Jump to content
Sillyspeed

156 Jts Mcsf, Lambdas, Connectors And Catalysts...

Recommended Posts

I'll give it a shot here on AD as well, hoping that someone could give good advice ;)

 

And yes, this will be "JTS motor control system failure/lambda faulty?" thread number ten thousand. Sorry for those of you who I've bother on AO, ausalfa and alfa156-net..

 

Long story short: have had my may-2004 2.0 JTS with 118k km for almost two years now and motor control system failure light has been on and off (mostly on). No noticable running problems or misfires. Previous owners have used £1600+ to try to solve MSCF warning lights..(!)

 

History:

2009: 62000 km: MSCF, both lower lambdas changed

2010: 64000 km: MSCF, both upper lambdas changed, cat inspected

2010: 68000 km: MSCF, P0420 cat 1

2011: MSCF, cat 1 and 2 above upper limit

2012: 9x000 km: MSCF, misfire cylinder 4(?), 1 coil changed.

2013: 100000 km: MSCF mostly on. Inlet cam checked for wear at workshop, OK

2013: 102000 km: 3 coils replaced, all are 2012 or newer. MSCF light came back after 100 km (P0420 and P0430)

2013: 103350 km: Spark plugs replaced. 800 km with no MSCF, then it came back.

2014: 108000 km: Serviced at workshop, which had previously replaced lambdas. Same error codes, but this time I told them to keep their hands off.

 

2014: 118000 km: Had to replace oil sump, and I purchased a new maniverter/catalyst from Belton Massey since this has to come off to do the oil sump. By some huge misfortune, the maniverter was not fabricated to tolerances, and would not fit properly (this one: http://www.cats2u.co...A-ROMEO/156/2.0). So the old catalyst had to be installed, and I was not able to rule this out as the cause of the errors. 3 new error codes as well that have not previously been seen:

 

P0156 02 Sensor Circuit Malfunction (Bank 2 Sensor 2)

P1161 Heated Oxygen Sensor (HO2S) Heater Control Circuit (Bank 2 - Sensor 2)

P2237 O2 Sensor Positive Current Control Circuit / Open (Bank 1 - Sensor 1)

 

The mechanic, who has 25+ years of experience with Alfas commented that the thermostat seemed to open a bit early, suspecting that some low quality part was fitted 3-4 years back when it was replaced. He said that the old catalyst monoliths didn't look too bad, but that the engine seemed to be running hot based on the appearance of the lambdas. Couldn't catch all the details here. He reset the adaptation parameters and the car ran for ~200 km before errors showed up (P0420 and P0430). But still no noticeable issues on performance.

 

 

My self I have changed coils and spark plugs as per above, and cleaned and checked all the small and large connectors in the engine bay.

  • Should I try to get a new, original catalyst?
  • Air or exhaust leaks?
  • Is it the injectors?
  • Connectors or cables? <-- the 3 new error codes seem random and don't make sense to me, at least
  • Is the engine coked up and needs a cleaning?

Keeping in mind that the engine runs and revs as happy as the day I bought it. No issues or hesitation, good power, emissions OK.

 

All help hugely appreciated :)

Edited by Sillyspeed

Share this post


Link to post
Share on other sites

I also get the MCSF, but only rarely, with no associated running problems. It always comes up on MES / Torque as P0420. The lambda in question was replaced with a genuine Bosch part (from AlfaShop) the day after I bought the car (after the MCSF came up for the first time on the way home from the dealer).

 

I'm curious as to when your MCSF comes on. Mine only happens when I've been driving normally, and then end up cruising gently / driving Miss Daisy at a steady, constant speed anywhere between say 30 and 50 mph with no blipping the throttle. I did once dig up some info from, I think, a German Alfa forum that stated the system was only looking for errors between IIRC 32 to 48 mph (or similar).

 

I'd love to hear a definitive answer to this snag. I know some folks solder the lambda connectors and have reported success, and seeing as I've just had all the belts and bits & bobs done, and a full service, I'm happy to give it a go but I'd just like some confirmation as I'm possibly the world's worst solderer and don't want to go there unless its a definite fix.

Share this post


Link to post
Share on other sites

Our problem sounds similar, then. From what I can remember, the MCSF has come on either when cruising steady (possibly below 50 mph), but at least also once or twice when coming to a stop (less than 20 mph). Can't remember it coming on when accelerating hard or such and has never been noticable.

 

Last time I had a look at the wiring loom, I could not seem to trace the 4 lambda connectors back to any of the two 20-pin connectors at the fire wall. It seemed like they went into the firewall further to the right (as standing in front of the car). Does anyone know for sure? I see that the coil wiring and various others end up there...but not sure about the lambdas.

Edited by Sillyspeed

Share this post


Link to post
Share on other sites

Someone once recommended unplugging the big purple connector at the firewall and cleaning the connectors. Unplugged mine, spotless, sprayed some quality electrcal contact cleaner all over just for shits & giggles, and replaced the plug. Didn't make any difference. In fact the MCSF came back on again this morning when pootling along behind a 4x4.

 

Thinking back, the last time it came on was as I slowed and stopped at a junction, definitely below 30mph.

Share this post


Link to post
Share on other sites

Just an update as the car has passed 128000 km.

Still the same P0420 and P0430 codes, constantly on now (don't bother removing them anymore!). The 3 other codes in the first thread have not returned. The car runs sweet and never skips a beat. I cleaned the throttle body the other day, slight dirt on both sides, and afterwards the idle was smoother than ever. There is a periodic rattle that has started the last few months. Initially I found that it was one or two of the small heat shields on the manifold, but after removing the broken shield there is still some rattle.

 

So, should I buy a new catalyst?

 

Any thoughts....Smaky?

Edited by Sillyspeed

Share this post


Link to post
Share on other sites

Well I have a 156 JTS too for a dialy hack which is now on 158,000miles and also does this, I do have a very experienced theory on this though.

 

You haven't mentioned oil consumption, I bet this is high???

 

I know the power is there, but when your on gas is there quite a bit of smoke???

 

The codes are relating to CAT efficiency, when cold mine throws these up too and when it does I can feel a slight misfire as the lambdas try to overfuel the engine to compensate, but rev it a bit and get the needle off the 50 mark and the MCSF stops and running smooths out. Does that explain how yours runs too???

 

Have you done a compression test??? I have and I know that 2&3 are higher than 1&2, I also suspect the head gasket has gone on mine due to the requirement of a monthly coolant top up and I know the system isn't leaking externally as I can pressurise it and it doesn't.

 

 

SO in conclusion I know that my engine has worn pistons on 2&3, with a possible head gasket issue between those 2 cylinders, this is allowing excess oil into the combustion chamber which is contaminating the MANIVERTOR, BUT I use a bottle of CATACLEAN twice a year which has always got the emmisions back down to pass the test and for about 3 months after I don't get the codes, so I'd recommend you get a bottle of CATACLEAN (available from eurocarparts in the UK for £15) add it to 1/4 tank of petrol, run it for 50 miles and then fill up the tank and see if the problem goes away, as the warning code is based on the Lambdas reading high CO then it is also worth replacing the air filter so the engine can breath easier. The only thing I haven't mentioned is the direct injection, because the injectors are in the cylinder and not the inlet manifold this also creates a fueling issue, they coke up quickly, the cataclean though also cleans these if they aren't too bad to begin with, but the main problem is the cat is contaminated and this stuff is the best at rejuvenating a dirty cat that I've used.

Share this post


Link to post
Share on other sites

Thanks for your insights, Smaky, much appricated! :)

 

The oil consumption is around 1 litre per 1000 miles. More or less the same with 10w-60 and 5w-50, the latter which I've been using this winter here in cold Norway. The car has had oil changes twice a year for the last 5-6 years afaik, only with 10w-60 except for this last time with 5w-50.

 

There really aren't any signs of misfires, hesitation or white smoke. If I delete the error codes, they both come back, always P0420 and P0430 in pair, after a few hundred km's or so, sometimes less. Regardless of hot/cold engine, speed and rpm.

 

Compression has not been tested. No coolant consumption, pressure tested 2 years ago @ radiator replacement. Air filter replaced every 2 years or 20000 km.

 

Is it not correct that the post-cat lambdas do not provide feedback to the fuelling system on this generation engine management? I've read somewhere (on the big internet, mind you) that only the pre-cat lambdas adjust combustion, while the post-cat lambdas only are a Euro 3-requirement to monitor cat. efficiency (and to throw a stupid warning when the emissions are slightly off).

 

Could it just be that due to the inherent oil consumption of the JTS, possible slightly fuel-leaking injectors and aforementioned misfires caused by failed coils (causing unburnt fuel to be sent to the maniverter) - that the catalysts have done their job and are showing a steady decline over all these years since 2009?

 

Trying a bottle of Cataclean can't hurt, I suppose, I've only tried direct injection cleaner once a year, but without noticeable effect.

 

Last fall at "MOT" (some 5000 miles ago), the emissions were borderline, and merely passed. The workshop did not give me the CO/Lambda values, unfortunately, because "it was not required to record values for a passed test". But I take it that in 1.5 years, the emissions will be off.

 

If the persistent rattle is actually coming from the maniverter - the death rattle - is this proof enough? Or is it better to get emissions checked, try some fuel system/cat. cleaner, and check again?

Share this post


Link to post
Share on other sites

The air filter should be replaced annually as this will affect the CO level when it clogs up, this lowers the Lambda figure and can in extreme cases cause the codes you're getting as the Lambdas will tell the ECU that more fuel is required which is actually the opposite of what the engine really needs to maintain it's 17:1 air-fuel ratio.

 

I ran my JTS on the gas analyser today and it was through the roof at idle, air fuel was 11:1 (way too rich) at idle, but get the revs up to 3000rpm and the figures came back to near enough spot on. This I would conclude is a CAT issue, oil contamination from the excess consumption. I've put a bottle of cataclean in today and shall do the 50 miles and fill her up tomorrow, run her for the week and then test her again next weekend.

Share this post


Link to post
Share on other sites

OK, I guess I have to correct myself. Checked the codes this evening, and there are lots! 8 codes, new record!

 

They seem to originate from all 4 sensors. I open and cleaned the 4 connectors, deleted the codes and drove an inspired 100 km trip - none of them returned. I obviously need to check to see which return once the MSCF light returns.

 

So now what - are all 4 sensors haywire, or does this suggest a connector issue? Could be two different issues I suppose, as the 6 latter codes are new.

Note that from last year (10000 km ago), two of them were not the same (first post... P0156, P1161 and P2237).

 

I can add that with key in MAR, the ECU voltage is 11.8 V. The error codes, engine running, show 13.7 V or up.

 

2015-05-25.PNG

Edited by Sillyspeed

Share this post


Link to post
Share on other sites

All that equals..... Time for a new MANIVERTOR.

 

I agree that most evidence point in that direction, but why would the upper lambdas start showing heater malfunction, short circuit or signal errors?

 

I am considering using a Bosch car electrician service as they, as opposed to the Alfa workshops, have both gas analysis and oscilloscope diagnosis. Which is the way to go to properly diagnose catalysts and faulty or sluggish lambdas.

 

First, let's see what code is thrown up next.

 

BTW Smaky: How is your idle with AC/climate turned completely off/on? Very rough with AC on, from my experience. Off, and after cleaning throttle body, the idle is very smooth (for a direct injection engine)...

  • Like 1

Share this post


Link to post
Share on other sites

The proper way to go to diagnose Cat faults is to test the gases before the Cats, but on a JTS the only way to do that is to fit a CF2 manifold and exhaust then check the gas, but that is a hell of a long winded way to go,

Share this post


Link to post
Share on other sites

Well, that's not going to happen, as I don't have CF2 exhaust lying around ;)

 

I actually spoke to the Bosch Car Service electrician, and in their vast catalog, the MED 7.11 ECU was not available. Bloody typical. Still, I guess an exhaust gas test could give an indication if the emissions are way off the typical values.

 

Latest check after a few hundred kilometers driving is still the P0420 and P0430 errors. No sign of any of the others. Those pre-cat lambda connectors are getting tired of all the opening and closing...

Share this post


Link to post
Share on other sites

The problem here is this is an engine type with multiple renowned problems on the fuel and ignition systems.

 

The most common issue is the lambda plugs, the pins are too short and barely make a connection, I've seen various solutions for this and even the dealers will cut the plug out and hard-wire the lambda into the circuit, though even this doesn't solve it in some cases.

 

Then there are the coil packs made of cheese, these can blow at any time, and if there are any still working after 60,000Km then I'm astounded, to confound this the connectors again, work loose and this causes a weak signal to fire them, so there's 2 more possibles.

 

Next is the rocker gaskets (main + plugs), any of those leaking and oil will get to the plugs, also if you spill any during topups that will go to #1, any oil down the plugwells will create a path to ground and the plugs will not provide a strong enough spark to ignite the fuel meaning high HC in the emmisions and the lambdas will try to trim fueling, this then causes the lumpy idle and poor economy.

 

Piston ring wear is a huge issue on this engine, they appear to be made of balsa wood and no matter what oil is used seem to evaporate faster than a line of shots at an AA meeting, these allow oil to pass too easily, increasing the CO reading and contaminating the cats and clogging up the injectors which then loose their spray pattern and there goes the CO limit again.

 

 

Share this post


Link to post
Share on other sites

Yes, several known issues with the jts, unfortunately. Not their proudest moment in engineering history. Wonder how any sort of testing during both development and initial years did not trigger any corrective actions from Alfa's side. It's that kind of "Fu*k you, you're on your own" that pisses me off.

 

Anyway, the car is in for a service and diagnosis shortly, with Norway's Alfa expert, will update with next status.

Share this post


Link to post
Share on other sites

New code today, together with the usual twins. P0159, which is slow response bank 2 post-cat sensor.

 

Seriously considering acquiring one or used sensors before going to the mechanic, so to swap if needed...

Share this post


Link to post
Share on other sites

It was there to ignite the remaining gases to create an increase in pressure whithin the cylinder 5 degrees after the exhaust valves opened allowing a faster flow through the ports aiding the fluid dynamics through the mill. It also provided an average of 20BHP on top of the single plug normally aspirated engines of the time.

Share this post


Link to post
Share on other sites

What I still don't get is that on 16 valve TS engines, at least on CF1 and CF2, both sparks fire at the same time on both power and exhaust strokes, and then the center spark would be enough to do the job you are mentioning, I think. still skeptic about the TS technology on 16 V engines...

Share this post


Link to post
Share on other sites

I wouldn't bother too much with skepticism for the twin spark, all the time these 4-cyl's have had (design) issues wrt. oil consumption, timing belt longevity and bottom end bearing failures (at 200k km, though). And the world's highest sensitivity for engine oil level ;)

 

I wonder how much of this could have been avoided, while still maintaining the character that drivers find attractive, such as... Well, power delivery and revvyness?

 

I would like to know more about engine design, and what factors that affect things other than power..

Share this post


Link to post
Share on other sites

The only thing that limits power is the damn euro emission limits, get rid of them and we could all run round in 200Bhp 1.6s

 

Share this post


Link to post
Share on other sites

So, time for service at 130000 km.

 

Initially showed high CO at 0.38 %, which would be "MOT failure". After resetting the adaptation parameters, the CO dropped to 0.08 % - see attached link:

 

https://goo.gl/photos/pWTgddXBEc3cLeEY8

 

So, seems that the catalyst is not all that bad. But the rattle is definitely not only heat shield, it comes from the inside of the exhaust.

 

One more fault code today: P0354 which is coil 4 circuit malfunct. Which is funny, seeing as the oldest coil is from 2012! Hopefully just a connector glitch, shitty Bosch bastard quality.

 

The mechanic has been working on an ECU software modification that eases the parameters that throw these standard JTS errors. It is currently being tested by another owner with a 156 @ 185000 km, with similar symptoms (and exhaust gas results). 2-3 weeks on the road, and I'll have updates on the experiences.

 

May come to a new/used catalyst in combination with ecu to get rid of this everlasting issue.

Share this post


Link to post
Share on other sites

I'd quite like to hear about how your mechanics has got on with that software. The Jts is a decent engine until it gets strangled by all this euro 4 shit.

Edited by SpoiledGT

Share this post


Link to post
Share on other sites

The "software" is developed in cooperation with a company modifying ecu's for higher end italian cars (Maserati, Ferrari) in Poland, on request of said mechanic which has ~25 years of experience with Alfas and a genuine interest to solve problems (not only replace parts). I was told that there are no changes to the map, only the emissions parameters (presumably diagnostic lambda after catalyst). The process involves swapping the entire ECU, as there is no way to "chip" or replace ROM.

 

I will be sure to keep you updated, and share contact info if needed.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...