Lesson One.

Pull off a vacuum line, and put the little hose on the can of carb cleaner. Spray a bunch of it in the vacuum line hole.

If it still does not start, it's not the fuel injection, if it starts for a second, then dies, it is the fuel injection, that has a problem.

Lesson Two.

The injectors should always have power, they work by grounding.

Lesson Three.

On 75 Manta's there's a little brown ground wire at the back of the Intake, to the firewall. Check that, if it's broken, the car won't run.

I don't know why, it just won't.

 

Lesson Three.

On 75 Manta's there's a little brown ground wire at the back of the Intake, to the firewall. Check that, if it's broken, the car won't run.

I don't know why, it just won't.

I moved my power ground back to the rear.

 

I, too, am an FI nincompoop. But, I've had a few conversations with Charles Goin since he did his great write up on Opel FI and he's tried to explain some of it to me, though.

It's not really all that different from the machines that I work on every day. Mail processing machines are 100 foot long tractor trailer sized contraptions that are chock full of simple on/off sensors and a couple of variable sensors. The computers/controllers read the on/offs from the sensors and the computer then decides what to do.

That's essentially what FI does. To the best of my knowledge, the simplistic Opel FI's work based on just 3 sensor inputs: The tach signal which provides engine speed ; the air sensor telling how much air is flowing through the system ; and the oxy sensor in the exhaust which tells how efficiently the fuel is burning.

Charles tells me that the computer don't do no computin'. It decides what to do based on a fixed "map" or "chart" of preset configurations of what to do based on sensor inputs. It "reads" the 3 sensor inputs, then it refers to it's map/chart and looking for a matching configuration/scenario, which then tells the computer what to do with the air/fuel/spark. The computer doesn't compute nuthin', it just reads a chart that tells it what instructions to send out.

Some guys, like Markandson, use aftermarket FI computer systems that allow you to individually control and fine tune the air/fuel/spark.

That's all I think I know and I may be wrong in what I think.

:veryhappy

 

The Bosch L-Jetronic EFI is almost an electronic carb, and much like a carb, if you look at it as the injectors are nothing more than electronically controlled jets, you're close.

Long story short.. the Injectors fire at each firing of the spark plug ( Yes, 4 times a cycle ), Rich/Lean is controlled by a function of three things.

1. Amount of air thru AFM / Throttle Body
   
2. Length of time the injectors are opened
   
3. Fuel Pressure to injectors

Computer sees these inputs:

Crank Signal from Starter --> Starts Fuel Pump Relay

Run (+) Switched --> Keeps Fuel Pump on

RPM --> From (-) of Coil ( Engine RPM signal )

Air ---> From Air Flow Meter.. The AFM is the most important part of the equation..

Temp --> Engine temp, the warmer the motor the leaner the injector cycle

Throttle position sensor --> Only three signals - Idle, driving, acceleration/full throttle

• Idle - Computer ignores Temp sensor and uses Idle map
• Driving - it pays attention to the AFM for ramping injectors
• Acceleration - It goes full band on the injectors

>> Everything else is mechanical

The Throttle itself, opens like that on a carb, and as it opens the AFM opens.. The AFM has a spring tensioned door. The more open the AFM door the more time it opens injectors. Thus more fuel and richer mix. This spring tension can be adjusted to affect idle and performance. The AFM has a bypass adjustment screw to lean out as well. To allow more air by the AFM flapper without affecting the ECU calculation based on the flapper.

The Fuel Injection Pressure is controlled by vacuum of the engine.. and the more pressure in the fuel rail the richer the mixture.

Everything else on the EFI is all about cold start and running..

Cold Start Valve :

(+) Is CRANK SIGNAL -

(-) COLD - Closes the contact and the cold start injector richens the mix until start

(-) HOT - Open and injector doesn't turn on.

Auxiliary Air Valve :

Heated Coil that works just like an electric choke.At start up its closed so system is richer.. as it warms up.. it opens up and a set amount of air bypassed the Throttle and leans the mix out.

It's the one of the SIMPLEST of L-Jet injection systems

Sorry Gordo.. But in our system its so simple it doesn't even have a 02 sensor, that comes in later (Mid 80s) it's not that smart. Later model LE, LU, LN etc.. started adding crank sensors, O2/Lambda sensors, and even altitude and knock sensors. That just added more feedback and adjusted the EFI for better fuel economy and emissions.

http://www.opelgt.com/forums/factor...orums/factory-fuel-injection/45954-bosch-injection-theory-trouble-shooting.html

The "Tweaks" that can be done to the L-Jet are limited.

1) The AFM can be adjusted both by the mixture bypass screw (Allen wrench adjustment on outside of AFM) and the AFM flapper spring (Which is trickier and on the inside of the black box of the AFM)

2) The Fuel pressure can be adjusted to be at a single set point and not affected by the vacuum. Same rules apply.. more pressure, more fuel, less pressure less fuel. This requires a aftermarket Injection regulator.

3) Change the computer or Fuel Injectors from off another car (This is more a wing it and best guess thing..)

JUST Like a Carb.. Most problems with EFI can be traced down to a vacuum leak, or a clogged jet (Injector).

Unlike a carb, the EFI has relatively few parts and all are easily replaced and checked.

 

The Bosch L-Jetronic EFI is almost an electronic carb, and much like a carb, if you look at it as the injectors are nothing more than electronically controlled jets, you're close.

Long story short.. the Injectors fire at each firing of the spark plug ( Yes, 4 times a cycle )...

I may be wrong but wasn't there some kind of frequency divider..two pulse per 720?

 

Excellent write up.

So on modern cars there's a "mass airflow sensor" and on our cars there's an "air flow meter" which serves the same basic purpose?


With the injectors firing on each pulse of the distributor, does that mean that each injector fires four times per intake cycle on each cylinder? That seems counterproductive.

 

#1

MASS Airflow sensor.. is MUCH more accurate it measure the air as it passes thru.. the density, amount, etc.. It MEASURES the Mass of the air.

Airflow Meter as in the L_Jet, is a spring loaded door on a pivot.. As the engine opens up and creates a vacuum, the air is sucked into the engine and pushes the door open. The computer then gets how much the door opened and calculates the amount of air flowing thru it, not the mass.

#2

Yes, no more counter productive than a constant stream of a gas/air from a carb.

In this case, the injector is sized for pulsing 4 times.. At 2000 RPM it's a more precise fuel measurement than that of the carb. Yet, it's also simpler than trying to measure one big shot and time it with the valves properly. IT doesn't have to be super accurate in the timing of the injectors. Just real close. Remember, the Old LE system didn't even adjust spark.. it was Fuel only, and only signal from the motor it got was the RPM one.

New cars control spark on each cylinder and time it to the fraction of a second..

There is a reason my LS2 in my GTO with 400 HP gets the same MPG as my 100 HP Opel Kadett..

 

Does anyone happen to know the pulse length for the injectors?

 

On my Fopel 4 ms idle.

 

On my Fopel 4 ms idle.

View attachment 113018

That chart is good info, except there aren't any discernable labels.
Also, are you pulsing all of the injectors simultaneously or are you pulsing them only on the intake stroke (actually I think one would want to begin the pulse about 25 degrees before the intake stroke begins)

At 4ms, though...

At 600rpm the engine fires 5 times a second. That means you have 200ms between pulses. So, 4ms pulse works fine for that.
If you go to 6000rpm, though, you end up with only 20ms between pulses. Plus you would be needing a longer pulse to maintain a good fuel/air mix. This doesn't seem unreasonable unless the pulse length goes over 20ms at 6000rpm.

Am I correct in thinking like this?

 

Pardon me for asking, but I'm can't for the life of me figure out why you would want to know any of this information, unless you were planning on designing your own FI computer from scratch.

Then there's your question about whether all the injectors fire simultaneously. Huh? Why would you even think they would do that? They would have to fire SEQUENTIALLY. Otherwise, you'd be squirting fuel on the exhaust stroke sometimes.

As I understand it, you are trying to set up your new car's 2.2 block/2.0 head to run, right? You've got a lot of issues to conquer on that car without adding the complexity of adapting an FI system to a Frankenengine like that, plus all the other FI mods. You're perfectly set up to just put a Weber 38 on it and be done with it..........for now. You can always revisit designing your own FI computer at a later date.

As far as all this business of pulse widths, time variables, micromilliseconds, etc., the computer does all that calculating for you based on the sensor inputs.

Pardon me if I'm missing something here............

:thinking:

:veryhappy

P.S. PJ has no use for the 2.4 head on the engine I traded him. Maybe you could get it from him, rebuild it, and then put the Opel FI system that was made for a 2.2/2.4 engine on it.

 

Pardon me for asking, but I'm can't for the life of me figure out why you would want to know any of this information, unless you were planning on designing your own FI computer from scratch.

Then there's your question about whether all the injectors fire simultaneously. Huh? Why would you even think they would do that? They would have to fire SEQUENTIALLY. Otherwise, you'd be squirting fuel on the exhaust stroke sometimes.

As I understand it, you are trying to set up your new car's 2.2 block/2.0 head to run, right? You've got a lot of issues to conquer on that car without adding the complexity of adapting an FI system to a Frankenengine like that, plus all the other FI mods. You're perfectly set up to just put a Weber 38 on it and be done with it..........for now. You can always revisit designing your own FI computer at a later date.

As far as all this business of pulse widths, time variables, micromilliseconds, etc., the computer does all that calculating for you based on the sensor inputs.

Pardon me if I'm missing something here............

:thinking:

:veryhappy

Well, since you are the king of modification, I'm sure you would understand someone wanting to create their own FI computer. But that's not my main goal at this time.

I'm asking because there are a lot of options for controlling FI.

I looked earlier in this thread and it appears that the Opel FI brain DOES fire simultaneously. Each injector fires four times per cycle. But you are thinking incorrectly on the possibility of the injector firing into the exhaust since the intake valve opens to allow gas to go in.

Think of it this way (although I try not to ~LOL~)
Have you ever seen a smoker take a drag off a cigarette? They suck a mouthful of smoke from the cigarette and then open their mouth and suck it all in their lungs in one swoop. So the air mixes with the smoke as they inhale, not as they are sucking in the smoke.

So, the Opel FI system is set up to fill the port full of "gas" fumes (similar to the mouthful of smoke) and then it all gets sucked into the chamber during the intake stroke.

I am just thinkiing it would be more efficient to spray gas into the moving airstream instead. And I believe that's the way modern FI systems work.

So, in essence, I'm wondering if there is a relatively easy way to accomplish this.

As for having a lot to do to get the 2.2 to fire, I first need to understand HOW it works. I know I could just hook up all the wires to the proper connectors but what's the fun in that?


P.S. I HAVE an Opel engine with a Weber. Heck, I have TWO of them. I could go with tried and true, sure. But, like you, I'm stepping outside my box.

P.S. PJ has no use for the 2.4 head on the engine I traded him. Maybe you could get it from him, rebuild it, and then put the Opel FI system that was made for a 2.2/2.4 engine on it.

Something to think about but would that be an advantage over a modified 1.5 head?

 

Okay, then, I can understand this discussion as an excercise in mental gymnastics.

It still seems crazy to me to have all 4 injectors fire at the same time. That would mean that on some cylinders the fuel would squirt at the perfect time(just as the intake valve was opening) and on other cylinders that same simultaneous squirt of fuel would sit in the intake runner/port until that cylinder did a cycle before it's intake valve opened. You want the gas to remain as airbourne droplets not evaporated(vapor lock) or condensing on the sides of the intake/port waiting for a valve to open(kinda like flooding). Maybe someone can straighten out my thinking.

I've read discussions here about having two injectors per cylinder. The oem ones that are close to the intake port for normal driving and another set farther from the intake port for high rpm driving.

Ha! Let's see ya calculate the quasimilliseconds and transition timings for that!

:lmao:

:veryhappy

 

I think you read that wrong.
I was told (above) that all four injectors fire whenever there's a signal from the distributor. So they ALL fire on the intake, exhaust, combustion, and compression strokes. So no cylinder actually has an advantage over the other.

Calculate nanoseconds for dual triggers? It's all just the same math.
The problem is finding an easily programmable system that can handle the calculations. I know they are out there.

Otherwise it's piecing together the right analog components to function together to deliver the correct pulse lengths to the correct components. A variable pull-down resistor ladder would probably work.

 

Hmmm. A carburetor feeds fuel continually. I believe Bosch CIS fuel injection also sprays fuel continuously in proportion to the air flow sensor position.

 

Right. And I bleive this is why the FI system was designed like it was. In all basic, for dummies, terms. It works.

Could it be improved? I think so.

 

If you want to learn look at www.megamanual.com it will not answer your questions about the old Bosch systems but it will educate you about fuel injection in general and then the simple systems will seem like no brainers.

 

This link is NOT for dummies :haha:


(good info though)

 

injector timing

Go nine teeth in front of the missing tooth...TDC
Jeff's probably fires his GT injector around the same spot.

BTW sequential fuel injection cylinder two injector shown.

 

Go nine teeth in front of the missing tooth...TDC
Jeff's probably fires his GT injector around the same spot.

BTW sequential fuel injection cylinder two injector shown.
View attachment 113074

Yup, trigger wheel is 36-1 and missing tooth is set 90 Deg. out front (BTDC), which equals 9 teeth.

 

Missing tooth? I don't have any missing teeth.

I assume the missing tooth is where the arrow is pointed.
And is this a 20ms span?

 

The screen is 200ms in length.
There's 10 blocks of 20ms per block.

 

IMHO

Megasquirt = NOT for dummies.. and requires a lot of money, and skills, patience and knowledge. Also for a daily driver its only marginally better than the Bosch system. Again IMHO.. I don't think its worth the effort unless its a Very custom, and high performance motor.

Bosch system = Does the job, big improvement over carbs and if parts are sourced from the right places you can do the whole thing for just the price of the Megasquirt computer. For a stock to only mild performance motor, its more than enough and works well.

This is why I wrote these articles:

Info on Opel 2.0LE / BMW 318i system : http://www.opelgt.com/forums/factory-fuel-injection/42962-2-0l-le-injection.html?daysprune=365

Info on tuning it : http://www.opelgt.com/forums/factor.../47065-bosch-l-jetronic-fuel-injection-afm-adjustment-tuning.html?daysprune=365

Info on Bosch systems and theory : http://www.opelgt.com/forums/factor...fuel-injection/45954-bosch-injection-theory-trouble-shooting.html?daysprune=365

 

MY two cents
Unless your going for a period correct car the old, simple, Lame-jet system is
worthless.
Try putting a non-stock long duration camshaft using the above mentioned.
It will drive you crazy.
The lack of tuning ability read injector pulse after the exhaust closed event is a killer.

 

injector timing part 2

Cool now that we know nine teeth before is TDC.
Nine teeth after is also TDC so let's add the next injector into the mix.
As shown ~360° of crankshaft rotation.
720° is a full cycle.

Another look with some place markers. Full 720° of crank rotation.

 

First Opel 1981 asked a question
and I tried to answer it the best way that I know how.

Yes I know which place this ? was posted "Factory Fuel Injection".

I couldn't help myself :lmao:

 

First Opel 1981 asked a question and I tried to answer it the best way that I know how.

That goes without saying.. :haha:

As you even added charts.. :lmao:

 

Bob when you "peg" the MAF,AFM nasty things happens also.

 

Okay, Bob, now on that point and pertaining to FO81's specific 2.0 head/2.2 block, do you think that L-jet could adequately handle his poorly breathing head for that size block?

:thinking:

 

Whoa down there, buddy.
Who has the poor brathing head?
I have cams at the grinder right now being worked for better flow and a little longer overlap.
I'm having a 1.5 head opened up with bigger valves.

I'm not putting together a run of the mill setup. I am building a true MUTT!

 

OK, to put this argument aside. Let's look at the basics again.

On a stock Opel FI system, all four injectors fire simultaneously, triggered by the spark trigger.
Each cylinder gets four small squirts of fuel for each time it fires.
The amount of time of each squirt is based on feedback from the airflow flap. The more it opens, the longer the squirts of fuel.

Is this correct?

 

Yep..

YOU can richen the fuel with an aftermarket fuel pressure regulator.. by increasing pressure.

You lean with the AFM by adjusting the spring to get you in the ball park, and then with the air bypass screw to fine tune.

I use the a gas analyzer to tune it in and then fine tune by driving.

As I haven't gotten the LU Injection complete on a car yet. Only difference between the BMW LU and Opel LE is that it has a O2 sensor, so theoretically it should lean the motor for better emissions and MPG.

Also get yourself a 75 distributor, install a pertronix and change the springs and set to a 10 degrees from TDC.

This has worked well with a combo OR-66 cam.

My setup is a 2.0L HC with 2.0L Valves and Opel springs.

But as Bob said, if your custom grinding the cam, etc.. then all bets are off.. as the lopping of the motor at idle can make adjusting it much harder as it pulsates the AFM flap as Bob mentioned.

 

No it's sort of a banked injection
That's why it's used anymore ****ty exhaust emissions.
Repeat after me "more power-less fuel"

 

That and it was designed in the late 60s / early 70s when controls were more rudimentary solid state and not as fine tuned as the newer computerized systems.

Technology improvements made it obsolete.. Its also why carbs arent used anymore

 

I would like to talk about "Load"
With a high load more fuel-less spark timing.
Low load more spark timing-less fuel.
Now you can mix and match all of the above...have fun!

 

:dunno:

 

WOW! What the heck are all you guys arguing about. The three systems IMHO are all completely different. Carbs is carbs, old FI is old FI, and modern FI is just that MODERN. There are still millions of horses in our country but very few of us ride them to work. Why are all the carbs gone? Why are all the old FI systems gone? PROGRESS. If you want to use an old system, go ahead, but that does NOT make it better, and no amount of discussion will change that fact. The other thing is the "dummies" attitude. None of us here are are too stupid to figure out fuel injection, you just have to WANT to learn fuel injection and if you don't want to learn that's fine too. It still is no grounds for arguing or throwing stones at others, in either direction.

 

WOW! What the heck are all you guys arguing about. The three systems IMHO are all completely different. Carbs is carbs, old FI is old FI, and modern FI is just that MODERN.

Exactly..

Carbs is 50s-60s tech

Bosch L-Jet is 70s-80s tech

Modern custom EFI is 90s + tech

My reason for liking the L-Jet over the modern tech is that our motors were designed in the 60s and its pretty simple and straightforward to install on our older motors with minimal modifications and off the shelf components. It is better than Carbs, but not as good as a custom EFI. It splits the difference.. Effective, and easy to install and understand.

Modern EFI, requires custom modification, and fabrication of parts. It may not be for "dummies" but for those of us looking for upgrades that are "bolt-on" and can be explained in a simple step by step process, its not for us either.

If upgrading to a more modern sequential EFI was "easy", it would be able to give a simple step by step guide in how to do it and all components to do it would be "off the shelf". That of course is not the case as it is CUSTOM..

If you want to use an old system, go ahead, but that does NOT make it better, and no amount of discussion will change that fact.

This is where I think the confusion comes in.. BETTER THAN WHAT exactly, and in what situation.. ?

I am advocating that Bosch L-Jet is better than a 32/36 or a 38 DGAS, that's all. Not that its the cream of the crop or the most modern or best system in the world. Only that its better, in the right situation, than the older carb system.

I.E. Many upgrade from a 32/36 to a 38 DGAS because it is better for the right engine.. is it the best ? Yes and no, while it has the potential to be better it won't be better without modifications to the jets, emulsion tubes, etc..

Just as 1975 L-Jet is BETTER than a Solex carbs (If it weren't, would Opel have gone to it over the Solex..? I don't think they spent the thousands and possibly millions to switch if there wasn't a reason to do so)

Just as 80s LE/LU Jetronic is BETTER (Better injectors, DME/ECUs, inclusion of things like O2 sensor, etc.. it EVOLVED) than the first generation 1975 L-Jet

And

Just as custom Megasquirt, etc.. is BETTER than 80s LE/LU, because its CUSTOM designed to meet the needs of the custom motors performance curves, etc.

The options between a 32/36 DGAV and a Custom Megasquirt system, and which one to use are obviously based on the complexity of your engine build and its needs.

So this black and white argument that XYZ is better, or not, misses the overall point.

Would you invest in a Megaquirt system on a 2.0L With 2.0L Valves and a mild cam..? No its not worth it.. what you get for your investment would be negligible compared to just running a basic Jetronic based system.

Would you invest and install a LU system on a low compression 1.9L..? No.. the investment to results ratio isn't worth the investment there either, just stick to a 32/36.

Unfortunately, a few here, tend to over think things and are stuck in their ways.. and seem to miss the point I am trying to make.

I blame it on an over reliance on charts and graphs to make their point.

 

O-kay Charlie! Enough. You made your point!

We accept what you're saying. Your L-Jet system would be a bit more reliable than carbs and WAY simpler and cheaper than modern FI.

We get it.

Some of us will go your route.

Some of us will go the modern FI route.

Some of us will stay with carbs.

Time to close your pie hole!


:veryhappy

 

Time to close your pie hole!

onder:

 

What Harold says is true. Sometimes carbs can be incredibly reliable.

I had a 32/36 on my Ole Yeller car for 225K miles. I never jetted it properly, or ever took it apart to clean or check anything. I just messed with the screws on the outside and kept it clean with carburetor cleaner. I didn't know donkey about cars. 15 year daily driver. 225K! Brand new 2.0 with a combo cam. All I did was change the oil and keep the various bolts tight. 225K!

I could always get it started fairly easily and it ran great.

Even the Red Baron's massively f'd up engine with 50-50-90-50 compression would start every time for me and perform like a fire-breathing dragon on the highway.

Yeah, it took me 3 years to get it that way, so maybe bad example.

But eventually it was very reliable.



And I didn't have to learn no diggity-dang computer code to make it happen.



What fun is an Opel that runs perfect all the time?

I love that roll of the dice every time you drive one!

What's gonna break or fall off this time?

Big FUN!!!!!

Wheeeee!

:lmao:

 

No real knowledge so I fit the dummies part of this well.

I do own two Opels
1972 GT, from an engine standpoint it be stock with 32/36 Weber
1975 1900/Ascona also stock with L-jet FI

Both sat for about 2 months this winter. GT in garage, Ascona outside under car cover. Went to start them for first time about two weeks ago.
For GT, turn key to on position and press peddle to floor and let off. Take foot off peddle and crank for about 30 sec. Wait a few seconds and repeat crank. After about fourth crank motor sputters and dies. After a couple more times motor catches and spins like a top. Let it sit on high idle for a few minutes and it's ready to go.

For Ascona, Turn key to on and then ignition. Crank about five seconds and car starts. Granted plugs seemed to foul at first but soon ran fine, put it in gear and go.

Typical summer driving

GT, Float bowl dry in the morning takes some cranking to fire up but runs smooth. Drive it long enough and second start will be a flooded start due to raw gas in throats. Push peddle to floor clear gas thru and car starts, after a minute or so you are ready to go. Cold starts require the need to replenish gas that boiled out of float bowl. GT runs fine.

Ascona, First start of day takes a few cranks, I think I have some pressure loss. After that about two cranks, hot , cold or other wise and it's off we go. About three years of ownership now and no problems.

I drive Opels because I enjoy them. I try to be a good maintainer and maybe improve them when I can. They will never be #1 show cars or performance machines because I want to drive them cross country to Opel events. I read the posts here and try to pick up tips. Some of what I read might as well be Klingon. No problem, in some cases all I want to be able to do is steer someone who is supposed to know what they are doing in the right direction.

In summation I find the FI to be more drivable on a day to day basis.