I've been stuggling to get my lambda link to work properly for a while now and need a bit of help. I've wired the thing so many different ways and it seems to make no difference. I've now wired it as recommended by Bob Rawle.... signal from the ecu, signal ground to the ecu chassis bolt (which has a seperate wire from this to the batery -ve as part of my earthing mod), display +ve from the ecu battery feed and the display ground to the ecu chassis bolt. I've also changed the lambda sensor for a second-hand one and have now changed it for a brand new one.... again this didn't do anything. The ecu was rest between each change of the wiring or sensor too.

Basically what happens is that while driving around town it shows full rich unless it is on overrun in which case it goes lean (off the display). It also does this while idling... blip the throttle and it goes off the scale then back to full rich. On the odd occasion it will 'rock' about the display as it should do. On the motorway it sometimes sticks on full rich but it seems to 'rock' about and behave itself more often. When it is actually doing the disco show if you put some load on to it (1-2 psi boost) it goes into the orange... bit more boost into the green and WOT full rich. So it seems that it does work ok..... at times . I've tested the voltages at the sensor and they are what the lambda link is displaying so im confident that it's wired correctly. One weird thing is that when the ignition is on (engine not running) it shows rich on the display .... looking at the diagnostic manual for the pre97 cars when the ignition is on the voltage should be 0.6 volts... mine seems to be 0.8 volts????? This was measured at the ecu and at the sensor too???? The heater circuit has been tested and it's getting the correct voltage so that's not a problem.

Im just a bit confused at the moment and getting a bit pissed off with it to be honest..... any help would be much appreciated.

Tony.

 

Tony,

You seem to be assuming that the Lambda Link is faulty, even though you say it appears to be reading the voltages correctly.

Maybe, it's just showing you what the ECU is doing with your fuelling. Could be time for a re-map !

Mark.

 

Mark.... why would it be fueling it at full rich at idle and cruise tho. I thought the Jecs was supposed to constantly 'rock' the fueling around the ratio of 14.7 : 1 . The full rich while the ignition is on is also puzzling..... it's not supposed to do this is it?

Tony.

 

Hi Tone,

Try wrapping your downpipe mate.

Sound to me like you might not be giving the lambda sensor time to warm up. It needs to be pretty warm before it gives anything like sensible readings. I found that after wrapping the downpipe, the time taken for the lambdalink to read properly was reduced significantly.

Just pootling round town, the sensor will take a while to get hot. that may be why it is reading ok on the motorway.

That's my ideas anyway.

Cheers

Rich

 

it's what I would expect to happen also.

do you happen to have fitted an uprated fuel pump?

Paul

 

John.... what sort of fault do you think would cause that?

Tony.

 

Maybe an uprated fuel pump overloading a stock fuel pressure regulator? Hence pavlo's question.

 

Ooops forgot to answer that question..... still stock fuel pump and regulator so that shouldn't be an issue.

Tony.

 

Something that would make it run uncontrollably rich on low loads so it can't be pulled down.

Coolant temperature sensor? (don't know what they default to if failed on your model?)
MAF, TPS misreads?
Excessive fuel pressure?
Pressure sources switching solenoid leak??

On vaccum, a leak should make it leaner not richer, but on boost it would make it richer.

Leaky recirc DV?

Some funny interplay between ISCV and a leak?

Struggling a bit, but your description is not normal behaviour.

 

Tony

Had a silmilar problem on my STI 3, initially I had the power coming from one of the injectors (i think) I thought it was the ignition feed to the ecu, Bob Rawle changed that but the problem was still there, he diagnosed it as a dry solder joint in the end after checking the lambda volatages either side of where I had splices into the loom.

Maybe of some help

Paul

 

Paul....where was the dry joint? Where you had soldered the lambda signal to the signal feed to the ecu?

John.... one thing that it might be is the coolant temp sensor. I say this because sometimes the fans switch on but do not switch off (these are control by the ecu from the temp sensor signal aren't they?). However i did have a lap top connected to the ecu and the temp signal was normal (fans coming on and off as they should at the correct temps) but the lambdalink was still showing rich.... it did start off ok rocking about and then stuck. This was all why the car was sat idling. It didn't move an inch .

Tony.

 

P.s thanks for the help so far guys.

Tony.

 

Tony

Yes about 4" back from the plug, just a thought

Paul

 

Paul.... when i had the voltmeter on there it seems that the voltages were ok either side. I'll double check tho.

Thanks,

Tony.

 

My Link reads the same, Bob has told me it is due to a weak earth and has recommended I do the earthing modification!! I am having some new Bosch coils fitted next week and at the same time I'm going to have my engine re-earthed and also the Link ecu earthed.

My Lambda link is behaving exactly as you describe so you could have the same problem!!

I have loads of jpegs on how to earth etc mail me if you want them!

Good Luck

Dom.

 

Dom.... i've already done the earthing mod. A six point one. I do however have the link manual and it says you should rewire the earths going to the ecu. Put two new wires from the engine block to the ecu, the two wires then split into four connections to the ecu. If you have any info on this bit i'd appreciate it if you could e-mail me that.

Cheers,

Tony.

 

Got the e-mail Dom. Cheers .

Tony.

 

Bit of an update:

After getting my car back from the garage (having new cambelt and oil seals) the lambdalink has been working fine. They did say they changed the PCV (forgot to ask why... doh).... would a faulty one have caused the constant rich scenario?

Tony.

 

Tony,

Just got back from 2 weeks in rainy Spain, my car has had the earthing mod and the bosch coils fitted and guess what...the gauge is still stuck on Rich mixture on tick over!?!?!?!

I haven't done the ECU earthing mod. as my car is going to Branko's and Bob's to have the waterspray module fitted in a couple of weeks so I'll hopefully get them to have another look!

What did the garage change on your car??

On the plus side the coils have cured the hesitation at low rev's and I'm hitting 1 bar of boost well before 3000rpm....very nice!!

Cheers
Dom.

 

The garage changed the purge control valve (PCV). It's basically part of the breather system and operates depending whether you are on boost or vacuum. Im assuming it was this as the lambdalink has been behaving correctly ever since. It went in for a cambelt and basically all the oil seals doing..... so don't think it's those. The valve was about £3.50 or something.... i'll check on that. The car's going back in on Thursday to have the engine checked over to make sure the new oil seals are all fine. I'll ask about the pCV then and let you know.

Interestingly the car use to sometimes limit the boost to 0.6bar (limp home mode) but hasn't done that since.... no CEL either. Maybe the PCV had something to do with that??????

Tony.

 

The ECU is unable to go into closed loop in idle and some cruise situations on your individual car because of a fault IMHO. A healthy car will go into closed loop within a few minutes even on a cold morning.

It is probable that if you had it on a Select Monitor and displayed air fuel correction % it would go to -25% and then go back to zero and stay there. It can't pull the mixture down far enough to get it to stoich so it gives up on that occasion.

[Edited by john banks - 5/6/2003 8:52:28 AM]