Modifying k-jetronic FI Unit [Archive] - SaabCentral Forums

: Modifying k-jetronic FI Unit

21st November 2005, 02:14 PM
I've started reading up on modifying and using alternative K-jet FI units, so far i've found out that an old V8 merc had k-jet so using one with 8 injectors rather than 4 could be an option, the 2nd bank of 4 would be electonically controlled.

The other thing i found was a mod for the Porsche 930 turbo, it uses a pressure switch to up the control pressure of the fuel unit, raising it a 0.6 bar to help with extra fueling. under parts and 930 Turbo ~ Fuel Enrichment System

So i've read a bit more about the control pressure regulator, somehow i need to drop the control pressure under boost, this allows the plate to open further as there is less fuel pressure pushing against the air pressure lifting the metering plate.


21st November 2005, 04:57 PM
I've just been reading about the warm up regulator as it seems a good way to influence how much fuel your injecting, there is a bimetal strip which is heated when you switch the ignition on, when the strip is cold it pushes on a plunger which reduces control pressure and injecting more fuel per volume of air passing over the meter plate, as it heats up the plunger moves up and increases fuel control pressure.

So i just need to figure out how quickly this strip moves when voltage is applied to it (and heats it up), then in theory you could add a resistor(s) to the circuit and reduce the voltage therefore cooling the strip down and reducing control pressure

Make any sense what so ever???

Any idea's?

21st November 2005, 07:03 PM
From what other people have said it sounds like the stock k-jet should be able to easily handle the about of power your car should be dealing with - when its working properly.
So it would seem to make more sense to fix yours first - and then start looking at improving it. :cheesy:

There has been various mention of using the fuel distributor off the porsche before. I dont think theyre that easy to come across though.

The old units used in the 99's have 6 'sockets' on the top, 2 of which are just blanked off.

21st November 2005, 08:42 PM
There are a whole bunch of K-Jet mods out there for early watercooled VW's...I know I've come across links, I'll search and see if I can post anything up here.

I have a cousin who mod'd a K-Jet Volvo B21FT, plenty of fueling for about 210-220 HP at the wheels on that old 240.

22nd November 2005, 03:43 AM
I agree with Tom, you need to get the K-Jet working correctly first before trying to modify it.

22nd November 2005, 04:06 AM
tomarse, I have 6 ports in my k-jet distributor, so did my brothers '84 c900, so you should be able to find one too, Si, if you don't have one...


22nd November 2005, 05:10 AM
Don't get me wrong i will sort out basic fueling issues, just from what i've read you can do a bit to increase fueling over stock levels by modding it.

I'll hopefully test the fuel pump at the weekend, and replace that or the feeder pump if nessesary.

I'm going to try and lower the control pressure under heavy boost then have a 5th injector which would trigger when the meter plate is wide open and add extra fuel, i'll also be running WI and a MBC rather than the APC, i'll restrict boost to 1-1.1 bar and have WI on over 0.6 bar.

Once i've sorted out the datalogger/controler that will replace the MBC.

I've just spend £40 on books (well last night) about K-jet/modifying it so hopefully i'll have a good understanding of it built up in the next few weeks, watch this space for up and comming mods:cheesy: !

22nd November 2005, 09:43 AM
tomarse, I have 6 ports in my k-jet distributor, so did my brothers '84 c900, so you should be able to find one too, Si, if you don't have one...


funny thing is i have a friend who has 6 ports too..but the 2 are blanked with 2 use them, just unplug and connect...while all the others i've seen are blanked'd have to drill a hole if you want to use any of the 2 ports

not sure if his was original saab or not? he used one of the 2 ports for his 5th injector controlled by a boost pressure switch running at 0.92bar...


22nd November 2005, 11:08 AM
Early non-US turbos had the 6 port with two blanking plugs. Later ones have the two undrilled ones. And it's not just a case of drilling and tapping. There's nothing in there at all so would take extensive work to get useable.

22nd November 2005, 11:31 AM
I think for the mean time i'll look to mod the control pressure and add a 5th injector from the cold start valve, if i get a chance after doing the fuel test i'm going to get my spare throttle body, cut out the mount for the CSI and weld it onto the throttle body on my manifold so i can run 5th injector and WI from the throttle housing.

Just bought a micro switch for the throttle body which will switch on the 5th injector, i'm going on a scrappy run on friday to look at other k-jet units, old volvo's audi's and mercs, i'll try and get a Warm up reg off another saab aswell, so i can look at modding that, my initial thoughts are to remove the bi metal strip and put an electronicaly controlled acutator in, then connect that to a pressure switch set to 0.6 bar, when it switches on the actuator will lower the control pressure and therefore inject more fuel.
Should also get my 2 books by the w/e aswell, one on the basic's of K-jet the other on modding them so hopefully i'll havea few more idea's of what can be done.

Hopefully once i've got it sorted MS won't be the only option for 8valve fueling.

23rd November 2005, 05:05 AM
Will be an expert by the weekend;)

23rd November 2005, 05:44 AM
I'd have thought that the 900 would already have a throttle microswitch? The 99 has one that activates on WOT.

What fuel pressure does the k-jet system run at? I was reading some LPG stuff earlier and there was discussion of using the k-jet system to do liquid gas injection as it can cope with the required pressures.
Maybe i'll have to borrow your book sometime! ;)

23rd November 2005, 05:50 AM
I think the US version has but not sure about the UK 900, i've never noticed it anyway.

Only thing is i think it would be better to switch on when the meter plate is wide open and not the throttle as the plate may swing open before the throttle does, may have to see if i can fit it onto the arm of the plate rather than the throttle.

23rd November 2005, 06:09 AM
The warm up reg on the 900 T8 has a pressure signal from the manifold. This increases the delivery fuel pressure as the car comes onto boost.

23rd November 2005, 06:34 AM
I'd seen the vac line running to the pressure reg but could'nt find anything on what/how it adjusts it, hopefully my books will tell me.

Have you any idea how it adjusts pressure under boost?

23rd November 2005, 09:20 AM
So, i've started reading my book, manifold pressure acts on a diafram pushing against atmos pressure causing the control pressure to drop allowing more fuel to be delivered per volume of air through the metering unit.

The easiest way to mod the Unit is to adjust the fuel delivery at idle, which will enrich the mixture throughout the rev range, the second way is to replace the the fuel pressure regulator with a Rising Rate Fuel Pressure Regulator.

I'm trying to hunt down a UK supplier at the moment to get a price.

On the cold start injector, bad atomisation and it's to close to the manifold so you cannot guarantee that the extra fueling you inject gets to all 4 cylinders, so i think i'm going to weld part of the throttle body onto my existing one, then use the additional one to mount the 5th injecor & water injector on, I will also use the additional throttle body to connect to the bypass valve, which will hopefully reduce the chance of fuel/water being dumped to the turbo.


23rd November 2005, 10:24 AM
Si, you should be able to modify the excisting fpr to allow more pressure, the bronze-plate on the back of it can be removes and fitted with a screw. Read it a long time ago, but should be duable...
You can highten the overall pressure over the injectors with shims. There is a 16mm bolt sitting on the side of the fuel-distributor. You can pull the bolt out, there will be a spring on it, be sure not to loose it. You can add shims to increase the pressure. Adding the same amount of shims as there is on there atm, should increase pressure approximatly 1 bar. Standard, there is either 1 large shim, or 2 smaller shims. The 2 small combined makes the same width as the one large one.
Let me know what you find out Si, as I might want to look into it too, of you sort something out :)

23rd November 2005, 03:18 PM
si, i've just junked a 86 8v turbo and still have the injection system, if you want it you can have it

23rd November 2005, 03:53 PM
si, i've just junked a 86 8v turbo and still have the injection system, if you want it you can have it

You didnt put it in the classifieds though did you? I've been watching them as i wanted some bits for my 900T :cry:

23rd November 2005, 06:39 PM
Just spent another few hours reading my books and searching t'internet, i've come back around to either manipulating the warm up reg or buying a rising rate fuel pressure regulator.

If i either use more shims or adjust the CO screw it will increase fueling throughout the rpm range, if i can figure out how to manipulate the warm up reg i can manipulate the fueling under heavy load, the RRFPR would also give additional fueling under heavy load.

Just starting to wonder about wide band lambda now, just a bit too expensive for me at the moment.

24th November 2005, 04:03 AM
Si, did you see this wideband lambda?

24th November 2005, 07:31 AM
Saab-Daniel, i'd seen that one it's a bit to ££££ for me at the moment so looking at this one, hopefully i'll be able to link it to my data logger.

I think i'll have to start reading up on the DIY O2 siteåler_1guide-filer/02sensor.gif

Wideband Oxygen Sensor Ref: DT041

Bosch Oxygen Sensor Bosch LSU4.2 5-wire, wide-band O2 sensor.

Price: £60.16 (Incl. VAT)

24th November 2005, 08:13 AM
Where can you get that one Si?

24th November 2005, 10:03 AM
S-D have a look at this site, they've got all the LM ones listed aswell as narrow/wide band/cables etc etc.

I think i need to learn a bit more about lambda sensors etc before i invest in a wide band one, but i think i'll give narrow band a miss completely as they don't seem to be very usefull when it comes to the high end of engine tuning.

From what i've read you can set the car to run slightly lean for max fuel economy and slightly rich from max power so i think you really need a wide band Lambda to get the A/F ratio spot on and get it in that max power band.

I've also got a Fuel pressure tester on order so that will come in handy, i think i just need a bleeder valve now to be able to test the control pressure.

I'm going to try and get the spare unit of boxman so a can pull it apart, get the shims out and have a look inside without worrying about not being able to put it back together!

28th November 2005, 07:53 PM
These guys have been tuning CIS for a looooong time.

My cousin facilitated his mods to his 240 by playing with the C0 adjustment...but he had also done a turbo swap, so he needed an increase of fueling across the range....he used a fuel pressure regulator off of a late 70's Porsche 911.

Too bad we don't run CIS-E (KE-Jetronic)...autotech sells a nice little mod for those too.

29th November 2005, 09:02 AM
As i've got to get one of these to do the fuel pressure testing if it holds up OK i might try adding one to the Control Pressure Circuit and have it bleeding to the fuel return line, that way I can tweek the control pressure without having to pull the Warm Up Reg apart to add/remove shims as it will effecively do the same thing.

The alternative would be to modify it so that it automatically bleeds a bit of pressure under boost, maybe add some kind of actuator to the screw that can open and close it. I'd also have to build a small control unit for that which can detect boost levels.

If i do it this way i can increase the fuel pressure & the control pressure using shims then fine tune it using the bleed valve. (

I'm going to hold off modding the fuel system until i've got a WB lambda so i can do it properly.

29th November 2005, 09:37 AM
Probably a good idea...if you don't have a good way to measure AFR, then you are probably going to do more harm than good.

The MegaSquirt guys are working on a WB controller that will be compatible with some cheaper Bosch WB 02 sensors, or you can adapt Innovate Motorsports sensor into it....but they have been pretty swamped with MSII stuff recently, so I have no idea what the status of the WB is.

K-Jet is a delightfully simple system...I'm sure there are a myriad of ways to successfully trick the system into providing more fuel, electronically or mechanically.

29th November 2005, 10:01 AM
I'll just use my datalogger and laptop to set the A/F from the O2, you can get a Bosch WB O2 for around 60 UK sterling so i can just about afford that before christmas:confused: , i'll probably get an EGT at some point aswell but will only use the WB O2 & EGT sensor every few months to tune the car, that way they should last a good few years.

As i'll be tuning for power i'll need a WB O2, from what i've read NB O2 are OK for sensing if your rich or lean but pretty usless if you actually want to tune your car rich as they are limited on that side of Lambda. The ratio for max power is just under lamba, somewhere between 14:1 & 14.7:1 i think.

You'll see any difference it makes when i dyno the car next as i'm not doing any more tuning until i get the fueling right. If i get a leap of the 15-20bhp which is expected once A/F is set right it should be a pretty good modification.

29th November 2005, 10:07 AM
Sounds like you're on the right track...just keep us posted...this spring my younger borther and I are going to be doing a turbo swap on his T8, intercooling it, and doing some K-jet we'll be grateful for any advice you might have regarding your experiences.

BTW, what is your headlight modification? You have a pre-facelift, I looks very trick!

29th November 2005, 10:22 AM
Hopefully i'll be doing a little work on them (Headlights) this weekend, taking out the spot lights and replacing with the Golf driving light that go with the headlights (they're from a MkII), then making a screen for them, just waiting for a load of black ABS plastic to be delivered.

I'll update this post with everything i do to the K-jet, and the end results.

29th November 2005, 06:46 PM
Just to come in here (a bit late, but been busy) The only thing you will do by altering control pressure is to lift the air flow sensor plate higher. In my case I tested the car on the rollers with the plate held fully open & still the car ran lean. I also had the mixture control unit machined to deliver 25% more fuel & still it ran lean. The only way was to add another electronic injector to supply more fuel, this was mapped using a K-Star unit designed for the Golf.

29th November 2005, 07:12 PM
That's definitely on the list of things to do, at some point in the next week or 2 i'm going to put a micro switch in under the arm of the plate and position it to switch on when the metering plate is wide open, then trigger the 5th injector off that.

I'm looking at modifying the throttle housing to take the water injector and the 5th injector, just set back a little to give them more chance of getting to all 4 cylinders evenly, if that does'nt look like it will work i'll just have to mod the pipe from the intercooler to throttle housing, just worried about the BOV dumping air/fuel mix into the engine bay.

30th November 2005, 03:17 AM
Si, why not just do as John-w, and pulle back the dump, as we talk about in another thread?


30th November 2005, 05:35 AM
The thing is (unless i'm wrong) i figured if you have a 5th injector any where before the throttle plate you will always risk dumping a bit of air/fuel mix into the engine bay, even if the BOV is behind the injector any pressurised air in the inlet before the plate will be foreced out when the BOV opens.

Maybe it's not as much of a problem as i think:confused: .

The other problem is i'm using steel piping and the mounting bit for the CSI is alumin so would be easier to weld on an extra mount onto the throttle body rather than having to custom build a mouting point onto the steel inlet piping.

30th November 2005, 10:01 AM
I changed my dump valve from a dump to atmosphere to a recirculating for that very reason.

30th November 2005, 10:21 AM
I'll just get a plant pot or something similar and sit the BOV in it:cheesy: .

There must be some easy way of capturing and fuel before it hit's something hot, mind you i'm sure i read somwhere that even if you tipped petrol onto a hot manifold it probably would'nt ignite, i'm not going to test the theory out though!

3rd December 2005, 05:19 PM
Just spent the afternoon in a scrap yard, was after a couple of throttle bodies that i could cut the CS injector mounts off, but got destracted and ended up removing this instead:cool: (

It's a K-jet from an old audi 5 cylinder, i'll run the solenoid controlled 5th injector off a metered fuel line and have it triggered by boost level, over 0.6 bar or at WOT it will inject metered fuel into the inlet, so as the metereing plate rises it will inject more fuel:cool: .

Sweet:cheesy: Just got to go back and get all the braided fuel lines now, was having difficulty getting them off the injectors so gave up, but will be re attempted next weekend!

3rd December 2005, 06:07 PM
Should have just taken the injectors too :) Probably no use but stick them on ebay for 50p and see what happens :D

Looks like a 6 port unit? How does its capacity compare to a 6 port Saab one? It looks bigger so might well flow more?

3rd December 2005, 06:17 PM
I'll have to measure the 2 plates and the shape of the cone to see if they are different, to the eye they look the same, but that's going from memory.

The 6th port is for the Cold Start Injector, i took that off and the braided line but somehow managed to loose it either in the Audi engine bay or on the way up the scrap yard, i'll try and get that aswell when i go back.

I got the 2 braided lines for the warm up reg and for the filter to fuel distributer, it would be nice to get the whole set, just Audi's are really awkward to work on, the inlet manifold does a U around the injectors so it's really hard to get 2 spanners in to take the fuel lines off.

Time to go onto an Audi forum and see how you get the injectors out, ohh and pop the bonnet, i dropped it and it locked and i could'nt figure out how to repoen it!

3rd December 2005, 06:23 PM
nice find. What sort of audi was it off? I want some braided lines for mine! (and i can't really justify the cost of a new set :( )

3rd December 2005, 06:28 PM
nice find. What sort of audi was it off?

:confused: a square 80's one!!!

Go down to a scrappy and look for any older Audi, i dont know if they all have braided hoses but the one i got it off was'nt anything remarkable.

Yea the will look cool to, definitley worth a trip back to get the full set:cool: .

3rd December 2005, 06:34 PM
:confused: a square 80's one!!!

Thats good enough for me!. I dont know one audi from the other anyhow but i can probably hunt down a square looking 80's one ;)

3rd December 2005, 06:35 PM
OK so it had wheels like that, i mean that kinda rally look, and it was kinda square like that too, but just did'nt really look from the side, so maybe i got lucky and found a quattro by chance:cheesy: .

3rd December 2005, 06:41 PM
I be they wont have anything good in the scrappy round here. They never have anything that i want stuff off :evil:
I've been after a header tank off an LDV van for years - but they never ever have the right one in and there are millions of LDV vans!

Yea the will look cool to, definitley worth a trip back to get the full set:cool: .

As well as just looking cool - give your current plastic injector pipes another 5 or 6 years and they'll be as brittle as the ones on my 99T :(. I've got through 2 car 's worth so far.

3rd December 2005, 07:29 PM
If anyone is interested have a look at the evil bay link, i'll be off to the scrapy tommorow i think to recover the last bits of mine:cheesy: . meZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting

4th December 2005, 05:07 AM
Si, measure the diameter of the air-flow plate & compare it to the Saab one.

A bigger plate will let more air in & more air = more fuel = more power :cheesy: :cheesy:

4th December 2005, 07:19 AM
Any idea what the saab plate diameter is, the Audi is 8cm.

4th December 2005, 08:28 AM
Saab 99/900T are both 8cm as well. Don't know about 8v injection though. Probably the same. A golf (GTI?) one I have is the same. Just out of curiosity, what is the part number of the airflow meter you have? It's stamped on a plate on the side (not the fuel distributor one) The Golf one I have is 0 438 120 189.

4th December 2005, 12:27 PM
I went back again today to get the last bits, also got another throttle body off an 8v so i could cut off the mount for it and weld it to another section.

I held the rubber dome/outlet thing off the flow meter for audi & the saab and they were the same size, so it will fit from the inlet to turbo, just got to check and see if the saab air bucket will attach the same.

This is the full set up, i found another Audi in there so i took the injector hose off the Cold Start Injector as it has a different connection to the standard injectors. I've also got the warm up rag but hopefully i can still use the saab one and won't have to mess about with this one.

Complete set-up includes (All from an 1985 Audi Quattro, the second Cold start injector line was from a slightly later quattro)

4*standard injector lines

2*cold start injector lines

6 port unit(5 metered ports, 1 unmetered port)

Cold staer injector ( ( (

4th December 2005, 12:48 PM
Not a big suprise its different, but hey, stranger things have happened :D Is the plunger in the distributor free? If not you might have fun freeing it up without damaging it. I used copious quantities of carb cleaner, and careful use of pliers to tug on it. When it was out I soaked it in carb cleaner again, and polished it lightly. Has worked fine ever since :)

4th December 2005, 03:37 PM
This thread set me wondering; could the ecu from another make of car using K/LH/LE be a swop? I've noticed that the scappys are now full of cars with Bosch efi systems and if you don't say they're out of a Saab, ideally something far more common (!?!) - various bits are dirt cheap. Obviously many of the sensors are common to many makes but are all ecu's unique? Does anyone know if anyone has ever managed to swop one, or 'tweaked' one?

5th December 2005, 09:18 AM
This thread set me wondering; could the ecu from another make of car using K/LH/LE be a swop? I've noticed that the scappys are now full of cars with Bosch efi systems and if you don't say they're out of a Saab, ideally something far more common (!?!) - various bits are dirt cheap. Obviously many of the sensors are common to many makes but are all ecu's unique? Does anyone know if anyone has ever managed to swop one, or 'tweaked' one?

I think you may have difficulty with Electronic FI units as they will be mapped for a certain engine, the benefit of the K-Jetronic system is the fuel is injected continuously and the fuel injected is measured by how far the metering plate lifts so it's not dictated by the engine, i may have to change the fuel pressures a bit with the Audi unit but that's about it.
You can get a fuel chip for the L-Jet systems aswell so your able to mod them a bit if you need extra fueling, where as the K-jet is pretty standard and can't really be modified.

5th December 2005, 10:45 AM
Flap type airflow meters have a limit to how much air they can measure - once the flap is open all the way you are at the limit of fuel delivery and measurment but not the limit of how much air can flow into the engine as this will keep increasing and thus create leanout. Also the shape of the 'bowl' or throat in which the flap sits will control the ratio of fuel to air - I seem to remember that the sides in the injection only cars have a step in them but the turbo cars are smooth. Machining a different profile would perhaps control the fuel flow vs airflow ratio. It 's all a bit hit and miss opening up extra injectors at WOT as if you overfuel you can wash the bores and create rapid wear as well as cholking the engine and not creating much extra power. The stock fueling system was good for 210bhp in the 99 when it had water injection - why are you sure you need extra fuel?

5th December 2005, 03:32 PM
why are you sure you need extra fuel?

I've got fueling problems which probably are caused by a failing pump, on the dyno the car was showing an A/F ratio of 15:1 or over from 2,000rpm up, at full boost it can't keep the pressure up enough to keep the injectors open.

First i will be checking/replacing the fuel pump, then use the Audi metering head/fuel distributer, the plate and cone are the same shape and size, so the only different will be the 2 extra fuel lines rather than 1, just gives me 2 alternatives for an extra injector, 1 metered line and 1 unmetered.

I think PDA was running lean at around 3,500 and he's at 170-180bhp mark.
Ideally i want to be running slightly rich, i'll fit a wide band lambda and use data logger/laptop to set the 4 main injectors and the 5th injector. If i can't get a smooth A/F ratio all the way up the rev/boost range i'll look at MS II, in which case it will be controlling when the 5th injector fires.

5th December 2005, 04:13 PM
Trying to find my plot but failing :(

At 173bhp I was running very rich at the first Ipswich RR day. I ended up in the high 8.x:1 FR :o I was down a lot on power the second because I'd slapped water injection on and it was dumping too much water in.

I still maintian the standard Kjet is good for over 180bhp without mods - probably much closer to 200bhp.

5th December 2005, 05:11 PM
Ohh i forgot, i'll have all steel braided injector lines too:cool: . Apart from anything it's a bonus over the plastic ones as they snap really easily.

Dunno if i'll do enough to the car to get it over 200bhp but next year i'll be looking at getting a fast road cam and the flywheel lightened, and maybe a Trim60 (??? think) Garrett turbo so i'll have the option when it's needed.

I'll also upgrade the downpipe to a 3" system, and replace the full exhaust with a 2.5" to back box.

6th December 2005, 01:03 AM
me running lean :nono; :nono; no sir............ it was just fine ;) my last dyno at LPS was not as "rich" as the first one 10:1 A/F Ratio but it was still very good


Sleeper baby, no so & all GO.....................................

6th December 2005, 05:11 AM
me running lean :nono; :nono; no sir............ it was just fine ;) my last dyno at LPS was not as "rich" as the first one 10:1 A/F Ratio but it was still very good


Oh well atleast i dragged you into the debate!

It's 1 more toy to play with!

It will be on the car by the next dyno day (hut hum Mr PDA;) ...yes i will make it this time!) so should be interesting to see what my cars like with proper fueling.

I have swapped one of the vac lines on the car, i had the Warm Up Reg line from a T piece with something else so i've swapped it to a dedicated vac line of it's own and the car seems to have a little more go now, i have'nt started running with APC again as i want to test the fuel pump aswell.

If the Audi unit helps is can't be a bad solutuion, for £20 anyway!

The problems only really started when i changed the pipe work from around the IC to over the radiator so whether or not the fuel pump is working properly i think i'll probably still need some extra fueling.

9th April 2006, 11:30 AM
Started to dismantle the Audi distributer, at the moment i'm thinking along the lines of putting the Audi Distributer onto the Saab meter plate, maybe if possible just swapping the distributer head and keeping everything else the same on the Saab unit so i keep the same meter plate and distributer (wont have to mess about with the distributer pressure then), and just swap over the head with the 6-ports, very much depends on the Saab unit having the same internals but with a different plate and 5 port head.

I'll try and sort out doing the flow tests etc this week, then i can figure out how easy the mod will be, hopefully i won't bugger both fuel distributers in the process of swapping bits about. (

9th April 2006, 11:41 AM
Trying to find my plot but failing :(

At 173bhp I was running very rich at the first Ipswich RR day. I ended up in the high 8.x:1 FR :o I was down a lot on power the second because I'd slapped water injection on and it was dumping too much water in.

I still maintian the standard Kjet is good for over 180bhp without mods - probably much closer to 200bhp.

just for my own curiosity, what was the BHP at the wheels for your car?

9th April 2006, 12:06 PM
Si, good luck getting that to seal again :o

Dave, I'll dig out the plot, but pretty sure it only put the flywheel figure.

edit: found it. The spikes are the APC detecting knock and pulling the boost down and trying again.

9th April 2006, 12:24 PM
I was going to ask you about that as i was sure you'd played about with them!
Starting to wonder if it will be too complicated to bugger about with:confused:, ah well figuring this stuff out is half the fun!

I was suprised how easily it all came apart, no kind of sealant between the head and body of the distributer or the plate that sits between them, i want to pull apart the Saab one on my car now but wondering if i'd be better off getting a spare one to pull apart and set-up, then if it does'nt work atleast i can put the origional back on, alternatively i could play about with them both and if it goes pear shaped pick up another unit, just wish i had'nt left the spare i had behind at my old place now, sods law....bring loads of useless bits with me and leave the good stuff behind:roll: .

17th April 2006, 07:03 PM
Just been doing a little more digging to try and figure out what rate the 8v injectors flow at, discovered the Porsche 928 used the same injectors as Saab and there maybe uprated ones availiable, so i'll do some more digging and see whats about:D .

Interesting mod to the 928 k-jet:

Porsche 928 Aluminum Adjustable CIS Fuel Distributor

Application : Porsche 928 78-83 with CIS K-Jetronic Fuel System

Ideal for CIS Supercharged, Turbocharged or Stroker Motors

Modified for 30% More Fuel Flow: We start with an aluminum, adjustable CIS fuel distributor (very rare) and completely rebuild it. Then we re-machine the fuel metering system to deliver more fuel at wide-open throttle (WOT). The fuel delivery at idle is unchanged - so your 928 will still idle nice, but just off idle, we start to deliver slightly more fuel than before, graduating smoothly to a 30% gain at WOT.

Individually Adjustable: All the injector ports are flow-matched and set before it is shipped. However, unique to this very rare fuel distributor, you will have individual adjustments on each injector line so you can tune individual cylinders if you need to for your application.

and a modification to the Warm up reg:
Also called a Warm-Up Regulator)

Application : Porsche 928 78-83 with CIS K-Jetronic Fuel System

Ideal for CIS Supercharged or Turbocharged Motors

Modified to Respond to Boost: We start with an aluminum Control Pressure Regulator (aka Warm-Up Regulator) with vacuum-sensitive enrichment (rare and hard to find), and completely rebuild it.

Then we modify it so that it will respond to boost. Normally, the Regulator will change the fuel pressure at the injectors according to sensing either manifold vacuum (lean) to the absence of vacuum aka: wide-open thottle (rich). BUT: we take it a step further and modify the Control Pressure Regulator to respond to positive pressure, and enrichen the flow to the injectors even more. The fuel delivery at idle is unchanged - so your 928 will still idle nice.

Individually Adjustable: We also add a set-screw in the bottom of the Regulator so you can adjust the entire range of fuel delivery up or down as your application desires.