COLD engine shake on GU 4.5

[4by]

I recently bought a GU 4.5 auto on dual fuel. Here's the problem that is annoying me and I can't find a solution.
When I first start the engine it shakes bad and is worse when putting it in gear. Once I drive above 1500 rpm it seems to go away. When the engine warms up the shake is still there but only a shimmer and sometimes shakes when accelerating from a standing start.

Things I have done so far.
~ Changed plugs to iridium.
~ Tappets checked and adjusted to spec.
~ Cleaned throttle body and LPG system.
~ Cleaned MAF.
~ Cleaned air cleaner with compressed air.
~ Checked all spark plug leads ok.
~ Cleaned and checked dizzy cap ok no cracks.
~ Adjusted idle speed and timing running about 7-8 btc. (lpg)

These made the vehicle idle bit better when warm, but still really bad when cold.

I also noticed the fast idle cam was disconnected and some of the pipes were blocked. I replaced new hoses and reconnected the fast idle cam. This didn't make much difference but not sure why they would have bypassed this. Does anyone know if this system works better disconnected??

I'm going in circles and running out of things to check........ I was going to look at the coil next.... perhaps it's not supplying enough current.... I'm not sure where to look next.

Has someone had a similar problem or suggest some help please..............

[Bigrig]

Is it happening for both fuel types mate, or only on one?? If one, which one??

Hopefully it's fuel related (maybe super lean at idle for some reason) and at least if that's the case it'll rule out major engine issues ...

Hopefully others will be able to chip in here also.

[Ben-e-boy]

have a look at the vacuum lines, sounds like one could be disconnected.
Cheers
Benny

[Bob]

I would get a Compression Test.
I had the same and it turned out to be a burnt out Valve
I hope its not

[Ben-e-boy]

I would get a Compression Test.
I had the same and it turned out to be a burnt out Valve
I hope its not

yeah, I was thinking that but if ther isnt a disconnected vacuum line that would be the next step I think.

[4by]

I would get a Compression Test.
I had the same and it turned out to be a burnt out Valve
I hope its not

Crap...Don't say that......it sounds expensive. So a compression test will reveal this huh.......

I did check all hoses for leaks and sprayed wd40 around for leaks but all seemed ok. I did get a whistle from the pollution box (think that's it...located behind the LH headlight) but I pulled the hoses and it stopped....

[4by]

Just a thought..... Would a loose vac line cause the engine to run bad when cold and gets better as the engine is warm.

It tends to happen on both petrol and LPG but sometimes runs well on petrol. I believe LPG enhanses any faults.

[Ben-e-boy]

Just a thought..... Would a loose vac line cause the engine to run bad when cold and gets better as the engine is warm.

It tends to happen on both petrol and LPG but sometimes runs well on petrol. I believe LPG enhanses any faults.

Yeah mate I had an old hilux ute petrol and would cough and splutter when cold, ran a little bit rough when hot, it was missing a vacuum line

[Robo]

Possible's to check as Faulty.

Need vac schematic.
recheck vac lines.
you may find 1 has been blanked off internally.
Or 1 that could have a reducer fitted internally, even moved to wrong position.
"Personally found that 1 in the past".

does the elec system have self diagnose?.
using instrument light blink system.

re-clean maf.
with maf cleaner not carby clean.
carb clean has dry a lube.
faulty maf.

fuel filters.
coil, as you said.
leaking/faulty idle valve.
aacv faulty blocked
Blocked-up exhaust system,
check cat converter.
o2 sensor.
tps.
injectors.
injector seals.
crank angle sensor.
battery earths including engine-bay earths.
leaky intake manifold.

hopefully 1 of these and not a valve.
cheers.

[Yendor]

I'm with Ben and Bob,

I would do a compression test before spending time and money on other items.

[4by]

Update..... I doubt it's a burned valve....
I went out yesterday and the car was shaking at idle. This morning it drove fantastic, no shake and purred like a kitten. I was so excited that I even had to video it..... ;). I got home and let the car cool for about 2 hours and went out again for a drive...... Again bad shake at idle. All on LPG.
I flicked the car to petrol and pulled out the injector connection one at a time. Engine changed revs on each one except when I plugged no 6 back in the engine revs increased slightly. Flicked it to LPG and running smooth again on LPG and petrol..... WHAT THE ....?????
I was out there tonight checking vacuum lines and connections, changing from LPG to petrol and back, checked timing and all seems to be running smooth.

Ok, so if it was a burned valve wouldn't it be shaking all the time????

I'll be out there tomorrow morning and try it again......fingers crossed and I'll let you know the outcome.

P.S. Robo, I used maf cleaner so hopefully it's still ok. Ecutalk shows no faults codes.

[4by]

Ok, so this morning I started the car on LPG, choke working and the engine was shaking for about 3-4 seconds then cleared and idled smooth. No shake.
Went for a 2 min drive. Switched off the engine for 5 mins and stared it again. It shook for about 3 sec and then smooth as. Beauty.....

So, it must be something with the last injector connection when I plugged it back in. The problem is not completely solved as it still does it for about 3 sec after starting. Maybe it takes a few seconds for the computer to wake up an kick in.... Don't know!!!

Overall, I'm happier that it running better and seems to have more power. I'm going to clean or change the o2 sensor as I don't think it's working correctly according to ecutalk.

Thanks for your replies.....

[Robo]

If the o2 sensor is worn, they can take a while to warm up and send signal.
Does your car take a while to respond to peddle , tell tale sign of worn o2 sender.

I'd be putting injector cleaner through.
Morreys upper cyl lube is a good injector cleaner/ maintance product added to petrol tank.
Won't harm a thing.
I use this for upper cyl lube in a dripper system for LPG.
and a small amount in petrol tank 4.2s patrol to lube petrol system while not in use while running lpg.
Penrite have a upper cyl lube, but it does not contain any cleaner products, as a result cheaper than Morreys.

Don't like flash lube, found it made another car in the past ping really badly.
And also fuel doctor in my Wife's old lance returned 3 Lts worse per 100k so forget that to.
cheers

[4by]

Ok, so my engine shake is definitely related to the injector plug on no6. If I put some pressure on the plug pushing it, the engine starts to shake. If I push it back the other way it's idles smooth. Most of the time it works ok but at least I know the problem.
I'll hit it with some contact cleaner on the plug and if that doesn't work ill change the connection.

[Robo]

If it doesn't work .
"I'll hit it with some contact cleaner on the plug and if that doesn't work ill change the connection".
After you clean but before you restart engine Maybe also try swapping an injector to say, No1 cyl and 6 around, and see if problem moves with it or stays on cyl 6.
Its just that this connection is a fairly sound design and shouldn't be causing this sort of problem.
1 of 2 things.
dirty injector.
broken connection on, or in loom.

Now I know I'm probably going to get an ear-full here but this can be done successfully.
But it's up to you, just food for thought.

I have cleaned injectors by hand it's not hard.
2 different cars successfully.
3 time each now.
You just have to be very careful.
safety glasses, maf cleaner,compressed air, a small clamp, old tooth brush and a workbench.
Shake fuel from injector.
Carefully remove seals from injector as they don't like cleaning products
hold upright, place in say a cup.
Carefully fill injector with cleaner let soak a while, finger over end and shake if ya like.

The tricky part is opening injector tip by hand without damaging tip.
Gently but firmly so it won't move clamp injector to bench on it's side, near edge of bench.
Steadying your hand against edge of bench with a tooth brush to gently push tip open a little
Need to be able to carefully squarely push injector tip inwards a little while blowing compressed air in from opposite end.
leave on bench and more cleaner, open again and blow, and repeat etc
You may get nothing out the tip end for first few attempts.
but it will slowly clear and come good.
Might take several goes but does work and you can physically see it clear better each attempt.
you could use carby clean but they have a dry lube product in em and I'm not sure if ok in injector or not.
I did use carby clean the first couple times but learned about dry lube since then and thought twice.
Cheers