Hello.

Still trying to figure out what might be causing overfueling (Cinq 899); A specialist recently adviced me that it could be due to the dead catalytic converter and possibly the dirty fuel filter.

I checked lambda (works fine); changed air filter; had diagnostics for the ECU with no errors; spark plugs are ok; no dragging; no leaking; no overdrive.

And still all i'm getting is 30MPG

try good old injection cleaner with some optimax, only few ££'s

Service and a tune-up may be in order also, i know youve mentioned to have done some things but the others may be necessary.

Also, are you a fast driver? having your foot planted will do yourself no favours either

HTH

how did you check the lambda?

uno_94 said:

try good old injection cleaner with some optimax, only few ££'s

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Injection cleaner by mixing a substance into the fuel? what is optimax?

AppleSei said:

Service and a tune-up may be in order also, i know youve mentioned to have done some things but the others may be necessary.

Also, are you a fast driver? having your foot planted will do yourself no favours either

Click to expand...

What exactly do you mean by service and a tune-up and what other might be necessary?

I am trying to drive wisely with no sudden acceleration/stops.

philbo said:

how did you check the lambda?

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First, I let an electrician check it with an oscilloscope and it gave a frequent fluctuating output, and then the ECU has no errors accumulated (which probably means the lambda is good).

nomatter said:

What exactly do you mean by service and a tune-up and what other might be necessary?

I am trying to drive wisely with no sudden acceleration/stops.

Click to expand...

Just a general service, oil filter, air filter (although you have done this) plugs etc

change the lambda anyway

philbo said:

change the lambda anyway

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What about the Catalytic Converter? Could it be jammed (or dead otherwise) and causing exhaust gases not to pass through the pipe freely leading to deterriorated performance and increased fuel consumption?

The guy offered me to take out the guts from the Catalytic Converter; he said as it does not function, it does no good anyway to the environment and letting gases out without having to pass through it will increase both performance and mileage.


Also, does it matter whether the Fuel Filter is jammed or not?

Please, tell me, how much do the mentioned two components matter for the consumption and performance.

when cats fail they usually just melt and youll notice the loss of power before increased fuel consumption. if you want you can smash the inards out of the cat as its only ceramic honeycomb. you will need to replace it before next mot otherwise itll fail. the fuel filter could be blocked and they are only 10-15 quid so change it anyway. a new lambda sensor is around 40-50 quid for a non genuine cinq specific one and is well worth it. dont go for the universal ones!

uno_94 said:

try good old injection cleaner with some optimax, only few ££'s

Click to expand...

By injection cleaner do you mean mixing some substance into the fuel? what is optimax?

philbo said:

when cats fail they usually just melt and youll notice the loss of power before increased fuel consumption. if you want you can smash the inards out of the cat as its only ceramic honeycomb. you will need to replace it before next mot otherwise itll fail. the fuel filter could be blocked and they are only 10-15 quid so change it anyway. a new lambda sensor is around 40-50 quid for a non genuine cinq specific one and is well worth it. dont go for the universal ones!

Click to expand...

OK, I will take out the inside of the cat and clean the fuel filter (they say it's possible to clean it).
Also, I am planning to change oil. Should I put semi-synthetic oil and expect any betterment?
I will also try to fit another lambda and see if it helps.

I will let you know what happens.

Thanks for helping.

injector cleaner is an additive you chuck in with a full tank of fuel. optimax is expensive fuel from shell garages.
fuel filters cant be cleaned out! buy a new one to replace it. not sure about oils as i use wilkinsons £2.50 stuff cos my engine drinks the stuff. or did before i blew it up. search the forum for info on oils. its been talked about a lot. best thing you do for your engine is change the oil regularly.

You won't always fail without a cat.. You're allowed upto 3.00 on CO emissions and a 2l tipo without cat will be somewhere around 3.05 - cinq should be a less poluting engine. See if you can get an MOT guy to do a quick emision check before you decide to buy another cat.

After reading some posts about oils I'll probably go for Castrol Magnatec 10W-40 or 15W-40; I hope it to be the right choice.

Thanks.

go for 15w-40