New Gen 5 GM V8

[sambo]

Tomcat, I think you're referring to carbon build up on piston heads, which is a different issue. In a DI engine, fuel doesn't pass through the inlet valves, but crankcase gasses and EGR vapours do - a fuel additive does very little to help the situation.

[Gav]

I have a DI Pajero, It has just done 140K, and I have not had any issues at all.
That being said, I have been told by several sources that regular servicing with the correct lubricants is the key.
The cokeing issues with the inlet valves is interesting, but I won't be finding out whether mine has it, I am changing it over this week!!

[Gaz64]

Originally Posted by Gav

I'll go out on a limb here and say I reckon you want to start to get used to it!

I'm a Gold Certified tech for a Holden dealer, been way used to it since '04.

Originally Posted by sambo

Volkswagen have been using FSI (fuel stratified injection) since 2000. It was adapted from their Le Mans car. I've had the TFSI engine (turbo FSI) in two GTIs since 2006 and they keep being awarded engine of the year, so direct injection isn't necessarily a bad thing.

They do get carbon build up on the intake valves and intake runners, which hurts performance over time and in really bad cases can damage intake valves and other components. A catch can lessens this to an extent, but my mechanic recommends spraying a decarbonising solution down the intake from time to time. Eventually with enough kms all of these engines will benefit from a tear down and a proper clean. This is recommended at the same time as they do timing belts, cam followers, etc. I doubt many Cobras will be doing that many miles though - in the order of 100,000+.

Been decarbonising VE SIDI engines since the problems starting arising.

If I owned one, I'd fit an air/oil separator ventilation tank including a replumbing job.
And possibly a electronic water/methanol injection system.

[sambo]

Gary, I've looked into catch cans for my daily driver but the full kit with adapter plate etc is around $400. A water/methanol injection system is a bit radical for me. Mine's a turbo that I drive hard at times and I change the oil every 6 months. I'm going to start dumping a $15 can of Subaru UEC (upper engine cleaner) into one of the vaccum hoses and run it for a short while prior to every oil change. This is what a couple of the dealers have offered as a preventative measure when I've asked about the problem. Except they want $130 for the "job".

Apparently Toyota is now using an additional injector to squirt fuel into the intake runner on their direct injection engines, in the hope that it will solve the problem. Sounds like a good idea to me.

See here for some photos of what's happening to the VW engines.

[Gaz64]

Great pic, one can see how the buildup hinders airflow into the cylinder over time.

I have used Subaru Upper engine cleaner for about 15 years on too many cars to mention. Wonderful product.

When I get a complaint vehicle, I strip the intake manifold on a hot engine, I fill the intake port on cylinders that have valves closed, wait 5 min, turn the engine to do the other cylinders, reassemble intake, start engine, run another 1/2 can through the intake at the throttlebody, smoke the workshop out , roadtest the car at mid to high rpm and load until the smoke clears.

AC Delco also make combustion chamber cleaner, which appears to be the same product.

Obviously Toyota sees a problem, and are trying something to fix it.

Direct injection came about to meet Euro 5 emission standards.
It will interesting to see if Toyota can still meet Euro 5 with an outboard injector.

[sideshow]

I've worked on afew Vws lately
All around 10 years old and not maintained
I would not even own one if I was given one for free
And it came with a hot Blonde in the passenger seat heheheh

Can't go past toyota these days

Anyway back to the new gm motor
Shouldn't be too long before we can play with these ecus

[Aussie Mike]

I bought a turbo diesel VW Jetta new for my wife back in 06. It has over 100,000K's on the clock now and been the most reliable trouble free car we've ever owned. I'd happily buy another.

Cheers

[sideshow]

i stupidly said ok to work on afew that are from a cheap car yard where they buy cheap vw cars from auctions for 10 bucks then expect to pay 5 bucks to fix them
they have the most stupidly designed diagnostic system where u need to buy a book
too tell u which number to punch in to get certain data from the ecu
i guess its so u can take it back to vw and get shafted
anyway id never ever ever own anything made in europe
hhehehehehe

[Jaydee]

Would you get the same problem with LPG?
JD

[puttputt]

Yeah, good question, direct injection converted to LPG

If i can't afford the gen 5, it will hopefully cause the gen 4 to drop in price.

[Gaz64]

Sooner or later all manufacturers will realise the mistake of going to direct injection,

[T.L.]

I find the current engines okay for my useage, wouldn't they be more prone to sooting up with less use?.

[Aussie Mike]

Originally Posted by Gaz64

Sooner or later all manufacturers will realise the mistake of going to direct injection,

I think it's more likely they will come up with methods to eliminate the carbon build up. Water injection or special coatings on the valves and ports or something like that. They won't want to pass up the power and economy potential of the technology.

Cheers

[puttputt]

I was thinking that maybe the new gen 5 won't be a lotmore expensive then the gen 4, new cars with new technology normally are the same price as the previous models, and the gen 4 engine isn't more costly then the gen 3.

So I'm thinking to wait a bit to see what happens !

[Aussie Mike]

Originally Posted by puttputt

I was thinking that maybe the new gen 5 won't be a lotmore expensive then the gen 4, new cars with new technology normally are the same price as the previous models, and the gen 4 engine isn't more costly then the gen 3.

So I'm thinking to wait a bit to see what happens !

I'd go with the one with the best aftermarket support. There's a ton of info and parts available for the gen 3/4 motors. It'll take them a while to get into the gen 5 especially if it has another order of complexity with variable valve timing and direct injection.

Cheers

[Gaz64]

Originally Posted by puttputt

I was thinking that maybe the new gen 5 won't be a lotmore expensive then the gen 4, new cars with new technology normally are the same price as the previous models, and the gen 4 engine isn't more costly then the gen 3.

So I'm thinking to wait a bit to see what happens !

Gen 5 has direct injection, heads are different with the injector in the combustion chamber, variable valve timing with a single cam phaser for 16 lobes, AFM (or DOD) technology carried over from Gen 4.

Each "generation" has had improvements that makes them more costly to produce and maintain.

When will GM be able to produce a roller cam and lifters that will live?

Have one in the shop now with cam lobe failure on cylinder 4, 37000km, this type of failure is completely random.

[Modena]

A mate just had the cam and lifters done in one of his LS3's with 45,000kms, cam lobe was completely chewed out and it was rattly as hell.

[sambo]

What generally causes this extreme cam lobe wear - uneven spring rates?

[Modena]

the original spec lifters are shi-te apparently - there is an upgrade kit that goes in to replace them, for those that fail under warranty of course.....

the cam part itself is ok and although it is screwed by the dodgy lifters, the new replacement is not an upgraded part I believe, just a new one of the same design.

[Gaz64]

Originally Posted by sambo

What generally causes this extreme cam lobe wear - uneven spring rates?

It could be a spring on the light side of minimum full open spec.

Once the roller starts to skip, the flat spots start happening and it's goodbye roller wheel and cam lobe. I have seen more than one failure in an engine, but generally only one failure per engine.
For only one from sixteen to fail is extremely odd, I can't put it down to anything else.

Originally Posted by Modena

the original spec lifters are shi-te apparently - there is an upgrade kit that goes in to replace them, for those that fail under warranty of course.....

the cam part itself is ok and although it is screwed by the dodgy lifters, the new replacement is not an upgraded part I believe, just a new one of the same design.

I think it is a hardness issue combined with light valve springs.

The springs would be the lightest GM could use to allow the engine to rev to factory fuel cut, and not be too heavy for fuel economy loss.