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Discussion Starter · #1 ·
Recently purchaced 1.8 16V, full service history by Mangoletsi, one fastidious owner,has had every thing checked changed or overhauled, but after 1K miles has started to develope a misfire. Initialy the engine began to vibrate slightly at idle and over the last 10 days the misfire has become worse, as the engine warms up it now runs on 3 cyl's until it gets past 4 thou unless you are on a very light throtle. Has any one out there got any idea's. Thanks
 
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Discussion Starter · #2 ·
A fairly common fault with the 155 is one of the plug wells filling up with either water (steam cleaned the engine bay recently?) or oil (from a leaking cam cover gasket). However,I would get it back to Mangos pronto and try and get it done under warranty.

Simon
 
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Discussion Starter · #3 ·
Hi Lee

I've had similiar (but not as bad) problems, mainly when the engines cold.

It may be worth having the Lambda sensor checked but it could also be what Simon suggested. I too have had oil in the plug wells, changed the gasket but it still leaks into one well.

Basically send it back!!!

wrinx
 
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Discussion Starter · #4 ·
Thanks for the replies, did'nt actually buy it from Mangoletsi- private sale and I don't think he will take it back. Going to spend today checking her out will let you know the out come.
 

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Premium Member
Tesla Model S
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8,046 Posts
Trust me... Go down and buy a the sensor, that is where your problem lies!!!!

Even if for some reason it isnt that(doubt it wouldnt be) you will need one at some stage of owner ship! Or Good luck with it!

Best regards
 
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Discussion Starter · #6 ·
I'm now on the fourth sensor in five years and 90k miles. I asked the Service guy at the local dealer why this was such a problem. His reply was that Alfa had been shafted by Bosch in a bad deal!!!! Not very technical but possible. I think there is an upgraded sensor available so check for that.

wrinx
 
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Discussion Starter · #7 ·
Guyz,
I am not a technical person at all, maybe you can help me as I fear I may have a similar problem. Noticed some oil leakage down the side of the cam-belt cover and collecting on the large plastic uder-engine tray thingy-bob. Had the cam belt cover gasket changed but I think the problem may still be lurking.
Any ideas what I should do?
In appreciation
Raj
Btw, bought mine from Mangoletsi- hope its not a dealer jinx!
 
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Discussion Starter · #8 ·
In reply to Wrinx's problem, I too am on my 4th lambda sensor (I've only ever paid for one though as it's always been replaced under Alfa spare parts warranty). Mangos had a look at the the reason why and came up with what could well be the answer within 10 minutes.

They found some corrosion on the coolant temperature sensor connector which was causing the ECU to think that the engine was a lot colder than it actually was, thus richening the mixture and the unburnt fuel was killing the sensor. 5 minutes cleaning things up (and a bit longer changing the sensor) and the car runs much better.

Other things that can kill lambdas are leaded petrol (kills the cat too) and some fuel additives.

Just on another note, and without sparking off the dealer/specialist thing again, Mangos have consistently been very helpful and pretty proficient at dealing with problems that are beyond my scope, I'm very happy with them.

PS NGK do a guide to lambdas which includes why they die along with replacement part numbers. You can get one and a spark plug guide by calling 01442 281000 in the UK.

Simon
 
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Discussion Starter · #9 ·
Alfa must have had a bad batch of Bosch sensors , my 155 had to have it's lambda sensor replaced at 30K km
. I replaced it with a 4-wire Denso sensor for US$20. Working ok till now.
 
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Discussion Starter · #10 ·
Hi Simon
Your reply is interesting, mine runs a bit erratically (one day smooth, another rough) so your reply may help me. Where is the coolant temperature sensor?? Afraid all these sensors confuse me! I now have an aftermarket Lambda fitted which has increased tickover slightly but seems ok so far. I've had to pay for the last two


Raj - my gasket is still leaking, perhaps the cover/top has warped? Does any1 have experience of this. If I remember correctly(?!?) there are two gaskets, did you have them both changed?

wrinx
 

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715 Posts
I've changed the top rocker cover to a 156 one on mine as they have a better gasket. You have to make an earth lead for it an bugger about with the breather pipes a bit too. It covers up the injector rail reasonably neatly and stays cleaner and doesn't corrode.
 
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Discussion Starter · #12 ·
Wrinx,

The coolant temp sensor is mounted on the thermostat. Stand in front of the car, looking over the engine. To the right of the block is the thermostat, it should have a large hose going off to the top of the radiator. The csensor is mounted in the top of the thermostat housing. To disconnect it, remove the wire retaining catch (don't drop it now!) and pull off the connector. Look for the tell-tale green corrosion and if there is any clean it all off. You might also want to check that the contacts are tight on the spade terminals.

Otherwise I would suggest a trip to a dealer/specialist and get the analyser on it.

Good luck

Simon
 
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Discussion Starter · #14 ·
Hi Simon

cleaned the sensor, didnt look green but worth it anyway. Engine seems to be ticking over a fraction lower and the drive I just did was smooth. Will have to monitor over the next few days to be sure


wrinx
 
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Discussion Starter · #15 ·
Seems I started some thing with this misfire question. Just in case anyone is interested all that was wrong was that the plug wells had filled with water, no I havent steam cleaned the engine since I have owned the car, but the engine bay was very clean so I guess the previous owner did. Can only presume that all the cold weather we have had recently has caused the water to freeze at night and forced it into the plug caps. The engine now runs beter than it has ever done, not supprising realy.
 
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