Dead S2

[S2central.net]

The ecu only activates fuel pump when it is happy the engine is spinning fast enough. So a dead G28 means no fuel. I posted G4, G28 and G40 waveforms here before so a quick search should find them.

You are on the right track. What year is yours ?


Paul

[Evilgoat76]

Was looking at the waveforms earlier so I have the thread bookmarked. AFter I posted that I went out and had a root. Have found some bogification on the vac lines. Not relevent but it bothered me so took parcel shelf off...

I really really wish I hadnt. I would do Jail time if it meant I could do something horrible to the inventor of Scotchloks. I need to clean up down there before I do any more, its possible the fault is in the wiring it really has been bodgificated that badly

I've also got a vac hose adrift by the ECU, also as a result of bodging. Car is now scheduled for a major wiring check to see what else has been screwed with.

Fog light LED is flashing when locked up and does go out when unlocked. The Autolock immobiliser is in the +ign feed from the ignition key and one other (green+yel?) line.

Its an M so thats 94/5 IIRC

I have to say I've done a fair bit of auto electrics and Audis are a learning experience

[Evilgoat76]

Right time to give in I think.

50hz sinusoidal waveform on crankshaft sensor so something really not right there, I suspect its my scope though. Nothing quite so annoying as having broken tools. Noise on speed sensor. Not metered the sensors out on the ECU plug yet but I'm loosing the will to live.

Battery just died again but I notice that the fault code has now gone, may just be the battery being stupidly low but we will see when its charged again.

Does anyone know a VAG specialist round pompey?

Had a rummage again and now its getting interesting. Sounds stupid but the washers have been jamming onand I think its related.

Cranking over I'm seeingan RPM reading in VAG com, so I'm ignoring that speed sensor. 80 RPM sounds about right given the state of tha battery at that point.

Now, looking at the attached screen I'm getting the feeling I may have a probelm with the throttle switches if I read the section in red right. Throttle angle changes when I touch the pedal but the switches dont.

The Washer is jamming on, its done this before and I thought I resolved it by reseating a connector. Seems like I havent as its come back. I noticed that pulling the fuse or relay wont cut it off and then noticed my relief relay is warm too. Satin the car I can also hear a relay that sounds like its on the tailgate cycling every 10 seconds. More investigation shows the tailgate wiring harness has been bodged and prodding this starts the washers up.

The Speed sensor has also been done before, The old one is still in there and had been disconnected and left hanging loose. I'm now wondering..

A) Can anything in the tailgate immobilise the car?
B) Is there a relay in there if so, what is it?
C) Are those switches faulty and whats the upshot if they are?
D) If someone has played this game before with this car

[TDi90]

Im guessing wiring on a Defender is like a walk in the park compared to this then!

[newsh]

Had a similar thing with my ur years ago, someone had wired an immobiliser into the fuel pump wiring with scotchlocks. Crank for ages and nothing, bang the glovebox just right and it would start right up..

[Evilgoat76]

Well thats probobly where I'll go next, removbe the immobiliser and go find out how to disable the Audi one. I'm sure the fuel pump relay is now working as I can hear the pump, not visually checked it though.

Need to do something about the 1/2" backlash in the Suzukis UJs first

Think its S2 Sunday at Robs next weekend

Rob, comparing LR wiring to Audi wiring is like comparing a mini to the space shuttle, Not even the same league. Theres enough wiring on on of the S2s to do about 6 defenders.

[S2central.net]

Bet you cannot hear the fuel pump... The afterrun pump does a few second test run when you first turn key on. Strange but true. Also you cannot trust throttle swich values in vagcom unless the engine is running. You need a good scope on g4 and g28 really...

Don't forget that an led tester will let you see if the fuel pump and injectors are being activated. Stupid question but have you checked all ecu fuses and ground points ?

[Evilgoat76]

Checked all power and earths, all seem ok, no high resitance paths anywhere.

Sheilds and gnd present in the engine bay on both sensors. Hall sensor is pulsing as per the Motronic manual. Will pull both sensors off and test them off the car. Also check for the pin, I hope its not that. What makes this so much harder is the constant 'using VAG cable.....' in the manual.

Not totally happy about the MAF, wouldnt mind pinouts and resistance measurements if anyone has them. Failing that I'll meter out Robs MAF on sunday and compare notes.

LED tester on the injectors would be handy, will give that a go tomorrow. Need to check relay activation again too.

[S2central.net]

VAG1598 breakout box is THE best thing ever for Motronic wiring fun & games... I love mine

I have thought about making up a clone breakout box for this, but its a lot of work - anyone who can source the right connectors could easily do it - would be expensive to make as sturdy as the lovely quality of factory item.

It might be cool to invent a lil widget that can plug into G4 and G28 to give some sort of visual check by an LED that the there is a signal there - seeing as so few people have an oscilloscope (or two) at their disposal. Would have to be some cheap, simple analog circuit I think.... even if it was just an adapter into a microphone input on a PC so you could detect the signals audibly... Kind of a reverse version of those audio tool tricks that can be used to simulate G4 and G28 - search of 'engine simulator' to find more here... yet another project of mine that has been parked up for way too long.

Check S2central.net for how to test the MAF, but I very much doubt that is your problem... Engine will start without MAF plugged in for example.
A quick resistance check can sanity check G4 and G28 but until you see the waveforms then you are somewhat in the dark.

[madpugger]

A few things of note...

Audi immobiliser - there should be a light on the dash, like a picture of a key, if this goes out then your audi imob should be fine...
Cam hall sender - this only has an effect in two situations. a) when the car is trying to start. b) When the engine is above 4K rpm... It is maybe giving a signal on a scope, but it may not be good enough for the ECU. Have you tried the water trick first off? after that, try a new one, in the states you can get just the sensor with no bracket for a couple of $s, have a search for the thread here. If this sensor is not giving a good signal, the fuel pump will run but the injectors will not pulse, and there will be no spark.

And yes, you will get speed sensor not working when the engine is not running.

Hope this helps.

[Knight Rider S4]

Were was the water leak that you fixed?

[S2central.net]

The immo/key light is only for IMMO-1 system (MY95 onwards)... there is another anti-theft system that was used before that. Not saying more in public for obvious reasons.

[Evilgoat76]

In theory it shouldntbe had to check that the signals there are within certain parameters to give a go/no go with a PIC.

I need to pull my scope to bits, the LCD one I have isnt fast enough, Its great for most things but looking at anything fat it sucks. The CRT scope kicks ***, when it works.

I would imagine getting those connectors would be a bundle of laughs, specially the male.

I've done a lot of data aquisition work so it shouldnt be too hard to do what you suggest. They both have the same pin outs and it is just a pick up at the end of the day, I have the software to do it and should be able to have it work in paralell with the ECU. Might seriously look at that tomorrow. Again go/nogo measurement shouldnt be hard but would need a cal signal of some kind to make sure sound card gain doesnt get in the way.

I have a LED in the fog light switch for the audi anti theft. not sure if there relaly is an immobiliser in there or not. Looking at whats coming off the hall sensor its a good signal and at the right period.

[Evilgoat76]

Were was the water leak that you fixed?

Temp sender, right hand side of the block weeping at the sender. Its a very slow leak I've been chasing forever. Think its normally steam it leaks.

[S2central.net]

@evilgoat - send me a PM with your car's VIN so I know what flavour security it should have from factory... by the mention of all the shyte botchloks in play then you could have all sorts of issues. I can send you the schematic sheets you need to debug it back to as it should be - if you can convince me that you aren't a potential thieving, bodging, gypsy scumbag who would use such information for evil purposes... ;-)

The frequencies in play on those signals are ALL in audible range of order of kHz so you don't need a fast scope at all to analyse 'em.