Does low fuel light cause ecu to go into limp mode

[VTEC]TL said:

Just what the subject says. If my low fuel light is on does it cause the engine to go into limp mode? I heard that you cannot go into VTEC if your low fuel light is on? Is this true?

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I don't know about Limp Mode but I can go into Vtec just as well as if I had a full tank.

Why are you running your tank down that low?! You could kick up all sorts of shit from the tank. I realize that you car isnt that old but rust and debris settle in the bottom of the tank and then gets sucked up when there is nothing left. It costs the same to fill the top half as it does the bottom half. All I am trying to say is."You have a sweet car, dont let it get f'ed up."

whoaduck said:

Why are you running your tank down that low?! You could kick up all sorts of shit from the tank. I realize that you car isnt that old but rust and debris settle in the bottom of the tank and then gets sucked up when there is nothing left. It costs the same to fill the top half as it does the bottom half. All I am trying to say is."You have a sweet car, dont let it get f'ed up."

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The fuel filter will catch any sort of shit before it has a chance to do any damage.

[VTEC]TL said:

Just what the subject says. If my low fuel light is on does it cause the engine to go into limp mode? I heard that you cannot go into VTEC if your low fuel light is on? Is this true?

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Explain "Limp mode". To my knowledge there is no such thing. You can run in VTEC all day long until you run completely out of gas. Perhaps what you were experiencing is the pre-warmup. You ECU will not engage the VTEC solenoid until the engine is up to normal operating temperature.

I also agree with Biff, the filter will catch debris before it is allowed to cause any damage, however, running your tank down low with cause the filter to plug up more frequently.

As soon as your fuel light comes on it is time to pull in and fill up.

Re: Re: Does low fuel light cause ecu to go into limp mode

Maniac said:

Explain "Limp mode". To my knowledge there is no such thing. You can run in VTEC all day long until you run completely out of gas. Perhaps what you were experiencing is the pre-warmup. You ECU will not engage the VTEC solenoid until the engine is up to normal operating temperature.

I also agree with Biff, the filter will catch debris before it is allowed to cause any damage, however, running your tank down low with cause the filter to plug up more frequently.

As soon as your fuel light comes on it is time to pull in and fill up.

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when the ECU throws certain error codes, your car will go into a limp mode that mainly just keeps the vtec lobe from ever engaging. I've never personally experienced this but i've read about it's existence.

also, isn't the fuel drawn from the bottom of the tank? The only reason having a fuel tank near empty would be bad at all is

1) fuel pump has to work harder b/c there is less pressure created by gravity. This hasn't been proven to cause premature fuel pump failure ever, so it's a pretty useless thing to worry about.

2) in a hard turn, fuel could move to one side of the tank or the other and you end up starving the motor for fuel. but that will practically never happen b/c most people instantly start granny driving when the fuel light comes on.

Re: Re: Re: Does low fuel light cause ecu to go into limp mode

chunky said:

also, isn't the fuel drawn from the bottom of the tank? The only reason having a fuel tank near empty would be bad at all is

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Yea I can see the ECU going into a handicapped mode when an engine code is thrown. I've never seen this happen but it would be a good safe guard. Under normal conditions VTEC should be there all the time until you run out of fuel.

Fuel is typically drawn from the bottom of the tank but there is usually an inlet nub that protrudes into the tank slightly so that you are not grabbing the scum directly from the bottom of the tank. Fuel filters do eventually plug up over time so that is good indication that dirt, scale, slime and rust do get into the fuel lines and it likely happens when the fuel level is lower and you are throwing the car from side to side in a corner and get the fuel sloshing around.
If they drew fuel directly off the bottom of the tank I am certain we'd see the fuel filter plugging up a lot more frequently.

actually one time i was in a real hurry one morning when it was cold and my car didnt want to go into vtec. until i got down the road and it kicked in about 6500 and i was like whoah. big kick, i wanna delay my vtech.

blueSI said:

actually one time i was in a real hurry one morning when it was cold and my car didnt want to go into vtec. until i got down the road and it kicked in about 6500 and i was like whoah. big kick, i wanna delay my vtech.

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Your main cam lobes run out of go power at about 5500 RPM. Taking it up to 6500RPM on those lobes is possible but the powerband would be sucking badly.

The idea of the temp. fail safe is help protect your engine from damage. It's your car, but I would suggest waiting until you engine is up to operating temp. before you go anywhere near 5000PRM or more.

BTW, VTEC engagement is 5500RPM so I am not sure how you are certain you kicked in at 6500RPM?