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Matt
Matt, Engineer
Category: Car
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Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
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Eagle Vision Vision: 93 Eagle Vision TSI cranks over fine but

Customer Question

93 Eagle Vision TSI cranks over fine but has no ignition. No spark and no power on the input wires to the coil unit. Ignition fuses and "shutdown" relays are ok. What about the ignition switch? Other ideas?
Submitted: 1 year ago.
Category: Car
Expert:  Matt replied 1 year ago.
Hello

1st check for spark by removing one of the spark plugs and plug it back into its lead and rest it on the metal of the engine ( DO NOT hold it on place by hand) then have your assistant turn the engine over whilst you watch the plug. It should give a fat blue spark at regular intervals.

If not then check that there's power to the coil pack (at the other end of the plug lead) using a meter. If there’s 12V at the pack but no spark then check the ECU power supply (fuse and relay) and also the connections to the crankshaft speed sensor.

If there is a spark and its still not starting then its likely that the ECU isn't opening the fuel injectors, if the injectors are working you can hear them click - its difficult to hear them with background noise so use a long screwdriver like a stethoscope, placing the handle end in your ear and the metal tip against the body of the injector whilst your assistant turns the engine over.

If you can't hear anything check the ECU power is present by measuring voltage at the fusebox and on its relay socket if OK then check the connections to the crank speed sensor and consider replacing this sensor if the wiring / connections look OK

If the car will start using a squirt of quick/ easi start into the intake then this confirms the problem is lack of fuel

Also its worth checking that the electric pump that feeds the injectors is working correctly, it should run for a few seconds then switch off when you first turn the ignition on. If you remove the filler cap to the fuel tank and listen inside while your assistant flicks the ignition you should hear it clearly

If the connections to this are corroded or damaged then the pump could stop at any time. Check that its relay switches in and out and the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse, ideally measure the voltage at the pump and check its getting 12V.

You should be getting around 3 bar measured at the injector rail check to see if the plugs are getting wet indicating fuel is flowing – if not and the injectors are opening then there’s a problem with the pump or the filter or even the pressure regulator

Customer: replied 1 year ago.

there is no power at the coil pack. The spark plug wires do not create any spark. I have not checked the fuel system because there is no spark. Before that, I did try starting fluid with no success.

Expert:  Matt replied 1 year ago.
Hello Steve

Ok if there's no spark and no power to the coil then 1st check to see if there's 12V at the fusebox for the ECU and main power relays
Customer: replied 1 year ago.

Thanks Mat,


Ok I have power through the fuse labeled "ign run" and the one labeled "ign start". There is no relay or fuse labeled ECU. I have one EAXL relay and one called Auto shutdown. I have swapped several of the relays around as they are all the same but nothing changes.


 


I guess I need a schematic to see if the ignition switch is before or after the fuse to rule it out or in. Also I need to know what components are between the fuse and coil.


 


Is there supposed to be power at the coil and the crank sensor tells it when to fire or is there more complexity to it like a computer that decides when to fire the coil for each plug?


 


If you think I need a computer diagnostic in the shop, I'll do that and still be satisfied with your efforts, especially if you tell me whether it is worth replacing the ignition switch. I see that mentioned in several internet blogs, but not necessarily associated with my problem specifically.

Expert:  Matt replied 1 year ago.
hello Steve

power should run through from the battery to the ignition switch then onto the ECU relay which will switch on if the immobilser is disabled

If the immobilser is off the ignition coil is then powered up with 12V and switched via the ECU when the ECU sees a crank speed signal as yours has no distributor the ECU will fire teh right sides of the coil pack at the right times to run the engine

if you look on the coil there should be 4 posts which are in fact the ends of 2 coils and both ends of the coil fire at the same time in a system known as wasted spark

if you remove the plastic trim around the steering column to reveal the switch and use a meter to probe for 12V before and after the switch then this will show if it needs replacing or not
Customer: replied 1 year ago.

Ok thanks, XXXXX XXXXX info. One last question and then I'll complete the rating. Since you mentioned the "immobiliser" I need to understand what that is and its basic design since I suppose if it was defective, it could cause the ECU to not switch on. Maybe I can temporarily disable the immobilizer to prevent it from shutting down the ECU relay.

Expert:  Matt replied 1 year ago.
Hello Steve


the security or immobilser unit receives a signal from the key fob to allow power to the ECU

if the car is immobilized usually it won't crank / turn over and the dash won't light up

its not an easy thing to bypass as its designed not to be easy to bypass if it was easy the car could be easily stolen.

from your description I don't think that this is your issue and I'd agree that getting a diagnostic done shoud be the next step
Matt, Engineer
Category: Car
Satisfied Customers: 17283
Experience: Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
Matt and 10 other Car Specialists are ready to help you
Customer: replied 1 year ago.

Just a follow up, the problem turned out to be the timing belt was broken so the cams were not sending a position signal.

Expert:  Matt replied 1 year ago.
Thanks for letting me know Steve

I'd reccommend getting a compression test done to ensure that the valves haven't touched the pistons

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Matt
Matt
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Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.