diagnostic reader help

[steveo3002]

its for a gt actually but struggling to get info i need ..guess a g40 will be same pinout

basicly i have a code reader ,manual says both K and L  line need to be connected , only K line is connected on my car , does anyone know where L line should go ?   i.e earth or a pin on the ecu etc

thanks 

[ereeiz]

Have a look here. There's a few threads that may help. https://www.polog40.co.uk/forum/index.php?board=30.0

[hayesey]

you shouldn't need the L line, just the K.  You might find those code readers a bit hit & miss, I've always had the best results using an old VAGCOM lead (with an rs232 connector, that old!) and "VWTOOL.EXE" software.  Info and a link to the software you can download here:

https://www.polog40.co.uk/forum/index.php?topic=213.0

[steveo3002]

right i got it going...was a grubby pin in the join under the dash

measuring blocks- ign timing - its going ape 0-22 and every number between erraticly , is this normal or should it hold a steady reading ?

[hayesey]

yes it's normal for that reading to be constantly moving.

[steveo3002]

bah i was hoping that was the problem ..

any pointers /websites i can check my info against , nothing is jumping as dodgy apart from that

no codes to say the o2 isnt fitted either?

gona try another set of injectors  i had laying around

[hayesey]

whats the problem you're trying to solve?

[steveo3002]

think youve seen me on fb group

basicly its a conversion into a mk2

bad idle,bit bumpy pop pop sound  and refuses to start hot - between 3-20 mins , will start with bts undone , drives fairly okay above idle

a few things ive tried /done

timing set as per the book
air bypass mixtured tired various settings ...its set to 14.1 afr via a wideband gauge at the moment
tried another dizzy /cap/arm
tried another coil
correct plugs fitted
earths good
tried another tps
no obvious air leaks + charcoal can deleted
correct 3 bar pump fitted
new genuine blue sender plus tried others i had laying around

engine basics should be fine as ive had the car driving for 2 years on a carb ..ive not touched the internals since

after getting the diag working and cleared the codes non have come back

things i havent tried ...ecu , injectors(got a set will try today )  no o2 fitted yet...i have one but fear it will try and compensate /mask the problem

so while i can get the diag working and obvious stuff like temp and tps is clear if good /bad , im not that clued up what i should be looking for 
 

[hayesey]

what do you mean by air bypass?  They should have the lambda/O2 sensor connected but even without it, it should run better than it sounds it is doing, that will be making matters worse though.

has it got the correct air flow meter connected?  these have been known to fail, I don't think there's a fix other than replacement.  Ideally, you could do with getting hold of a spare to test if you know of anyone else with a 3F engine near you?

[steveo3002]

air bypass = screw on side of afm

yes its the correct afm

do you not agree leave the o2 off until its right , its clearly not right and for one i dont want the o2 to try and cover the problem , and second i dont want kill and brand new bosch sensor

[hayesey]

I don't think it really matters, it should run better than it is with it disconnected that's for sure.  It shouldn't damage the probe unless unburnt fuel is getting into the exhaust (either because of over-fuelling or a misfire). 

I think next I would check the whole engine wiring loom, using a multimeter in resistance mode, checking that the wire to all the sensors goes back to the ECU plug with almost no resistance.  You've said the earths are all good, how have you checked that?  There's a point in the wiring loom where a load of earth wires are connected together with a metal crimp, I can't remember exactly where it is located though, I think somewhere near the ignition coil but it's been a while!  If that's in bad condition then you'll get earthing problems.

[hayesey]

what's the condition of the loom in general?  any cutting & joining in it?

[steveo3002]

its all been untaped , looks good , any repairs done myself to a good standard , proper terminals used /soldered joins with heatshrink

all checks out to the ecu plug pin numbers , good battery voltage when running ,fatter earths fitted instead of factory ones

wiggling plugs while its running has no effect

got a ecu and afm coming...might as well throw more ££ at it lol

[hayesey]

I've come across GTs with dodgy AFMs before, there's no easy way of diagnosing it that I'm aware of other than swapping for a known good one.  So lets wait and see what happens when you put that spare AFM on you have coming. 

I had a fault on my g40 years ago that turned out to be the ECU itself, spent ages trying all sorts (fortunately I owned a GT as well at the time so could swap a lot of parts over to test), in the end tried an ECU out of desperation and it worked.  I still have the duff ECU, there's nothing visibly wrong, suspect a component on it has failed internally somewhere.

[steveo3002]

i will smash whatever it was into 1000 pieces , ive spent way too long messing on it now