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Discussion Starter #1
Hi all,

So my wifes Astra elite 1.8 is developing an issue and its getting worse.
The engine is fully serviced by myself every year, and 6 months ago i fitted a genuine GM Delco DI pack as well.
Engine is at 115,000 miles.

First start of the day in the morning it will start and struggle to idle. Idle will go up and down from about 800 to 1300rpm as the idle valve tries to get the engine at a stable idle. It sounds like its missing as its rough. And very occasionally i can hear a quiet induction backfire.
After say 15 seconds it clears and its sweet for the rest of the day.
TECH II shows no codes, and the engine is running on the latest software.

Im thinking a leaking or sticking injector. Anyone know if thats an issue on these ?.
She has been using morrisions fuel in it. But as of last week its now on Shell V-Power for a few tanks just to clean it through.

As it has a new DI pack, and the correct NGK plugs, it almost certainly has to be fuel. IMO.

Interested in everyones thoughts.
 

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If the issue is only on cold start and it runs fine once warm, its worth checking the readings from the temp sensors, you have air and coolant temp sensors that can both influence the fuelling during cold start.
 

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Discussion Starter #3
I dont think its a sensor. The missing / running rough is for about 15 seconds only during the very first start of the day.
Which to me is a leaking injector which has flooded a Cylinder overnight.

Was searching last night and it seems the injectors are about £55 each for VDO ones. So i guess its time to open my wallet.....
 

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I would not throw money at a "might be" fix for a 15 sec rough start/run. There are a number of possibilities like Ayressy suggested and dismissed it out of hand. Modern day cars run on sensors and so that should be the first port of call. And why do some people accuse the supermarkets fuel as being inferior to other suppliers fuel of the same Octane rating? I would have thought the ministry people who check the fuels of all suppliers would have highlighted any discrepancy in the standards of the fuels used. It is against the law and I have never heard of any of the suppliers being accused have you?
 

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Discussion Starter #5
I was right, its leaking injectors. Flooding the bores over night.
Took the plugs out this morning, and plugs and piston crowns soaking in fuel.

Put back. Started engine for 3mins. Stopped and took plugs out. Everything bone dry.
So.... 4 New Injectors it is then. Wallet injury time !.
 

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Were all 4 leaking and if so I imagine the fuel will have worked its way into the sump? Might be worth emptying the oil and do a sniff check on it I would have thought. What are the injectors like to remove from this engine?
 

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Discussion Starter #7
Were all 4 leaking and if so I imagine the fuel will have worked its way into the sump? Might be worth emptying the oil and do a sniff check on it I would have thought. What are the injectors like to remove from this engine?
I was right, its leaking injectors. Flooding the bores over night.
Took the plugs out this morning, and plugs and piston crowns soaking in fuel.

Put back. Started engine for 3mins. Stopped and took plugs out. Everything bone dry.
So.... 4 New Injectors it is then. Wallet injury time !.
.
In past weeks its been getting worse and worse, so time for some new fuel injectors. Managed to pickup some VDO ones for £55 each.
And the rear silencer was blowing too, so new exhaust needed as well.

Old injectors out. Was actually fairly easy. Only took about 10mins.


New injectors fitted to rail.


Old exhaust with just a few holes !.


New exhaust fitted and aligned. The old one always annoyed me as the tailpipe was at an angle.
 

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Discussion Starter #9
OK update. Rather annoyingly this started again this morning.
It has been starting sweet since i changed the injectors. But this morning while i was outside the Mrs started her car at like 0745 and it was coughing, spluttering, barely running. And i could hear little backfires which im sure were through the intake.
Did this for like 20 seconds then suddenly cleared and was fine after that.

So now im really stumped....
Brand new GM Delco coil pack, all new plugs.
New Injectors.
No codes logged at all.
Live data feeds all look good on Tech II.

I think this weekend when im not working im going to get the live sensor feeds running and then start it cold and watch whats happening. See if i can figure out from the live data, or at least get a hint.
Clearly the ECU itself thinks all is well.
 

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Discussion Starter #10
So today i have done a compression test. Cold engine, not run.

P1 135 psi
P2 145 psi
P3 145 psi
P4 145 psi

Those seem a little low to me. Should a regular modern petrol engine not be about 170 / 185 psi ?.

Also what i did find today was that i started it up for the first start of the day and as usual Cough, Splutter, Lumpy, and occasional Pop, Pop through the induction side. 30 Seconds later its sweet. Was running for maybe 2 mins max then i took the plugs out.
They were completely black and sooty. But if i take the plugs out after its had a drive then they are as you would typically expect.
So its like its getting too much fueling on initial start up.

Check resistance from Battery to Engine / Inlet manifold. 0.3 ohms.
Removed battery and battery tray. Removed both Chassis earths and cleaned them up with a wire bush on my drill.
I notice what appears to be the ECU and injector earth comes off 1 wire which is attached to a bolt that also holds the ECU onto the side of the inlet manifold. All the alloy looking a bit crusty. So removed ECU and cabling. Cleaned up all the mating points on the inlet manifold and wire connectors. And refit.
There appears to be no earth from the battery to the engine block, it takes it from the chassis and just relies on mounts etc to transfer the earth from what i can see. So i made up a heavy duty earth cable and connected to the Cyl head.
Refitted everything. Re-checked earth at multiple points over the engine. Now bang on 0 Ohms everywhere.

Took it out for little drive and it drives so nice and smooth. You wouldnt think it has this annoying problem.
Anyway time will tell when i go to start it tomorrow morning. Fingers crossed !.
 

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Figures are off TIS and it says to check at operating temp (oil over 80C) so I assume that's what it's geared round.
 

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z18xer has problem of leaky valve cover gasket and integrated PCV failure. not sure if that is applicable to your engine.
 

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entry #10 Good detective work there mate. I cannot believe there was no separate earth cable from battery to block1 Is that normal I wonder?
 

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Discussion Starter #17
FYI: Fully HOT compression test came out at 185psi per cyl.
Oddly, the last 3 days it has not done it !, go figure. Just started right up with no coughing or spluttering.
 

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Discussion Starter #19
Still with this never ending and rather annoying issue.
Could this be anything to do with the Fuel Evap system ?.

Im wondering on the 1st start of the day if the engine is engesting a ton of fuel vapour. Hence backfires and pops and lumpyness for approx 20 seconds. After which it settles and is sweet for the remainder of the day.

As a test, perhaps i could remove the fuel evap hose from the throttlebody and plug both openings. And then test the 1st start of the day. ?.
 
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