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Taking that into account, I would blindly trust you guys to be able to come in out of the rain. Sorry, could'nt resist...

If same thing is happening with the gas gauge, buy it fast!

I reused mine three times without apparent problem.

The cat and maybe part of the exhaust system might be good.

Don't presume the light is not working cause you dont see it with the other idiot lights when the ignition is at ON and the car has not yet started. That's how it works. Dont ask me why. You really have to drive your tank to the last few liters for it to come on. I tested it once, with a jerry can, and IIRC i was able to drive close to 70 kilometers (highway) before the engine began to stutter. Dont completely trust the gauge either. The needle often goes under the E mark without the low level light coming on.

According to the pressure gauge I installed under the hood of my car, it's around 30 psi at idle and goes almost up to 40 psi under acceleration. If you briefly pinch the fuel hose downstream of the pressure gauge, a good working pump will up the pressure to around 60-65 psi.

Wawalker, A good discussion is one where all participants learn something they did'nt know before and it's also been my case. But like you I end up with more questions than answers. The first part of my little experiment shows vaccuum plays a role in the engine braking effect but much less than I expected. The second one also is disappointing in that respect. I aggree with you that friction probably plays a greater role than I initialy tought possible, and particularly in an AWD car (4 tires, 4 bearings, 1 engine, 1 trans, 1 transfer case, 4 half shafts, 2 differentials and let's not forget alt, ps, etc). If I ever find or think of something new, I'll report back.

I did a little experiment last night along the lines WaWalker suggested. 1) First experiment (in a vacant parking lot): took the car to 30 Kmph in second gear and turned the ignition off just passing a selected lamp post, first with throttle closed and after that with gas pedal to the floor. The pass with throttle wide open gave me around a fifth to a quarter more distance than with the closed throttle. Not very conclusive... 2) I stopped the car at the top of a medium incline (street with no traffic near the parking lot), shut the ignition and let go of the brake. After initial acceleration the car got to a "cruising" speed of around 25 kmph. When I pushed the gas pedal to the floor (throttle wide open), I felt no clearly perceptible acceleration. ?????

See "Smoke after engine braking" for the beginning of this discussion Maybe not full atmospheric pressure but more pressure than in the cylinder. Did you ever suck on a PCV valve (new:) ) with you mouth? I did and it closes when the vaccuum exceeds a certain amount.

I opened up a new thread. I have difficulties having access to the Board since last night. That explains the repeated new thread. I'll try to remove the first one (second one going down the list).

See "Smoke after engine braking" thread for beginning of this discussion. Brilliant idea! If it were not so dark outside, I would go to MontRoyal (10 minutes ride) and try it myself. Will certainly do it tomorrow.

Let's hope this discussion will have helped the first poster better understand the functionning of his engine and his problem. Otherwise, i could certainly be proven guilty of having criminaly hijacked this thread. So this will be my last post tonight and we could open a new thread if we both have developed a taste for it. The case for compression braking is, in my opinion, completely destroyed by the Jake brake explanation I've quoted above. There are only two possibilities : (1) If little or no air is compressed during the compression stroke then little or no energy is dissipated = little or no braking effect (2) if enough air is present in the cylinder during the compression stroke it acts like a spring when comes the power stroke and gives back the energy it absorbed in the compression stroke. If you add to that a little fuel and a little combustion (like you yourself state) then the engine produces more energy than it has dissipated in the compression stroke and the result = no braking effect whatsoever. Have a good night!

I just reread it and I think it's wrong. I think I found something, also in Wikipedia, that strongly support my point. It's the explanation of the Jake brake functionning. Here goes : "The Jake Brake or Jacobs Brake is a particular brand of engine brake manufactured and sold by Jacobs Vehicle Systems, Inc. While the term Jake Brake technically only describes Jake Brake brand engine brakes, it has become a genericized trademark and is often used to refer to engine brakes or compression release engine brakes in general, especially on large vehicles or heavy equipment. "Jake Brake" is a registered trademark of Jacobs Vehicle Systems, Inc. An engine brake is a braking system used primarily on semi-trucks or other large vehicles that modifies engine valve operation to use engine compression to slow the vehicle. They are also known as compression release engine brakes. When the accelerator is released on a truck, its forward momentum continues to turn the crankshaft and compress air inside the engine's cylinders. When the crankshaft passes the top-dead-center position, the compressed air in the cylinder acts as a spring and pushes the piston back down the cylinder, returning the energy to the crankshaft and pushing the truck forward. Little of the energy absorbed by compressing the air is lost, so the engine does not effectively aid in slowing the truck. Of equal importance, even with zero accelerator input, there will be some trace introduction of diesel fuel (make and model dependant) which will still undergo combustion. Any power created from this will hinder efforts to decelerate. In a gasoline engine, some engine braking is provided during closed-throttle operation due to the work required to maintain intake manifold vacuum, the balance coming from internal friction of the engine itself. Diesel engines, however, are unthrottled and hence do not provide engine braking from throttling losses. A compression release engine brake uses an extra lobe on the camshaft to open a second exhaust valve at the top of the compression stroke. The stem of this valve telescopes during normal operation so the valve remains closed, but is locked at full length by a solenoid when the engine brake is engaged so that the valve opens as directed by the cam. This releases the compressed air in the cylinder preventing it from returning its energy back to the piston and accordingly, the vehicle." In fewer words, compression does not have a significant effect cause it acts like a spring giving back, on the power stroke, the energy it has absorbed during "compression". If diesel trucks needs the Jake brake or in other cases exhaust brakes, it's because compression braking in itself is nil and cause they are unable to use vac braking due to the lack of a throttle plate. That strenghtens my point. Compression is not what brakes a "petrol" engines cause, like I said, there is minimal air in the cylinder to be compressed to begin with AND the compressed air, acting like a spring gives back the energy it has absorbed. Which leaves vaccuum braking. Thanks for bearing with me WaWalker.

And have you read post #30 ?

If you read post #24, you'll see where I finaly saw the light . (Edit) In post #21, I was tinking "open intake valve" and forgetting "closed throttle plate". Which shows I can admit it when I'm wrong. Nothing I've said since that post has been proven wrong, in my opinion of course.

I completely agree with the last part. But the fact that the engine is braking shows that almost no energy (pressure) is produced during the power stroke. I like seat of the pants experiments but the only problem with the one you're describing is that's it's imaginary. If you could really put up such an experiment I would trust you with the results no problems. I hope I'm not overextending the limits of your taste for discussions on technical points:burnout:

Yes, but that's not what's happening during "compression braking". During the compression stroke on "compression" braking, there is not a "cylinder full of air" to be compressed. To make this (open to discussion) statement I rely on three things: 1) According to your own numbers there is only a third of the volume of air getting inside the cylinder on the intake stroke when on "compression" braking compared to what's happening at idle. The maff is showing 3.1 gs instead of 2.35 gs on engine deceleration, but the rpms are 4 times higher . For the same volume of air to get into the cylinders on "compression" mode at the stated rpms, the numbers would have to be around 9.4 gs. 2) On a normal intake stroke (at idle for example) the injectors are squirting a vaporized mist of fuel that must certainly occupy an additionnal volume inside the cylinder. This, according to your own numbers, is almost nil during "compression" braking contributing to the vac being produced at the intake stroke. 3) The last argument is part intuitive and part scientific. I think we all agree that a vaccuum is created inside the cyl at the intake stroke when "compression" braking (this is what explains the oil being sucked inside the cylinder). Vac means air is not completely filling the void produced by the piston moving away from the valves and that atmospheric pressure is pushing on the other side of the piston. In that situation it does'nt take much energy, if at all, to push the piston back up. I rest my case .

Thanks for the scientific experiment Wawalker. But I'm not sure I understand your last statement correctly. When an engine is idling and even more when it's running at part or full throttle there must be, like you say, a big difference between the energy needed to compress a full mixture of air and fuel and the force needed to suck that same mixture inside the cylinder while the thottle plate is open. But on "compression" braking, the shutting of the throttle plate and the partial shutting (like you measured) of the injectors not only means the energy needed to move the piston on the intake stroke increases considerably, but the force needed on the compression stroke must become not only nil but probably negative : the vaccuum produced during the intake stroke is pulling the piston up on the "compression» stroke. If I'm right - and I'm all willing to be shown where my logic is failing - the name "compression braking" is false and should be replaced by "vaccuum" braking. What's your expert opinion on this?

i'm only answering cause you're in a hurry and i seem to be the only one at the screen at this hour. Wait for more knowledgeable answers if you can, but your have most of the symptoms of a busted head gasket. Ask the guy at the garage to look for bubbles in the overflow thank and/or exhaust smell at the radiator. Is the coolant gushing out of the overflow thank?

Thanks. That shows I was part wrong in my last post cause I was overlooking the restrictive effect of the closed throttle plate when the engine is in "compression» mode. So, if I read correctly, this shows the braking action of the engine is mainly due to the higher vac present at the intake stroke cause of the closed throttle plate. There might also be some braking action at the compression stroke but certainly less cause there would not be much air present in the cylinder to be compressed (some getting past the closed throttle plate and some metered by the IAC). But this brings us back to Susam's post : oil being sucked in the cylinder, thru the valve guides and/or rings, during the high vac situation of the closed throttle intake stroke and not being completely burned (cause of "minimal combustion» or «extra lean» situation as pointed out by Skip) and finaly appearing as grey smoke at the tail pipe when full combustion is resumed. I still cannot see anything wrong with this (Susam's) description but it would not be the first time I miss something. :-\

Without, for the moment, having a look at the thread you're posting, I thing I get the point you're trying to make. There is «minimal combustion» going on, but the braking effect does'nt come from increased vac on the intake stroke cause the intake valves open just the same. The braking effect is due to the compression stroke not being followed by as strong a power stroke (minimal) as is the case when one is pushing on the gas pedal. Is that kosher to your taste or am I still standing on the old wife's tail ?

Is'nt what you're saying the same as «a minimal amount of combustion going on»? If that was not the case, where would the engine braking come from ?

With everybody's permission and trying not to step on the old wife's tail, with what part of Suzam's description are you in desagreement with? I always thought that's exactly what's happening when an engine is on compression and I dont see how what you are saying contradicts this. Just trying to learn.

The Brighton started last year at -35C° (-31F°). It took no longer than usual but the unhappy noises the engine made during the first few minutes almost broke my heart.

Yes, it's the one on the pass side with only one wire going to it and it has a simple slide on blade connector that can more easily oxidize. Check the connection before doing anything else.