Ignition System Advice Request

Randy Gibson

New Member
Hello Folks,

I need some advice, I am at a point where I am not sure where to attack next.

1987 Bertone X, fuel Inj. Was hard to start, but would get there and Idle OK, but rough. I decided first to replace plugs, wires, rotor, cap, coil, coil resistor and O2 sensor. No real noticeable change. I then adjusted the valves to spec. Better, but not good enough, so I then replaced all 4 injectors with rebuilt OEM and also re-spliced the harnesses at all the injectors with easier to remove connectors. I have never been able to get it to start again after the injector swap. It coughs at points like it wants to go, but either floods, starves or does something else that talks it out of going.

Ok, so here is what I do know:

1. All 4 injectors appear to fire as designed.....I think. I tested this by removing the injector(s) from their mount and cranked the ignition. A tiny amount of fuel is expelled from each unless I manually push open the mass air flow gate, at which point they fire more fuel - but again, only a nominal amount at ignition until the air flow sensor gate is held open.

2. The cold start valve is operational as intended. It fires during ignition startup when the engine is cold for about 8 seconds.

3. Timing marks on the cam wheel, flywheel and main pulley are all lined up as they are supposed to, rotor pointing to #4 when everything aligned. No doubt ignition is NOT timed properly at this point, as I have been slightly moving the rotor left or right as I turn it over hoping to get it to catch, however, even so I am not significantly far out to time.

4. Spark is present at all 4 plugs, but it is quite possibly weak spark. I am not sure how to test spark intensity. Voltage across the coil is 12v straight, and 9v with the ballast resistor. The plugs being new, still look good and clean.

5. I followed the troubleshooting guide for "starter runs, engine will not start", and everything checks out through step 19, at which point which it says replace control unit. I am not sure I buy that, but then again, that's why I am where I am at this point, asking for suggestions.

Thank you for reading.

Randy
 
Hello Folks,

I need some advice, I am at a point where I am not sure where to attack next.

1987 Bertone X, fuel Inj. Was hard to start, but would get there and Idle OK, but rough. I decided first to replace plugs, wires, rotor, cap, coil, coil resistor and O2 sensor. No real noticeable change. I then adjusted the valves to spec. Better, but not good enough, so I then replaced all 4 injectors with rebuilt OEM and also re-spliced the harnesses at all the injectors with easier to remove connectors. I have never been able to get it to start again after the injector swap. It coughs at points like it wants to go, but either floods, starves or does something else that talks it out of going.
Randy

How old is the gas? Could it be bad from long storage?

Paul
 
Randy, the cold start system is independent of the rest of the fuel injection system except the pump (which is turned on by a switch on the airflow flap), so if it's an FI system problem, it should still catch momentarily, if it has fuel pressure to work with. Starter fluid can also be helpful to get it to 'catch'.

Repeated non-starts can flood the plugs from the cold start system, too.
 
Thanks guys, I appreciate the advice. Fuel is fresh (good call). I put the old injectors back in and at least it runs again, although still rough. So it looks like my starting problem is with the new injectors.....the rough running....well....I am not sure yet, but given time I will get to the bottom of it. Thanks again.
Randy
 
Randy, I cannot offer a definite answer but I can comment on a couple of your points.

The air flow meter ("flapper box") door needs to be open (at least a little) for the fuel pump to supply pressure to the injectors. Cranking the engine when starting is enough air flow to achieve this. The injectors should not spray anything until that door opens a little, but many injectors can dribble a bit. However this should not necessarily prevent starting. With the door open the injectors should give a healthy spray while cranking.

If you can see the spark plugs firing then chances are it is enough to allow the engine to run. Try putting it on your tongue to test like you would a 9V radio battery - only kidding. Try putting a screwdriver into the plug wire end, then hold it further and further away from a good ground as you crank it; the spark should be able to gap a decent distance (even up to 1/4" if everything is in top shape).

These ECU's (main computer) almost never fail. If it runs at all then the ECU is good.

Strange why the new injectors would not work. Is it possible the spliced-in new connectors may not be connected properly? Although you say it started again with the old injectors back in. Very odd...maybe worth closer investigation.

Overall your description might make me think there could be something wrong with the whole cam timing thing. This is a rather confusing process that can easily get messed up on these engines. In my opinion the design is not great to start with. Lots of possibilities; flywheel 180 degrees out giving you a false indication on proper TDC for the correct cylinder, pointers not in correct positions, belt a tooth off, etc. Any of these may allow it to run, but poorly and could present much like you describe. So I'd go back through the whole cam timing process from ground zero, following one of the excellent guides step by step.

Can you do a leakdown test or at least compression test? A blown head gasket can also cause similar symptoms at times.

Follow the basics - fuel, spark and compression.
 
Strange why the new injectors would not work. Is it possible the spliced-in new connectors may not be connected properly? Although you say it started again with the old injectors back in. Very odd...maybe worth closer investigation.

Injectors are made with different resistances, the resistance as well as the flow rate need to be matched. This might be why the new ones do not fire,

Paul
 
Good point Paul. I assumed the "rebuilt OEM" ones were the correct injectors. But that isn't necessarily true, vendors do get things mixed up at times.
 
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