Rosco
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 posted on 6/5/08 at 09:35 PM |
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Engine Fault Finding.
I'm trying to start my Toyota 4AGE, 16 Valve for the first time and not getting anywhere. It's on OMEX 600 and TBs, but while the engine
turns over on the starter motor there doesn't appear to be any spark at the plugs and no smell of petrol, so I assume the injectors aren't
pulsing either.
The fuel pump is running and I'm pretty sure I have fuel in the injection manifold, and since the pump is controlled by the OMEX I assume this
is also working. Ditto the Lambda sensor which is heating up.
I've also re-gapped the crank sensor to 15thou.
Having checked the wiring for the nth time I'm getting a little frustrated.
Any suggestions on other checks. The difficulty appears to be how to check the OMEX without a PC link. I was thinking of putting an LED in line
with the injectors to see the voltage pulses - has anyone tried this? But otherwise I'm running out of ideas.
Any suggestions?
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sminney
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| posted on 6/5/08 at 10:03 PM |
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A friend had a similar problem with his setup, fuel was getting to the rail, but not into the cylinders. With him it turned out that the injectors
were stuck closed by the fuel drying out in them, sticking them closed. A gentle tap with a plastic hammer was enough to free them up
you never know....
Regards
Steve Minney
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vorn
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| posted on 6/5/08 at 10:52 PM |
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I second the stuck injectors , had same problem with donor motor that had been sat for years , changed injectors and it fired first time .
Cheers
Vaughan
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Dusty
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| posted on 6/5/08 at 11:42 PM |
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Have you wired an ignition live supply to the injectors and coil? The ECU works by switching earths not feeds.
I usually hear the fuel pump run for a couple of seconds when switching on the ignition.
Also the crank sensor is polarity sensitive. (pic is my ford one)
[Edited on 7/5/08 by Dusty]
 
Rescued attachment plugpins.JPG
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zetec
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| posted on 7/5/08 at 03:49 AM |
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I suspect the crank sensor first. Emerald have a little led which glows green when it locks on to the flywheel timing, is there nothing similar on the
Omex? Also how about squirting some fuel down the TBs while cranking and then you will know for sure if you are getting sparks and the injectors are
at fault. Must be someone over your way with a laptop to check the software etc, it is nearly impossible to get a ECU working its best without being
able to tweek the settings.
" I only registered to look at the pictures, now I'm stuck with this username for the rest of my life!"
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Paul TigerB6
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| posted on 7/5/08 at 07:14 AM |
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As ^^^ I'd also start with suspecting the crank position sensor first if you are getting neither sparks or fuel. Is the sensor wired the right
way around?? Reversing the polarity will stop it working (and certainly did with the megajolt set up i had on a pinto).
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Rosco
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| posted on 7/5/08 at 07:40 AM |
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Thanks for your help - I didn't know the crank sensor was polarity sensitive so I will check this and also try tapping the injectors as
suggested - the engine has been sitting idle for a couple of years so siezed injectors is a possibility.
One more question; am I right in assuming the injectors see the full 12V from the battery during the 'on' pulse? And in which case can I
simply simply check them, and 'exercise' them, by putting 12V across them for a second or two without risk of burning out the coil? I
guess if I do this with the fuel manifold pressurised I should be able to hear and smell the fuel, and maybe even see it through the TBs. The
thinking here is that the lower battery voltage during cranking may not be enough to operate seized injectors but full battery voltage with the engine
stationary may do the business.
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Schrodinger
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| posted on 7/5/08 at 10:24 AM |
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I have done that in the past but would suggest trying one thing at a time and rather than squirt petrol into the inlets I would spray cold start into
the inlets.
Keith
Aviemore
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Dusty
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| posted on 7/5/08 at 10:26 AM |
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One terminal of the injector should have 12V supply all the time the ignition switch is turned on. The ECU then earths the other terminal for the full
period of opening calculated from the fuel map with various corrections applied. No problem connecting to a 12 volt source and giving them a blast for
a few seconds!
As you have no spark it would be nice to tie up single cause for both no spark and no injector firing such as no crank signal?
[Edited on 7/5/08 by Dusty]
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