Lambda problem

[simonman]

i had a problem with my fd since i bought it about a month ago..at idle it was very lumpy, and sometimes it would want to stall. i thought it was the plugs so i changed them all. the problem persisted, so i thought fuel filter could be blocked, and changed that. still no change. finally, i thought lambda sensor as it was running extrealy rich with black smoke to boot. after i changed the lambda, things have changed, the car pulls strong all the time and idles fine.

if someone else is having this problem, give the lambda a try as its not expensive to replace

[dubber91]

do you know WHY the car acted as it did? i would guess that it was down to open loop fuelling; essentially at idle the ECU is closed loop; this is to trim back any excessive fuelling to reduce fuel cons and hydrocarbon/CO emissions. When the sensor plays up it essentially means that the ECU reverts to registering greater CO than is actually present, thus trimming fuelling so the revs drop and it stumbles. When the engine stumbles an 'anti-stall' map is introduced where fuel is thrown in to prevent it from stalling. this would continue to happen over and over.
This applies all the way up to around 40% throttle; so generally in normal driving conditions the vehicle would be in closed loop fuelling; a malfunctioning lambda sensor would therefore produce rough running in normal driving conditions.

just my best guess!

[simonman]

****! the problem is back. i drove the car all day without a problem...then suddenly the problem came back...the idle was very low, and when i tried to accellerate hard, its very jerky, i had to let off. i must say, that the car running low on fuel when it got jerky/hesitatant. 8 hours later, the car is back to its fine self....whats going on?? i know the hesitantcy/jerkyness will return. just when? any ideas? when it goes into this funny mode, the car is normally hot, running rich, and idle is very rough. when the throttle is blipped, its very rough.

[dubber91]

right if its running rich i'd suggest its running open loop.....the lambda sensor is usually only used to trim fuelling, not increase it.
Lumpy or rough running should only be experienced through either a) lean running or b) malfunctioning spark (be it too far advanced or retarded). I am not familiar with your engine, but is it ECU controlled spark or distributer controlled? If ECU i would suggest maybe looking at the crank angle sensor or possibly the temperature probe just incase this is simulating warm-up when it is actually hot.
IS it turbo? it could also be some confusion there ECU wise.....

[bassman]

sounds like you have the same symptoms I'm having.

The last few times it has been jerky when entering the high revs and I thought it may be the spark plug because although they are brand new, the car was flooded by my paint shop a few weeks back. I haven't had a look at them yet.

[banned advertiser]

Have a look at this, there is a water temp sensor that feeds the ecu with info if buggered it assumes car is still cold so runs rich, costa about £20 for parts and takes about an hr to fit. I had very similar symp.

[dubber91]

makes sense....

[simonman]

im gonna give the water temp sensor a try. where is the sensor located?

[allstaruk]

If its the one that goes to the gauge in dash aswell then its below the oil filter and a bit of a pain to get to.

[NixRX7]

mine is playing up as well, symptoms sound identical, wheres the best place to get the lambda sensor and the water temp sensor?

I found a place online that sells the Lambda sensor, but is a 93RX a single/double or triple wire

Nick

[simonman]

i got mine from an autofactors, its just straight plug in. ones with wires are universal. one for the FD are availavle for about £40. i dunno about wather temp sensor. my water temp gauge works ok in the car, does it mean the water temp sensor is ok?

[banned advertiser]

its not the one that does the guage, dont know where it is as Rotechniks found the fault and rectified it.

[simonman]

ok been out for a drive tonight.been driving fine all night, then i parked up and spoke to a friend. as the car idled, the 'Heat' Light came on for a couple of seconds, then went off again. after about 30 seconds, the 'heat' light came on again, then went off. i noticed when the heat light comes on, idle drops a bit. when the light goes off, the idle speed goes back to normal. im sure the running rich, the poor idle, and the 'heat' light, and the hesitancy.

some questions that i dont know the answer to :
so how can i get rid of this 'heat' light?
whats the cause of heat light?
where is the cat heat sensor located?
what is this...found on a standard FD exhausthttp://photobucket.com/albums/v369/dawnbreakdealer/th_cat.jpg

thanks people

[NixRX7]

Got the Lambda ordered, just need to sort out the location of this water temp sensor, if its not the main one then i would guess its a Mazda only part.

Anyone know where it is ?


Nick

[GerbilStuntFarm]

The cat overheat sensor is located by following the wires through the bung under the drivers seat tunnel side, if you dont have a cat then solder the wires together.

If you have an apexi ecu then it will use the cat overheat lamp to report errors in either the sensors or when slipping out of the set range for 'whatever', ie. injector duty 100%.

It sounds like somethings messed up with your fuelling or ignition. What's the service dates on your plugs and leads...

[simonman]

i changed the plugs about a month ago, changed the lambda last week, changed the fuel filter last week. i dont think it will be the leads as it sometimes drives fine. i have bridged the cat heat sensor. i am thinking of trying the water temp sensor as someone mentioned it could be that. what do you think i should try?

Simon

[GerbilStuntFarm]

sorry can you clarify that you dont have an apexi ecu?

[simonman]

i dont have an apexi ecu.