drilling disc brakes

[jtbo]

Originally Posted by mikehallbackhoe

dfco is a nice feature, but if the engine is running , it is still burning fuel. the reason I bought this crx is that it has no power steering or power brakes, and a manuel transmission. I do eoc whenever the opportunity arises, which, up here in the mountains, is quiete often. on steep , twisty roads, that means using the brakes a lot. as long as the brakes are up to the task, that's all right with me. If I have to replace the pads more often, that's ok too, pads are cheap.

But, you can engine brake without engine running, idle cutoff solenoid actually does that automatically and I read from other responses that your car should have that too, so you can kill the engine or not and result should be same, no fuel goes trough engine.

If car ignition lock is operating properly, one should have no steering lock issues when turning key to ACC, that would not allow engine to start while coasting engine off, only when key is removed, steering is allowed to lock, but if there is problem with steering lock, playing with key on speed might give some issues, so one need to be bit careful with that of course.

However engine braking on steep hill cools engine more than if engine is not running at all, so that would reduce economy in your situation, I believe, so for you braking might be better, maybe, it is bit hard to know how much each thing affects, how much are brake pads and how much more fuel engine warmup will need then, lot of factors to consider.

Also brakes don't like from not being used, so they stay in better condition when used, that is too one point that needs to be considered.

You know it best which method will work, you can also make test runs of each method, we can only note things that affect to other things so you have all the information and ideas available to make best decision, so that is my view and opinion on this subject.

[mikehallbackhoe]

I am trying to wrap my brain around this concept. dfco means that with the engine off,no throttle, engine braking, will not use any fuel? Isn't the engine still acting as a pump, and use some fuel? also ,will this put undue stress on the engine? I would rather replace brake pads than an engine.

[CigaR007]

The ignition is still on, only the fuel injectors are cut-off. No fuel is injected during the DFCO. The moment you depress the accelerator, the ECU/ECM will once again send pulses to the injectors, thus leaving the DFCO mode. There is no inherent engine stress related to DFCO.

[mikehallbackhoe]

my crx has a carburetor, so I don't see how this would work.

[CigaR007]

You are right, it would not work on your given car.

[jtbo]

Originally Posted by CigaR007

You are right, it would not work on your given car.

Is this certain?

I have 1988 Volvo with carburetor and it has fuel cutoff solenoid, it cuts off idle circuit of carburetor when I do engine braking, I would think that his Honda might have similar too?

[Vman455]

Originally Posted by Ryland

All of Honda's CVCC engines had deceleration fuel cut off (DFCO) starting in 1978 or whenever it was that they started making them, that is part of the reason for 57 vacuum lines controlling the carburetor, including 4 or 5 valves that are built in to the carburetor that can cut off fuel to all of the jets.

Originally Posted by mikehallbackhoe

my crx has a carburetor, so I don't see how this would work.

Your CRX has a CVCC engine (E-series), and, if the above is correct, DFCO.

[CigaR007]

I cannot say for sure. It could have a similar system. One would have to investigate each system to see if such a feature is present or not.

[mikehallbackhoe]

I have the cvcc engine.

[Ryland]

I just checked my service manual and the CVCC engine started in 1975, so that was the first year that the engine was able to cut fuel 100% while the car was engine braking and by that I mean that any time you take your foot off the gas pedal and the engine starts to slow the car down that the solenoids in the carburetor close off the fuel supply to all of the jets, to do this the key must be turned to "run" (so don't touch the key!) the oil pressure switch needs to see that there is oil pressure (oil light on the dash is off) the engine RPM needs to be slightly above idle, the switch on the clutch pedal needs to see that the clutch is not pressed in and there needs to be enough vacuum to keep the brake booster charged, as long as all of those fail safes are met the mess of vacuum lines will turn off the fuel so no fuel is being used while the engine slows you down.
So as long as you keep the stock carburetor and keep all of the vacuum lines in tact (something teenagers like to pull out to "clean up" the engine bay) your car will DFCO whenever you take your foot off the gas pedal.

If you would like I can dig around and see if I still have the dealer service manual on online somewhere that you can look at the wiring diagrams and vacuum hose routing your self, but if your car is stock then I can say for sure that yes, it has this feature.