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L Jetronic help required


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I am having a problem with a misfire, but have a new injector arriving in a couple of days.

 

I have noticed almost no servo assistance in the braking circuit and when I remove the pipe from the manifold there is very little suck so to speak,

 

I understand little of the Bosch L jetronic system that is fitted to my car, but on the left side of the left inlet manifold, there is an adjusting screw, for what I know not.

 

does anyone have any suggestions please, the car is going to the Bosch doctor next thursday in the Wirral, but I would appreciate any help regarding the no servo suck frrom the manifold.

 

regards

Peter

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I have noticed almost no servo assistance in the braking circuit and when I remove the pipe from the manifold there is very little suck so to speak,

 

I understand little of the Bosch L jetronic system that is fitted to my car, but on the left side of the left inlet manifold, there is an adjusting screw, for what I know not.

 

It's probably the idle speed adjusting screw?

You could always try taking the rubber vacuum pipe off the pressure regulator (located at one end of the fuel rail) and see if you get much suck there.

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I am having a problem with a misfire, but have a new injector arriving in a couple of days.

 

I have noticed almost no servo assistance in the braking circuit and when I remove the pipe from the manifold there is very little suck so to speak,

 

I understand little of the Bosch L jetronic system that is fitted to my car, but on the left side of the left inlet manifold, there is an adjusting screw, for what I know not.

 

does anyone have any suggestions please, the car is going to the Bosch doctor next thursday in the Wirral, but I would appreciate any help regarding the no servo suck frrom the manifold.

 

regards

Peter

 

Hi Peter.

 

I have installed a Bosch L-Jetronic on my TR6.

If you have no or very low suck from the manifold , chech if you have any leakage between the Air flow meter and the air input plenum.

This can also cause the misfire because of wrong mixture of air and fuel.

Also check that the PI input manifoils on the cylinder head is properly fastened.

Good luck.

 

Oystein

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Hi Peter

The L Jetronic system will only operate correctly, if all the air entering the engine passes through the “Air flow meter”. As the flap is opened, the resistance changes and this is how the ECU measures the mass airflow to the engine and fires the injectors with enough fuel to maintain the correct air/fuel ratio.

If you have an air leak large enough to effect your servo, this will mean that your air/fuel ratio will be far too lean and this is probably why you are misfiring.

As Oystein has mentioned, you must check all the usual places, for an air leak, it may be that your servo is at fault and air is entering the manifold this way.

Hope this helps

 

Mike G

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Thanks to you all will have a good look round the system tomorrow, the injector was dribbling but now It may not be the problem if it is an air leak.

 

will let you know the result in a later post

 

regards

 

Peter

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I'm very interested by your discussion on the EFI units as you may have noted from the other thread I started relating to fuel economy.

Do you have any advice or guidance for installing the Bosch L Jetronic system on the TR6, ie. parts needed, advice etc, please.

 

My mental list of parts is as follows: (no idea about the value of the bits from a scrapper, might be cheaper to buy a whole car).

 

Ex-Vauxhall/Opel Senator/Omega 6 cylinder Bosch L Jetronic system to include:

Mass air flow meter

6 Injectors

Fuel Rail

Crank position sensor

Water temperature sensor

O2 exhaust sensor

Throttle switch sensor

Knock sensors

DIY ECU

Fuel Hose

 

Is there anything I've forgotten?

 

Which ECU do you recommend?

 

What about distributors?

 

(On the subject of the misfire - I agree from my experience from other cars that air ingress is a likely cause of the problems).

 

I'd really appreciate your comments. Cheers.

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Sadly I know sod all about the system.

 

THE man is Mike Pumford, who devised and sorted the system initially, he has a garage bussiness on the Wirral Tel 0151 632 0002.

 

I am going to take my car to Mikes garage next thursday, but speaking to him directly would be more beneficial.

 

It is a far superior system than the Lucas system fitted initially I am informed by the forum.

 

regards

 

Peter

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Oystein's and Mike's suggestions seem pretty logical to me - I have no experience of the L-Jetronic system on TRs, but I have had a little experience of both K and L-Jetronic systems in other applications, road and race.

 

Excellent fuel injection systems when they're working properly, and a right pain when they're not. Speaking as someone with 3 Bosch-injected Quattros in the lock-ups . . .

 

We all curse the old Lucas PI system, but it's still not without its virtues. Economical it isn't, but it can unleash the horses. Would I swop Lucas PI for Bosch K or L ? No, thanks. No way.

 

Cheers,

 

Alec

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I'm very interested by your discussion on the EFI units as you may have noted from the other thread I started relating to fuel economy.

Do you have any advice or guidance for installing the Bosch L Jetronic system on the TR6, ie. parts needed, advice etc, please.

 

My mental list of parts is as follows: (no idea about the value of the bits from a scrapper, might be cheaper to buy a whole car).

 

Ex-Vauxhall/Opel Senator/Omega 6 cylinder Bosch L Jetronic system to include:

Mass air flow meter

6 Injectors

Fuel Rail

Crank position sensor

Water temperature sensor

O2 exhaust sensor

Throttle switch sensor

Knock sensors

DIY ECU

Fuel Hose

 

Is there anything I've forgotten?

 

Which ECU do you recommend?

 

What about distributors?

 

(On the subject of the misfire - I agree from my experience from other cars that air ingress is a likely cause of the problems).

 

I'd really appreciate your comments. Cheers.

 

Hi.

 

If you plan to convert your TR6 PI to a Bosch L-Jetronic EFI I recomend that you dismantle the system by yourself from the donor car a Vauxhall or Opel Senator 2,5 .

Mybe you also can use the L-Jet from a Vauxhall 3 liter.

There you will get all the parts needed for the conversion.Also you learn how the system are connected.The best is if you can dismantle it from a running engine.

The only part of the job I will recomend to farm out is to drill bigger holes with O-ring grooves in the PI manifoil for the new injectors.

The holes are about 1 mm bigger than original.The L-Jet I have on my TR6 does not have O2 or knock sensor.I use the original ECU from the Opel 2,5 senator.I also use the original TR6 distributor.

There have been some complains about the Air Flow Meter that mybe have a too narrow airflow opening.

I have bought an Air Flow Meter on Ebay from a L-Jet from a BMW 535,and plan to convert it to fit the system I have on my TR6,it has almost twice air flow opening than the 2,5 have.

 

Oystein

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Oystein's and Mike's suggestions seem pretty logical to me - I have no experience of the L-Jetronic system on TRs, but I have had a little experience of both K and L-Jetronic systems in other applications, road and race.

 

Excellent fuel injection systems when they're working properly, and a right pain when they're not. Speaking as someone with 3 Bosch-injected Quattros in the lock-ups . . .

 

We all curse the old Lucas PI system, but it's still not without its virtues. Economical it isn't, but it can unleash the horses. Would I swop Lucas PI for Bosch K or L ? No, thanks. No way.

 

Cheers,

 

Alec

 

Hello Alec

 

are you saying that the Bosch job would be less powerful than the original Lucas set up, I know northing as Manuel said, about either system, but it sounds like folk fit the Bosch for

 

ECONOMY? surely not, if its true then I will be dissapointed.

 

regards

 

Peter

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Oystein's and Mike's suggestions seem pretty logical to me - I have no experience of the L-Jetronic system on TRs, but I have had a little experience of both K and L-Jetronic systems in other applications, road and race.

 

Excellent fuel injection systems when they're working properly, and a right pain when they're not. Speaking as someone with 3 Bosch-injected Quattros in the lock-ups . . .

 

We all curse the old Lucas PI system, but it's still not without its virtues. Economical it isn't, but it can unleash the horses. Would I swop Lucas PI for Bosch K or L ? No, thanks. No way.

 

Cheers,

 

Alec

 

Hello Alec

 

are you saying that the Bosch job would be less powerful than the original Lucas set up, I know northing as Manuel said, about either system, but it sounds like folk fit the Bosch for

 

ECONOMY? surely not, if its true then I will be dissapointed.

 

regards

 

Peter

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Hi Peter,

 

In the days when I ran Lucas PI systems I had a simple philosophy, and a good PI mechanic - he set the system up, serviced it at the normal intervals, and I left well alone. It worked, no problem, all of the time.

 

K-Jetronic is a good and relatively simple system. If it can be made to produce more power than the Lucas PI system I'd be amazed. I wouldn't expect any improvement in fuel economy under hard driving conditions. However, unlike the Lucas PI, K-Jetronic doesn't overfuel to the same degree for a substantial proportion of the operating range. Hence under more restrained driving, it's likely to be a little more economical. Similarly, by providing a more equable mixture through a wider operating range, K-Jetronic ought to be able to offer rather better emissions - as in lower.

 

Good stuff, theory. In practice, the comparatively crude and ancient Lucas PI can be made to produce surprisingly good emission levels from the Triumph 6, approaching those of a well set-up K-Jetronic system. The real problem with the Lucas PI system, then as now, lies more with the 'mechanic' than the system. K-Jetronic is rather more foolproof.

 

L-Jetronic is, for all practical purposes, good old-fashioned Lucas EFI. Rather than re-invent the wheel, Lucas and BL did a deal with Bosch back in the 70s. Early EFI systems had Bosch badges underneath the Lucas stickers . . . even then it wasn't cutting-edge technology, remember the fuel-injected VWs of the late 60s and early 70s ?

 

Given the advantages of a relatively primitive electronic brain over a purely reflex mechanical system, it's reasonable to expect a modest improvement in overall efficiency - power, torque, fuel consumption and emission levels. Which is pretty much what was achieved, bearing in mind that the all-important criteria was that of emission-control. But emission control comes at a price, reduced grunt. You can't have the cake and the halfpenny.

 

Would I favour a Jetronic system over a PI ? Yes, on an Audi or BMW or Ford or Opel. But on a Triumph ? No, thanks.

 

In the same way, and for similar reasons, I'd stick with a 4-barrel Holley or Edelbrock on top of a V8 rather than Lucas EFI or Bosch L-Jetronic. If it's a sports car, then bloody well drive it. Sod the economy and the emissions.

 

Cheers,

 

Alec

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Hello Alec,

 

well thanks for that, its not what I wanted to hear, but you would have to think why did they bother in the first place ( bearing in mind what it must have cost),

 

still onwards and upwards so to speak.

 

regards

 

Peter

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Hello Alec,

well thanks for that, its not what I wanted to hear, but you would have to think why did they bother in the first place ( bearing in mind what it must have cost),

Peter

 

I don't know how much, but it need not have cost Triumph a lot. The Pi system was one that Lucas had been developing for a long time. At that time, it was fitted by Ford to race Capris and by the factory to production Maseratis. Triumph would have leased the system, not contracted Lucas to develop it.

 

John

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An update on the L jetronic fault.

 

I took the car on a trailer to Mr Pumfords garage in Heswall, on the Wirral, On driving (spluttering) into the garage Mike suggested that it was badly overfueling. another TR6 and Stag were in the

garage and on one car ramp a jet engine!

 

It was assumed the regulator due to lack of use was stuck but subsequent investigation has also revealed a wiring problem which was causing some injectors to be permanently open.

 

I had to cut the wiring loom when changing the bodyshell and I must have made more than one error resoldering the wiring loom. Adjustment of the throttle position sensor has been

 

neccessary and that info is not being recieved at the ECU, so more work is required. This system developed by Mike Pumford was also used on racing TR6's and he is to delve into his archive and dig

 

out some history for me, apparently he did work on Daryl Uprichards TR and managed to get 350bhp from the tractor engine, an amazing man and a nice person.

 

I have scewed up here and some of the problems are down to my mistakes, but for those with L jetronic I will try and get some usefull info from Mike which may benefit everyone.

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Hi Peter,

 

Now you know why I dislike electronics !!

 

Mike Pumford is a very capable and talented engineer, he'll sort it out.

 

Personally I wouldn't go to the expense of changing a good PI system for an L-Jetronic. But then I'm a Luddite !

 

In your case, you've got an L-Jetronic system already, so PI considerations don't apply - it's ultimately a better system than PI, so make the most of it. It should go well once it's sorted.

 

350bhp from a tractor engine ? A short life and a merry one :P

 

Cheers,

 

Alec

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An update on the L jetronic fault.

 

I took the car on a trailer to Mr Pumfords garage in Heswall, on the Wirral, On driving (spluttering) into the garage Mike suggested that it was badly overfueling. another TR6 and Stag were in the

garage and on one car ramp a jet engine!

 

It was assumed the regulator due to lack of use was stuck but subsequent investigation has also revealed a wiring problem which was causing some injectors to be permanently open.

 

I had to cut the wiring loom when changing the bodyshell and I must have made more than one error resoldering the wiring loom. Adjustment of the throttle position sensor has been

 

neccessary and that info is not being recieved at the ECU, so more work is required. This system developed by Mike Pumford was also used on racing TR6's and he is to delve into his archive and dig

 

out some history for me, apparently he did work on Daryl Uprichards TR and managed to get 350bhp from the tractor engine, an amazing man and a nice person.

 

I have scewed up here and some of the problems are down to my mistakes, but for those with L jetronic I will try and get some usefull info from Mike which may benefit everyone.

 

Hi.

 

When you look at the wiring diagram on the L-Jet , the throttle position sensor has three states .

If you measure with a voltmeter between chassis and pin 18 on the trottle switch you should measure +12 V all the time the engine is running.

 

The pin numbers also refers to pin no on the ECU

 

1:Ideling state , pin 2 get the +12V from pin 18 on the throttle switch .

2:Not ideling state , not any voltage measured on pin 2 or 3 on the throttle switch, only +12 V between pin 18 and chassis.

3: Full throttle , pin 3 and pin 18 are connected together, +12 V on pin 3

You can run the engine with the throttle switch not connected.

Tip:If your engine run rich on idle or low RPM check that you not have + 12V on pin 3 on the throttle switch,this will give richer mixture.

The 12 V should only be there at full throttle.

The L-Jet system pulses fuel on all injectors simultaniously.

Also check that the fuel regulator has the vacum connection fitted.The fuel regulator should reduce the pressure on ideling.

Another important check is the water temperature sensor.

If you have a broken wire here then the ECU will belive the engine is ice cold all the time and push richer mixture.

When engine not running,unplug the cabel connection on the water temp sensor,should be on the other side of the thermostat than the

original temp sensor.Unplug the cable and measure with an ohm meter,readings

should be 500-700 ohms on a cold engine, and 250 -300 ohms on a hot engine.

 

For those of you who want to power tune a L-Jet here is where you on a simple way can manipulate the system to give richer mixture on

demand by changing the resistance to higher than standard on a warm engine by adding potesiometer or a more sofisticated resistance regulator.

On my supercharged L-Jet TR6 it is here I have modified for more fuel on boost.

 

Oystein

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Thanks to everyone for their input and help, I trailered the car home from Mike Pumfords garage in Hoylake, it sounds fine now, Mike having sorted the wiring removed the fuel from the sump

 

changed the relay (wrong one fitted ) air flow meter and throttle switch adjusted etc etc, I also picked up a spare ECU from Mike at a reasonable cost. It uses a little more fuel he says.

 

Oystein, when you mention changing the resistor, is it only one resistor which needs changing? I presume that this was done before EE proms were available, have you a wiring diagram of the ECU?

 

showing this/ these resistors.

 

Next question is how do you know which resistor/ resistors to change say from a standard Senator system.

 

Just waiting for the bonnet to arrive from the painter and its off for an MOT, then back to the painter to have the door I damaged on the trailer repaired!!!!!!!!!!!

 

but too late for Malvern.

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