Mk3 Cavalier Owners Club | Vauxhall Cavalier Dot Com

Would my error code - 65 cause it to not start?

It would probably cause poor running, but it should not create a non-start issue.

This is so frustrating. This car owes me thousands but all it gives me is aggro. I got rid of my x20xev SRi because it gave me too much grief, this one is worse.

Oh this brings back memories of my engine swap in 2012.

So -
Have you tried powering up the fuel pump to ensure that fuel flows (you can hear if it is buzzing).?

Have you checked for a spark at cranking - plugs and crown lead.?

The only thing that I have missed so far is the single black connector between the X5 barrel connector and the coil (black wire).

And definitely no problem with fuse 11 or any retro-fit immobiliser / alarm system.?

I think we have covered everything.

ECU, and it's connector
Coil and it's connector.
Fuse 11,
Fuel pump relay,
Fuel pump,
No fuel leaks.
HT leads, distributor cap and rotor.
Plugs clean and dry.
All earth leads
Crank angle sensor.
Throttle position sensor / mass air flow sensor
(Car should start with MAF disconnected, but will run lumpy).

Have you tried a donor throttle position sensor?

I cannot think of much else.

Surely not a blocked exhaust / catalytic converter...

My next check was going to be ECU as my Ecotec one was water damaged a few years back so worth a look.

Fuse 11 - fine
Fuel pump replaced a few months ago
Swapped fuel pump relay for another used one (different part number tho)
No fuel leaks I can see
Plugs, Leads, Diz cap and rotor all recent
New crank sensor
MAF sensor recent
Coil looks ok but I might be missing something

I'm going to swap throttle position sensor with the one on my V6 when I've got a minute

Again, I'll probably sound a stupid here but how would I go about checking for spark?

Pull off one lead, stick your finger in the spark plug lead, get someone to turn it over, the height that you jump determines the voltage.

Or just get an old plug, put it in a lead and hold it to the engine. If you dont hold it to the engine, then see the part about how high you jump.

You should have 12v on the coil too.

If you have Rev counter, you should see the needle move when you crank the engine.

If you don't have a rev counter.

Unscrew a spark plug, or get a spare.

Unplug the centre lead (crown or king lead) from the distributor cap.
Put the plug into the unplugged lead cap.
Using pliers, hold the electrode end of the plug against the cam cover.

Get someone to crank the engine...
You should see a good blue spark jump across from the plug electrode to the outer part.

A spark means the coil is working.
No spark means duff coil or poor connection / unplugged from ignition live feed.

Reconnect the crown lead to the distributor cap.

And repeat with a spark plug HT lead.
Unscrew a plug / unplug the lead from the plug.
Fit a spare plug in the lead end cap and crank.

If you get a spark, then it is not the ignition side of things.

This all assumes that the crank angle sensor is triggering as it should.

If it's a fuel problem try a new filter, i would change it with the pump, i'm assuming it just wasn't mentioned.

If that doesn't work check the hoses and fuel pressure regulator. A new one fixed my 20NE way back.

Out of interest do you use E5 or E10?

Fuel system is an easy check, put 12v on F11, then check from pressure at the rail valve.

ilovedmymantas wrote: ↑Tue Oct 05, 2021 2:54 am If it's a fuel problem try a new filter, i would change it with the pump, i'm assuming it just wasn't mentioned.

If that doesn't work check the hoses and fuel pressure regulator. A new one fixed my 20NE way back.

Out of interest do you use E5 or E10?

I've still got about 1/4 tank of E5 in there at the mo after that I'll be putting super in it.
pretty sure the filter was done with the pump a few months ago.
I'll have to test for spark this weekend to rule that before I go and buy anymore new parts, I'm already 50 quid down on a new crank sensor

If you were reasonably local, I would have a butchers for you. But nobody lives within spitting distance of me these days.

Fingers crossed for the weekend.
Sadly, I think you are 3+ hours away...

Yeah it's a shame there's nobody nearby, I think I'm the only Cavalier owner for about 100 miles. I certainly haven't seen another one on the road around my way.

Ok so I've put a spare plug on one of my leads and managed to stretch myself long enough to crank engine and hold plug against throttle body at the same time - no spark.

I've unplugged the crown lead and held a plug between it and the block - no spark.

So could very well be a duff coil. Is there any other test I can do on the coil before I try and source a new one?

According to haynes, unplug the coil from the crown lead and remove the low tension connector.

Using a digital test meter, measure the resistsnce across the terminals.

Test across 15 terminal ( black ignition live) and "1" terminal (green wire for rpm signal).
You should get less than 1 ohm

Then from the crown lead to either of the other terminals (15 or 1). You should see between 4,000 and 20,000 ohms.

If your tests give significantly different results, then the coil is pooped.

If the coil checks out okay and all the wires are fine, then we are looking towards the ECU as that produces the spark for the coil based on the crank-angle signal from the crank sensor.

You have replaced the sensor, and tested all the wiring, so the last man standing is the ECU.

(Bear in mind I'm using a cheap Chinese multimeter with bare wires on the ends because both the test pins broke off)
- Assuming I've done this right I've got Primary resistance of about 1.6 and Secondary of 21,000

So I think that's new coil time

Looking at TIS... coffee and toast in hand.

The official non-start check list is.

Battery - I presume check for a battery in a good state of charge.

Compression - I cannot see an issue unless the engine has been rebuilt or stood for a long time.

Primary Voltage - Low tension leads.
12 volts on the black ignition live wire to the coil.
Pulsed voltage on the green wire of the coil when the engine is cranking / turning over.

Secondary Voltage - HT leads
Sparks from crown lead and plug leads.
You have done this test.

CO & HC measurements - cannot really test emissions with a non-start engine, so I presume it means recent history of poor emissions.

Injection Signal - You would need an oscilloscope, Tech 1, Autoscanner or OpCom to test for a signal.

Engine Speed Signsl - Inductive pick up - again you have replaced the crank angle sensor.

Before condemming the coil - although we know you had it connected, did you check for ignition live voltage on the black wire to the coil?

Do I need to be cranking to check ignition live voltage on the black wire to coil or just have the ignition in the on position?

Possibly needs to be cranking, I think the coil is powered from the fuel pump relay (along with a lot of other things).
I'd have to dig out the manual, never really done much fixing on 8v engines, but I'm sure the it's was pretty similar to the later LET engines since they kept the distributer..

Looking at my notes, the 20SEH coil gets it's ignition live voltage from the ECU pin 1.

So yes - check for voltage when cranking.

Haynes mention a coil module K20, but I would be darned if I had ever seen one.

Assumption is that any "module" is within the ECU.
Same as the ignition amplifier.

With regards the relay, I assume you have the black relay, NOT the grey one with the I on it.
Grey ones should have been binned years ago.

You should have part number 90 378 651 / kat No 12 38 966.

Ok I'll give that a go when I can grab someone to help.

Would you say the resistance readings I got were significantly different?

The spare relay I tried has that same part number. The one on there doesn't, must be aftermarket.

There's a very small black box plugged into the coil with a part number 90307510. Apparently it's a capacitor. Any chance this could cause any problems?

I've found a used coil that matches the part number from mine (off a saab 900) for £20 so might grab that for what it's worth

Right, so I've binned my crap multimeter and bought a new one;

- Taken out the coil to test it again and I'm now getting resistance of 0.8 across the primary and about 8500 across the secondary.

- I've got 11.6v at the cable plug to the coil with the ignition in on position (haven't had a chance to do it cranking, no mates around)

Are we now pointing at the ECU?

Crank sensor maybe, that detects the engine turning so the ECU knows to get injectors and coil should be fired.

Though I think it usually waites a full turn of the engine to get the cam signal (hall sensor in distributer) for the injector timing, though it will start without that and just non-optimised injection.

Any fault codes, or aftermarket immobiliser?

Aftermarket immobiliser was chopped out over a year ago. They had cut into the wire to fuse 11 and wire at the ignition barrel so I just crimped them back together. I've checked the crimp behind fuse 11, it's still good.

Crank sensor is brand new bosch part

About a week prior to this problem I had a fault code 65 which I think is throttle position sensor

Fault code 65 would not stop the car from starting.

The ECU uses substitute values for the sensor to allow the car to run - just not as efficiently.

Looking at the Haynes schematic for the Bosch Motronic 4.1 system, there is no hall sensor.
And I must admit that I don't recall seeing a hall sensor when I fitted my C20NE engine. And no external ignition amplifier

This system relies wholly upon the crank angle sensor to tell the ECU where the engine is.

The ECU does everything else.
So if all else checks out - the ECU does sound likely.

Not sure how easy it would be to get a replacement ECU.
The later Motronic 1.5 ECUs -alpha code GE for the 20NE / C20NE are quite common on ebay.

You could be right on the cam sensor, I'm sure the 16v engines has SFI on them to represent sequential fuel injection, the 8v didn't have it.