Digifant Fault code reader

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Mon Apr 26, 2004 12:36 pm

Cheers, Ill give it a whirl. What concerned me was it was ok for about 5-10 mins before it got stuck at that voltage. IT did fluctuate when i revved it but it stayed at quite a high voltage IIRC above 0.5V ish. Would full throttle or very rich mixture produce a high voltage? Its kinda a chicken and egg situation here. either the lambda is knackered ang giving dodgy readings or something else is knackered which means the cars running fully rich which means im getting dodgy lambda readings. I kinda hope its the lambda now, at least its easy to sort.

amstrange1 · Post by **amstrange1** » Mon Apr 26, 2004 12:44 pm

I've just thought about this again - and it may not be the lambda at all, it really depends upon how quickly your multimeter is responding to the fluctuating signal. Having said that though, high fuel consumption is normally a sign of a screwed up lamdba probe so it's probably worth getting it changed. I think a new lambda is about Â£50+VAT from GSF, or you could get a universal (3-wire I think) one a bit cheaper still. Or maybe try a Bosch dealer?

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Mon Apr 26, 2004 1:29 pm

Â£50 ish isnt as bad as i thought then if its a genuine bosch one. Im gonna try and get one off a scrapper I think. Im not gonna throw money at this engine seeing as i have a fully working one with only 65K on it to drop in once the fate of the car its in is decided (the blue one). But if my luck runs out, Â£50 wouldnt be a bad investment...

amstrange1 · Post by **amstrange1** » Mon Apr 26, 2004 1:44 pm

Exactly - Â£50-odd is probably worth it if you've not got the time to try swapping the lambdas over, or getting one from a scrapper. You said the black one's very tappety - when was the oil last changed? I remember worrying about my G40 being very tappety, but once I'd changed the oil it was fine. My current GT engine is a good 'un though - been stood outside for two years or so, but with fresh oil in it's not noisy at all.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Mon Apr 26, 2004 9:52 pm

Yeah, the oil needs changing urgently. Got the filter, just waiting for nicksiggy to get me the oil from maccess.

Fingers crossed chaps, I think ive fixed it. With a little help from my dad. Went to a scrapper and got a lambda off another polo. For Â£5 I might add (I didnt actually pay for it - just bought something else that didnt work - bugger) Swapped it over - didnt make any difference. So then my dad got involved. He started messing with the throttle position sensor plug and the idle started to drop. Switched the engine off and took the sensor off and gave it a good clean. Put everything back together. Restarted. - Fine! Well, not fine. Wouldnt tick over - idle set too low. Kept throttle open so the engine could warm up, then tried to set the idle. Disconnected blue temp sensor and revs didnt chnage. Got the idle to about 950 by moving the screw. Then plugged the Blue temp sensor plug back in. Idles rose to about 1500. But we did it again and got it to idle properly. Ive disconnected the battery again overnight to reset it all. Hopefully tomorrow Itll be ok.

hardhitter · Post by **hardhitter** » Mon Apr 26, 2004 10:09 pm

Get yourself down GSF Gareth, treat it to some synta silver oil and they can get mk 3 bosch lambda probes for about 50 odd quid.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Mon Apr 26, 2004 11:17 pm

Nick said he would defo get me some but if i dont hear from him by this weekend I prob will pop down to gsf and get some of that instead. I dont think I need a new lambda now hopefully. I guess we will see.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Tue Apr 27, 2004 12:55 pm

Is there multiple viscosities of synta silver cos 10W40 is right at the bottom end of the viscosity spec for oil for the GT and I would have rather used 15W40 GTX magnatec which is VAG approved but more expensive in the black one since its a bit knackered. (sounds like a diesel) Well I guess that stuff can go in the blue one when nick gets it me

grahamgt · Post by **grahamgt** » Tue Apr 27, 2004 9:37 pm

I think synta silver is the one to go for.My tappets started getting noisy after a bit of a thrash so i put some Castrol magnatec in when i changed the oil and it was no different.So 2000 miles later i had another go and bought some Synta silver from gsf and i've not heard a peep since.As for the running probs if you don't get it running right it might be worth a trip to a VW specialist to see if it has any fault codes logged.

optima21 · Post by **optima21** » Tue Apr 27, 2004 11:31 pm

well on my mk2 I've used magnatec basic (the thicker stuff)for the last 6 years, and its now got 135,000 miles on the clock, and still sweet as a nut, with cylinder wear checked using a leakdown gauge and getting 6 - 8% leakage suggests that its just run in. To be honest as long as you're using decent quality oil its probably going to make no difference, as long as you change it regularly.

remember when oil goes it its a different colour to when it comes out, and thats because all the time its there is picking up crap and combustion by-products which damage the engine, remember its the same stuff that goes down the exhaust pipe and rots that.

My mk2 seems to be tappety after I change the oil rather than before, but I guess thats due to trapped air in the tappets.

also while on the subject of changing oil, how many of you guys disconnect the ignition to reduce the load on the bearings while the oil system get re-primed and pressure builds up. Running the engine without the bearings getting a supply of oil will cause damage.

On classic cars people some people wire the ignition earth to the oil pressure switch so the engine wont work until oil pressure is acheived. without doing this, some engines needed replacement bearings at 30-50,000 mile intervals, due to wear

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Wed Apr 28, 2004 8:35 pm

Argh, the car still aint right. The idles gone wrong again so Im guessing I need a new throttle position sensor/potentiometer. Im pretty sure theres something not right as the reistance of one of the terminals in relation to either one of the others cannot be read since it is too high. On the other two terminals the resistance varies from about 800ohms to ~2.5K. Im going to check the one on the blue gt on friday but can someone else check theirs when theyve got time so I can have a few sets of good results to compare with, cheers.

Tahrey1043 · Post by **Tahrey1043** » Wed Apr 28, 2004 11:20 pm

Optima, come again? Are you talking about every time you start the car, or just after an oil change (or an overhaul?!).... mine sees a lot of starts (especially of late, having to knock it off at lights!), though i do try not to put it under any load until the engine note becomes a bit quieter (5 or 10 seconds), sometimes you just have to churn & burn yknow?
Sounds like a good engine saving tip, if you can spare the extra 5 secs of running the starter until the oil pump has done its thing, and shouldn't be too hard to do.
(what about popping the bonnet, pulling the cable off the coil, running the starter 10 seconds, then reconnecting, dropping it, and starting like normal? -- the long winded method of doing it

)

And would the heavier weight car be something generally suggested on a 10 years or older car? I was once thinking about putting a lighter one in (instead of the bog standard 10w40) for some reason, can't remember the thoughts behind that.... but i'd be prepared to go for slightly thicker stuff if it would protect the motor. After all it's kind of like what Slick50 does

... and i'll be most disappointed if there aren't still a good contingent of Mk3s running around (converted to corn oil

) in 2020, on classic car tax - even mine!

Oh and Gaz... if the crappy orange multimeter I got from Lidl for three quid fifty is up to the job (please someone tell me yes/no in case i zap myself), tell me where to stick the electrodes and what procedures to carry out (revving etc), and i'll give you some example readings.

Gareth_GT_Hatch · Post by **Gareth_GT_Hatch** » Wed Apr 28, 2004 11:36 pm

Im not sure, but I think its a GT specific part. Its seems like ages since I had my SPi engined polo so its difficult to remember. It would be good news if there is one on urs cos Itll be dead easy to pilfer one off a scrapper.

Btw, optima just means when u change the oil cos there will be no oil in the bearings at this time.

Tahrey1043 · Post by **Tahrey1043** » Wed Apr 28, 2004 11:51 pm

Well that's a good one to remember for the next oil change then - leave it settle for a couple hours, then disconnect the ignition (and fuel pump power) and run it "gently"

on the starter for a half minute. (I just remember something similar from browsing through the full-engine rebuild bit of the haynes). If I leave it jacked up I can put it in top and measure how fast the starter spins too, off the speedo...

As for GT specific bits or otherwise... I think it has a "knock" sensor (or.. is that the G40). Not entirely sure how that thing works but its supposed to stop you knackering your high performance engine with rubbish fuel (ie anything you might buy in france or the USA, not available in the UK) by telling the ECU to forcibly ease off the power.
If what you need tested is the Lambda, then I sure hope mine has one

If it's the throttle potentiometer, then I'm -fairly- sure I have one too - the "thingy" (circular lever thing where the cable connects) on the side of the throttle body seems to have a shiny coppery semicircular trace, though I never did note whether there were any wires there. Mine probably needs a clean if there are any...

tshuss

optima21 · Post by **optima21** » Thu Apr 29, 2004 8:52 am

yeah I just mean to remove the ignition HT lead when you change oil filters and oil. Just run it on the starter motor until the oil pressure light goes out. On modern cars (1970's onwards) the oil filters tend to have valves inside them to prevent the oil from draining back into the sump when the engine isnt running. I've got a Triumph herald which was designed in the 1950's and its oil filter doesnt have a valve in it, and thebase of the oil filter points down to help even more oil drain from the filter.