C20NE Eratic Rev Counter & No Spark

[GeraldGTE]

Hi All,
Really hoping you can help me out with this... I am trying to recover a Cavalier C20NE that has been sitting for over 5 years !!
- Put in fresh Fuel and new battery and it fired up ! Then it went downhill.. It started missing really badly and finally died, and cannot get it to restart.

Checked plugs and they were dry, new fuel pump relay offa working car, still no joy.. Checked the output voltage to the fuel pump and it was around 7V???? pump was not running. Input to the relay when not cranking over was 12V, so something pulling it down..

Got pump running by wiring directly to another battery, still not starting ! Plugs now wet with petrol.
Checked for spark and nothing. Checked all earths etc, jump lead to engine direct from battery to engine, cleaned contacts in distrubitor and new king leed.. Still no good.

Now i think these maybe the important things which will hopefully trigger some thoughts or solutions,,,

- When cranking it feels very sluggish as if battery is on way out, and the rev counter is jumping all over the place, up to redline back to zero at a hell of a rate !
- Just to make sure it not battery i paired it up with a running car and still same..

Any ideas ???
What gives the signal to the rev counter??

If no joy the poor old girl will have to be broken !

[Robsey]

Rev counter is fed by green wire from the coil.

Coil spark control is built into the engine ecu.

First port of call is check and clean the coil connections.

7 volts on the fuel pump relay.
Hmm - check for a dirty / corroded brown earth wire from the relay.

Lastly - check the ECU connector(s) - they are in driver's footwell.
If you have a corroded A pillar or leaky window seal... or even damp due to the car being stood for 5 years, them moisture may have caused the ECU connector pins to get wet or become corroded.

Check all connectors and ground tags for rusty or dirty / loose connectors.

[GeraldGTE]

Hi mate,
Thanks for the reply.. Checked all connections in the drivers foot well and all is dry and connections nice and shiny.. All earths have been cleaned also..

The coil fitted to the car only has one 2 pin connector going to it ? No green wire to be seen ! lol

Forgot to add its a 93 car if that makes any difference

[Robsey]

Hmm coil must have 2 low tension wires...

Black for ignition live from the barrel shaped connector near to the battery.
coil terminal number 15

Green for tacho / revolution signal to ecu pin No 1.
Then to the instrument cluster. (From ECU pin number 6)
Coil terminal number 1

Without the green to the ECU, the engine will not run.

Model year makes no difference.
It is the same for all 20NE and C20NE engined cars.

[Robsey]

It has to be the connections to and from the coil.

If the fault was the feed from the ecu pin 6 to the rev counter via the green wire in the cluster of three small connectors near the ECU, then the idling / rumning of the engine would not be an issue.

The fault has to be between the ignition live feed from the barrel shaped connector and ECU pin 1.

So options are -
1 - The pin in the barrel connector (X5) black wire. (Pin 5 I think)
2 - The single pin connector that joins the wire from the X5 connector to the black wire on the coil terminal 15.
3 - The connector on coil 15 terminal
4 - The connector on coil 1 terminal.
5 - The green wire between the coil 1 terminal and ECU pin 1

Fuel side is working fine as you have wet plugs.

This leaves ignition side,
Which is -
Coil low tension circuit detailed above.

High tension circuit which is leads, rotor arm and distributor cap.

The C20NE is a very simple set up.

Thinking of sensors - a duff crank angle sensor would stop the fuel pump / injector relay.

The MAF sensor can be unplugged and the ECU will use default settings.
The idle control valve / stabiliser valve can be unplugged and the ECU will use default settings.

This leaves the trottle position switch and the coolant temperature sensor.
These won't prevent the car from starting.

over sooted plugs caused by a dodgy lambda sensor could prevent an effective spark, but you have cleaned your plugs...

We are looking more and more at -
A faulty coil or it's wiring,
A faulty ECU or it's wiring.
Dirty or pitted distributor cap or rotor arm.

[GeraldGTE]

Hi Mate,
You are a star ! May help me save a cavalier !

I checked for voltage on the pins to the coil and one did go to 12V when the ignition is on.

Seeing as there is no spark and the rev counter is all over the shop i would say the coil has had it.

Would i be right in thinking that it could be the duff coil that is dragging the voltage down making the car turn over sluggish and cause the voltage drop i am seeing at the fuel pump relay ?

Thanks again, been a great help !

[Robsey]

If it has been stood for 5 years, any manner of stuff could be affecting the voltage.

If the starter is dragging too much current during cranking, then it would affect whatever output voltage and current that the battery has left to offer the rest of the car's electrical systems.

I would go for -
Check the big earth strap from the gearbox to the battery negative terminal.

Check security and cleanliness of the starter, battery and alternator terminals.

If necessary - remove, clean and refit the terminals securely

[planetc]

It sounds to me like it has an earth or supply issue somewhere, I'd be volt dropping everything.

[GeraldGTE]

well i have final got it going.... Very strange one..

I had to run a seperate fully charged battery to the fuel pump and bingo !

Whats odd is that if i bridge across a supply to fuse 11 the pump runs, but not happily, groans away instead of buzzing nicely ? Power to the pump still around 10V?? Also if i run the fuel pump directly off the cars battery the fuel pump still does not buzz happily, just groans away...

Happy got it running, hopefully get it back to house for deeper investigation !

Thanks all for help.. and any further ideas much appeciated !

[Robsey]

Good to hear that you've got it going.

Sure does sound like a dodgy live feed or earth to me to cause the volt drop.

Probably corrosion on the terminals from being stood in the tall damp grass.

[planetc]

Bear in mind that if you have left the wiring connected you'll be back feeding everything on that circuit from your separate supply. Depends how you have done it really. Certainly consistent with my original suspicion though. Also worth swapping out the fuel relay, I've seen a few that only pass a limited voltage under load and the circuit supplies more than just the pump.