Ford Focus ST Forum banner
1 - 20 of 31 Posts

·
Registered
Joined
·
40 Posts
Discussion Starter · #1 ·
I've been having this problem for a while now & it's doing my head in. About two months ago my car went into limp mode & was showing faults that where all pointing to the sensors & was saying the system was too rich at idle so I replaced the maf sensor, turbo solenoid & the map sensor which seemed to have cured it for abit but then the problem came up again so I replaced the knock sensors & same again was ok for a while until this morning when it went into limp mode & was pointing at one of the sensors & saying the system was too rich at idle. Has anyone got any ideas as to what this might be? I've checked all pipes for leaks etc & everything seems fine. Any comments will be appreciated.
 

·
Registered
Joined
·
10,290 Posts
Is it possibly the sensor is faulty and is telling you porkies?

Is it the front lambda sensor that controls all that?
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #3 ·
Is it possibly the sensor is faulty and is telling you porkies?

Is it the front lambda sensor that controls all that?
I hope not I bought the pack of 3 off dream science so I would imagine they would be ok. I think it's the maf sensor that controls it. I've replaced all three which are about 4 weeks old.
 

·
Registered
Joined
·
10,290 Posts
I hope not I bought the pack of 3 off dream science so I would imagine they would be ok. I think it's the maf sensor that controls it. I've replaced all three which are about 4 weeks old.
The MAF sensor tells the ECU how much air is going in so it know how much fuel to put in.

But the lambda sensor will tell the ECU if that mix is right, and whether it still needs to adjust.

I think that's right in lamens terms...
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #5 ·
The MAF sensor tells the ECU how much air is going in so it know how much fuel to put in.

But the lambda sensor will tell the ECU if that mix is right, and whether it still needs to adjust.

I think that's right in lamens terms...
Do you know where the lambda sensor is at all?
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #10 ·
Gna have to get it in the air tomorrow then & check them out not gna b a cheap job lol deffinently can't be a boost leak if checked & double checked for boost leaks & all seems fine
 

·
Registered
Joined
·
10,290 Posts
Downpipe is the one you want to be looking at.
The one in the cat does nothing fuel wise. Only to check emissions.
 

·
Registered
Joined
·
253 Posts
It will highly likely be the sensor in the down pipe that one controls the mixture the rear just fine tunes it and measures if the cat is working or not, cheapest way to find out for sure is get the exhaust gasses measured at a garage first that will tell you pretty much how the engine is running before you spend obscene amounts chasing the issue
 

·
Registered
Joined
·
115 Posts
Thought it took reading front and rear then adjusted the mixture for emissions that's how they work on the volvo T5
 

·
Registered
Joined
·
2,952 Posts
it may look ok but you need a smoke test to check for boost leaks.
thought mine was ok but had a leak at the IC outlet.
 

·
Registered
Joined
·
40 Posts
Discussion Starter · #20 ·
I can't really remember what codes I'm getting I just remember it says mass or volume a circuit & then another saying system too rich at idle had those up a few times now then they disappear every time I try & solve it then pops back up again. The lambda sensor sounds promising though but so did the knock sensors but that obviously hasn't solved it if the problem has come back up but I will let you all know once its done thinking of just taking it to this guy near me who specialise in st's wanted to take it there anyway for a new plenum & radiator.
 
1 - 20 of 31 Posts
Top