Rough idle and injector cleaner

G

Gaffa22

Member
Thought some of you may find this interesting

Last winter if the car had stood for more than 2 weeks on start up it would idle really rough. Fault code reader showed misfire on 2 cylinders. I stood the car again for 2 weeks then removed the spark plugs. Two were really wet.
I was going to replace all the injectors, but as the car had only done 29500 miles I replaced the spark plugs and decided to try injector cleaner.
Now I normally consider injector cleaners as snake oil but thought what can I lose.
So used two full tanks of fuel treated with Techron then changed the oil.
Since then each tank of fuel has been treated with Lucas Upper cylinder lubricant / injector cleaner. Fuel used for each fill up was Shell V Power.

I started to notice an improvement after the first two tank fulls with the Techron, the car would start instantly with no misfire. Even after being stood for 3 weeks.
The car was last used end of October so had not been started for over 2 and a half months, this morning it stated instantly and idled as smooth as a sowing machine.

It is is possible the improvement was just down to the Shell V Power, but I will continue with the Lucas treatment as I bought a litre bottle.

So am really pleased with the results and the difference it has made. The Idling is now perfectly smooth a considerable difference to how it was before, The fuel consumption has also improved
I can only assume the rough idle and misfire was caused by dirty injectors, and the V Power and treatments have cleaned them out.
 
You replaced the plugs, used the snake oil, posh petrol and UCL ? - You won't ever know for certain what fixed it :D
 
flybobbie said:
Surely wet plugs means faulty ignition coils. Ambient temperature would make a difference.
Click to expand...
Yes I thought that which is why I wasn't sure it was improved until the colder weather, and I tried swapping the coils which made no difference still got misfire on same cylinders so pretty certain it was injectors
 
Well done Gaffa, I've always wondered about the so called benefits of using aftermarket additives. No problems with mine as of yet but think I'll give this a whirl to keep the E89 dreaded injector problems at bay :thumbsup:
 
Is Redex ok? With all the sensors on the exhaust side and the cats, I‘m a bit concerned about potential contamination?
 
I've been chasing an annoying issue down on my old E46 320d for the last year. The car would occasionally stutter during light acceleration and it was gradually getting more frequent. I'd replaced the usual suspects like MAF and MAP sensors (they were long overdue anyway), fixed several boost leaks and replaced the fuel filter but still no improvement. It was looking like it was either a failing injector or bad electronic wastegate on the turbo which are both fairly expensive things to resolve.

I was always of the opinion that injector cleaner was snake oil too but by chance I stumbled across a YouTube video where they took a couple of really old high mileage cars, ran them on a dyno then carried out several service items like changing spark plugs, oil, filters and finally fan a tank of fuel system cleaner though. Each step was followed by another run on the dyno and each step resulted in single figure horsepower gain including the fuel system cleaner which I think revived around 5hp from the engine. I found plenty of other videos with some fairly convincing tests and all appeared to show some improvement and none looked obviously sponsored by Techron.

So I bought a pack of Techron diesel cleaner from Costco for £10. Treats 16 tanks of fuel in total, I'm only 2 tanks through it and already the issue is completely resolved. Really didn't expect it, but I'm happy with the results.

My Z4 has new injectors courtesy of the warranty so no need to use any in that car just yet.
 
I wonder if those with injector issues are using super-unleaded or normal fuel?
In theory the detergents in super should prevent this sort of thing :?
Rob
 
Smartbear said:
I wonder if those with injector issues are using super-unleaded or normal fuel?
In theory the detergents in super should prevent this sort of thing :?
Rob
Click to expand...

I've always used premium fuel in the Z4, purely because the tune requires it.

Injector issues in the 35i are common regardless of fuel, age and mileage of the cars. BMW now have a new revised injector design that is less prone to failure.
 
Well it does make you wonder how many injectors have been replaced that just needed a clean

I am absolutely certain my injectors were leaking which is what can cause the rough idle, as the spark plugs get wet because of the excess fuel in the cylinder.
Admittedly mine were not leaking too bad, as it only ran rough if stood for more than two weeks.
But I am also convinced that either the premium fuel or the additives, or a combination of the two, cleaned what ever deposits were causing the leaks

In which case I believe its definitely beneficial to run our cars on premium fuels
 
It does make you wonder especially when there are companies that recondition injectors.
Maybe all they do is clean them.
 
Gaffa22 said:
Well it does make you wonder how many injectors have been replaced that just needed a clean

I am absolutely certain my injectors were leaking which is what can cause the rough idle, as the spark plugs get wet because of the excess fuel in the cylinder.
Admittedly mine were not leaking too bad, as it only ran rough if stood for more than two weeks.
But I am also convinced that either the premium fuel or the additives, or a combination of the two, cleaned what ever deposits were causing the leaks

In which case I believe its definitely beneficial to run our cars on premium fuels
Click to expand...

When mine failed they got stuck open and fuel was pouring out of the exhaust pipe. :fuelfire:
 
Nictrix said:
It does make you wonder especially when there are companies that recondition injectors.
Maybe all they do is clean them.
Click to expand...

Does anyone actually recon the BMW Direct injectors though ?

R.E92 they were properly f**ked then did it melt the cats ?
 
Gaffa22 said:
Nictrix said:
It does make you wonder especially when there are companies that recondition injectors.
Maybe all they do is clean them.
Click to expand...

Does anyone actually recon the BMW Direct injectors though ?

R.E92 they were properly f**ked then did it melt the cats ?
Click to expand...

I don't think so but the warranty rectification involved 12* new injectors, 6 new plugs, 4 new cats and 4 new O2 sensors.

They replaced most of that trying to chase down a problem with a misfire which turned out to be caused by them not installing the decoupling elements on the injector. So they had to replace the injectors twice.
 
Ah yes I remember you having problems
If you get neat fuel in the cats they are knackered so a bloody good job you were under warranty as I bet it came to lots of £ the injectors are over £1200 a set
 
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