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Discussion Starter #1
So, today ive gone out and run a few different logging sessions to try and get to the bottom of my long running power/smoke problems. now im just trying to make sense of the results.

as you can see in the attached excel doc, each time i put my foot down (shown by the arrows, first was in 3rd from 2k upwards, 2nd in 4th from virtually idle) everything starts to build slowly (feels very sluggish and hesitant), then at around 2-2.2krpm Fuel pressure + Airflow suddenly drops off. its not reflected in the rpm very well, but very noticeable when driving. after that it picks up and revs fine... throughout the whole range its smoking badly

so what im wondering is, firstly any thoughts what could cause this? and second, the air flow readings are all over the place (and in other runs i did the actual is generally alot less than the target) what sort of figures 'should' i be getting?

The sudden power loss is still there when running with MaF disconncted which rules that out(and smoking alot more severe), and the EGR is totally blocked off at the mo...
 

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Hmmm your fuel pressure seems a little on the low side (well compared with mine anyway - but that could be due to my map) I'll see if I can do some recordings tonight ...

.. would it be possible for you to record the boost too?


also I presume you've checked the pipes for leaks?
 

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Discussion Starter #3
Thanks chris, that would be great! not sure what these run at standard, had thought i read 1600bar once. but seemed to peak pretty consistantly art 1400 so maybe i missread?

Here's one i made earlier! :D. not quite such a good sample, but you can see the massive difference between the expected and actual airflow! had hoped when i logged these i would see either the fuel pressure or air flow drop when it looses power to give me some sort of clue, not both!

pipes are all good. only part of the air intake i havnt removed and inspected is the intercooler (and that looks a bast of a job)
 

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I must admit that my car is also smoking more than it used to, I spotted a big difference between target and measured airflow too ( target of 260 = measured 30 and target of 1200 = measured of 600) ...


... another thing that popped up was that I had 2 error codes from the MAF (air temp and pressure),
 

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Discussion Starter #5
Thanks for doin that, most helpfull! at least now i know the Maf expected and actual readings are not supposed to be spot on like like fuel pressure!

not sure where to go from here tho, only other noteable thing on the logs for me was the drop in airflow/fuel pressure when i floor it. maybe i should do some more readings from other sensors and try to replicate...
 

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It might be that both our MAFs are on the way out (as my car smokes more now than it used to) ... I'll send some PM's to get more people to post ...
 

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does your car work as should then loose boost, whilst still fuelling as normal, thus causing the smoke?
You really need a boost guage to see this happen.

I am working round the readings, on fuel rail at the mo, I have issues with my car, I think its down to the severity of the map, but I need to diagnose what cause the above mentioned symptom I suffer - loss of boost.

These old 2.4's were deisgned so long ago now, really old technology.
 

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I'l try and do some tests in the next couple of hours or so and post them up. I'll have to get to grips with Alfadiag and contend with the dodgy battery on my laptop too. I would say it indicates the MAF, but then when disconnecting it should improve. It's almost like the MAF can't cope with the extra flow of air when booting it, then it doesn't match the fuel to the air from the revs as the MAF isn't telling the ECU.

I forgot to connect my MAF a while back and it took the car 52 miles to bring up the warning light that it wasn't connected, so I wonder if the car registered it wasn't connected when you disconnected it.

I'll post again later after loggin the data.

How's the fuel consumption?

Cheers,

Mark

Update; my alfadiag link isn't working, I'll reload it then try again.
 

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Discussion Starter #9
sdfsdf

With mine the smoke is all the time, just heavier when booting it. and much worse when cold.. It also got alot worse when i disconnected the Maf (so much so i couldnt go for a proper test drive as it was just hazerdous!) I have no power when you put the engine under load, particully low down.

if you look at the 1st graph i posted, and the 2nd place ive marked it what happens is; it very slowly picks up, just as it starts to accelerate properly, it looses power (where the dip in airflow/fuel pressure is) then it will eventually pick up again and pull to the redline. Smaky has driven it and found the same lack of power, unfortuantly we didnt have time (or weather) to take a proper look...

My MoT is due in a month or so, and at the mo got no hope of getting through emissions!

Fuel consuption, im getting about 450 miles from a full tank (tho down ere in doRset we don't got many of them big posh fast roads!)
 

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dodge00 when looking at your second file (airflow + boost) I see very slow increase of measured air flow. Also very slow increase of turbo pressure.
Could it be your turbo vanes stuck in one position? Your MAF is OK IMO, because in idle it is very close to the target airflow ~300 which is fine... also it peaks around 1000mg/stroke which is not too low, but the way the blue curve on your graph rises it got me thinking that the turbo vanes are stuck and you got much more turbo lag than you would have with properly operating turbo...
Check if your turbo vanes move freely...

Chris156 your MAF readings are way too low... try disconnecting it, or maybe find someone to lend you his MAF for a test... but I'm quite sure it is the MAF...
 

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Discussion Starter #12
Thanks for your input,

i've done the test on the actuator in alfa diag, and they seem to move freely. i did remove it at one point a fair while back thinking they could be jammed. with the actuator disconnected it moved very freely by hand. unfortuantly the bolts were stuck fast, so couldnt split the turbo to check internally.

Another symptom i have; it always fires out a HUGE ploom of smoke immediatly on startup. at those low Rpm could a duff turbo cause that amount of smoke? (always black/grey smoke, never blue)

i had been leaning down the fueling side of things, injectors etc untill i ran those logs, now not so sure...
 

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Well common rail pump seems OK to me, as fuel pressure readings are fine. Injectors are different story. If the the injectors are clogged the spray pattern on your injectors is affected... This could be the problem, but there is no cheap solution for that. Here in Slovenia we have Bosch Diesel Service centres where they unmount and test injectors for spray pattern and injection quantity on specail test benches. The injectors can also be cleaned, but it costs around 80€ per injector... not cheap.

Black smoke on startup si probably just a sign of soot in your exhaust, because the engine is smoking so much...
 

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Discussion Starter #14 (Edited)
I had thought about taking it to the local Bosch centre, but as you say, its very expensive. if i new for sure that was the fault i would do it, but cant afford to throw that sorta money away on a hunch.

thinking about it, i read in e-learn service manual that when the engine is idle or cruising it injects smaller amounts of fuel, at a few stages in the combustion process. where as when you put your foot down (or maybe when the engine is under heavy load?) it injects one large quantity at the start of the combustion process.

i notice in alfa diag there are various of sensor groups for injectors, are there any useful ones i could log?
 

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oh, and my cars standard, (as far as i know) apart from a K&N filter
there have been (many) story's (but nothing proven) that the K&N filters breaking MAFs ....

d

Chris156 your MAF readings are way too low... try disconnecting it, or maybe find someone to lend you his MAF for a test... but I'm quite sure it is the MAF...
The thing is that the performance of my car is still pretty good (it just seems a little slower than normal), the only issue I have is that it smokes more than it used to when I boot it ... tbh I don't think disconnecting the MAF make much difference in my case, but tied with the 2 MAF related error codes I think I do have a problem in that area ...
 

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Well I've been out tonight and cleaned my MAF with some electrical contact cleaner ... and it has made no difference whatsoever (same results) :lol: ...

... but another thing I have changed is the fuel, I've been using BP ultimate for the last few thousand miles, thought I'd give there normal stuff a go (when my car was mapped it had normal petrol in it) ... and tonight no smoke (and also seemed pretty swift too), so it could just be that my car likes the cheap stuff :thumbs:
 

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Quick update ... I've been using Tesco Stripy Diesel and my car is running like a treat again ... good job my car is a cheap date :lol:


I've also raised a support question with Derek at AlfaDiag just to see if the scaling for the messages is correct for my car ...
 

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Derek @ AlfaDiag said:
I have done some more investigation. It appears for the 5 cylider diesel engines the scaling is infact different, it scales the measured in Kg/hour not in mm3/stroke, why I have no idea. The problem is the conversion factor does not make much sense and it is also impossible to therefore correlate measured and target since they use to completely different scales. I will have to do some more thinking about how I can add the additional/different scaling.
So looks like there is a scaling problem in the current version ...
 

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Is that with the 3.2 version or the 3.3 ver of A/D? Should really point out the other A/D error with the throttle pedal scaling too.
 

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Is that with the 3.2 version or the 3.3 ver of A/D? Should really point out the other A/D error with the throttle pedal scaling too.
It's both versions ... my thottle seems to be fine so if you want to email Derek you're move than welcome :thumbs:
 
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