Muncher

Ok, today I decided to fit my Phantom electrical AFR meter to my 95WRX scooby.....

My starting point was to get at the ECU so I could go and tap into the lambda sensor wire that goes in on pin 65...

Finding the ECU protective plate...



Found the ECU....



Which one is pin 65 with the white wire ???



Just for reference : ECU no



Ok, I take the cover off the ECU and look for pin numbering, the pin numbering only goes up to 63 !!!!



Time to take a different route. If I can't figure out the ECU wire then I'll solder my feed closer to the Lambda sensor. (Note that PE replaced my Lambda sensor with a three wire version a year or so ago)



All soldered/taped up with protective sleeving pulled over solder joint.



New blue sensor wire is fed through the bulkhead to underneath the dashboard and before someone mentions it, if you notice in the red circle that I have no dump valve whatsoever



The sensor has been mounted and plumbed in with my +12v and Ground tacked on to the other sensor in picture. Just starting tipping it down with rain too.



Ok, so the storyboard is finished, the results. Well according to the spec of the AFR meter the first 4 red leds are from 0.050 V to 0.249 V (lean)

The 10 yellows are from 0.250 V to 0.749 V (stoich)

The 6 greens are from 0.750 to 1.0 V (rich)

When the car is warmed up and at idle the lights are as shown in the last picture. When I floor it all the lights go out. Should they not be in the green set of leds to indicate that it's running rich and slowly head towards the orange as the lambda sensor heats up ?

I'm going to put an oscilloscope on the sensor voltage tomorrow to see whether the AFR meter is reading properly.

Cheers

Giles

Cosie Convert

If you want to tap the wire at the ECU it is the 5th wire in from the right hand side on the top row. It is white with silver bands.
You can see it quite clearly in your picture.

I found that my original lamda sensor in the manifold was giving strange outputs. I have since purchased a new sensor and fitted it in my magnex downpipe. This is the recommended fitting point as the sensor does not overheat as quickly.

ps Good quality photos, ideal for anyone thinking of tackling this task for the first time

cc

Muncher

Cheers for the reply CC.

Just for clarity is it this wire ??



I believe I hooked up to the Lambda sensor in the manifold but I'm could have sworn there was also one in my PE T75 Downpipe. I'll have to check in proper light tomorrow. Was the new sensor you bought a 3 or 4 wire ?
How much would I expect to pay for a new one ?

Cheers

Giles.

Cosie Convert

Yep, that's the one

You may well have another sensor in your downpipe, it's a temperature sensor.
As the downpipes tend to be universal fitment you should have a blank plug fitted near the top of it. This is where the lamda is fitted on later models.

I got my replacement lamda from Halfords 49.50. 3 wire 18mm thread. (black wire is signal)

I'm not sure if that's a good price or not ? but the guy was very helpful and said I could try it in the car and if it didn't give the results I expected then I could take it back, even though it was used !

Unlike my local Scoob agent who said "For an Import? nah, don't stock them" [img]images/smilies/mad.gif[/img]

cc

Muncher

Yep, it's the temp sensor that's on the downpipe. Is that the temperature of the pipe or the exhaust gas temperature ?

Re-wired the AFR to tap onto the white/silver wire. Still getting the same readings 250-300mv at idle and goes straight to lean when you boot it.

I'm guessing my lambda sensor is shafted so I called up 3 different Halfords enquiring about a new Lambda sensor for a 95 Impreza.

All of them didn't know what a lambda sensor was and all said they didn't stock them !! One person said they were too techcical for Halfords !!!

Maybe I asked the wrong question ? Can you remember exactly what you asked for when you got yours CC ?

Giles.

Cosie Convert

Yea, I asked for a Lamda sensor !
They don't actually list one for the Impreza turbo, however the guy told me that just meant that they did not do an adaptor loom to connect it to the car. They only hold three types of sensor. 3, 4 & 5 wire. I just chopped the plug off my old one and connected it to the new one.

The sensor is made (or marketed) by "hotwires" the till code on my reciept is 13 180398 Ignition part.
the store I bought it from was No 552 Straiton Main Edinburgh
Tel 0131 448 2248

Hope this helps

cc

Muncher

I called them up again and quoted the part number 180398. Guess what, all of a sudden they have one in stock

So I'm off to pick it up right now before they forget what a Lambda sensor is (incidentally for anyone wanting to buy one on their sheets it's an Oxygen sensor).

Thanks CC, most helpful with the part no.

Giles.

Muncher

I picked up the lambda sensor from Halfords, took out the old one that PE installed a year ago (was a four wire sensor ??). Put in the 3 wire sensor and hey presto an AFR meter that now shows the correct readings that I woould expect !!

Car seems to idle more smoothly now. I'm guessing here that if my old lambda sensor was reading low then the ECU would have been overfueling the car at idle ? At boost it wouldn't have mattered seeing as the sensor is ignored anyway.

Giles.

lumby

Muncher where did you get the AFR meter from ?

Cheers

Muncher

Got it from Scooby Mania, it's the carbon fibre faced gauge (white faced one is shown on the web site)

lumby

MUNCHY
Thanks

Out of interest how did you get the blue wire out into the engine bay from inside the car .

I need to thread a feed in for a boost controller and the rubber gromet on the main wiring loom looks really tight , too tight to get another wire through

Cheers

ssubaru

HI why no dump valve
ssubaru

Muncher

Actually it's easier to feed the wire from the engine bay to inside the car. I think I threaded mine through where the throttle cable goes through the bulkhead, just poke the cable through the gromet, once it gets past gromet just keep on feeding the cable through until you can see it from under the dash.

In the end though I pulled it all out and tapped a feed from the ECU instead thereby keeping all the cabling inside the cockpit. The only reason I started in the engine bay was because I didn't know which wire on the ECU was the Lambda sensor, I do now

Muncher

SSubaru: 'Why no dump valve ?'

I didn't know the dump valve was missing up until a few months ago (doh). Did a bit of research and decided not to buy a new DV seeing as my turbo had lasted at least two years already.

However I bought a Forge Re-Circ DV on Friday and fitted it as I'm in the market for a Link upgrade and BR Developments advised me that they will not perform any work unless the DV is there.

I certainly lost a bit of throttle response after fitting the DV and lift off noise (Blitz induction) is greatly reduced. I haven't driven it enough over the weekend to make any real conclusion about the new DV though.

BTW I am in no way suggesting everbody should ditch their dump valves for better throttle response !