156 2.5 v6 - poor poor poor performance - Alfa Romeo Forum
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(Post Link) post #1 of 23 Old 26-08-16 Thread Starter
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Moaning 156 2.5 v6 - poor poor poor performance

Hello guys!

I found this forum and its like the last help i think i can get. I bought a 1998 alfa 156 2.5 v6 busso - excellent car, I really love it though there is a problem botheing me for last few weeks which i somehow cant fix or find whats going on.

The main problem is that it doesnt run as good as it used to, its like sluggish, fuel reactions till like 1/2 of fuel pedal, if you press it more - nothing happens, it gets slowly to the +-4k rpm and then starts to accelerate a bit better, but its still slow as hell. I think it runs more smoother while cold, sometimes it does these problems, sometimes it runs perfectly. Iam no mechanic, Ive tried few and no one was able to do anything with it .. its like, i dont know how to describe ite, the fuel reaction and acceleration is poor as hell, if you give it some gas on lower gear it still runs fast but not as fast and smooth as it should.

It didnt die on me anywhere, it starts well and is reliable, idle is somewhat rought, in most times not visible at clock but hearable, if visible revs jump about +-100 up and down, its literally a milimetre.

MAF is not new, its secondhand but shows absolutely no errors or data deviations @ diagnostics. Ive got it for a try from a friend and its from a car which was running OK until the mains got ripped apart - it runs the same as with the old one, however i didnt try to clean it as i dont really know how :/ Fuel butterfly is clean, the rubber intake hose with air IS ripped, but repaired with good glue for these cracks.. and vulcanizating tape.

Ive found a similar thread http://www.alfaowner.com/Forum/alfa-...-of-power.html (156 2.5 V6 lack of power) seems basically the same thing but there is no solution

I used to drive lancia kappa 2.0 114kw, its bigger with weaker engine and now the driving feels kinda same, which is not OK thx to anyone willing to give me some advice. Im really starting to lose faith.
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(Post Link) post #2 of 23 Old 26-08-16 Thread Starter
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I love that car though
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Dont lose the faith. Alfas are testing to say the least!


Ok, what HAVE you done to it?


Start at the beginning.
Air filter. Blocked?
MAF? clean? Bosch? (non bosch doesn't agree with oem electrics)
Oil? does it have any? Right grade?
Plugs. Clean? Rear three are a total pig to get to, so have they been changed or checked?
Cat? If its clogged or collapsed then the gas has no where to go. Resulting in crappy running.
Fuel. (v6, does it have a filter?, 147 twinny doesn't) filter? injectors sticky? has it been sat for a long time?
Does it rev out in neutral? Is it manual or auto?
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Hi Egon! Alfas are testing - ive heard that before :-)

Anyway:
-Air filter - new and clean, airflow is OK - first thing ive checked.
-MAF - used, IM NOT SURE whether its bosch or not - but ive tried two already (both used tho) and with exactly same result, do you think it might be MAF? Ill repeat myself, but no deviations at diagnostics and ive had one in car and tried two different wit same result (i had to throw out the first one ase the airbox screws rusted and due to that MAF was KO and had to be replaced - for like 6 months after that car ran great) .
-Oil changed 4000km ago, selenia.
-Plugs brand new 3 months ago.
-Cat was clogged, straight pipe for now ill buy new cat soonish, depends on the other stuff.
-Fuel - what ive read the filter is part of the fuel pump :/ injectors, i dont know how to check it - haven been not sat for a long time, driving it every day to work.
-Manual , revs are a bit rough, but ... i dont know what exactly do you mean by revving out. It jumps for +-100rpm which is barely visible/hearable.

On monday Im going to give it to a family friend who has a garage, although hes doing mercs and mainly concern cars, he has a big business but is not fond of italian cars at all .. i wanted to give him tips for what to look or something. blah. Shouldve learn how to repair stuff like this by myself

the only things i can think of now is buying a brand new bosh maf and pray itll be it - if not - 230$ out of the window, i dont really feel like it. Its.. impossible to guess and to help through the internet- i know I hope someone who experienced similar problem will stumble upon this thread. Cheers for taking your time and reading this through.
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A poorly functioning lambda sensor can make the car sluggish and it may be worth checking the engine temperature sensor too.
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And the cam timing would be worth checking.
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no worries, you'll get there in the end, but inventing new swearwords for things will keep you sane!
What sprint and gtvtb said are also great ideas. If you unplug the maf it should throw a code and go into limp mode but it will still run.
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the filter is part of the pump and chances are hasn't been changed since day one. you have to remove back seats (4 bolts) and the boot liner (2 bolts). Then i think it's 6 bolts on the cover that protects the pump and finally there's a plastic screw that gols round the pump to hold it down, be very careful when removing this. i used a bit of wood against the plastic and just gently chapped it till it came loose. very stiff as been on there since day 1 but its plastic so could break really easily if you hit it too hard. think i got mine off ebay for 100.
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Hey Dan,

It's like Egon says, try unplugging the MAF, and the engine should idle even worse and the dash light should come on. If disconnecting the MAF will make no difference, then you'll need a new one.

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i would check all induction hoses for loose clips or holes in the rubber pipes
regards fala..........
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Compression test? Worth doing to make sure internals are ok, before you go spending money on new parts.

Best of luck getting to the bottom of it!
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Exactly. Hot engine compression test, all plugs removed, first dry then with a teaspoon of motor oil syringed into each cylinder. Without knowing the motor well I'd suggest anything below 195 PSI to be cause for concern.
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I'd certainly start with GTV-TB's suggestion.

Lambda sensor is notorious but easy to fix
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Bosch MAF says Bosch on the insert - if it isn't Bosch, bin it.

MAF problems don't show on the diagnostics unless it is unplugged.

Get the free copy of Multiecuscan and post the lambda graphs. 1st stage should be cycling every second, after cats should be rock steady at 0.46 v or so. If the precat lambdas are sluggish, then they are knackered.

Check the plenum rubbers for perishing/leaks.

If you don't know the history - compression and cam timing. When was the belt last changed, has it jumped a bit?
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Quote:
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Bosch MAF says Bosch on the insert - if it isn't Bosch, bin it.

MAF problems don't show on the diagnostics unless it is unplugged.

Get the free copy of Multiecuscan and post the lambda graphs. 1st stage should be cycling every second, after cats should be rock steady at 0.46 v or so. If the precat lambdas are sluggish, then they are knackered.

Check the plenum rubbers for perishing/leaks.

If you don't know the history - compression and cam timing. When was the belt last changed, has it jumped a bit?
Before going any further, may I suggest a couple of things things that are simple, quick and free.

A/ Check that the battery terminals are tight and without corrosion, bad battery connections can cause all sorts of performance issues and cause ECU errors and things to go "out of wack!"

B/ Then do a Throttle Reset.
1/ During the reset at no time touch the accelerator pedal
2/ put the key in the ignition and turn to MAR, wait 90 seconds
3/ turn key to off for 90 seconds
4/ turn the key and start the engine (dont touch the pedal)
5/ let engine idle for 15 min or till engine reaches operating temp (80-90 on the gauge)
6/ turn engine off, remove key, wait 10 minutes, then take it for a drive and see if it makes any
difference.

It will either do absolutely nothing to solve your problems, or, it just might surprise you.

Baz

Patty - 2004 Alfa 156 2.0JTS Sportwagon

Ruby - 2000 Alfa 156 2.0 TS Selespeed with Sports Pack
(Eibach 2.5 Lowering Springs)
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Check the age, and condition of the battery. Alfa's hate old worn out batteries
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(Post Link) post #17 of 23 Old 05-09-16 Thread Starter
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Hey guys! First of all thanks for all the advices. Ive had a hell of a week and ive been busy as hell to do anything with car
Anyway..its in the garage now and they say.. like theres nothing wrong with it, they cant see anything.. strange thing is they told me they filled in 1litre of oil (but im 100% sure to checking it daily to be within limits-oil disappeared because ive scratched the bottom..had to be resealed) diagnostics, again, clean as a whistle. Cambelt without a problem, well timed, almost new..

Lambda - if it would e broken, would it show at diagnostics? I think it would right?
MAF - really it may show 0 errors and be ****ed up(non bosh)? If i disconnect it engine idles really bad.. when i plug it in its ok.
I cant do any compression tests and guys told me they wont do that also as they have limited time/space..
Induction hose - a small crack found, again, i hate that rubber stuff , fixed now gonna see if it makes the difference but they told me it was like 1mm thing
Battery is worn, but contacts are fine and clean and it starts fine, no coughing while starting.

But what is in my mind... Throttle reset - guys is that really a miracle thing? Cause ive read through some forums that some people experienced the same problem, done the reset, then gave it hell and car ran like a new - i thought its some kind of fairy tale
2/ put the key in the ignition and turn to MAR, wait 90 seconds - MAR is the position when the lights on the dashboard go on? Imma going to try it later this week.

I think ill just f@$k it, ill replace upper arms as they are f@$d and.. i think ill stop searching cause i cant find anything and people working with car...cant find anything neither prolly will just drive it with thoughts it could run better

cheers for all the help guys, youre the best
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Quote:
Originally Posted by Dan_v6 View Post
Lambda - if it would e broken, would it show at diagnostics?
Not necessarily, a malfunctioning oxygen sensor can still send a plausible signal to the ECU and not trigger a fault code but still hamper engine performance.
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2/ put the key in the ignition and turn to MAR, wait 90 seconds - MAR is the position when the lights on the dashboard go on?

Yes
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[QUOTE=Dan_v6;15230529]
MAF - really it may show 0 errors and be ****ed up(non bosh)? If i disconnect it engine idles really bad.. when i plug it in its ok.[QUOTE]

Non bosch can confuse the ecu. May not show any faults but could still interfere with smooth running.
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Quote:
Cambelt without a problem, well timed, almost new..

Lambda - if it would e broken, would it show at diagnostics? I think it would right?
MAF - really it may show 0 errors and be ****ed up(non bosh)? If i disconnect it engine idles really bad.. when i plug it in its ok.
I cant do any compression tests and guys told me they wont do that also as they have limited time/space..
Hmmm. If they really told you that, I would suspect everything they say.

To check the cambelts, you have to take the plenum off and the cam covers, and then put locks on. Doing a compression test is then just a matter of unscrewing the plugs. What they may have said is "we looked at the belt and it seems OK" rather than "we have confirmed the timing is good".

Some thoughts:

Go here Multiecuscan - Diagnostics software for Italian cars and get the free version. Get a cable if you don't have one (15 or so). Graph the lambda output, see this thread for an example http://www.alfaowner.com/Forum/motor...on-time-2.html, Post 32. Post your results. I'm very curious about 2 things - "cats blocked" and "oil consumption". If the cat has blocked, the something bad has happened in the past - it may be running catastrophically rich, perhaps a failed coilpack. The lambda may be b0rked, which can produce similar results.

With multiecuscan - look at the engine temperature - does it seems sane? The sensor may be b0rked, and running on "choke" the whole time, which would explain the cat and oil consumption (loads of petrol washing out the cylinders).

The MAF - as others have said, you won't get an error code from the MAF until it is really broken. If it is producing bad or sluggish data, the engine management has no way of knowing.

If you're anywhere near Berkshire, I'd be happy to stick a current clamp on your starter and do a basic compression test.
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(Post Link) post #22 of 23 Old 16-09-16 Thread Starter
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Hey guys ... kindof.. good news? Last days ive been busy as hell and had no time checking @ car unfortunately .. and again many thanks for your tips and tricks to check. Yesterday ive picked it up at garage 150km from the city i live in and - what the hell - it runs like a sweetest car in the world. It runs great, i mean - really great, 100-120km/h at 5th gear (hell even 6th gear reacts great), round 2k - 2.5k rpm climbing up a moderate hill, I press gas slightly and it starts to accelerate like it should :-))))))) its overally more quiet, sound from the exhaust is not that rattling (due to the straight pipes it is, but it was a lot more) its muffled, deeper and whole engine sounds more cultivated andits not that loud. I dont know guys. Lads from the garage told me they took almost whole engine apart, found nothing wrong and then reassembled it together. Only thing which i can think of is that previous mechanic who has been working on my car forgot to do something or set up the engine back in a wrong way or ... I dont know. They have done absolutely nothing to it, only dismantled the whole thing and reassembled it back together. Ill be watching it closely now... but it was like a totally different car yesterday, consumption was lower aswell.. can anyone explain this to me? Im happy as a bug in a rug :-))
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But what is in my mind... Throttle reset - guys is that really a miracle thing? Cause ive read through some forums that some people experienced the same problem, done the reset, then gave it hell and car ran like a new - i thought its some kind of fairy tale
Well if they did the work that they said they did, and the workshop actually know anything about Alfas this would have been done as standard after the reassembly.

It may have been all that was needed . . . guess we'll never know . . . .

Baz
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