CEL from high flow cats

Zep

Moderator
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1,708
#21
@Zep the CEL does not come on immediately it takes a few hours of driving generally motorway cruise after 2-6 hours

I see, said the blind man. You will only get a light when the ECU is working in closed loop (idle and cruise) but if the emissions are out of bounds for a long time during these conditions I can see there still being a problem. But I continue to observe with interest :)
 
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conaero

Forum Owner
Messages
27,543
#22
I used to get a CEL on my first GS with full Larini with secondary de cats now and again. Usually after a long run on the motorway when I came off and dropped onto the slow roads to home.

Just reset it TBH. Didn't do it on my second and older GS with the same system????
 
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1,094
#23
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1,094
#24
For £6 a go should be worth a try if it's an easy fit..I believe there are 4 sensors...do they all need a spacer fitted?
As I understand it it is only the 2 post cat sensors that pick up on the cat efficiency error sposo you only need 2 of them

You just need to safely jack the car up using axel stands unfasten the lambdas, fit the spacers in the lambda hole and install the lambda onto the spacer
 
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1,094
#25
@Zep the CEL does not come on immediately it takes a few hours of driving generally motorway cruise after 2-6 hours

I see, said the blind man. You will only get a light when the ECU is working in closed loop (idle and cruise) but if the emissions are out of bounds for a long time during these conditions I can see there still being a problem. But I continue to observe with interest :)
I have taken a few opinions on this profusion up in Slough after looking at the photos said that spacers might work while the specialist who looks after my car is thinking along the same lines as you and the system is a write off due to poor welding, bending, wrong spec cats etc. so I have already conceded that I will need to replace the system eventually I am just getting my monies worth out of it before I spend twice... the mini cat lambda spacers may not be worth it but at £6 for the spacers and a couple of hours on the weekend it's worth a shot
 

Zep

Moderator
Messages
1,708
#27
I have taken a few opinions on this profusion up in Slough after looking at the photos said that spacers might work while the specialist who looks after my car is thinking along the same lines as you and the system is a write off due to poor welding, bending, wrong spec cats etc. so I have already conceded that I will need to replace the system eventually I am just getting my monies worth out of it before I spend twice... the mini cat lambda spacers may not be worth it but at £6 for the spacers and a couple of hours on the weekend it's worth a shot
Totally, every day is a school day. Fingers crossed!
 
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188
#28
Or measure the resistance of the lambda sensors and use a resistor to bridge the wires from the loom. I actually used a couple of small LED on one of my American V8. Worked fine. Cost about 40p. But is only good where ECU measures Good/Bad. If it's smarter than that and measures for feedback to fuel injection then unlikely to work.

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#29
If it's smarter than that and measures for feedback to fuel injection then unlikely to work.
My understanding of it is that "closed loop" implies, that the sensors feed data in real time, to the ECU. Fueling is dependent on this data within the closed loop.
...if someone knows different ..?
 
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Messages
188
#31
Or tickover or cold start (or anything on a VW Diesel). So fully supports the drive like you robbed a bank approach. I admit that fuel injection is alot better than trying to balance 4 X SU or 3 Twin Webber's but **** engines are getting far too smart.

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Zep

Moderator
Messages
1,708
#32
Or measure the resistance of the lambda sensors and use a resistor to bridge the wires from the loom. I actually used a couple of small LED on one of my American V8. Worked fine. Cost about 40p. But is only good where ECU measures Good/Bad. If it's smarter than that and measures for feedback to fuel injection then unlikely to work.

Sent from my ONEPLUS A5010 using Tapatalk
My understanding of it is that "closed loop" implies, that the sensors feed data in real time, to the ECU. Fueling is dependent on this data within the closed loop.
...if someone knows different ..?
You are right, our lambdas are smart. The rear ones are a narrow band sensors and they provide a constantly moving signal so linking them out isn’t an option sadly.
 

dunnah01

Junior Member
Messages
536
#33
Does your code reader allow real time reading of the O2 sensors? If you can read the amps/volts of the pre/post cats on each bank this could point you in a direction either towards the sensors or elsewhere. I can let you know what my 200 cell cat values are for comparison.
The sensor replacement can be a 5 min or a days job depending on the above exhaust temp history. I'd suggest that you have one of these and an angle grinder to hand before you start any sensor removal:
https://www.ebay.co.uk/i/223145863062?chn=ps
If you need to replace the sensors then I'd also have a proper 22mm socket to hand so that you can cut the sensor and get full purchase to remove it, the open socket just slips off the sensor if they are tight. They can be on effin tight and often strip the threads of the attachment lug.
However, if you get lucky the sensor will just unscrew and bobs your aunties husband
 
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11,259
#34
I have run three 4200s with miles from 29k to 72k with zero issues with CAT degradation or break up.

I suspect it is down to damage and driving styles rather than a design flaw... after all its hardly like Maserati invented a new CAT system for their cars, it's just the same aa many others.
 

dunnah01

Junior Member
Messages
536
#36
I have run three 4200s with miles from 29k to 72k with zero issues with CAT degradation or break up.

I suspect it is down to damage and driving styles rather than a design flaw... after all its hardly like Maserati invented a new CAT system for their cars, it's just the same aa many others.

This was my Maserati design masterpiece!
Luckily endoscope shows no damage done to engine and proved a good opportunity to go for 200 cell stainless cats - every cloud 'n' all that
 

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188
#37
I have run three 4200s with miles from 29k to 72k with zero issues with CAT degradation or break up.

I suspect it is down to damage and driving styles rather than a design flaw... after all its hardly like Maserati invented a new CAT system for their cars, it's just the same aa many others.
If a CAT breaks up before the warranty expires it is a fault, even poor/faulty design.
If on the other hand it satisfies the term of the warranty in either miles or months then it has performed exactly as required to meet minimum requirements.
Anything after that is a bonus.
Get old cats too hot and give them a good knock whilst they are hot will do it.
I think aound 10 years is about right for moderately abused Cats. Anything else is a bonus.

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