Hot start/stalling problem

**PaulFraser** · 26th May 2023, 23:43

Originally Posted by troutybrown

Do a scan for any fault codes also look at live data for rpm signal when turning engine over.

No fault codes—will have a look at RPM signal tomorrow. Only thing I noticed was battery dropping from 12.4V to around 10.5-10.7V while cranking.

**northpole** · 27th May 2023, 08:01

it's a NA petrol engine so it needs 3 things to start: air + fuel + spark... so check air is getting in properly (clean MAF + intake and throttle valve, plus check the operation of said valve)
fuel (put on a clean fuel filter and check if the fuel actually comes out the injectors), spark (new spark plugs, and check the coilpack is working properly...

than there are the sensors, cam- and crankshaft sensors that'll stop a NA engine from running so worst case replace those to items too.. and make sure your battery is charged up fully.. the engine should start if all these things are sorted.

PS i noticed you said no DTC's so probably it's the MAF that is dead... disconnect it and try to start it... if it runs than you've found the problem... and in that case it needs to be replaced.

**PaulFraser** · 27th May 2023, 16:11

Thanks Northpole, I’ll start working my way through that lot once I find out where they all are and what I need to do with them. Think I’ve done the Air Flow Sensor, but I’ll try it again. I should add that, after changing the crankshaft sensor, it ran fine for 40 minutes, and restarted while still hot—it was only later the next day when I went to move the car that it wouldn’t start at all. Weird.
Did I mention that the bonnet wouldn’t open a couple of days ago (luckily cable stretched not broken . . .)

**PaulFraser** · 27th May 2023, 17:53

Disconnected the Air Mass Sensor, no ignition (noted engine rpm on software was ~200 rpm, so assume it isn’t the crankshaft sensor either).
Took out the spark plugs (which smelt of petrol), see attached image below (looks like they need replacing).
I assume I check for a spark by plugging them into the ignition coil and making sure the screw threads are earthed on the engine before turning the ignition? (Sorry for the elementary question, but the last car I did this to had ignition leads, not a pack).

133EAE83-A8CD-4E80-9707-AF6088F9DB18.jpeg

**northpole10** · 27th May 2023, 18:39

Will be hard to do with the coilpak of ot's the one that sits in the middle of the head... but yeah try that.

**troutybrown** · 27th May 2023, 19:24

Standard plugs are single electrode.

**northpole10** · 27th May 2023, 20:27

Those look like NGK R's platinum plugs... they are supposed to be better than the oem plugs.

**horaa** · 27th May 2023, 21:59

Except they aren't for some reason, or at least on my mum's astra z18xe the OEM ones were much better compared to the ngk, and lasted a lot more

**troutybrown** · 28th May 2023, 09:38

Have a look at desired fuel pressure and actual fuel pressure.

**PaulFraser** · 28th May 2023, 13:58

Cleaned the plugs with a wire brush and put them back into coil pack with the screw threads lying on the engine. Cranking produced about eight yellow sparks and then stopped. Found a couple of the plugs had slipped out of the rubber sleeves but, even after securing them with hose clamps, no further sparks.
Have I blown a fuse somewhere, or killed a relay or the coil pack?