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Discussion Starter · #1 ·
Hi Guys,
Wonder if anyone can help with this one.
Was on the motorway on Saturday in my V6, when I noticed at highspeed (you know what I mean! 80+)
The car seemed to be slighly surging, then holding back, then surging again and so on.
On returning home, while stationary, I tried holding the engine revs first at a constant 3000rpm (which it vaied +/- 400rpm), at 4000rpm (same problem) and finally at 4500rpm (same problem). I've run some injector cleaner through it, but its made no difference. Could this be a problem with the Airflow meter?. The fuel injection light's flashed on and off a couple of times, but thats all.
Has anyone had this problem before?

Thanks/Mark :)

FYI: the cars done 96K, and otherwise runs and starts fine.
 
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Discussion Starter · #2 ·
It sounds like the fuel mixture is being adjusted too much during running. Too rich, then too lean. Maybe it's that damn Lambda Probe again or an air leak in the air intake system (knackered gasket).

Had a similair problem on another car (not Alfa) and it turned out to be a gasket. The injection light might suggest it is the probe though.

Marlon
 
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Discussion Starter · #3 ·
.....Forgot to add, it does it when both cold, warm & hot, so I suppose that eliminates any of the temperature sensor.
By the way, as its looking like the Lamba sensor's at fault, where's the best place to get a replacement, and are the universal fit one's any good?

Thanks/Mark. :)
 
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Discussion Starter · #4 ·
Just a thought, but the oxygen sensor is not active at higher speeds...........dunno when it stops though :confused:

wrinx
 

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3,806 Posts
The lambda sensor was upgraded on 2.0 16vs to prevent faulty warning lights and give better life. The part is Alfa 60812717, current price about £80-90. This is BOSCH part LSH24 0258003772.
It would be best to check that this is the correct part for the V6 too, but if so the Bosch part number should help ypou at an aftermarket shop.
My 156 V6 has two lambdas - I dont know about the 155 but its worth checking before you buy, after all, if you have two you don`t know which one has gone! :confused:
 
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Discussion Starter · #6 ·
Had mine replaced and there is only one..............far as I know!!! They can be bought for half the Alfa price.

wrinx
 
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Discussion Starter · #7 ·
Hi guys,
thanks for the advice. Further to this, I've been in the garage tonight looking for obvious signs of air leakage in the air intake system. I've also checked the ECU for faults, and its giving me code: 4-4-4-4, which I understand to mean no fault? :confused: (I read back on some old postings, where I think you were having similar problems Wrinx, where If you press the accelerator pedal 5 times, the injection sys. light flashes off any codes)
Does this mean the Lamda sensor's ok, or are they notoriously unreliable? :confused:

More advice very welcome.
Mark. :)

p.s The tickover's fine, steady at 800rpm when warm.
 

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Premium Member
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2,023 Posts
Have this surging thing on my V6 occasionally usually when I begin a trip somewhere but then disappears never gives too much of a problem and has happened for a while-now and again. frown
 
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Discussion Starter · #9 ·
Thanks Pat,
Its more noticeablle going up hills on the Motorway, nearly made me sea-sick going up Windy Hill on the M62 on Saturday, coming back from Manchester. Mind you, nothing passed me up there, so can't be much wrong (hope the Cameras weren't on!) eek!

Cheers/Mark. :D
 
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Discussion Starter · #10 ·
Hi all,
Had a right good look at the intakes, sensors etc last night, cleaned up some connections and it seems to be running better now.
I have two more question now:

1/Does the V6 require a special spark plug wrench? Tried everyone I've got in my possession and none would fit, the larger size socket wouldn't even fit down the reccesses in the rocker cover!

2/Regarding the Lambda Sensor, is it active at all engine speeds, or just low revs? :confused:

questions,questions!

Thanks/Mark :)
 
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Discussion Starter · #11 ·
As far as I know the lambda is active at all engine speeds, finetuning the mixture for optimum fuel consumption and emissions. Has also got something (not too rich mixtures) to do about prolonging the life of the cat, I read somewhere in a previous discussion.

If it is any help, my lambda always seemed to be fine when connected to the "Examiner" of my mechanics (3 times). The problem persisted and I took the chance of replacing the lambda anyway. Since then it has been running okay.
 
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Discussion Starter · #12 ·
The spark plug wells on the V6 are very narrow, not helped by misaligned rocker cover. Get an expensive spark plug socket which will have a thinner wall than the cheap ones. I turned down a cheap socket on a lathe.
 
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Discussion Starter · #13 ·
Thanks El ****** & Jacques,

I'll spend this weekend's beer money on a good Spark plug socket and a new (Bosch) Lambda sensor, and just make do with water :D

All The Best,
Mark. wink
 
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Discussion Starter · #14 ·
Mark,
Have you tried disconnecting your lambda sensor first? It could give you a clearer indication if it is the culprit.
 
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Discussion Starter · #15 ·
Another thought - could there be something wrong with the fuel pump? My father had a similiar problem (admitedly on a Volvo estate) and it turned out that there was a second fuel pump actually in the tank to work against gravity - this had become faulty. Your fuel pump might have dodgy power connections or be on its way out.

Anybody else had problems with the fuel pump, or know where it is on the car?

- Honkytonk.
 

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3,806 Posts
Fuel pump is in the tank. You can get it out through the top access panel and then taking the cap off the tank (everything comes out as a full assembly).

If it is the pump you could try measuring the fuel rail pressure at high revs to see if it fluctuates a lot but I have found that if you disconnect power to the pump for about 1 millisecond when at high revs then the engine dies very noticably i.e. the engine is damn quick to notice if the pump is faulty
 
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Discussion Starter · #17 ·
Hi Again Guys,
Further to my first post, I was out tonight and the injection light flashed on for a couple of seconds, then went off, while going up a particularly long steep hill (1 in 4 Gradient). Following this the Cat stank like bad eggs for a minute or so.
On returning home I tapped the accelerator 5 times to see if an error code had been logged in the ECU. It came up with code 1-2-2-4, which according to Wrinx's fault code list is The Heated Lambda Probe.
I assume this means the Lambda sensor's at fault while warm and will need replacing? :confused:

I'm I rigfht to assume this?

Mark. :)
 
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