L-Jet on Euro Motor
- Thread starter Stuartc
- Start date
kmead
Old enough to know better
As I recall a few folks didn’t machine in the scallops on the intake ports and didn’t have an issue.
fiatfactory
Steve Cecchele
@Stuartc seeing as your X19 is a 1988, are you going to be required to fit a cataliytic convertor and associated emission control devices? You may actually be required to fit the EFI to get your car registered - as a 1988 model - so it compllies with 1988 ADR's?
Australian legislation I'm pretty sure will require a catalytic convertor to be fitted, as everything manufactured after 1986 was required to be ULP filler neck and C.C... obviously the filler neck requirement is now defunct as leaded fuel isn't sold retail any longer, but the C.C. requirement I don't think is optional for any petrol vehicles manufactured post January 1986. (and over 700cc which is why the FSM Niki - Fiat 126 was exempt)
SteveC
Australian legislation I'm pretty sure will require a catalytic convertor to be fitted, as everything manufactured after 1986 was required to be ULP filler neck and C.C... obviously the filler neck requirement is now defunct as leaded fuel isn't sold retail any longer, but the C.C. requirement I don't think is optional for any petrol vehicles manufactured post January 1986. (and over 700cc which is why the FSM Niki - Fiat 126 was exempt)
SteveC
Stuartc
True Classic
Hi Steve,
I’m being told as long as the vehicle passes a roadworthy pit inspection, has 3 point seat belts and correct lights then that’s the only things they will be concerned with.
The import process into Australia was flawless, car wasn’t even required to be cleaned, sailed through customs so I’m hoping the licensing will be smooth sailing also.
Lots of food for thought and thanks for all the views. I think Steve’s sheet on the head work will most definitely be a good investment. As I mentioned I have owned a stock 81 1500 UK x1/9 which I put twin DCNF’s on and was more than happy with that outcome even without any head work so I would like that outcome again with my current “X”. I still like the idea of putting FI on but as I’ve read with most L-Jetronic equipped cars the AFM is the weak link along with the fact that the ECU is not programmable. But agree a way forward would be Microsquirt ECU mainly as I’m not really wanting to add cam & crank sensors and be happy to stick with stand alone ignition.
So I think for the short term I’m staying with the DATR and adding/changing to DATRA so I can manage the A/C idle then possibly Cary out Steve’s advice while it’s all apart getting tidied up. This car has been untouched since new.
After this twin DCNF’s or Fuel Injection.
Bjorn Nilson
True Classic
I am quite sure you need a crank sensor at a minimum. A standalone ignition system would just make it unnecessary complex. The ECU works like a unit and is constantly adjusting ignition, fuel/air ratio based on load, revs, knock, temp etc.
Go all in or stay with your carbs.
Dr.Jeff
True Classic
Yes, there isn't a need for a cam sensor. This is only needed if you want to program for fully sequential mode, which is extreme overkill on a street vehicle - especially one with a very old technology engine design.
And you could retain the standalone ignition if you wished. However that reduces one of the big benefits of going to a aftermarket ECU. As Bjorn said, controlling the spark together with the injection makes things MUCH more efficient. And efficiency is the key to everything - power, drivability, economy, reliability, performance, etc.
And you could retain the standalone ignition if you wished. However that reduces one of the big benefits of going to a aftermarket ECU. As Bjorn said, controlling the spark together with the injection makes things MUCH more efficient. And efficiency is the key to everything - power, drivability, economy, reliability, performance, etc.
kmead
Old enough to know better
You can get by without a crank sensor. It will be better with one but can certainly be done using the same distributor signal the Bosch unit uses.
Going that way would net you an adjustable injection system which could compensate for a variety of parameters and not be limited by cams. It would be better than the Bosch system but not as good as it all being controlled by the ECU.
Ignition advance will be effectively be the same (unless you integrate a knock sensor which would broaden the possible range), the strong advantage of making the ignition controlled by the ECU is some of the tricks you can use at low, no load RPM to stabilize idle and of course at the top end or custom advance curves.
Bjorn Nilson
True Classic
The distributor signal is a trigger wheel in a way, but I doubt it is supported. At least my MaxxECU required a trigger wheel (60-2 or similar), but maybe Megasquirt is different. I assume you didn't mean to have a separate ignition system. If so, you will miss some qualities with the ECU; no common interface for settings/adjustments/tuning/error log... It would add complexity and I can't see why not use all the basic features built into the ECU. Adding a trigger wheel and a sensor is a small thing. A knock sensor is probably luxury on a N/A engine, but possibility to set custom advance curves is good. As you say, ignition advance (together with fuel/air) is also used by ECU for setting idle, A/C idle up etc. This is especially important if not having an idle valve.
kmead
Old enough to know better
Agreed but the nice thing is the system can be built up in increments as systems are completed.
Using a later Fiat or Yugo Motronic seal carrier will net a place to put the sensor and the crank pulley has the wheel built in. Otherwise it’s a bit of a hassle to add on at least for those of us in the US.
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Dr.Jeff
True Classic
Actually some aftermarket ECUs (including MegaSquirt) will allow the use of the Bosch distributor impulse to control the fuel and spark. It supports several types of electronic ignitions that way, but not all. Basically it uses the lower half of the dizzy (no cap, rotor, wires) and reads only one pulse per dizzy rotation (the other three are removed). However it is not quite as accurate as using a crank trigger wheel. The distributor has more play and variability than the crank. But with a very conservative tune it will work for a fully batch/wasted spark setup on a mild street build, especially on a old technology engine like these. It would definitely be the easiest approach to going aftermarket ECU. And as Karl said, the system could always be upgraded later.
Another option for using the distributor trigger signal is to utilize it as a cam sensor, to program fully sequential fuel/spark. However that is still not as accurate as a true cam sensor, for the same reasons. But going fully sequential is very overkill for these engines, it really won't result in any improvement from semi-sequential and little improvement from batch. Programming the system as semi-sequential is a nice option, and does not require a cam position sensor nor the distributor (as long as you have a crank position sensor). It gives many of the efficiency benefits of sequential but much simpler all around to do.
Another option for using the distributor trigger signal is to utilize it as a cam sensor, to program fully sequential fuel/spark. However that is still not as accurate as a true cam sensor, for the same reasons. But going fully sequential is very overkill for these engines, it really won't result in any improvement from semi-sequential and little improvement from batch. Programming the system as semi-sequential is a nice option, and does not require a cam position sensor nor the distributor (as long as you have a crank position sensor). It gives many of the efficiency benefits of sequential but much simpler all around to do.
dcioccarelli
Dominic Cioccarelli
Hi, first post on here so hello everyone. . Done a lot of reading here and elsewhere on the subject matter but nothing really specific.
First off 1988 Bertone X1/9 UK Euro motor with 24/66/64/28 Cam, Weber 34 DATR 85 BHP so completely stock.
What I’d like to do is put the L-Jet FI on the car that US cars came out with.
Again a few things, I’m aware of all the differences regarding head design so I know I will need to change thermostat housing to accommodate water temp sender and probably the thermo time switch and add aux air valve, O2 sensor etc.
I’ve also read that Matt from Midwest Bayless said that on the US spec cars that if you raised the compression added either a set of headers or euro exhaust and cam that the motor would produce about 100bhp.
As the Euro motor already has the exhaust & camshaft & compression lift would it be logical that I would see the same power output and also will the std L-jetronic be able to accommodate for the cam, exhaust and compression of the Euro motor.
I’m not looking for a race car just drivability gains primarily as I’m fitting factory air conditioning.
Any feedback will be appreciated.
Hi Stuart,
I did this on one of my cars although I think 100bhp is optimistic without additional modifications (such as a big valve head). Here is a writeup I did for another member @maz124s (also in Australia):
Bolting the stock FI system onto a carb head (essentially what I did) requires the following modifications (none of which are difficult).
1) Notching the head so that the flow from the injectors isn't interrupted. This can simply be done with a dremel (or similar). Ideally, you would have a FI head available that you could copy, but in the worst case I can take some photos of a spare FI head I have here.
2) The thermo time switch. This is part of the cold start system (which you should note is completely separate from the injection control unit) and controls when the cold start injector will operate. Essentially, it is simply a time delay system based on a thermoswitch and heater. When cold, the contacts are closed powering the injector. With the electrically controlled heater element, after about 8 seconds the switch will open causing the cold start injector to shut off. With a warm engine, the switch will already be warm so the contacts will already be open.
3) The Auxiliary Air Valve is also part of the cold start system. It is responsible for bypassing air around the throttle plate causing a richer mixture when the engine is cold. As the engine warms up, the amount of air passing through the AAV becomes less until the valve closes completely. It also contains a heater element so that the closing of the valve is somewhat time dependant. With a warm engine, the valve will be warm from the block, so it will remain closed.
I was able to get around the second two issues (the thermo time switch and the AAV) via a simple Arduino micro controller connected to the standard temperature sensor in the head. This effectively allowed me to emulate the function of the thermo time switch (the cold start injector is driven from a relay connected to the Arduino). For the AAV, I used a PWM controlled idle control valve similar to this one:
Basically, you program the micro controller to change the duty cycle of the PWM output so that the valve opening is proportional to temperature. I added an extra potentiometer to one of the Arduino inputs to provide an (optional / additional) manual idle control.
You will probably need a thermostat housing from an FI car which has provision for the temperature sensor used by the fuel injection ECU. I was going to eliminate this as well and simply get the arduino to send the appropriate voltage depending on the temperature measured by the temp sensor in the head (as I felt that multiple temperature sensors was essentially redundant) but this car (with the FI engine) was written off in a crash the week after I finished rebuilding the engine (not my fault and the insurance paid up nicely). As a result, the project was put "on hold". The car is currently in Poland (at my in-law's place) and just acts as an incubator for the engine which fires up every time.
I'm back to my Australian delivered 1300 X1/9 which is a very different beast. High revving, and no electronics whatsoever. Just a nice, big single carb.
You should also get yourself a copy of this book which explains how L-Jetronic (and other Bosch systems of the era) work.
https://www.amazon.com/Bosch-Fuel-Injection-Engine-Management/dp/0837603005
Also, check out the FI links (pretty much all from my bookmark collection) from the wiki page:
http://x19.xwebforums.org/wiki/index.php?title=FuelSystem
Anyway, if you need any additional information, I'd be happy to help you with the project.
Stuartc
True Classic
Hi Dominic,
Thanks for info.
What would be interesting is your observations on how the car performed compared to previously fitted with carb?
lookforjoe
True Classic
Just to add to this - I would say adding the stock EFI is not worth the investment, especially given the rarity/reliability of some the main components. Of course, if you are after a 'factory' or 'stock' setup, then I can understand wanting to stay with what production cars had in place.
Any aftermarket setup that includes ignition management (it should) will require very careful ignition mapping. I know from personal experience how quickly head gaskets will blow from too much midrange advance. Also knock detection is useless unless the system you are adding is programmable to the specific frequencies of the motor. I tried using a Bosch system from an 80's Volvo, and it did not register any knock that absolutely was taking place - frequencies of the 1500/1600 Fiat motor did not jive with what it was tuned for.
Any aftermarket setup that includes ignition management (it should) will require very careful ignition mapping. I know from personal experience how quickly head gaskets will blow from too much midrange advance. Also knock detection is useless unless the system you are adding is programmable to the specific frequencies of the motor. I tried using a Bosch system from an 80's Volvo, and it did not register any knock that absolutely was taking place - frequencies of the 1500/1600 Fiat motor did not jive with what it was tuned for.
Dr.Jeff
True Classic
While I agree with you, I think using some of the stock FI system is worth it when converting from carbs to FI. Things like the complete intake manifold/throttle body/injector rail, etc, would be extremely costly to assemble with purely aftermarket stuff. There are independent throttle bodies, custom fuel rails, and such available but they are quite expensive and will require a lot of engineering to make them fit and work right. Having the major items - like the intake manifold assembly for one example - that are a direct bolt on application makes the whole conversion much more doable....particularly for the majority of X owners that may not have the resources to do a lot of custom/fabrication work or don't want to spend a fortune.
But I suspect that wasn't what you were really saying. I would agree fully that the stock ECU and ignition could be upgraded to a aftermarket unit, eliminating the air flow meter and some other components, and offer much better control of the fuel and ignition systems. However even that does require some programming and tuning to make it work correctly. So it is not a "bolt on" job.
On the other hand, if someone found a complete original FI system that was in proper working order and wanted to make the conversion as simple and straightforward as possible, then using the entire stock system is still better than most carb systems (please see my last paragraph to qualify that). As for the availability of stock FI components they are out there. I happen to know of two full systems that could be had.
However these comments are in reference to a regular street driven stockish X1/9, and not a extreme custom build or full race car. So the individual's goals (and budget) certainly play a role.
Stuartc
True Classic
Probably should start new thread but I’ll drop this here first.
Has anyone changed out their Std Bosch fuel regulator for a Variable Rate of Gain fuel pressure regulator to compensate for any limitations of the L-Jetronic being able to supply more fuel following modifications ie Cam, compression, head work etc?
As the regulator is/can be adjusted for load/WOT without affecting idle or low load settings I’m just trying to identify this would be the best way forward with L-jets limitations on higher output motors.
Has anyone changed out their Std Bosch fuel regulator for a Variable Rate of Gain fuel pressure regulator to compensate for any limitations of the L-Jetronic being able to supply more fuel following modifications ie Cam, compression, head work etc?
As the regulator is/can be adjusted for load/WOT without affecting idle or low load settings I’m just trying to identify this would be the best way forward with L-jets limitations on higher output motors.
Dr.Jeff
True Classic
I have a adjustable, variable rate regulator as past of my ECU swap. But for a stock FI system you would have to consider a few other things. Do the injectors flow enough volume for the modded engine's needs? Does the fuel pump provide enough volume and flow to make the targeted pressure? Will the AFM supply enough air flow to support all of the added fuel? And others. Some of those factors can be upgraded to increase your fuel supply (pump, injectors, etc), but other items really cannot (AFM for example). And more importantly, consider that increasing the fuel pressure is not the same as reprogramming the ECU to supply the correct air/fuel ratio for your mods. These ECUs are not programmable and tweaking the spring on the AFM won't get you there. So the question isn't a simple one.
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Stuartc
True Classic
Yes, appreciate it’s a “bit what if” equation but I’m trying to do as much research as possible before I commit down this path but I’d be lying if I said I hadn’t already started purchasing a few bits already 
.
So some assumptions first!
Target h/p would be around 100bhp 34% up from stock l-jet but 17% increase over ROW 34DATR (my model).
Std fuel regulator is 36psi for F.I.
Head ported for fuel injectors, manifold & runners port/gasket matched as a minimum. Not sure much be gained from opening plenum chamber and making any improvements but probably open up/smooth entry to butterfly.
Std injectors.
Variable rate of gain regulator added to the return side of the stock regulator (as per instructions). Purpose being to increase pressure to fuel rail for 4000rpm or so upwards & WOT, pretty much where O2 Sensing & AFM are not providing any more input to fueling. Results being increased fueling in the higher load range.
Without going into a huge explanation the calculation for determining the proportionate increase of fuel delivery for increased HP is (1+%increase)squared - apparentlyin this situation
1+34 = 1.34 x 1.34 x 36psi = 65 psi target pressure.
From what I’ve researched the std Bosch fuel pump can deliver at least 90psi so 65 psi well within capacity.
I know this is all a bit “pie in the sky” stuff but the numbers seem to check out so far assuming the injectors can deliver higher flow at the pressure and duty cycle.
A lot of people say these variable rate of gain devices are a waste of time but it does appear that they do work on air vane style AFM’s ie L-Jet FI rather than other variants of FI.
Apologies if I sound like a “nutter” just my logical mind trying to make sense of the limitations to L-Jetronic on higher output engine.
Any comments/recommendations for a therapist welcome.
.So some assumptions first!
Target h/p would be around 100bhp 34% up from stock l-jet but 17% increase over ROW 34DATR (my model).
Std fuel regulator is 36psi for F.I.
Head ported for fuel injectors, manifold & runners port/gasket matched as a minimum. Not sure much be gained from opening plenum chamber and making any improvements but probably open up/smooth entry to butterfly.
Std injectors.
Variable rate of gain regulator added to the return side of the stock regulator (as per instructions). Purpose being to increase pressure to fuel rail for 4000rpm or so upwards & WOT, pretty much where O2 Sensing & AFM are not providing any more input to fueling. Results being increased fueling in the higher load range.
Without going into a huge explanation the calculation for determining the proportionate increase of fuel delivery for increased HP is (1+%increase)squared - apparentlyin this situation
1+34 = 1.34 x 1.34 x 36psi = 65 psi target pressure.
From what I’ve researched the std Bosch fuel pump can deliver at least 90psi so 65 psi well within capacity.
I know this is all a bit “pie in the sky” stuff but the numbers seem to check out so far assuming the injectors can deliver higher flow at the pressure and duty cycle.
A lot of people say these variable rate of gain devices are a waste of time but it does appear that they do work on air vane style AFM’s ie L-Jet FI rather than other variants of FI.
Apologies if I sound like a “nutter” just my logical mind trying to make sense of the limitations to L-Jetronic on higher output engine.
Any comments/recommendations for a therapist welcome.