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Old 09-30-2002, 07:48   #1 (permalink)
donuts2001
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Fuel + Air + Compression + Spark = Non-working engine??

Okay I'm still having troubles with my car starting after my EA rebuild. The primary problem was that there was no petrol, as the fuel guage decided to be dodgy and show half a tank when it was completely empty. Fixed that problem, put in 10 Litres of fuel, new fuel filter and checked the flow again. The fuel injectors are all working as I have taken the fuel rail off to see if they were all firing which they were.

Checked the compression of the cylinders and they all came out fine. There are no blockages in the air intake as I have taken the intake tube off completely. Double checked the timing again, and adjusted the distributor accordingly. Was getting spark from spark plug lead number 1 before adjusting timing, but will test it again tommorow and will check all other leads.

Spark plugs are brand new, and I have cleaned the petrol off them before trying to start the motor again.

The shitty thing is, that last week when I started it before the car ran out of petrol the motor ran perfectly and would start everytime with a single key turn. Now the bloody thing doesn't even sound like it's trying to start, it just keeps turning over continously without firing, not even a splutter or any sign of life!

There is only 3 other reasons I canthink that it won't start, either the exhaust is blocked, the intake manifold is getting blowback through it or what I think is most likely is that the fuel injectors aren't firing the petrol in at the right time.

Does anyone know what controls when the fuel injectors fire the petrol into the motor? Is when the injectors need to fire detected by the TFI module? And could the ECU affect the the injectors as well?

The ECU has come up with no errors either, even though it has been disconnected from the battery for hours and I thought would have shown a "relearning" code.

Sorry for the long post, but I really need some help with this... I'm just about to go the extremes and get a mechanic to finish my project if I can't work it out soon!
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Old 09-30-2002, 19:52   #2 (permalink)
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i would think even if they arnt firing at the right time it should stil try and start. i think it fires 3 injectors at once so the petrol will be in there and should get at least 1 cylinder right.
double check that its definatly sparking and if it is then check hat you have it set up right. ( i think you put the engine on tdc then line the rotor up with the start line inside the dizzy and push the dizzy into the engine. the rotor will move to the finish line.) i did it this past weekend and it wouldnt try and start because i had it in wrong. then i put it in 180deg wrong and got some excellent backfires.
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Old 09-30-2002, 20:27   #3 (permalink)
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Disconnect the fuel in on the injector rail, and check that the pump worths, being a submerged pump, you may have bugged it when it ran out of petrol
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Old 10-01-2002, 01:58   #4 (permalink)
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Update

Falcon_Spac, have ready checked that and petrol flow is still good.

I did some more checks on it today and it seems to not be starting because there is too much fuel being injected. I disconnected the fuel pump relay and it actually sounds like it's trying to start.

I swapped the fuel rail with the one from my parents car and it did the same thing so the injectors and pressure regulator are not the problem. It looks like for some reason the ECU is telling the engine to piss lots of petrol in.

I've swapped the MAP sensor with one from my parents car and it's still doing the same thing so thats not the problem either. The TFI module was checked using the voltage tests in thegregories manual and came out fine, however it may be still suspect because it's the only sensor I can think of that would cause this.

Maybe the ECU needs resetting, but I have disconnected it from the battery lots of times and left it for well over an hour each time and it still does the same thing. I'll swap the ECU from my parents car tommorow and see if that helps any.

I'm pretty sure I've narrowed it down to 2 things now, the TFI module or the ECU. I just hope it's the ECU as the distributor was replaced only last year, and it's a pain in the ass trying to put the distributor back in on a mpfi model :|
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Old 10-01-2002, 07:09   #5 (permalink)
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The pip signal from the dizzie is what determines when the injectors fire. they fire with each pip module leading edge. During cranking and then alternatively with each third rising edge. Given they fire in two banks of three timing shouldn't be very critical. You will get a lot of fuel when cranking without starting as you have been doing. I'm thinking low fuel pressure as a result of a blocked fuel filter after running the tank to empty. If you haven't changed the filter for a while it might be time to, if you have try the old filter.
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Old 10-01-2002, 07:11   #6 (permalink)
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PS: you have got the MPEFI gasket (thick one) and not the CFI inlet gasket 9paper thin one) fitted I assume.
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Old 10-01-2002, 14:48   #7 (permalink)
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If it was going OK before it ran out of fuel, it would be 98% certain that it is fuel related again, and probably something simple.
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Old 10-01-2002, 20:13   #8 (permalink)
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Thats what I would have thought too.. that it was fuel related due to the car running good before it ran out of petrol before.

But you have to remember that before it ran out of petrol the pressure inside the fuel rail would have been very low because of the low fuel level... hence less fuel being injected, and engine working fine. Of course that seems like such a huge coincidence that something like that could happen that even I'm having trouble understanding it.

I know that the ECU "adapts" itself to conditions, and it's almost like the ECU has adapted itself to the low fuel pressure and refuses to reset itself back to default settings either with a battery disconnection. I guess thats a possibility, but it's more likely it's oe of the sensors telling it to keep the injectors open for a long time.

Aussieblue, I have got the right gasket on there. What tells the computer when these pip signals are occuring? Does that go through the TFI module, and part of the hall sensor as well?

I don't think it will be low fuel pressure related... as the motor seems to actually work better when the fuel pump relay is diconnected, which reduces the pressure inside the fuel rail, and makes the injectors put in less petrol. The second I plug the relay back in, the motor dies again and doesn't even want to try and kick.

Also I had another thought yesterday... my car was converted from a 4 speed Auto to a 3 speed Auto by the previous owners of my car. I have just put the 4 speed back in, so is there any difference between te 4 speed ECU and 3 speed ECU? And could they have put the manual ECU into my car?
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Old 10-02-2002, 06:03   #9 (permalink)
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The early 4 speeds (BTR 85s) had their own seperate computer module from the engine ECU so that should not make any difference.

The ECU uses the pip signal, the MAP and engine temperature readings to "caluculate" the precise amount of air entering the engine each second and uses this to determine when to fire each bank of injectors. The odd sized blade in the pip rotor (signature pip) also tells the ECU in what position the camshaft is. Unless you have bent the pip rotor blades so it's not passing cleaning through the hall effect switch sensor (or broken a blade off the pip rotor I wouldn't be suspecting the pip module or signals. Have you checked the TFI module yet; they fail more often. I would still be betting on the fuel filter until it has been eliminated as the source.
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Old 10-03-2002, 03:39   #10 (permalink)
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Things tested today:

Another distributor from my spare parts pile was put in today, still does the same thing. Changed the TFI module on my distributor, that didn't help either.

Swapped the ECU from my parents car(it's MPFI as well), and that still didn't help. Tested the Idle Speed Controller and it's coming up with the right reading as the parents car.

Put in a different Oxygen sensor, that didn't do anything either.

The only thing that was slightly different was the Throttle position sensor, it was testing about 0.5v different compared to my parents car, however I don't really think it's that significant to make it not start. I will change the throttle body anyways as I am running out of parts to change.

I will buy another fuel filter tommorow, and see if that helps any, but the car seems to work better with less pressure int he fuel rail so I doubt it will be that.

If I can't work out the problem tommorow, she's off to the mechanics... time to get the $$$ out I guess. No extractors this month :(
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