novicebuilder
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| posted on 19/3/17 at 01:20 PM |
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Sierra 1.8L CVH ignition puzzle?
In my Haynes roadster I have a 1991 1.8ltr CVH with all the donor engine electrics and original ECU. Car will usually start easily and run smoothly,
but after a while the engine stops and there is no ignition spark. Leave car for a while and it starts again fine - Why? Any bright ideas from
experts out there.
I thought it was probably an old wire from the 26 year old donor engine wiring but why would it work fine and then engine just stop while car is
sitting idling and not even moving?
I have had a basic look at my wiring but not undone everything to check every join (yet). I have replaced Ignition coil, spark and HT leads and spark
plugs, but problem not gone. I tried a new ECU but this didn't help. I wondered if ignition coil could be overheating, but it is a new Ford
part for this model of engine and doesn't feel hot at all. It sits in a well ventilated part of the engine bay.
I wondered about getting a diagnostic tool for the car, but not sure still available. It seems that something changes in the car and it is not
consistent when it happens. I wondered if the security system from the original car was activating an ignition lock, but can't see where this
would be happening.
Useful suggestions gracefully received - Thanks
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gremlin1234
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| posted on 19/3/17 at 02:01 PM |
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is it happening when an electric fan is trying to kick in?
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novicebuilder
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| posted on 19/3/17 at 02:03 PM |
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no
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gary gsx
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| posted on 19/3/17 at 02:12 PM |
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Not sure but hasn't the distributor got an amplifier unit on it if so that may be overheating.?
Gary
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novicebuilder
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| posted on 19/3/17 at 02:17 PM |
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Car doesn't have a distributor, spark is distributed through rotor arm on front of camshaft.
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gary gsx
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| posted on 19/3/17 at 03:10 PM |
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My mistake I was thinking of the old xr2s etc driven on other end
Gary
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plutos3
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| posted on 19/3/17 at 03:20 PM |
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Is the ignition amp mounted on the same ali heat sink plate as the coil
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gremlin1234
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| posted on 19/3/17 at 03:25 PM |
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quote:
Car doesn't have a distributor, spark is distributed through rotor arm on front of camshaft.
that is a distributor
how is the cam / crankshaft position measured?
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novicebuilder
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| posted on 19/3/17 at 05:29 PM |
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There is a crank position sensor on the toothed wheel of the crankshaft, which feeds into the ecu.
Pluto 3 - I'm sorry but I don't understand the question "Is the ignition amp mounted on the same ali heat sink plate as the
coil" could you explain further, so I can answer. The coil is anchored to the chassis in the engine bay with most of the coil sitting below
the upper rail of chassis in free space.
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britishtrident
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| posted on 19/3/17 at 06:41 PM |
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Both the crankshaft position sensor and the ignition amplifier module can be affected by temperature
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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novicebuilder
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| posted on 19/3/17 at 06:50 PM |
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I now realise the ecu is the ignition amplifier. It is mounted separate from the coil on the aluminium sheet that forms the front of the scuttle into
the engine bay.
The crank position sensor is in a well ventilated part of the engine bay, so I wouldn't expect it to get any hotter than normal.
Is there a diagnostic test I can do to check the crank position sensor is working correctly?
Is there any other diagnostic test you recommend so I can find what it is that is stopping spark?
Thanks
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Dusty
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| posted on 19/3/17 at 09:44 PM |
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The ESC Hybrid module that came with the 1.8 CVH doesn't have any security stuff built in. Just reads crank position, manifold pressure for
load, air and engine temp, puts them all together and adjusts spark timing. It has an input from coil negative and outputs to a choke heater and a
solenoid valve which both influence the carb. I would check/connect/disconnect these latter two carb controlling units.
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novicebuilder
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| posted on 21/1/18 at 03:13 PM |
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solution found
To complete the story in case anyone else has a similar problem, I have now solved this. I tested the signal coming from the crank position sensor to
the ECU by a voltmeter over the feed wire and it was not sending any current at all. So I changed the crank position sensor and problem solved. It
now starts first time everytime and continues to run without fault. Yahay! I solved it sometime ago but felt it might be good to post the outcome.
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rusty nuts
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| posted on 21/1/18 at 03:35 PM |
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Nice of you to let others know that you have solved the problem, I have a pet hate for those that ask for advice and then don't let people know
their advise has been helpful
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SJ
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| posted on 21/1/18 at 04:24 PM |
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I started out with a 1.8cvh and it wasn't half bad. Decent turn of speed and a nice sound.
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novicebuilder
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| posted on 21/1/18 at 05:24 PM |
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Glad it was appreciated. Hopefully it will help someone else at some point.
Car goes really well and I am delighted with the CVH.
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