system / brand will be decent before spending that money.

thanks for all the replys and comments so far guys.

[Stuno1]

You won't regret it fella. Will sound lovely.

Stu

[sean_co]

Good morning guys,

i just took my car in for scheduled service and a Lexus dealership. the mechanic at the dealership is saying that because of the cats being removed then engine will be running a bit rich. i found this strange because its the first O2 sensor that determines the AFR and the firs O2 sensor and cats are still the factory ones? though i would rather run rich and use a bit more fuel then run lean and seize up an engine so to me that's not too much of an issue.

if this correct or are the fishing for more business? His proposed repair is a whole new exhaust system with cats and sensors. but since i had those "mini cats" removed i have had no errors and the car feels like its running fine, so i believe the dealership is fishing for extra work to be done

[Peter P18]

I personally think they are talking out their rears! ;)

Best bet is to get the car on a dyno. That way they can check and print out your AFR readings for you.

Given the O2 sensors are all still there and working correctly, I'd be very surprised if you're running rich mate.

The ECU on these cars recalibrates to take into account fueling, airflow etc all the time. Hence the fact the couple of attempts to remap using piggyback ECU's failed.

You could also add an AFR gauge if you're worried? Thinking of doing it for mine especially if I decide to fit a nitrous kit at some point.

I think they just want to make some money out of you.

Hope this helps. :)

[Stuno1]

What Pete said. It would also be a lot cheaper to get any number of aftermarket exhaust options or custom one than a Lexus one putting it back to stock. Lots of folk in America run no cats with no adverse issues.

Dyno the car and see what you think. Sounds like some sort of exhaust system is needed to replace the bad job currently on the car though.

Stu

[sean_co]

What Pete said. It would also be a lot cheaper to get any number of aftermarket exhaust options or custom one than a Lexus one putting it back to stock. Lots of folk in America run no cats with no adverse issues.

Dyno the car and see what you think. Sounds like some sort of exhaust system is needed to replace the bad job currently on the car though.

Stu

thanks for the reply guys. i did have a feeling they were trying to get some more money while i was there :). unlucky for them we have forums like this.

sounds like these ECU's are extremely complicated and well protected software wise.

just wanted to make sure though. i do like the dyno idea to have it logged and also to see how much power we actually loose at this altitude. we about 1700m +- from sea level here. The AFR gauge as Peter mentioned also would be nice down the line but indeed the whole exhaust system is top of my list

[sean_co]

so not have the best of luck right now with this thing. comes back from the agent and CEL turns on, i was at that point right at the other dealer that did the initial scan. turns out this error is now caused by a "crank angle sensor", they checked the O2's again and those were fine this time. they reset the code went for a short test and seemed to be ok. 40km later CEL back on. so looks like ill be back at the shop tomorrow. so annoying!

could the location of the crank angle sensor be close to where the dealer was working todo the service. perhaps it was damaged while they were busy changing oil or the filters or the plugs?

is there a way to change the title of this topic?