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Model specific boards => Golf mk2 => Topic started by: Craigwilson on 19 January 2014, 22:51
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what can cause an 8v digifant to over fuel, and before you say blue temp sender or ecu both have been replaced. it over fuels and won't start as it's flooded and when I force it to start it reeks of petrol and runs horrible
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sticky plunger in metering unit?
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sticky plunger in metering unit?
digifant not the K-jet. :smiley:
First common question: Does the fuel pump prime for 3 seconds with ignition on or run continuously?
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it's primes normally, I don't see anything abnormal with the car but it just won't fire unless I unplug the injectors to clear the fuel from it, and the plugs are soaking wet with petrol. I replaced the plugs and it started perfectly for a while (still running crap tho) and now it's back to not starting. whole ignition systems been replaced
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Only thing I can think off is that the fuel pump relay is sticking.
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I would check the fuel pressure regulator and the return pipe coming off it for blockage. would also check fuel pressure.
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1) get plastic coke bottles and stick the injectors into start car
2) check each injector of spray pattern and speed at which they all should fill up.
3) check injector loom they get brittle due to being near the manifold.
4) either faulty injectors are stuck open or loom is earthing out.
5) Fuel relay check it
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if you can get the car to run at all take a long flat screwdriver and put the tip of it on each injector and your ear against the handle. you should be able to hear the injectors ticking quite clearly. if not check the wiring back to the ecu. if the wiring is fine then it looks like an ecu fault.
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apologies I should probably let you know what I've done already, I've replaced my blue sender my ecu my injector loom( got a good one off ebay as mine had been repaired) the loom came with injectors and rail and regulator and I checked them before putting them in by plugging in an old dizzy and turning it with my hand when the ignition is on, my hall sender and cap are new my leads are new I've swapped the relay with my other 8v and done a continuity test of all my plugs and switches going to the ecu.
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still nothing, it's been over a week now
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Whats the resistance of each injector?
Do you have the correct fuel relay and is it in the correct slot?
What condition does the knock sensor look like?
You could have a break in the ECU loom that's causing the enrichment
The ECU has a limp mode that enriches fuel by 25% so it does not run lean I've had two bad ECU's in the past and hall senders and coils I've learned to just borrow working ones before shelling out and testing the parts I own on other donor cars.
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are the new injectors the right ones? what colour are they? what about the regulator? is it the correct 3 bar one? if I ever get a running fault I change one thing at a time and if there is no improvement I change it back and move on to the next suspect. that way there is less chance of introducing another fault in to the system.
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sticky plunger in metering unit?
digifant not the K-jet. :smiley:
First common question: Does the fuel pump prime for 3 seconds with ignition on or run continuously?
maybe i should pay more attention!!!! :whistle:
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When ever I have a digi over fuel its through timing (running rich) or a faulty maf sensor.
Have you checked for a good spark? Swapped the coil just to rule that out?
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well the good thing is I have 2 1991 8vs so yes I so steal parts from my old man....... hence stealing his temp sender ecu and air flow Meter and with all those parts his runs perfectly. I replaced the spark plugs the other day and for the first while it did start right on key for a while but still idled badly, but now it's back to not starting because the plugs are drowned.
the injectors are yellow same as the originals and came from a PB and they were all opening and spraying a nice even pattern when I checked them.
could it be related to my spark?
I know the timing is spot on because I fiddled with it too see if that was an issue
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as for the knock sensor it looks okay, I removed it and tightened it to 20nm as I was following Johnny's setup guide. would this be affecting the starting?
one thing I did notice is I hade about 5 ohms of resistance on a couple of wires going to the ecu. isn't this high for a simple wire ?
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knock sensor should not affect starting as it only comes into operation when engine temp gets up a bit. when I was testing all the wires from ecu on my own mk2 I don't recall any resistance in any of them. was getting a buzz on multimeter from all of them. which wire you getting resistance on?
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I was getting about 4ohms on the brown/green wire from the blue sender, the meter was beeping but because there is still continuity but I don't reckon wires should be resistive
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I was getting about 4ohms on the brown/green wire from the blue sender, the meter was beeping but because there is still continuity but I don't reckon wires should be resistive
That's within tolerance 3.5 @ 10C so depends upon temp TBF.
Still think you have a bad earth in the loom somewhere?
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it's about 3 degrees in Glasgow, where would I find these grounds and how do I check
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it's about 3 degrees in Glasgow, where would I find these grounds and how do I check
Well the lower the temp higher the resistance so you are in spec!
All grounds ones near the ECU one from body to battery to gearbox!
One on the coil body!
Or a break in the ECU loom touching a ground causing issues.
I think everyone has commented on the most likely problems on here, but from the solutions you have tried already its go to be simple like a bad connection somewhere.
Guess you could start checking resistance on each ECU loom pins on a good car and then compare it with your problematic golf?
My Hall sender caused massive over fueling and broken injector loom feeder on mine, but you have already said you have changed it already???
I tend to change over any visible earths with new braided items and cables I even taken a Corrado battery loom because the cables are thicker and better insulated than our old Mk2's. Stick some grease over exposed cables and remove out any oxidised cables especially when they go green in colour.
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well my earth cabled are recently replaced because I came across my starter failing due to a broken earth lead, tommorow I'll give that a shot by running tests on my dads 8v then compare it with mine (the broke one)
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This pretty sums up what we have covered mate?
(http://upload.wikimedia.org/wikipedia/en/9/9d/Dgfisysmap1.jpg)
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doesn't have an O2 sensor does it?
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No it wont unless you have a CAT which is unlikely. It was a tick check off list for you :tongue:
One test you can do is disconnect the fuel pipe to rail and see if she will start remember to crimp it off first yeah LOL fuel pissing everywhere is not nice :laugh: See if she will run with whats being burnt up?
I've heard some numpty have connected the wrong fuel pipes and mistook return and main feeds its a shot in the dark though mate!
By the way if your over fueling is that bad the whole sump is probably mixed with oil this can cause issues so remember to change that oil!
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think I've done all of those, I ended up changing my ISV because the revs where taking so long to drop and were a lot quicker with the spare one, would this be related. and with the fuel hoses I don't quite see that plausible because the car was running perfect so unless they swapped round on there own,...... it's black feed blue return unless I'm mistaken?
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what is the blue/white wire on the air flow meter for, I've found it goes to the ecu but I pulled it accidentally and it broke from the plug very easily
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Here you go this might help you the blue white is defo airflow meter signal wire could have found your problem!
Looking at the loom pins top row no. 1 Lower bottom row last pin no. 25
1 Start (50) red/green
2 OXS purple
3 Fuel pump relay red/green or yellow/blue
4 Knock sensor white
5 CO Adjustment blue
6 Ground (Sensors)
throttle switches
OXS
Hall sensor
Coolant temp.
CO pot/Air temp. --- brown/white
7 Knock sensor brown or yellow in shielded black cable
8 Hall sensor red/black
9 Air temp sensor blue/white
10 Coolant temp sensor brown/green
11 Idle Switch red/blue
12 Injectors red
13* Ground ECU brown
14 Power main / Idle stab. valve black/white
15 Full Throttle Switch blue/black
16 not used
17 Not used
18 Hall sensor green/white
19 Ground brown
20 MIL yellow - Yes This is the wire that stores fault codes off your Eprom! Max two fault codes before limp mode kicks in!
21 Not used
22 Idle stab. valve black/yellow
23 Not used
24 Not used
25 Ignition coil green
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cheers ! that might be very useful now and in future. could you clear up wire 20? does it have fault codes and a limp mode? also I repaired my wires to my airbox and it's not mosfireing but running terrible but I do have the maf off of the other 8v on it so it may just be setup different because that one has 130k and mines is cammed
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Some cars had a VAG port as we called them, but they were on runout models and G60's esp American export models.
some were located near the handbrake lever, but don't take that as gospel they can be anywhere. Its highly unlikely you would have one, but you could always see if you can trace that yellow wire and see where it goes :lipsrsealed:
All digi's had default values if it senses two faults on sensors it would generically put higher values to ECU so you could get home on limp mode so to speak. If there was more than three down its limitations it cannot provide three default signals to help the car run better? My guess is that you still have a bit of work to get that running right, but guessing you might have more work to do yet fella and go through it again!
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there is 2 wires behind my centre consol area think there yellow and blue/grey and there just blank and tied together, could that be what there for, I'll have another look at the car tommorow after work.
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also what's classed as a runout model
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Runout models are the last MK2 to roll out of production, but like I said its just a two pin plug and I've only seen them in Corrados and G60's some in handbrake area some in the steering cowling. IMO the MK3's was the start of ODB, but the Late MK2's especially US market had some fitted to make a transition and test purposes of diagnostics better.
There are various diagnostic plugs that read OBD ports, but its not really going to help you without software.
You could ring around a Bosch specialist to see if they still have that kind of equipment, but the interface is pretty basic all they will do is stick an interface between ECU and loom and read off the ECU Eprom unit. Don't forget its over 20 years old ECU system. I had this checked out when I had a rolling road mapp done, so the interface had to record a base mapp of the original Eprom chip before the new chip went in. Even then it was basic O2/fuel sensor flows readouts.
I would concentrate looking for grounds and earths and swapping them out!
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have you done the screwdriver test on your fuel injectors to check if they are clicking? you mentioned trying to start the car when an earth cable was broken. that's a very common cause of ecu failure.
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Have you checked for a good spark? Swapped the coil just to rule that out?
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If not that I would then try/swap the ignition mod that sits ontop of the ECU.
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have you done the screwdriver test on your fuel injectors to check if they are clicking? you mentioned trying to start the car when an earth cable was broken. that's a very common cause of ecu failure.
this all happened a while back that was when I replaced my earths, and it's been fine since, and I checked the injectors worked before I fitted them
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you really need to get your fuel pressure checked first. if its to high it will flood engine and if its to low the injectors will only be dripping which will also soak the plugs. pressure should be 3 bar with regulator vac pipe disconnected.
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I was hoping you would pick up the fact the other working 8Ver might have only two sensor faults and runs okay with only two?
This said your broken one might have three or more issues which would mean when swapping parts out from one car to another makes no difference! This is important. Hence I've only used a donor parts that I know are defo working to spec.
Is there a decent earth strap from the coil body to bulk head this made some Digi run like poo without a decent braided earth strap i.e made a bad spark!
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my car is now in someone else's hands I'll be sure to keep you up dated
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I think them small earth straps were fitted as a safety feature. so if your main earth cable decides to break when your flying along at 100mph in the fast lane your engine wont die on you. I found my car ran fine without that small earth strap.
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problem solved!
cam timing was 3 teeth out, looking at the cam pulley that would be 3 teeth anti clockwise.
blue temp sender wire was also cut and soldered along with the maf plug on the airbox.
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glad to hear its sorted man :smiley: if your cam was that much retarded you would be getting very little air drawn in to the cylinders.
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I think that's actully what it was, like choking itself