Page 1 of 1
Posted: Fri Oct 12, 2007 10:01 am
Hi all. I just want to ask a question about the above car's fuel system. Can anyone tell me what ecu if any is this car using and how does its injector system work. If anyone can, pls tell me how does this engine regulate it air/fuel mixture, how does it operate? I've attached a picture of its injector system.
In white = fuel rail and 5 injectors
In red = the only plug to the fuel rail
In blue = fuel lines
Posted: Fri Oct 12, 2007 10:21 am
Well It looks similar to an MP9 type setup found on the newer citi golfs - except that those are 4cylinder.
I dont know what ecu is controlling the engine, But i would hazard a guess to say that it probably has a MAP sensor on the throttle body which which sends info to the ecu for calculation on how much airflow there is,and the ecu will alter the injector pulse width accordingly to suplly more fuel..
I think theres more than just one plug on that rail - if the engine is using electronic injection - each injector will have its own plug..perhaps the one you identified is just taking power/ecu outputs to another connector on the fuel rails wiring harness where it goes to each individual injector.
Posted: Fri Oct 12, 2007 10:24 am
As the car is running Fuel Injection is has to have an ECU to control them.
I would've though it would be a Digifant but that doesn't look like a Digifant system.
Posted: Fri Oct 12, 2007 10:45 am
Like I said, that plug is the only plug that goes to the injector rail. The injectors doesn't have their own plugs. More than six months ago, I had burned valves so I opened up the motor and I was surprised by this system.
Anyway, I changed all valves and their goodies(engineering shop) and I personally put the motor back together. No problems up to this stage and I've done quite few trips of PTA-CT. At this stage, I understand how k-jet works, how electronic system works, but this is different to the widely used mentioned systems. My car is a 96 model if it will help.
Posted: Fri Oct 12, 2007 11:34 am
Anyone who like to share some light?
Posted: Fri Oct 12, 2007 11:37 am
The 2.6i Kombi uses the system similar to a Kombi 2.3i. This system is dgifant type system and your computor box should be under the rear seat and please be careful with it. Apparently this box can loose it's memory and you might have to tow to VW for reprogramming.
Now if you look into the engine from the back, sitting next to the coil (should be on the right side) there is a TCI-like unit with a small vacuum pipe connected to it. This is an airflow meter which tells your computor box how much air is going into the engine. Like any Vacuum-contrlled fueling system there must be no leaks in the pipes or else you will have a problem with the fueling
Okay, to me this system is a continous injection system.
Posted: Fri Oct 12, 2007 12:56 pm
The other day when I took it to VW for timing and CO setting, I asked the guy who was doing it if he could pick up other problem on the VAG like fuel pump and other things, he told me that my ecu is not like MP9 where you can plug it in and do diagonistic test. There's a plug though where one can plug in a VAG but I forgot what he said one can test with it, but it was only one thing that can be tested. Here's the plug im talking about.
As I was taking this picture, I notice that there is a plug on the throttle body and another one on the airbox. Hope someone can figure out how everything works together.
Posted: Fri Oct 12, 2007 1:25 pm
The plug on the throttle is for info like throttle position as well as idling adjustment. It is also for when you start your kombi. It works like the one on Mp9 whereby when your car is switced on it opens a little bit and readies the car for starting.
For your computor box just follow the round plug on the other side of the firewall and it should be there below the seat
Posted: Fri Oct 12, 2007 1:49 pm
I know where the computer box is, this thread is about the workings of the fueling system in particular. Another guy from VW once told me that the injectors works on vacuum system. He said when the piston goes down, they suck fuel from the injectors. Can someone confirm this?
Let me just make this clear, there's nothing wrong with my car, I just want to understand how does its fueling system work.
Thanks for your replies so far!
Posted: Fri Oct 12, 2007 5:33 pm
I donot see that piston sucking fuel from injector story as being plausible..
Since you mentioned the car has an airflow meter - it stands to reason that it the fuelling occurs by it measuring the amount of air it took in and meters the correct amount of fuel for that measured air..simple
Posted: Sat Oct 13, 2007 4:52 pm
basically a version of digifant yes. They measure throttle position and amount of air going into the motor from the airflow meter. Yes there is a single electrical injector connector as they use a parallel pulsed injection setup - so at every ignition signal it will fire all the injectors. Pretty simple and eorks just fine. Remeber k-jet sprays all the time so this is almost an electronic version of k-jet. Yes no motor does Definately NOT suck fuel from the injector.
Posted: Sat Oct 13, 2007 5:31 pm
IIRC..i think the system is called a Digi-Jet system - i stand to be corrected though..
Posted: Sat Oct 13, 2007 7:01 pm
It is a bosch motronic unit.
It has a singel feul rail that will pulse all at once per fire point [5 cyl]
as per panic.It has a idel steppe motor 1xt.b sensor ,water temp , air temp and manifold sensor.
How to adjust system.
1x adapter cable from vag plug to the 5pin plug in the picture as seen.
To get into the ecu the ign must be switched on
Enter ecu  then go adaption  enter channel 01
Start bus [make sure battery stong or it will kick you out]
Adjust the value in channel 01 up or doun [up richer lower leaner]
To adjust ign fire point there is a bridge plug on the adapter harness
plug it in and hold rpm at 2200rpm adjust till the correct timing.
C/O 1.2 +_ 0.2
Timing is 6deg. before tdc
Piggy back can be fitted to the system.
Posted: Sat Oct 13, 2007 9:00 pm
Gees! Thats a mouthfull! Unfortunately im not that clued up when it comes to ecu and electronic gadgets. Thanks for clearing this up. All this time I was under the impression that the piston sucks in the fuel. So I can safely say that this system is not fuel efficient because the injectors spray fuel even when a cylinder is not in its ignition/power stroke.
Do other systems like mp9 spray fuel only when in ignition/power stroke or do they spray it continuously as well? This question obviously cancels my statement where I said I understand how k-jet and other electronic systems work, but anyway, im here to learn and thanks to you guys for providing that necessary knowledge!
Thanks for your replies!!!
Posted: Sun Oct 14, 2007 12:15 pm
The fact that it's not full sequential does not mean engines are not fuel efficient. The time between when it sprays and when the fuel is used is very short - specially at higher rpm. At idle full sequential injection is better in the economy stakes but at say 4000 rpm there is very little in it. remember at 4000 on a 5 cyl motor it will basically open the valve 33 times on a cylinder per second.
Re: Caravelle 2.6i
Posted: Tue Feb 23, 2016 9:08 pm
Hi guys I have a misfire problem on my caravelle 2.6i on idle it can rev up fully with a slight miss but once driven it misfires like crazy and has no power, I've done the cylinder head over I've skimmed the block I've checked the distributor,coil,leads and plugs what else could be wrong? Please assist and could someone plz tell me how to post my own question on this site as it is my first time using this thanks
Re: Caravelle 2.6i
Posted: Tue Feb 23, 2016 9:25 pm
Jojozmotorworx wrote:Hi guys I have a misfire problem on my caravelle 2.6i on idle it can rev up fully with a slight miss but once driven it misfires like crazy and has no power, I've done the cylinder head over I've skimmed the block I've checked the distributor,coil,leads and plugs what else could be wrong? Please assist and could someone plz tell me how to post my own question on this site as it is my first time using this thanks
Firstly this here is called hijacking, which usually doesn't warrant a response. Since I pity you, newb, I shall respond.
On the main index page there is a small button that's marked "New Topic". It creates a new thread.
As for your kombi, get a fuel pressure gauge, test the output of your pump. I bet you eleventy hundred and one seventeen Zumas that your fuel pump is stuffed.
If I'm right be sure to replace the fuel filter same time
Re: Caravelle 2.6i
Posted: Tue Feb 23, 2016 9:58 pm
Lol thanks a mill bru, will do that first thing 2m cheers