O2 monitor discrepancy

steptoe · Post by **steptoe** » Sat Jan 16, 2010 4:14 pm

OK. I run LPG so needed to tune/adjust mixtures to zero things in to Lamda.

I used an $1800 Vane tailpipe monitoring unit that allows on the fly monitoring.

Got it running just nicely.

Now, just fitted up a little dash unit $80 or so PEEL DP200 O2 monitor with LED readout, warmed up car and it is reading most rich and lean off towards Lamda on backing off. I suspect my O2 sensor, even though it checked out under the Vane unit. So bought a new Bosch universal single wire O2 sensor to replace it. Getting same readings as my 24 year old sensor.

I expect the Vane unit to be accurate but maybe not at the tailpipe. . This little DP200 does not need to be assembled like a Jaycar kit so I made no error in construction. It does read straight off the O2 sensor behind the turbo so getting a sniff at it before it gets a chance to alter down to the tailpipe.

Maybe why my engine man says looks like it been running too rich and buckled me heads

Gannon · Post by **Gannon** » Sat Jan 16, 2010 5:00 pm

Any measurement taken after the cat converter is gonna mess with your readings. I think when tailpipe readings are taken, they have to be compensated in some way by either adding or subtracting from the displayed readout

mattl200 · Post by **mattl200** » Sat Jan 16, 2010 7:57 pm

and a standard single wire bosch o2 sensor is only really accurate at 14.7:1 if you want accuracy look at wideband sensor kits i have an innovate lc1 guage kit more expensive but ive found it to work well reads from 7.4 to well above 20 :1 and has settings for lpg in the laptop software retail is $360 might find one cheeper on ebay

Gannon · Post by **Gannon** » Sat Jan 16, 2010 8:30 pm

You want a wideband, these JAW's are much cheaper than commercial market versions and incorporate many features 14point7.com/Widebands

The JAW 7S is a small unit that displays just wideband a/f ratio and has a narrowband simulator to keep your ECU happy

The JAW 1.041 is a larger unit that has the above features, but also has datalogging.

AlpineRaven · Post by **AlpineRaven** » Sat Jan 16, 2010 9:18 pm

Have you tried changing knock sensor?
Cheers
AP

steptoe · Post by **steptoe** » Sat Jan 16, 2010 9:41 pm

No? Not knocking. May have a play with turn off boost retard at dizzy as sometimes it can have an effect on things, gas doesn't always need retard on boost like petrol.

Gonna hook up the Vane and compare, see if i have wasted my time and money in gaining a little experience. It'll be a costly knight rider light

DP200 reads pre cat. The tuning of the cones (hard to understand flow science - hand flowed!) in the mixer diaphragms give perfect cruise of 15.5:1 and shows with the Vane, and are not adjustable. My mixer is rated to 175HP ( about 4.1 litre old school Falcon) so tend to believe I run around a lot on the idle circuit with my little 1800cc

Might talk to PEEL about findings.

AlpineRaven · Post by **AlpineRaven** » Sat Jan 16, 2010 9:45 pm

steptoe wrote:No? Not knocking. May have a play with turn off boost retard at dizzy as sometimes it can have an effect on things, gas doesn't always need retard on boost like petrol.

Gonna hook up the Vane and compare, see if i have wasted my time and money in gaining a little experience. It'll be a costly knight rider light DP200 reads pre cat. The tuning of the cones (hard to understand flow science - hand flowed!) in the mixer diaphragms give perfect cruise of 15.5:1 and shows with the Vane, and are not adjustable. My mixer is rated to 175HP ( about 4.1 litre old school Falcon) so tend to believe I run around a lot on the idle circuit with my little 1800cc

Might talk to PEEL about findings.

Mmm fair enough... Im not familiar with LPG thing there...
Cheers
AP

steptoe · Post by **steptoe** » Sun Jan 17, 2010 8:11 am

Mate reminded me last night of changes I made to cooling system, the colder 170F big bore (or standard genuine bore) thermostat and my little inline (130 - 140 F) thermostat for my LPG converter. The aim of the inline was to reduce the temp of the converter to theoretically reduce or eliminate the chemical fallout of the LPG at higher temps leaving oil residue inside converter to have to maintain or have it rot non metal components.

Theory with LPG is that the hotter the converter runs, the leaner the fuel vapour exiting becomes, and rubbish falls out of gas state! A problem engineers had in early days of liquid injection - they got more power out of same volume than petrol when things went right though !!

I have cooled my converter - theoretically richening up my fuel without checking, confirming, dispelling or making adjustments for possible change.

My gas guru , on the other hand says Impco gear self compensates for temperature changes keeping mixture correct through temp changes.

Time to compare the Vane with the little PEEL DP200 made specifically for LPG tuning as far as I can gather....

twilightprotege · Post by **twilightprotege** » Sun Jan 17, 2010 9:06 am

suparoo i'm going to get a wideband from http://www.wb02.com - australian and plenty of options

and like the other guys are saying, 0-1v o2 sensors are pretty poo and can give different results even depending on the gauge even though you're using the same sensor!

i remember when i had lpg on my holden v8 ute - timing had a lot to do with how the engine ran. and the converter we used was from an old taxi (prob the same or similar to yours) and i'm sure it had a little mixture screw thingie that we could adjust

dont forget, although i'm sure yo're aware, that if you're tuning on lambda, it's different depending on which fuel you use because each fuel has it's own stoich

steptoe · Post by **steptoe** » Sun Jan 17, 2010 11:12 pm

This little baby is made by PEEL , who make LPG bits and switchings and even a tuner for tailpipe, so assuming and gonna confirm it that this will read LPG stoich 15.5:1 in the middle. The O2 sensor never knew LPG would be there. Have emailed to ask what each little bar is thought or designed to represent - fraction or whole ratio. Got some currency in the boot (Crownies) for the Vanes owner

It is Impco equipment and has basic idle mixture, screw out leans off, and a power valve adjuster external and can also get 1/64" shims (leaning rings) to fit to diafragm to adjust idle beyond the screw. Shape of cone inside takes care of mixtures on light load and cruise, then there is the little Command controller to keep things stoich but has components that state vacuum only. Boost does funny things to it

twilightprotege · Post by **twilightprotege** » Mon Jan 18, 2010 8:03 am

do you have the impco connection before or after the turbo??? that might have something to do with it's operation? i know sometimes MAFs dont like going after the turbo, maybe that could be a similar issue?

steptoe · Post by **steptoe** » Mon Jan 18, 2010 5:23 pm

air filter >> IMPCO 200 mixer >> turbo >> TB >>intake manifold. Using an IMPCO L converter

Calcs for 1800cc up to 6500rpm 8psi boost is about 326cu feet per min

The 200 does 276 cu ft / min rated at 172 HP
Normal to see the 200 buried below a 4.0 litre Falcon and they are rated above 172HP

There is no MAF, or air flow meter as there is no petrol.
The IMPCO gear is self metering. Some sytems use RICH base withO2 sensor and box of electronics and duty solenoids and vacuum to bring it to stoich. Newer system runs them LEAN base and uses O2 sensor and box and duty solenoids to add vapour directly from converter. The duty solenoids have a warning for vacuum only and BOOST is proving a problem so had no choice but to go fresh air so no intervention electronically to cause disaster and runs stoich and very clean according to the Vane analyser.

Disconnected the fuel pump and injectors by unplugging one of thee ECU plugs.

The little DP200 is no match for the Vane, but I am still happy I have it and new O2 sensor for safety, it is not going to used as a tuning device, more over a warning for leaning out. I added another leaning ring - supposed to be two ratios worth and got no start until I wound in the idle mix screw way more. Got it idling at 15.5:1, cruises sweet at 15.5:1 and adjusted the power valve a smidge from last time giving power/load/boost averaging 13.8:1 - 14.2:1, with the occasional drop down to 13.6:1.

In doing this I have gained a better response from the DP200 rather than just its rich LED only dropping to middle when decel. It is now working more over the range, whatever that is TBA from PEEL

twilightprotege · Post by **twilightprotege** » Mon Jan 18, 2010 7:40 pm

have you thought of putting the impco after the turbo? just something to try

steptoe · Post by **steptoe** » Mon Jan 18, 2010 8:48 pm

Thought? That is the way IMPCO Australia says is the only way for turbo - blow through, supercharger must be opposite - draw through, former IMPCO engineer also says only way, old 70's manual says either way (read later). So that is how I had it, the mixer on the TB - absolute pig, undriveable due to odd intake pulses of four cylinder with turbo. Local gas guru had told me so before i started. Started from scratch in all the hook up config and components , nother 200 mixer not stuck to a TB

, to do draw through.

Running sweet. The PEEL gauge has a trimpot that I may adjust to get the middle bar on my Vane settings of 15.5:1

Gannon · Post by **Gannon** » Mon Jan 18, 2010 9:01 pm

Maybe a hi-rise intake with its large plenum chamber might even out those pluses enough for a post turbo mixer. Then you could ad an intercooler between the turbo and the mixer

steptoe · Post by **steptoe** » Tue Jan 19, 2010 9:15 am

Steve rising sun devised over several months and packets of panadols a way in which to control all this for a blow through operation - ingenious, but still can flaw with boost sticking diaphragm where it is not wanted. Good idea though, worth investigating - the intercooler may be able to smooth out those intake pulses..... when I am the one being pointed out to a stranger at the newsagent as the lucky fella talking to the lotteries office about collecting $5mil. Mate was collecting his $70 win a few weeks back "See that couple over there on the phone...." said the agent