New Lambda Sensors or a Fuel Controller?

[pedrosixfour]

Hi folks.

 

Brought the NA for it's first dyno run on Saturday.

 

Seeing as I know y'all are chomping at the bit to know how it got on here goes,

 

187 manic ponies and 165 lb/ft

 

The thing is the tester reckons the car is running quite rich and suggested a fuel controller to eliminate the problem. I do realise that resolving this problem is not going to unleash Armaggeddon however I do like things to be at their optimum so this is bugging me.

 

This guy would be fairly respected in his field and any suggestion he would make would be based on years of experience.

 

He never mentioned anything about replacing the lambda sensors to me, which he did to another owner when fuelling issues were found on his motor. This would lead me to believe the the sensors are not the issue on my chariot or at least not totally.

 

So with all that being said does anyone have any knowledge that they would like to share.

 

If I bought a controller and the sensors did in fact turn out to be knackered is it possible that the controller could be used instead to manage whatever area they would usually cover?

 

Thanks for your time,

Damien.

[pedrosixfour]

Do I ask too much??

[Steve]

Its been 4 hours..........

 

Give it time

[Tricky-Ricky]

New lambda sensors defiantly, you would be wasting your money by buying an adjustable FPR, i doubt the std one is bad, but if it did turn out to be, replace with the std item.

IMO i would not trust a tuner if he suggested using FPR to cure something that was caused by something else:taped:

 

Does he have any proof that the FPR is faulty? IE conducted a test?

 

Apart from whats mentioned already over rich fuelling can be caused by, IAT sensor, MFA as well.

Edited March 1, 2010 by Tricky-Ricky (see edit history)

[pedrosixfour]

I get what your saying Tricky and its obvious that the sensors should be changed before anything else is even considered.

 

But just in case it makes even the slightest difference to what you just said I believe he was referring to something like an Apex'i SAFC and not a fuel pressure regulator.

 

Someone please tell me these are two completely different items so I don't look like a complete spanner!

 

It goes without saying that I bow to your superior knowledge so don't take this as a cheeky retort!

Edited March 1, 2010 by pedrosixfour (see edit history)

[RobSheffield]

Id say replace with oem lambda sensors if i was you. They do go off after time. Make sure its fully serviced and has new plugs, decent leads etc. I would have hoped you would have serviced it pre dyno anyway, but if not, do so

[pedrosixfour]

All serviced prior to the abuse Rob, whatcha take me for??

 

The car is running like a clock, a piece of piss to start, steady revs until warm and then dies down to it's usual burble, no evidence that anything is amiss.

 

Are lambda sensors not in the equation for only a portion of the rev range, ie, tickover and low revs and then on full throttle a different system is used?

 

This problems seems to be across the entire range and like I said he very quickly diagnosed the lambda sensor to be a possible culprit on a different car running a bit lumpy but never even mentioned them when I ask about a remedy for mine.

 

I'm not trying to cut corners here lads, I'll probably end up buying both remedies because of possible future upgrades anyway.

[pedrosixfour]

Here is pics of the dyno printout should anyone care to comment on the readings.

 

 

[Tricky-Ricky]

Looking at your lambda/O2 on the chart, i can see why he made a comment, it starts off in the 10s and drops to 8.0:blink:

lets hope his lambda is correct and calibrated properly.

 

But it does look to me like it could be a fuel pressure problem as it increases with the lack of vacuum, i would try another std FPR rather than add an adjustable unit.

 

I'm not 100% sure on when the N/A ECU goes open loop, IE no lambda feedback, ECU map only, but you shouldn't need to fix it with an AFC either.

Edited March 1, 2010 by Tricky-Ricky (see edit history)

[pedrosixfour]

He is one of the top tuner/mappers in the country, built or mapped the engines in the top 3 finishers in the 2009 Irish Time Attack series in which all 3 cars competed in every round, if his shit ain't together then there ain't much point looking elsewhere!

 

So if the fuel pressure drops the engine gets more fuel?

 

Is there a procedure to check the fuel pressure?

 

And what should the ideal reading be for the lambda value in a non turbo?

Edited March 1, 2010 by pedrosixfour (see edit history)

[Tricky-Ricky]

He is one of the top tuner/mappers in the country, built or mapped the engines in the top 3 finishers in the 2009 Irish Time Attack series in which all 3 cars competed in every round, if his shit ain't together then there ain't much point looking elsewhere!

 

So if the fuel pressure drops the engine gets more fuel? Sorry my mistake meant to say increases, i have corrected the above post now doh!

 

Is there a procedure to check the fuel pressure? You will need a coupling to T off the fuel supply to the fuel rail and a pressure gauge, i would need to look at the manual for the N/A pressure.

 

And what should the ideal reading be for the lambda value in a non turbo?

 

N/A engines generally make the best power at between 12.2 and 12.8 AFR however i am not sure what the N/A ECU open loop map is set for.

[pedrosixfour]

Thanks Ricky, I really appreciate all the help and guidance.

 

I found a bit of info on checking voltages at the diag. plug to guage whether the engine is indeed running too rich. I'll throw a meter onto it tomorrow and go from there I guess.

 

Thanks again folks.

 

But don't wander off too far, I may need further assistance!

[pedrosixfour]

Hey folks,

 

Looking for some info on the item circled in red.

 

What purpose does this vacuum controlled valve on the intake manifold serve?

 

 

Thanks,

Damien.

[pedrosixfour]

I've just discovered what this valve does, its the ACIS valve which alters the volume of the intake runners.

 

The vacuum pipe which controls this valve was split, meaning that the valve did not operate at all regardless of engine speed. Could this have been responsible for the poor lambda reading?

 

Also I tried to take the voltage reading which indicates whether the engine is running lean or rich as described in this write-up:

 

http://www.mkivsupra.net/vbb/showthread.php?t=35940

 

I got no reading on the meter and all that happened was that the engine began to idle badly if I kept the probes in place. Is there a different procedure for a NA?

 

And finally!!

 

Is there someway of stabilising the idle speed in order to take a proper ignition timing reading? When I put the light on it the timing mark jumps around constantly probably by up to 3 degrees or so.

 

Any help on this latest batch of crap would be greatly appreciated as always.

 

Thanks,

Damien.

[pedrosixfour]

Ok, found the proper procedure for checking the ignition timing.

 

 

Also found this for checking the lambda reading:

 

 

Would I be correct in thinking that one side of the meter still goes to battery negative and the other probe reads the value from one of these terminals?

 

I'm trying desperately not to blow any circuits so can anyone verify this for me?

 

Thanks.

Edited March 3, 2010 by pedrosixfour (see edit history)

[Ryan.G]

Looking at your lambda/O2 on the chart, i can see why he made a comment, it starts off in the 10s and drops to 8.0:blink:

lets hope his lambda is correct and calibrated properly.

 

But it does look to me like it could be a fuel pressure problem as it increases with the lack of vacuum, i would try another std FPR rather than add an adjustable unit.

 

I'm not 100% sure on when the N/A ECU goes open loop, IE no lambda feedback, ECU map only, but you shouldn't need to fix it with an AFC either.

 

Its reading in lambda not Afr

 

Starts of at 1.0 which is 14.7:1 and then drops to around 0.8 which is around 12.3:1

 

Looks fine to me fueling wise.

 

Check the base timing with a timing light as the dizzy might have moved and its retarded or over advanced

 

Ryan

[pedrosixfour]

Thanks for the input Ryan, I've been racking my brain trying to decipher the relationship between the lambda reading and an actual air/fuel ratio but it was beyond me.

 

Whats the formula to arrive at those figures for the ratio?

 

I can't for the life of me get a reading across OX1, or OX2 for that matter, in the diagnostic port which might have helped with remedying potential problems.

 

But seeing as you appear confident that the ratio is within normal parameters coupled with the fact that the ACIS valve was non functioning when the car was dyno'd I'm going to play it safe (cheap:)) until I can get it on the dyno again.

 

Hopefully with the valve back on line and with the new final drive installed we might shake a few more scabby nags out of the lump and get them to the rear tyres.

 

I set the ignition timing last night. I was going to go for stock but thought with the few breathing mods I have fitted and the engine speed usually living in the top third of the rev range a couple of extra degrees advance wouldn't go amiss. So its now set at 12-13 degrees. Running on E5 fuel, supposedly 98-99 octane.

 

Is this a fair assumption to make or am I just making shit up to suit as I go along??

 

Thanks,

Damien.

[Tricky-Ricky]

Its reading in lambda not Afr

 

Starts of at 1.0 which is 14.7:1 and then drops to around 0.8 which is around 12.3:1

 

Looks fine to me fueling wise.

 

Check the base timing with a timing light as the dizzy might have moved and its retarded or over advanced

 

Ryan

 

DOH!

 

I should look more closely at the chart, however wouldn't a decent RR use a wideband that measured in 0 to 5v and not 0-1V? still seems strange to me as normally 0-1 would indicate narrow band?? in which case 0 does not indicate 14.7AFR?

[pedrosixfour]

Maybe he has both?

 

A wideband for the turbo fraternity and narrow band for us mere mortals?

 

Jesus, I'm lost.

 

I'm still sticking to the theory that the valve was the problem!

 

Or at least until you pair can agree on something!

[Tricky-Ricky]

Maybe he has both?

 

A wideband for the turbo fraternity and narrow band for us mere mortals?

 

Jesus, I'm lost.

 

I'm still sticking to the theory that the valve was the problem!

 

Or at least until you pair can agree on something!

 

My apologies, for being unintentionally misleading, as i had genuinely failed to take notice that the RR scale was in lambda v and not AFR, however i am still confuesed as to how a wideband can be scaled as 0-1v?

 

But Ryan is far less likely to make a cock up than me concerning this sort of thing, as its his job;)

 

Which also brings the point, why did your RR tuning fella say it was too rich:search:

[pedrosixfour]

This is the actual dyno the car was on, I just thought it might be of some help in figuring all this out.

 

Thats if you haven't given up on such a pointless exercise.

 

Power from a NA........., what madness is this????

 

http://www.westwardeng.com/4wddyno.htm

[Ian C]

My apologies, for being unintentionally misleading, as i had genuinely failed to take notice that the RR scale was in lambda v and not AFR, however i am still confuesed as to how a wideband can be scaled as 0-1v?

 

But Ryan is far less likely to make a cock up than me concerning this sort of thing, as its his job;)

 

Which also brings the point, why did your RR tuning fella say it was too rich:search:

 

It's not scaled 0 to 1v my dear chap, lambda is measured as a ratio. Lambda is the stoichiometric mix, i.e. "ideal" and for gasoline, as you know, that's 14.7:1. So 0.8 lambda = 0.8*14.7 = 11.8 (not 12.3 Ryan )

 

That graph goes to 0.78 lambda = 11.5:1 afr which is good for a turbo but I'd say it is too rich for an NA engine. It should be more like 0.85.

 

There is a conversion table in this PDF, second page:

http://www.mrtrally.com.au/performance/docs/Lambda%20Brochure.pdf

 

-Ian

[Tricky-Ricky]

It's not scaled 0 to 1v my dear chap, lambda is measured as a ratio. Lambda is the stoichiometric mix, i.e. "ideal" and for gasoline, as you know, that's 14.7:1. So 0.8 lambda = 0.8*14.7 = 11.8 (not 12.3 Ryan )

 

That graph goes to 0.78 lambda = 11.5:1 afr which is good for a turbo but I'd say it is too rich for an NA engine. It should be more like 0.85.

 

There is a conversion table in this PDF, second page:

http://www.mrtrally.com.au/performance/docs/Lambda%20Brochure.pdf

 

-Ian

 

Yes it is a scale, but it is derived form a generated voltage, and therefore has to be scaled from that generated voltage of the oxygen sensor, whether its a narrow band or a wide band, the scale is still has to be decoded from a generated voltage or the whole thing doesn't work.

 

Unless of course its a Titania Oxygen Sensor which is scaled from a changing resistance.

[Wez]

Yes it is a scale, but it is derived form a generated voltage, and therefore has to be scaled from that generated voltage of the oxygen sensor, whether its a narrow band or a wide band, the scale is still has to be decoded from a generated voltage or the whole thing doesn't work.

 

You are correct but the voltage is not being displayed only Lambda, it would be wrong to assume its 0-1v which is typical of a narrowband, quite possibly more like 0-5v which is typical of most wideband sensors.

[Tricky-Ricky]

You are correct but the voltage is not being displayed only Lambda, it would be wrong to assume its 0-1v which is typical of a narrowband, quite possibly more like 0-5v which is typical of most wideband sensors.

 

Yes which is precisely why i apologised to pedrosixfour for making the cock up, which Ryan pointed out,

I'm not used to RR graphs, and was going more on the RR tuners comments about it being very rich, and so fell into the mistake of seeing the RR scale in AFR my bad!