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Curtis
Curtis, Australia Car Mechanic
Category: Australia Car
Satisfied Customers: 1606
Experience:  Qualified Automotive Mechanic, LPG & Airconditioning Diagnostic Technician.
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I have an 03 1.8 astra that is missing at idle have changed

Customer Question

I have an 03 1.8 astra that is missing at idle have changed Air flow meter,Plugs,injectors and Coil Pack. Reset fault codes with OBD meter and it still misses.OBD said that the coik is faulty??.Can anyone help
Submitted: 1 year ago.
Category: Australia Car
Expert:  Gary replied 1 year ago.

Hi there,

Can you tell me the DTC that is set?

Are you using a genuine coil pack? I have seen aftermarket coil packs cause the issue you are having.

Did you also fit the correct spark plugs?

Gary

Customer: replied 1 year ago.
VDO Coil pack (new)
OBD said 7Degrees.
New NGK plugs
and new Bosch plugs tried.
I have 13.6 volts at coil pack on all 4 incoming wires.
Expert:  Gary replied 1 year ago.

Hi again,

Can you give me the code that was set? ie: P0301

If you're real lucky the ECM is not fried from the coil.

Do you still have the original coil?

Gary

Customer: replied 1 year ago.
Gary,
I have the old coil pack.
I can not remember the fault code number.
Expert:  Gary replied 1 year ago.

Hi Stephen,

You can check for spark from each coil to ground while cranking, BUT it is best to check it with TECH 2 as you can test each coil one at a time, with just key on, not cranking.

Does the engine have a definite misfire on one cylinder only, or is it rough in general at idle?

Gary

Customer: replied 1 year ago.
Gary,
It seems to not be running on No.1 Cylinder The spark plug is clean where as the other 3 are fouled.
With the engine running I have 13.5v coming into the coil at all 4 wires and 13.5v out at the black wire(earth)???
The Engine is missing at idle and as you rev it up,and has no power at all.
Customer: replied 1 year ago.
Gary,
I just rechecked the OBD codes and came up with P0100 and P0351.does this help you.
Regards
Stephen
Expert:  Gary replied 1 year ago.

Hi Stephen,

The P0100 is a MAF dtc, it is fitted the correct way, arrow towards engine?

The P0351 is a faulty coil circuit primary/secondary circuit.

Can you please fit the original coil and see what it does?

And has the timing belt/valve timing been verified?

Gary

Customer: replied 1 year ago.
Gary,
Tried original coil and no difference. Maf is fitted correctly and I tried original unit with no change.
I am now checking fuel pressure to injectors.
Engine starts to well for valve timing to be out.
regards
Stephen.
Customer: replied 1 year ago.
Gary,
Just checked the fuel pressure and it is 50 PSI at start up and also when running.This seems to be acceptable pressure.
Expert:  Gary replied 1 year ago.

Hi Stephen,

Ok, with original coil fitted and the previous history DTC cleared, what code sets after starting the car.

You could have an original misfire on cylinder 1, but now a faulty coil circuit cyl 1 with an aftermarket coil.

I have seen ECMs go faulty after a non-genuine coil fitted.

So what code set after the genuine coil fitted?

Have you also checked for any vacuum leaks, especially the purge hose that runs from the manifold under the inlet duct towards the purge solenoid on the drivers inner guard?

Gary

Customer: replied 1 year ago.
Gary,
I have checked for vacuum leaks at injectors with a stethoscope and oiled around the injectors and no leaks found,if there was a vacuum leak it would not be missing only on one cylinder.
Expert:  Gary replied 1 year ago.

Hi Stephen,

Can you please fit the original coil and note the NEW code that is set?

Not interested in the old P0351 from the VDO unit for now.

The P0100 is because the engine is not inhaling the air it should be.

Can you perform a cylinder leakdown test?

Possibly riding valves once running.

Have you ever tried some upper cylinder cleaner and see what it can do for valves etc?

Like Subaru or AC Delco.

Gary

Customer: replied 1 year ago.
Gary,
Please answer me as I am running out of things to try and it is frustrating me.
Expert:  Gary replied 1 year ago.

Hi Stephen,

While you have a misfire from a faulty coil, the injector for that cylinder is then disabled.

Get rid of the VDO coil, refit the original coil and tell me the DTC that sets, as I requested above.

If is then P0301 not P0351, then your original coil is also faulty but not in the same way as the VDO coil.

Do you know anybody with another genuine coil you could try?

Gary

Customer: replied 1 year ago.
Gary,
I have just tested Plugs with the coil pack and there is spark at each plug when turning over the engine.
I also checked the firing of the injectors and it would seem that No.1 injector is not firing when the engine is running?.
.
Expert:  Gary replied 1 year ago.

Ok, have you still got the P0351?

The injector will not fire while the P0351 is set.

Try another coil first.

Then you may need to verify the NO.1 injector circuit.

My bet is your coil is the fault.

Gary

Customer: replied 1 year ago.
Gary,
I just tried the old coil and rechecked the codes and came up with P0001 and P0351 again.???????
Expert:  Gary replied 1 year ago.

Hi Stephen,

If you don't know the original DTC, you'll be guessing now.

I would say that your ECM is faulty, and your aftermarket coil has probably hurt the ECM.

I'VE SEEN THIS BEFORE WITH A CUSTOMERS CAR AND COST THE WORKSHOP ALMOST THE ENTIRE REPAIR COST.

On this car, not only did the original coil get replaced TWICE, it also needed an ECM since the coil circuit was damaged by the aftermarket coil.

Does your P0351 set as a CURRENT DTC with just key on, or after starting the engine?

https://tis2web.service.gm.com/tis2web/?target=AXCAJ7ABX9&target.method=onSubmit&leaf.AB5A01ANV9=1&bm=leaf.AB5A01ANV9#leaf.AB5A01ANV9

Gary

Customer: replied 1 year ago.
Gary,
code is with the key on only.
Expert:  Gary replied 1 year ago.

Ok, which way do want to go now?

You need to test the wiring between the coil and the ECM.

9 times out of 10, the ECM will be the fault.

Best for a Holden dealer now, as you will be unlikely to do this at home.

Gary