k jetronic fuel injection

[garbaldy]

Any experts on this mechanical fuel injection know what this is called and what it does?

Its from an 86 audi 90 quattro

 

 

[dollywobbler]

Might be part of the cold start. IIRC, there's a unit that adjusts the mixture and then the idle control valve (which I don't think that is) to bung the revs up a bit.

[Junkman]

Overrun Shut-off Valve (Air Bypass).

It's there to get around the inherent problem that when the throttle butterfly is suddenly closed (by you taking your foot off the accelerator when changing gear etc...) the airflow sensor plate tends to hang in the air whilst the air in the inlet system continues to pass by to fill the depression or vacuum in the inlet trunking between the airflow meter's plate and the now closed throttle butterfly. This of course holds the Fuel Metering Plunger in the raised position, resulting in over fueling and possibly stalling of the engine. To get around this problem, this valve is plumbed in between the bottom side of the airflow metering plate and the trunking at the top side of the metering plate. It opens whenever the throttle is closed to allow direct access for air trapped below the airflow metering plate to get past and fill the void in the inlet trunking.

It is a simple solenoid valve that is either open or closed, with no in between settings. It is normally in the closed position, sealing off the bypass, but is activated open by a small switch on the throttle body that makes contact whenever the throttle is fully closed.

It effectively shuts off the fuel supply by causing the airflow sensor plates to drop back to its idle position.

[garbaldy]

The haynes book doesn't show or explain this part as it only covers the 1.8 injection,

I don't want to sound like a right numty trying to explain to parts guy what I want.

[Mr Livered]

Bung it on the desk and say can I have one of those please?

 

(assuming you're planning to go to a motor factors in person)

[Junkman]

If you ask a parts guy in this time and age for components for a K-Jetronic, and someone looks like a right numpty, I suggest, it's him.

I want to see the parts guy that can still as much as spell K-Jetronic. Nowadays most of them would be hard pressed to spell a fuggin capital 'K'.

[garbaldy]

@ junkman. Thanks for that but what is the small vacum pipe for?

[Junkman]

I have no idea. I find the whole concept of injecting fuels highly suspect and suggest the purchase of a car with a proper air/fuel mixing device.

[Mr Livered]

Have you seen the current thread about a similar system on the blue place? http://retrorides.proboards.com/thread/156911/calling-jetronic-experts-overfuelling-rough

 

It relates to a 924 but there's an explanatory video in the thread (and a link further down, though I didn't bother to click on that).

[overrun]

Overrun Shut-off Valve (Air Bypass).It's there to get around the inherent problem that when the throttle butterfly is suddenly closed (by you taking your foot off the accelerator when changing gear etc...) the airflow sensor plate tends to hang in the air whilst the air in the inlet system continues to pass by to fill the depression or vacuum in the inlet trunking between the airflow meter's plate and the now closed throttle butterfly. This of course holds the Fuel Metering Plunger in the raised position, resulting in over fueling and possibly stalling of the engine. To get around this problem, this valve is plumbed in between the bottom side of the airflow metering plate and the trunking at the top side of the metering plate. It opens whenever the throttle is closed to allow direct access for air trapped below the airflow metering plate to get past and fill the void in the inlet trunking.It is a simple solenoid valve that is either open or closed, with no in between settings. It is normally in the closed position, sealing off the bypass, but is activated open by a small switch on the throttle body that makes contact whenever the throttle is fully closed.It effectively shuts off the fuel supply by causing the airflow sensor plates to drop back to its idle position.

Nice copy and paste lol.

[overrun]

@ junkman. Thanks for that but what is the small vacum pipe for?

The vac pipe goes to the ECU.

 

My RS has the same system.

[garbaldy]

The vac pipe goes to the ECU.

My RS has the same system.

It doesn't have an ecu as its a mechanical system

[Junkman]

It doesn't have an ecu as its a mechanical system

That is not entirely correct. It can have either an analog, or a computerised control unit for monitoring and regulating the mechanical system.

[overrun]

It doesn't have an ecu as its a mechanical system

Only the fuel injection is mechanical. Hence MFI.

 

Mine has twin coils, no dizzy. ECU controls the fixed ignition map.

Cold start valve, fuel shut off/overrun valve, warm up reg, metering head, fuel accumulator and injectors.

 

That's the basics of all K-Jet systems though.

 

Is yours knackered atm? What makes you think you need to replace the shut off valve?

[Junkman]

Nice copy and paste lol.

Shall I re-invent the wheel?

[garbaldy]

Only the fuel injection is mechanical. Hence MFI.

 

Mine has twin coils, no dizzy. ECU controls the fixed ignition map.

Cold start valve, fuel shut off/overrun valve, warm up reg, metering head, fuel accumulator and injectors.

 

That's the basics of all K-Jet systems though.

 

Is yours knackered atm? What makes you think you need to replace the shut off valve?

Balls I thought I had a future proof car with out all this electronic shite.

 

I am trying to resurrect the car which has been laid up since 98 and its not wanting to run,  a mate and I set to on cleaning the intake side and to cut a long story short an airline and vacuum diaphragm don't mix,   they make a nice bang though

[overrun]

Shall I re-invent the wheel?

Apologies. I deleted parrt of my comment before posting that.

It did say, I was reading that very web page the other week.

 

Handy explanations imo.

[overrun]

Balls I thought I had a future proof car with out all this electronic shite.

 

I am trying to resurrect the car which has been laid up since 98 and its not wanting to run,  a mate and I set to on cleaning the intake side and to cut a long story short an airline and vacuum diaphragm don't mix,   they make a nice bang though

Do the air flap and piston inside the MH move freely? Is the vac pipe connected at both ends?

 

What's the symptons?

[garbaldy]

Do the air flap and piston inside the MH move freely? Is the vac pipe connected at both ends?

 

What's the symptons?

 

yes clean and free.  I have just looked and the vacuum pipe connects to a sensor then branches of into the cab.

 

The fuel tank is out and awaiting cleaning as quarter of a tank of 16 year old petrol has disappeared leaving a sticky wax oil looking residue,  the fuel pump did not work so I cut it in half and it to was glued solid,  

I have a new pump and bike tank set up under bonnet and the car starts first time then cuts out after a few seconds, it wont take any throttle either.

[Junkman]

...the fuel pump did not work so I cut it in half...

What else would a self-respected Autoshiter do with a non functioning device?

[forddeliveryboy]

I have no idea. I find the whole concept of injecting fuels highly suspect and suggest the purchase of a car with a proper air/fuel mixing device.

 

Fuel injection is a German thing. Spitfire carbs would cut the fuel supply in certain manoeuvres, so rather than try and get injection to work we used Miss Shilling's orifice. For years Triumph had problems with FI on the 2500 and eventually it was discovered the pump was placed too close to the exhaust and got too hot. Or something as simple as that, but completely overlooked. Wasn't it Aston Martin who went all injected and the owners demanded a return to carbs? Which is what happened, for a while. Nowt like the feel of a good multi-carb setup. Nowt like the feel of two or more carbs out of tune, either.

 

Once upon a time people had the time to practice such arts. Today the same time is spent trying to get a laptop to connect with a car, then decyphering the screen when it does. Which I wouldn't consider an art, no matter how awkward. If a ten year old can do it, then it cannot require too many skills.

[alf892]

yes clean and free.  I have just looked and the vacuum pipe connects to a sensor then branches of into the cab.

 

The fuel tank is out and awaiting cleaning as quarter of a tank of 16 year old petrol has disappeared leaving a sticky wax oil looking residue,  the fuel pump did not work so I cut it in half and it to was glued solid,  

I have a new pump and bike tank set up under bonnet and the car starts first time then cuts out after a few seconds, it wont take any throttle either.

Fuel pressure/fuel not getting through? More bits glued up maybe

[overrun]

I wonder if it's just running on the cold start valve/fifth injector.

Try unplugging it and see if it still fires.

 

Varify if it works by removing it from the inlet (still connected) and stick it in a bottle or similar.

It should drip fuel when the engine is cranking and stop when it fires up.

 

I would also remove the inlet hose from the MH and pull up the air flap gently with pliers via the bolt in the centre of the plate, whilst someone else turns the engine over.

If it runs like this, you can be sure that the flap and piston are working as they should.

 

Some obvious things to check, do you have any splits or missing pipework? K-Jet hates this and will run very badly or not at all if you have issues here.

 

Do you have the fuel pipes on the right way? I mixed mine up from the tank and the engine would still fire up, but that was it. Turns out that the return was acting as the feed, back-feeding the MH up to the fuel filter.

So fuel was present, just not enough.

 

The system is very pressure sensitive. On that note, with your temp setup, have you bypassed the accumulator?

Again, it won't run without it.

 

Lastly, can you be sure that the mixture screw is set in such a position that would allow the engine to run?

I know this is next to impossible to determine, as it needs setting up on a CO meter.

Yet again, K-Jet is highly sensitive to this.

[fordperv]

Cracking advice tdciweigh,

When k jet works it is an alright thing, but if you think it's bad try living with the ke jet which is on escort arse turbos, your pretty much guaranteed problems they constantly go out of setting and are a complete pita, I'm currently collecting parts to run the mrs rs turbo on cosworth management so it can be setup and forgot about

[Junkman]

Fuel injection is a German thing.

The Oktoberfest is another German thing I'm not too fond of.

[overrun]

Cracking advice tdciweigh,

When k jet works it is an alright thing, but if you think it's bad try living with the ke jet which is on escort arse turbos, your pretty much guaranteed problems they constantly go out of setting and are a complete pita, I'm currently collecting parts to run the mrs rs turbo on cosworth management so it can be setup and forgot about

I became quite familiar with this alien setup when my 16i had issues.

It never hurts to know your way around your car. Once you understand K-Jet it is very basic, providing the components are in good order, it should be very reliable.

 

Age isn't too kind to these components. I was amazed my cold start valve still works. Lol.

 

I always wondered why KE is binned off for Cossie stuff. It sounds like it can be a mare, mate!

[PhilA]

Once upon a time people had the time to practice such arts. Today the same time is spent trying to get a laptop to connect with a car, then decyphering the screen when it does. Which I wouldn't consider an art, no matter how awkward. If a ten year old can do it, then it cannot require too many skills.

 

Ah, yes. That old gem.  Yes, I sit at a keyboard and press buttons all day. I'm sure you could train a monkey* to do that quite effectively.

Now train them to press the correct buttons at the right time in the proper sequence. That's why it's me sat here.

 

However, if it's that easy, why not do it yourself?

 

 

It might not look like an art, but it is. After all, tuning a carb is just twiddling a few little brass screws, how hard can that be?

 

 

--Phil

 

 

*practice not limited to simians

[fordperv]

I became quite familiar with this alien setup when my 16i had issues.

It never hurts to know your way around your car. Once you understand K-Jet it is very basic, providing the components are in good order, it should be very reliable.

 

Age isn't too kind to these components. I was amazed my cold start valve still works. Lol.

 

I always wondered why KE is binned off for Cossie stuff. It sounds like it can be a mare, mate!

Funny that's why I learnt my way around ke jet because of the rs turbo, age is a killer with ke as with most things, most tuners havnt seen a fully functional unit for about 10 years now, the thing I was pretty shocked about is most things are still available sensor wise and you can get a full New ke metering unit but your looking at around £1500 which is more than you'll pay for cosworth management, you get alot more benefits with cosworth management as well e.g. better fuelling throughout the rev range, greater adjustability, smoother power delivery, all round reliability and would you believe it's actually simpler than ke jet as well.

[overrun]

Funny that's why I learnt my way around ke jet because of the rs turbo, age is a killer with ke as with most things, most tuners havnt seen a fully functional unit for about 10 years now, the thing I was pretty shocked about is most things are still available sensor wise and you can get a full New ke metering unit but your looking at around £1500 which is more than you'll pay for cosworth management, you get alot more benefits with cosworth management as well e.g. better fuelling throughout the rev range, greater adjustability, smoother power delivery, all round reliability and would you believe it's actually simpler than ke jet as well.

The price of new metering heads is scary! Thankfully the other components don't seem too bad.

As you say, it's surprising that you can still get them.

 

That reminds me, I need the proper fuel relay for mine. Golf GTi mk1 is the same.

I need to make a trip to Euro Car Parts.

 

How much needs changing to run the Cossie stuff then? I can see myself with a nice S2 at some stage, bug even if not, I'm always interested in learning about new setups.

 

Until a few months back, I thought MFI was where you used to by furniture.

[fordperv]

You need a 2wd engine loom (the 4wd would also work but it's a bit messier due to it being 2 piece with an ugly multiplug in the middle of it), ecu I'm using a l8 from a non cat 4wd (have a suitable chip written) and engine sensors, a crank sensor set up, cam sensor set up (this replaces the need for the cosworth dizzy phase sensor), Efi cvh inlet manifold and adaptor plate, cossy injectors, cosworth throttle body with a pf09 tps, amel valve, Sierra cvh alternator and brackets also crank pulley, suitable throttle cable and bracket, there may be a couple of small things I've forgotten off the top of my head and not to make an exhaustive list, as for fitting it takes 4 wires to be connected up to power up the system, you need to extend a few sensor wires and shorten others (to do a neat job) the inlet needs modifying to take the throttle body and the rest is pretty much nuts and bolts