Digifant Fault code reader

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sat Apr 24, 2004 12:58 am

Ok so Ive made one of these as per the instructions on the polo-gt website. And (like everyone said) it doesnt work. I decided to put in an extra resistor on the LED to protect it as optima21 was saying he blew his LED straight away. I was just wondering (and I know its a long shot) if anyone has had any sucess with this for their polo. I get the feeling that the instructions on the polo gt website are for a golf. Theres a wire missed out on the diagram (one of the "signal" wires. Any idea where this goes?

Please help of you can!

Cheers

Gareth

Tahrey1043 · Post by **Tahrey1043** » Sat Apr 24, 2004 6:37 am

mebbe a buzzer or a normal light (torch) bulb would do you better? LEDs are designed for like 1.5v, 3v max sort of voltage. I remember having to attach relatively heavy resistors to them for a school project involving a 9v battery (and the sci lab's power supplies could zap them at maybe 6v or less). Dont know what the ECU puts out but it could be anything from 5v (borderline) up to 12v (death!) probably with a fair current attached.

good luck

hardhitter · Post by **hardhitter** » Sat Apr 24, 2004 10:38 am

Is it essential you have a fault code reader ? If theres a problem it can be usually diagnosed without a fault code reader.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sat Apr 24, 2004 11:23 am

The car is in limp home mode all the time - 15mpg! The blue temp sensor seems ok - it has the right resistance at the right temperature. And there are other less easy to test things like the lambda. Its not absolutely vital i make this but it sure would be useful. Im gonna do more testes today.

amstrange1 · Post by **amstrange1** » Sat Apr 24, 2004 1:39 pm

Are you bringing that car to Inters Gareth? One of Peter's air/fuel ratio meters can be used to test the lambda probe if it's calibrated on another car first. That's how Alan L confirmed his was knackered anyway.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sat Apr 24, 2004 2:22 pm

I was planning to. but at 15mpg it would cost me a hell of alot to get there. Hopefully i can fix it myself before then. Time will tell.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sat Apr 24, 2004 4:48 pm

I give up. Its a load of crap. Alan gibson's got alot of explaining to do...

Im gonna swap the lambda over with the one on the blue car I think to see If that makes any difference. Easyer said than done though. Does anyone know if I can disconnect it fron somewhere on the loom and where this connection is likely to be. I know where the earth is but I canne see where the other 2 wires go

Cheers

Gareth

hardhitter · Post by **hardhitter** » Sat Apr 24, 2004 5:13 pm

They just plug into the loom on the side if the inlet manifold where the earth is pretty much. Then reomve the earth and unscrew it from the downpipe and unclip the wire so it will come out. Pretty easy and if you have a spare to use, that works its a bonus.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sat Apr 24, 2004 6:58 pm

Cheers dan.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sat Apr 24, 2004 8:46 pm

Right, been doing more testing. Had a look at the lambda probe connector on the side of the inlet manifold. Unplugged it and found what looked like a piece of clear resin covering one of the pins. How it got there I will never know. Connected everything back up and installed a test wire on the signal wire on the lambda probe. I then used a multimeter (after disconnecting the battery and leaving it off for a few mins) to check the voltage from the probe. At first it fluctuated from between about 0 and 1v like the faq on club polo says it should. It was also idleing alot slower (but still too fast) at about 1100. So I let it warm up and then disconnected the plug from my new blue temp sensor. Revs dropped to about 950 (apparently this is bad as revs should rise in diagnostic mode apparently) Reconnected it and revs returned to 1100 ish. Couple of minutes later the revs went high again 1500-1750ish and I checked the voltage and it was contstant at 0.93 volts. It did change when I revved it but it always settled on this value. Is this just telling me that my mixture is far far far too rich or would someone say its knackered?

ereeiz · Post by **ereeiz** » Sun Apr 25, 2004 10:28 am

why not go to the dealers and have a word with a mechanic on his lunch break, give him a fiver and I'm sure he'd stick it into a diagnostics thing.

LogIK · Post by **LogIK** » Sun Apr 25, 2004 4:11 pm

Ouch. I hope you haven't bought a Lemon there, Gareth

. I hope its fixable.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Sun Apr 25, 2004 4:49 pm

Its a proper lemon im afraid. whatever it is it isnt obvious. Ive got to run some comparison tests on the blue car to see what kind of figures the lambda puts out. Its proper fooked the engine though - sounds like a diesel now and the tappits are well noisy. But goes well enough, easily as fast as the blue one. I might have to do that engine swap sooner than I thought...

hardhitter · Post by **hardhitter** » Sun Apr 25, 2004 6:30 pm

The voltage should always fluctuate at idle. So the constant reading at 0.93v is telling you the lambda is knackered basically. Get it swapped over.

amstrange1 · Post by **amstrange1** » Mon Apr 26, 2004 11:34 am

hardhitter wrote:The voltage should always fluctuate at idle. So the constant reading at 0.93v is telling you the lambda is knackered basically. Get it swapped over.

I agree with Dan - stick a new lambda probe on it, the voltage should only be stable at full throttle IIRC.