Ferrari 400/412 K Jetronic Metering Head Rebuild (Myths and Advice)

See http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/863588-cis-hp-hard-ceiling-cis-injector-flow-rates.html#post8607220

To make a long thread short, see last post page 1.

These are the 3 Bosch refs :
0437 502 009
0437 502 017
0437 502 057
(plus a few equivalent)

The later one (057) do reportedly deliver 5% more fuel.

 

One point about the printed Ferrari information for Bosch CIS is that they are often just copying text/information from a more general Bosch CIS manual (that covers many different implementations of their CIS system on many manufacturer's designs) so sometimes something more general leaks thru in the F text that isn't necessary to specify for a Ferrari manual that only covers a single exact Ferrari model. For example, they did a better job of "pruning" the more general Bosch CIS information down in the TR WSM, and only have a single spec for "full load" of 140 cc/min for the adjustment point -- i.e., deflect the airflow sensor plate to get 140 cc/min from the minimum flow injector and then check that the maximum flow injector does not exceed 153 cc/min.

 

Well no I don't. I really don't even know what the topic is.

For the sake of context what are you trying to fix? Coming into the middle of a conversation never really gets me anywhere.

 

Maybe you should chime in the Porsche forums, as the k-jet was more of a bottleneck wjen trying to achieve more than 350hp out of a single metering head. So they just documented all the variations quite extensively.

Based on these forums I've come to understand that depending on the system pressure, fuel line and injector spring and orifice, you can obtain different maximum flow.

I personnally think this is not a performace issue but more of a way to adust full throttle enrichement versus idle. (even if the Porsche guys do use it as a way to grab a few more cc of gasoline).

What the documentation says is that, there are three ranges of maximum flow (i.e full throttle enrichment). So in theory you could swap injector types in order to fine tune the mixture. Here again that's not really necessary in our case as it is more simple to adjust the wur full load enrichment (not all wur do have full load enrichment).

Here again that's assumptions, not something I've tested: I've personnaly only used the stock parts and adjusted the system as per the manual. I've just used the lowest recommended control pressure (better for more aggressive camshaft setting), and increased the cold pressure so as to avoid nasty fumes during startup (never driving the car when freezing).

 

I sure hope you have the very specific equipment to perform this. I strongly suggest using the services of one of the very few good specialists there are that do this for a living.

It was suggested to check comparison flow ratings at 3 different points in the range available of the assembled air flow meter. There was no precision way to achieve this or to replicate to the needed precision so flow measuring equipment that could test all 6 in a single set up is required. The Bosch KDJE 7451 is a Bosch workshop tool for doing that. The process was to adj by whatever method you chose to hold the airflow plate a small way open in such a way it will remain absolutely stationary for the duration of the teas and measure the output to every cylinder. Then test again at some chosen mid way point and then again at full open. The numbers given are only suggested flow rate points of measurement. Using that equipment for that reason is something I almost never do despite having a couple sets of the equipment to do so. I consider it a waste of my time. Once it is known by me there is a fuel distributor fault it goes in a box off to someone who is far better equipped to repair them. Considering its importance and the need for correct and very consistant operation to the functioning of the car I have never considered them a project for anyone outside of a highly specialized repair person/facility.

 

You need much more than a few graduated cylinders with hoses running into them. Thats a pretty oversimplified description of what it does. I thought it was a good book but I have a lot of years reading Germany's own special way of translating into English. They have their own terminology. Good luck with the project.

 

I am not so sure... You can see in my previous posts that I actually did this, but this was in order to check that the distribution was in the ball-park, not to adjust it.

Unlike Golf or other german cars, the fuel lines are short and only flexible on an even smaller length. So you do not have lot of room to keep the container vertical (~more fuel escapes) . If you want to accurately measure "in situ" you would have to use very small container, and use a reamer so as to make the smallest possible apperture for the injectors.

When we did this with my mechanic, he just said we should stop here and make it do with the 4% difference as we would only make it worse.

I know you do not jave access to a bosch service. Maybe you should
1) buy the Bosch tool
2) OR make your own
3) OR invest in 6 long fuel lines

Also, do not check the volume, just check the weight of the gasoline with a 0.1g scale.

 

My 250ml bottled were too big. In any case we managed to collect ~6x25g of gazoline on each run.

At 6x100g the fume will be horrendous (remember that if you fill the bottle with 100ml, there is 100ml of vapors that has to get out).

As said we did not modify the flow we just checked it was correct.

 

When the WURs outputs are cross-linked (which by the way is not the case on all 400i), the control pressure of the two WURs is "leveled", which in my case made it impossible to reliably adjust the control pressure.

I ended up removing the crosslink between the two WURs, in order to adjust each of them separately. for this purpose I had to replace the double port banjo by a single port one.

See here for the Banjo references : https://www.ferrarichat.com/forum/threads/where-to-buy-washers-for-fuel-banjo-fittings.371419/#post-141523447