Carbs and F.I.

[lancepar]

Hi All,
I'm to old to understand FI, well info' goes in one ear but don't stop in for long and quickly goes out the other.

Carbs I understand so when I read the threads on the Griffith and Chimaera forums regarding bits that can go wrong between the air filter and the cylinder and affect the running of the engine, or not running, I have to wonder would I be better off with a Griff' or Chim' that is using a carb.
Not looking for performance just a set up on say a 4ltr I can live with.
Any links to articles on the web?
If a carb is used what kit can be removed, ECU etc? What about MOT time, would this be a problem with a carb engine that once had catalysers and lambda sensors in the exhaust?

Thanks in advance.

Edited by lancepar on Wednesday 6th January 22:38

Edited by lancepar on Wednesday 6th January 22:39

[350Matt]

you would need a pre 93 car with no cat to make this work
as you stand little or no chance of passing an MOT test with a later car thats been converted to carb

to be honest I'd stick with the injection system
Its pretty simple by modern standards and well understood

[Sardonicus]

350Matt said:

you would need a pre 93 car with no cat to make this work
as you stand little or no chance of passing an MOT test with a later car thats been converted to carb

to be honest I'd stick with the injection system
Its pretty simple by modern standards and well understood

And pretty bloody reliable IMO

[KKson]

I've got two Wedges, both "flapper" EFi systems and every issue I've had with them has either been mechanical or HT related. The actual ECU/AFM/fuel injection itself has not been the issue. My personal view is that the EFi may be basic but problem free. It's all the usual "stuff" that causes the problems.

[Colin RedGriff]

I think it's just a perception thing. As all Griffs and Chims were originally fitted with fuel injection then you'll only ever see posts about problems with fuel injection equipped engines. Also bear in mind that the majority of posts are triggered when someone wants some help. If the car is running well then they probably won't be posting, they'll be driving

I felt a little like you did when I got my S2 nd latterly with my Griffith. I didn't understand anything about how the system worked. With the information and help available on these forums I feel a lot more confident about troubleshooting issues, although to counter your impression I've not had to do it very much (in 8 years of ownership).

There are tools like RoverGauge available for relatively little money (the cost of a lead) which can give you a lot of information about how the injection system is running.

[lancepar]

Thanks for all your input, lots to mull over.

[jamieduff1981]

Despite being young I do understand carbs, and crap old ignition systems too.

Carbs have a certain charm, but they are a nightmare to set up and keep in good order compared to fuel injection systems. Even working well they are inferior to even basic fuel injection systems - that's why they were replaced so quickly.

Fuel injection is about having fuel in a pressure envelope and the ECU knowing when and for how long to open an injector for. For a fixed~ish pressure the quantity of fuel injected is determined by how long electrical power is applied to the injector to open it. The ECU calculates this from a few bits of information provided by sensors to work out how much air is going in and how far open you have the throttle.

This is sense checked by feedback about how well the fuel is burning for fine tuning.


Carbs need all the same stuff, but set up by a human. Then they detune themselves usually.

[Slow M]

jamieduff1981 said:

Despite being young I do understand carbs, and crap old ignition systems too.

Carbs have a certain charm, but they are a nightmare to set up and keep in good order compared to fuel injection systems. Even working well they are inferior to even basic fuel injection systems - that's why they were replaced so quickly.

Fuel injection is about having fuel in a pressure envelope and the ECU knowing when and for how long to open an injector for. For a fixed~ish pressure the quantity of fuel injected is determined by how long electrical power is applied to the injector to open it. The ECU calculates this from a few bits of information provided by sensors to work out how much air is going in and how far open you have the throttle.

This is sense checked by feedback about how well the fuel is burning for fine tuning.


Carbs need all the same stuff, but set up by a human. Then they detune themselves usually.

Despite being old, I do understand EFI, and I am chasing a poor (st) idle and rough running condition, on my 1999 Ford truck. So far, I replaced the
-fuel pump,
-fuel filter,
-coil pack 1,
-coil pack 2,
-4 spark plugs,
-4 fuel injectors,
-MAF sensor,
and have still not found the problem. The items still to cross off my list, are the fuel pressure regulator, two oxygen sensors, and the computer (which has thrown NO codes).

I have never had this kind of problem with a carbureted engine, with point ignition.

While I appreciate the return in fuel efficiency, and reduction in emissions, I am willing to recognize the level of complexity that we are dealing with. While I was good at tuning my carbureted cars, I am not able to "tamper" with my factory preset EFI ones. They each have advantages and disadvantages.

Best regards,
Bernard.

[Dominic TVRetto]

Much as I am in agreement with much of what is being said here about EFI, one of the issues with EFI on these cars is the electricals...

Blackpool wiring was not class-leading at the best of times, but 20 years of use takes it toll, and poor/degraded/broken wiring can lead to excruciating experiences trying to fault find IME...

Many cars may be absolutely fine, but if a problem rears its head the "parts bin" construction of these cars can make it a much harder task than if it were a part specially developed for purpose.

I had one such electrical issue with the EFI system 5 years ago, and spent so much money trying to diagnose it, that in the end it proved more economical to rip the whole Lucas system out and go aftermarket with fresh loom etc.

Not what I expected and expenditure that I didn't want - but in the end resulted in a more powerful and responsive car. But at a price.

Caveat emptor.


Dom

[jamieduff1981]

Slow M said:

jamieduff1981 said:

Despite being young I do understand carbs, and crap old ignition systems too.

Carbs have a certain charm, but they are a nightmare to set up and keep in good order compared to fuel injection systems. Even working well they are inferior to even basic fuel injection systems - that's why they were replaced so quickly.

Fuel injection is about having fuel in a pressure envelope and the ECU knowing when and for how long to open an injector for. For a fixed~ish pressure the quantity of fuel injected is determined by how long electrical power is applied to the injector to open it. The ECU calculates this from a few bits of information provided by sensors to work out how much air is going in and how far open you have the throttle.

This is sense checked by feedback about how well the fuel is burning for fine tuning.


Carbs need all the same stuff, but set up by a human. Then they detune themselves usually.

Despite being old, I do understand EFI, and I am chasing a poor (st) idle and rough running condition, on my 1999 Ford truck. So far, I replaced the
-fuel pump,
-fuel filter,
-coil pack 1,
-coil pack 2,
-4 spark plugs,
-4 fuel injectors,
-MAF sensor,
and have still not found the problem. The items still to cross off my list, are the fuel pressure regulator, two oxygen sensors, and the computer (which has thrown NO codes).

I have never had this kind of problem with a carbureted engine, with point ignition.

While I appreciate the return in fuel efficiency, and reduction in emissions, I am willing to recognize the level of complexity that we are dealing with. While I was good at tuning my carbureted cars, I am not able to "tamper" with my factory preset EFI ones. They each have advantages and disadvantages.

Best regards,
Bernard.

No vacuum leaks? Fords of that era often had an Idle Air Control Valve on the inlet manifold; a solenoid operated valve which opened when the throttle butterfly closed.

Fords also used an air intake temperature sensor usually too. Normally they just let the fuelling go open loop though and only hurt fuel consumption.

I'd have a good look at the IACV.

[Slow M]

jamieduff1981 said:

Slow M said:

jamieduff1981 said:

Despite being young I do understand carbs, and crap old ignition systems too.

Carbs have a certain charm, but they are a nightmare to set up and keep in good order compared to fuel injection systems. Even working well they are inferior to even basic fuel injection systems - that's why they were replaced so quickly.

Fuel injection is about having fuel in a pressure envelope and the ECU knowing when and for how long to open an injector for. For a fixed~ish pressure the quantity of fuel injected is determined by how long electrical power is applied to the injector to open it. The ECU calculates this from a few bits of information provided by sensors to work out how much air is going in and how far open you have the throttle.

This is sense checked by feedback about how well the fuel is burning for fine tuning.


Carbs need all the same stuff, but set up by a human. Then they detune themselves usually.

Despite being old, I do understand EFI, and I am chasing a poor (st) idle and rough running condition, on my 1999 Ford truck. So far, I replaced the
-fuel pump,
-fuel filter,
-coil pack 1,
-coil pack 2,
-4 spark plugs,
-4 fuel injectors,
-MAF sensor,
and have still not found the problem. The items still to cross off my list, are the fuel pressure regulator, two oxygen sensors, and the computer (which has thrown NO codes).

I have never had this kind of problem with a carbureted engine, with point ignition.

While I appreciate the return in fuel efficiency, and reduction in emissions, I am willing to recognize the level of complexity that we are dealing with. While I was good at tuning my carbureted cars, I am not able to "tamper" with my factory preset EFI ones. They each have advantages and disadvantages.

Best regards,
Bernard.

No vacuum leaks? Fords of that era often had an Idle Air Control Valve on the inlet manifold; a solenoid operated valve which opened when the throttle butterfly closed.

Fords also used an air intake temperature sensor usually too. Normally they just let the fuelling go open loop though and only hurt fuel consumption.

I'd have a good look at the IACV.

Sorry, forgot. I replaced that, too.

Best regards,
Bernard.

[blitzracing]

Instead of throwing parts at it, Id be looking at the lambda probe outputs with a scope or possibly test meter to see how they are cycling voltage wise- it will tell you loads about whats going on in the combustion chamber, and the basic chemistry does not change whatever vehicle.