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Lupo 1.0 Misfire and Low fuel trim


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Hi all!

First post on the forum, after some help and advice. Bought a lupo 1.0 MPI as a cheap runaround for the next year of university, parking space in my apartment block is tiny so lupo it is! On the drive home it started hesitating and losing power on the motorway section, which luckily wasn't too long so I made it home fine but it's definitely misfiring and my scan tool confirmed it's cylinder 4 along with lean fuel trim.

I've done some reading on the forums, seems spark plugs, leads and coil packs are a must and they looked quite old so I've bought new ones which are in the post. While they're on their way I decided to clean the throttle body which cleaned up lovely, but I also wanted to clean the egr but couldn't find it?? Very confused because maybe the engine doesn't have one but most posts suggest cleaning it so maybe I'm being brain-dead but does the ALD engine have an egr? 

If the plugs and leads do nothing I will put a new fuel filter in anyways and check for fuel pressure, fingers crossed the plugs and leads fix it, coil pack after. I'll do a compression test too and get back with the results when the tool arrives, I know about the +-10% rule but any PSI values I should be aiming for?

Would appreciate any advice or help from you guys, hopefully get the car running sweet before uni, I'm not afraid of doing a head gasket or anything either but let's try the easy stuff first haha

Cheers!

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Yeah, if not ignition, check for air leaks. Injectors rarely fail. Not fuel pump.

If you're running it over winter, coming up rapidly... might be worth swapping the thermostat and coolant for a new one. That'll help the engine warm up quicker and save on cold running fuel costs.

If it were me, I'd also vent the sump breather fumes to the road under the car via a length of flexible electrical conduit. Means the engine will be breathing nice clean air, resulting in very slightly higher power! Bung the hole where the oil vapours get sucked in. Your throttle body will stay sweet.

They're good little engines that like being caned.

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1 hour ago, lupo 1.7sdi said:

The ALD engine doesn't have EGR.

2036401148_ALDcompression.JPG.f1d1f43b5a8468d4b5317e199876526c.JPG

First check the ignition on cylinder 4.

It woIMG_20200826_130103.thumb.jpg.98f37584c3a0ee4bcb887f276f7fdbeb.jpguld be useful if you posted the errors as given by the tester.

Thanks for the reply, I've attached the codes from my obd reader, I'll do a compression test when the kit arrives and report back. Any neat ways to check the ignition on cylinder 4? I was thinking of swapping some of the HT leads around and seeing what happens?

IMG_20200826_130107.jpg

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You know I have a gut feeling it's not ignition related. A manifold or vacuum hose / servo hose leak usually causes this type of problem. Try disconnecting the vacuum lines and plugging them if you get nowhere with new ignition bits to help isolate the fault.

But, could be compression :(. Hoepfully not the valves or HG. May just be a stuck ring and needs a good thrashing after an oil change (if low compression).

 

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So the compression tester arrived today, just did the readings and I've got to say I'm very relieved:

4 200 psi
3 185 psi
2 195 psi
1 200 psi 

3 does seem a bit lower than the others but correct me if I'm wrong it's within tolerance.

Also checked the plugs that were in there, all looked fine no soot no white crystals, only thing is they were Bosch plugs and I've read on here NGK is the way to go so luckily I ordered some NGK ones on eBay yesterday.

When the plugs, leads and fuel filter arrive I'll give an update but it looks promising! 😃

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Yeah, that looks ok. If mostly short journeys, I'd go one level hotter. So if it's a nnn7 plug, try a nnn6. Helps keep combustion chamber a bit cleaner, but shorter plug life.

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New NGK coil pack arrived today, put it on with new NGK BKUR6ET-10 plugs, it starts up smoother but once warm still feels a bit lumpy on idle. Any ideas on what to do next?

How big of a job is removing the head on the ALD engine, doesn't look like it would be too bad considering how small the engine is. If the head needs to come off I'll check the valves and rings but for now I'd rather keep it on.

I can upload a video of it running if that would help anyone :D

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I wouldn't pull the head off. At least not yet. I don't think it's an internal problem. 

Temp sensor ok? V Common fault.

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Another small update, I had some free time today so I did a fuel pressure test and took the injectors out to have a look. 

Fuel pressure was at 35psi and when the vacuum line was taken off the regulator it went up to 45 like expected. 

Fuel injectors are looking a bit sooty with dried oil in the injector wells and on the injector tips. Does this look especially concerning? I haven't owned or ran the car enough to tell if it's burning oil but the injectors definitely look a bit sorry for themselves.

I'm happy to have a play about with the car cos I have my astra, this car was for my girlfriend and myself to use as a cheap runaround to save on petrol and insurance :D

Any opinions are greatly appreciated.

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Could be a clogged up injector  - try swapping cylinder 4 injector with another and see if the misfire moves to that cylinder

Take care re-inserting injector into fuel rail - they don't go all the way in - the clip limits its height

Edit : those injector seals look really crusty, probably could do with a clean and lube with thin smear of vaseline

Edited by LR5V
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