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I bought an 83 280zxt for $600 from a guy who said he didn't have the time to work on it. He said it ran like a champ and then one day he couldn't start the car. Somedays it would start fine and other days it wouldn't start at all. When it did start it would die within a random period of time. I bought the car thinking i knew what the problem was, i though it was the cold start valve flooding the engine. (Little did i know turbo's don't have cold start valves.which i didn't know until yesterday)I spent a week trying to figure out why my attemps at rigging the known cold start valve(which i found out later was the air regulator) wasn't working. I bought distributor(crank angle sensor) thinking mabey my spark wasn't sparking at the right time and not detonating the fuel. No help there! I then replaced my spark plugs thinking if no spark occurs my engine wouldn't start. No help either. So i then took my fuel rail, off my intake manifold thinking well if my injector was stuck open it would flood my enigne out. I hooked each injector up individually making sure to hook the right wire up to the right injector, and no no avail they all fired and none were stuck open. But then i hooked all of them up and cranked of my engine a couple of times, WTF! they all fired at the same time! Eureka! i found my problem my ecu is bad. I looked up in my haynes repair manual and found the definition of the ecu

Control Unit-
The control unit is mounted under the dash on the left side wall of the drivers side of the vehicle. The essential role of this unit is to generate a pulse to the injectors. Upon receiving an electrical signal from each sensor, the control unit generates a pulse whose duration(injector open time period) is controled to provide the exact amount of fuel, accordinding to engine characteristicts at that particular time. The control unit consists mainly of three integrated circuts formed on a printed circut board.

I think the Ecu is the problem, But i wanted to know what all of you think before i buy a new one, I tried wiglling the ecu connectors and pushng them in and out to clean them also. So let me know what you all think. Thanks for listening to my blaber on and on.
 

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Re: I think i found my problem (83 280zxt won't st

call me nuts but i thought they all were supposed to fire at the same time.....mine does....humm i wonder.....
 

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Re: I think i found my problem (83 280zxt won't st

your nuts and your injectors fire in this order 1-5-3-6-2-4 your engine won't run if all your injectors fire at the same time hence my problem
 

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Re: I think i found my problem (83 280zxt won't st

not necessarily. It is probably a batchfire system, meaning they all go off at the same time, regardless or half will go, then the other half. Things like late lt1's had sequential firing fuel injection, but 1978 is a little doubtful.

Dylan
 

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Re: I think i found my problem (83 280zxt won't st

Save your money, the ECU is fine. The ZX is a batch fire system, meaning the injectors fire together. Sequential fuel injection did not come about till later when the processor capability was greatly increased. Even now a large number of systems are batch fire. If you have good spark at the right time and fuel you should be starting. Verify both of these. Make sure the fuel pump is running and stays running. Check all sensors IAW service manual. (you do have factory service manual, right?) Clean all injector and sensor connections. Double check proper dist installation (timing) and be sure firing order is correct. 1-5-3-6-2-4 as you said, with COUNTER-CLOCKWISE rotation.
 

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Re: I think i found my problem (83 280zxt won't st

Jeff is right, all 280's and 28zx (turbo's too) are batch fire. Even the 1st gen 300zx's are batch fire.
 

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Re: I think i found my problem (83 280zxt won't st

If that were true then i could switch my plugs on the injectors, and my car would run? but my car doesn't run. and if they all fire togerther then even the cylinder that isn't being fired still gets fuel, which doesn't make any sense. Why would my injectors fire all the time and my spark fire in order. Dude your Ignorant please don't reply to my posts anymore.
 

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Re: I think i found my problem (83 280zxt won't st

some computers like on the new cars, use what is called "Sequential" injection. That means only 1 injector will fire at a time To do a sequential system the computer needs a "Cam Position Sensor," and also a "Crank Angle Position Sensor." So if 280zxt have batch then wtf is the cas for?
 

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Re: I think i found my problem (83 280zxt won't st

no, that can't be right. They have to be sequential. You would flood your engine if they all fired at once. That's retarded to say that they all fire at once. And what about when one is at the compression cycle, and the other is at the intake cycle. The one on compression would already have enough fuel, and it would be going up, to compress the mixture. Saying they all fire at once, means you're saying that the one in the intake cycle (Which is drawing fuel and air) would draw fuel just like the one on the compression cycle. Which would be correct, but you have to have COMPRESSION on your compression cycle. So your injector would have to be closed.

Think about what you're saying. That's retarded.
 

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Re: I think i found my problem (83 280zxt won't st

103kzx,

You are the ignorant one here. You have a whole group of people telling you that the system is batch fire (which it is) and you start by insulting them and telling them they're wrong. This is from a person who can't even tell the difference between a cold start valve and an air regulator. Why ask in the first place. Just go ahead and replace the computer. If it fixes your problem then you got lucky. Spend your money any way you want. It is not this forums purpose to be abused by a no brain twerp. The fact that all the injectors fire in batch mode is correct. GET A FACTORY SERVICE MANUAL. While you're at it, get some manors too.
 

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Re: I think i found my problem (83 280zxt won't st

Well "Dude", you are free to act like an ass if you want. I for one will sure not go out of my way to help you again. Disagreement sometimes just helps to promote healthy discussion, but I am no longer interested in your problem (personal or cars). Buy a new ECU. I'm sure you are right. Good luck.
 

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Re: I think i found my problem (83 280zxt won't st

Just so everyone reading this series knows the right answer, here are quotes taken from my 82 factory service manual. (My 83 FSM says same thing)

1) EFI (non-turbo): "The injectors are electrically connected in parallel in the control unit. All injectors recieve the injection signal from the control unit at the same time. Therefore, injection is made independently of the engine stroke cycle (intake, combustion and exhaust). In the six cylinder engine, injection is made once every revolution of the engine, triggered by the ignition coil."

2) ECCS (turbo) "Injections are timed for each rotation of the engine by the crank angle sensor and are made simultaneously in every cylinder"
 

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Re: I think i found my problem (83 280zxt won't st

What is being overlooked here is the fact that the fuel in this car is being injected into the intake manifold, not the individual cylinders like some other vehicles. The fuel is then available when the intake stroke occurs and the valve opens to receive it. This is how simultaneous operation of the injectors is able to work. Just like a carburetor does not provide for fuel only during the combustion stroke, the injectors are providing the mixture into the intake where it is either sucked or pushed into the cylinders as needed! Ta-Dah!
 

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Re: I think i found my problem (83 280zxt won't st

Way to go. Call the people who were willing to help you morons. You'll never have another problem, right. You won't need any more help.

Here is a clue. By a FSM, and READ IT. You will see that you are quite wrong, and that you have no understanding of how the engine operates. But buy the new ECU first, so you can prove out your theory. We will still be here, laughing at you paying your stupidity tax.

The injector system is Batch fire. Spark is sequential. Fuel only gets IN the cylinder when the intake valve opens.

You owe a few people an apology.
 

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Re: I think i found my problem (83 280zxt won't st

so if all six injectors spray into the manifold yet only one or two cylenders are drawing it in does this mean that the fuel mixture is kept consitant though out the manifold and could be replaced by one big injector that particalized the fuel into the air well befor it flows down any of the six intake tunels in the manifold?
 
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