JTS running very rich

[josh18]

Thanks John, yeah I think all my tell tale signs at least say rich running, but the oil is going somewhere. With the manifold, looking at how close the variator gallery seems to be to number one I could see how oil could get in but not outside air. I have read of the issue now in a few places. By all accounts it looks like the manifold is a prick to get off with the head on.
I have ordered an OBDII cable and will buy myself a copy of MES. Seems like I am just guessing now where this setup might help me do some proper diagnosis. I also read that an ECU reset can help a lot. Im also going to try and give it a decarbon with one of the upper cylinder cleaners similar to seafoam. I keep hearing good things about this, particularly on JTS's.

I was going to buy a set of pre-cat O2 sensors but I will wait until my diagnostic stuff arrives to see what the mixture is actually doing to save possibly wasting a lot of money.
As for compression results they are in the range suggested by Bazz so Im happy with that at least. I dont know if good compression means no iol leakage from the rings but i think it's a good sign at least.
Cheers

[johnl]

I've never done it, nor had it done, but I think you could probably put the car on a dyno and do an exhaust gas analysis, to see how rich it actually is under varying throttle / loads...

Regards,
John.

[Colin Edwards]

Hi Josh,
Wise move to invest in some diagnostic gear.  It'll take a lot of the guess work out of the equation if you can talk to the ECU and get an idea of the injector duty cycle. 
Not unusual to richen up the mixture a bit at high rpms.  That plus a bit of oil geting into the inlet tract and mixing with the spray from the injectors could explain the black / sooty smoke.  Its sort of combusting with the fuel however because you have too much hydrocarbon at the time of ignition its too rich and ends up as soot. 

All things being equal, a direct injection engine will be more efficient than a similar port injected engine.  However the mixture produced by a direct injection / JTS is not as homogenous as the earlier port injected engines and soot is the result.

Blue (or heaven forbid) white smoke is usually a sign of oil vapourising as opposed to oxidizing. 

[bazzbazz]

As for compression results they are in the range suggested by Bazz so Im happy with that at least. I dont know if good compression means no iol leakage from the rings but i think it's a good sign at least.
Cheers

Did you READ ANY of the link I gave you on how to a compression test??

The results of what you posted tell you that the rings ARE shot. If they were in good condition there should be barely any difference from dry to wet readings. When doing a compression test if you get low and varying readings and then add oil and all the readings rise and become uniform then it is a direct indication of worn rings.

Also the PVC valve - the golf tee valve is in the little plastic cylinder at the end of the hose that connects to the variable inlet manifold just behind the Throttle Body.

Baz

Owner
On the Spot Alfa - When your Alfa puts you on the spot, we're there on the spot with you.

Mob:   0405 721613                 
E-Mail:   onthespotalfa@iinet.net.au
8 Hansen Court
Capalaba   4157

[johnl]

I'd have to agree, and to a degree, disagree. I agree that the rings aren't in the best shape, but "shot" is debatable.

In my experience a wet compression test will always give a significantly higher number than the same cylinder when tested dry (well, it always has for me, though I can't recall numbers off the top of my head and I haven't done any compression testing for a long time). The commonly accepted benchmark seems to be that a wet test should make no more than about 10% higher psi (or whatever unit) for the rings to be considered fully acceptable.

Assuming so, then 10% of 227.73 (psi) = 22.73, so 227.3 + 22.73 = 250.03. So, with 250 as the wet benchmark we should be seeing about 228 psi as the fully acceptable dry compression number. The worst dry number on this engine is 215, the best 220, so the compression isn't the best, but I've seen worse wet / dry ratio in engines that still ran quite acceptably and burnt reasonably little oil. Of course if compression is down to any degree then this will affect power output to whatever degree, but if you can live with that, at least until it gets worse, and it will...

Of course this doesn't preclude any particular engine with similar numbers to this one from burning oil. The compression only has to do with the compression rings, and it's the oil scraper rings that keep too much oil from getting to the compression rings. If too much oil reaches the compression rings due to poor oil control rings, then the compression rings can 'aquaplane' on the oil, allowing oil to pass the compression rings into the cylinder.

Even if the rings are actually allowing too  much oil into the cylinders, the rings themselves may still be OK. It's quite common for rings to get stuck in the ring grooves due to varnish build up and other muck, in effect gluing the rings into the grooves. If this happens the rings lose the capacity to push against the cylinder walls, and compression drops. Sometimes just cleaning the grooves and rings can work wonders. Pity it's still such a big job to get at them...

I think this is likely to be what products such as Seafoam, Auto-RX, and others largely do, i.e. dissolve deposits in the ring packs to free them up and improve compression. This is assuming such products actually do work, I've never tired them myself. Over a long enough period of time, high detergent oils might do something similar. Diesel oils are highly detergent, as are the better quality synthetics. Note that diesel oils often have a lot of zinc content, and zinc can poison catalytic converters, which could be a problem for engines already burning a fair bit of oil.

Regards,
John.

[bazzbazz]

I give in, I quit !

[josh18]

Sorry Baz, I have done compression testing before and thought like John that there is always going to be a difference between wet and dry compression readings. It's not like the rings totally seal in normal use anyway. At 220 psi this put the readings well withing the range you suggested,  and way higher than your average readings on a normal car. TBH I also give up as I think the car has now done a rod bearing (happened during my "Italian tune up" so my fault). At about 5500rpm the car let out what sounded like a bad pinking, coincided exactly with a plume of black smoke out the back. I backed off immediately but I guess too late. Upon driving home it now has a rattle (sounds more top endy) that goes away under load at low revs (not there at idle) but is pretty bad as the load comes off. Pulling number 4 coil out while running silences it, and from what I can read this is how to diagnose a rod knock. Seeing that it's not there at idle I am thinking it might not be too far gone and I will take the sump off to have a look and look at doing big end shells if the crank is not scored. Either that or a broken piston, or some sort of lifter issue? But I dont think it would run right with a broken piston.
This car seems to have a multitude of issues all happening at once, including the worn out cams and I reckon if and when i fix this issue then it will just be a matter of time before the next issue.
We love the car but I think it is more of a tinkerers car rather than a missus's run about.
Cheers for all your help guys

[johnl]

Not having much luck Josh...

Pulling a plug lead (or in this case a coil) helps diagnose which bearing might be bad, not really whether a noise is actually coming from a bearing (though usually it would be considered the likely cause of a regular 'knocking').

What confuses me about your symptom is that you say it's not there when the engine is under load. But, under load is when I would most be expecting to hear a knock from a bad big end bearing. Heard it many times, audible knocking even on  light throttle opening, but worse at wider throttle opening (and worst at peak torque rpm), but that goes away when the throttle is closed such as on the overun and at idle. I'm not saying that a bearing isn't bad, but if so just surprised it's not louder when the engine is working harder, and is happening when the engine isn't working harder.

You also say that it sounds like a rattle and is "top endy", but a bad big end tends to sound like it's coming from the bowels of the engine, and is a regular 'knocking' noise that changes frequency with rpm. I'm not convinced that it might not be, as you suggest, something more like a broken piston, maybe.

Regards,
John.

[bazzbazz]

Well I would suggest that the engine needs a rebuild all round to be honest. If you have spun a big end bearing, be careful when you drain the oil, siphon it out of the container and look for small balls/particles of white metal, same in the bottom of the sump. These are parts of big end bearing that come adrift when they fail and the definite tell tale of a done bottom bearing.

And while your there, get the head off, change the cams and valve stem seals as well as the rings. Also the inlet manifold gasket and you should be golden. Nuthin to it!   

[josh18]

Hey guys, I have pulled the sump off and yes it was number 4 big end bearing worn out. It is down to the copper but not through it, and the crank journal looks fine so I reckon I got lucky. I was looking to put a new set of shells in it and sell it on but I really like the car! We have decided to get my wife a much more sensible Subaru Liberty wagon and I will look at doing a rebuild of sorts on the Alfa in my own time.
My plan is to remove the head and inspect the bores, if they are not too worn deglaze them and fit new rings and try and find a set of good second had cams. I would also do the timing belt etc at the same time. I need to look at getting the injectors refurbed at the same time if it's possible.
Has anyone had any luck with regards to oil consumption by fitting new rings without deglazing? I really want to leave the block in the car.
I'll give you a ring Baz
Cheers

[josh18]

Grrr, just inquired about some second hand cams and found out they are almost 400 each. With that, and a timing belt/ water pump kit injectors etc I think it's gonna be just too much, especially considering the dubious bottom end. I don't really know where to go with it now, I like the car but I definitely don't want to throw thousands at it. 

[johnl]

Well, not a huge surprise that it did turn out to be the big end bearing. I was trying to be upbeat in the hope it might not be...

$400 each for S/H cams? It's not a Ferrari for fucks sake. Have you considered a complete second hand engine? A quick search found this from A-Twins in Sydney, for $900 (plus freight) with a 3 month warranty from a car that had done 122,000 km:

http://www.ebay.com.au/itm/ALFA-ROMEO-156-GT-GTV-SPIDER-2-0L-JTS-ENGINE-97-10-/132113780760?hash=item1ec2985018:g:t1MAAOSwOgdYqiXO

A more in depth search might do better?

Regards,
John.

[poohbah]

Was about to make the same suggestion

http://www.ebay.com.au/itm/ALFA-ROMEO-156-JTS-2-0-LITRE-MOTOR-FIT-SPIDER-GTV-GT-EXCELENT-CONDITION-/281275400634?hash=item417d5201ba:g:kK0AAOxy4fVTEAet

[josh18]

Thanks guys, that's definitely cheaper than the parts I was looking to fit to mine, by quite a margin. But it's at higher k's than mine, and at a wreckers. I reckon there's a pretty good chance it has all the same issues as mine too.
I think at this stage I am just going to do the big end shells and see how it goes. Then I will either decide to sell it or if it goes alright for a while make a call on doing the rest. Timing belt is due in 10,000 km so that would give me long enough to see if it's gonna live or not.
I measured up the suspect journal today and there is no difference between it and the good journals and looking at the specs for standard shells, withing tolerance. So at this stage it looks like it will live on.

Bazz if you're on here could you please let me know that supplier we talked about.

Cheers
Josh

[bazzbazz]

These guys have the shells -

http://www.precisionintl.com.au/Default.aspx

Baz