Sparks test

Alfa155 TS · #1 (**Post Link**) 03-05-10

Hi LAds,

Whats the best way to check if your sparks need replacing? I mean by actually driving the car, what should or shouldnt happen and how would it feel, would there be for example a hesitation when you thottle it then suddenly get a responce? Would any lights show up on the dash?
I have never done them on a 155 and would like to maybe replace them, how easy is it to get to them, even to visually check them?

celadon · #2 (**Post Link**) 04-05-10

Old worn spark plugs can cause hesitation, but the plugs are long lasting - replacement recommended every 65k iirc.

The other cause of hesitation could be oil in the spark plug wells.
What can happen is the seal on the rocker cover goes, and oil seeps in to the plug wells, this can cause arcing of the spark.

Remove the top engine cover, and you will find the coil packs that sit on top of the plugs.
Remove the 3 allen bolts (5mm i think), and then remove the coil packs completely, you will then be able to inspect the plug wells.

This will also give you access to remove the plugs and inspect them - remember to clean the plug wells before removing the plugs.

Also inspect closely the coil packs and plug connectors for hairline cracks, as again this can cause arcing.

Alfa155 TS · #3 (**Post Link**) 04-05-10

excellent, will try that,

kungla · #4 (**Post Link**) 07-05-10

I mean by actually driving the car, what should or shouldnt happen and how would it feel, would there be for example a hesitation when you thottle it then suddenly get a responce?

I have exactly the same behavior on my 155. But, I suspect that something is wrong with the MAF or the throttle potentiometer. Has anybody experienced similar behavior?

kungla · #5 (**Post Link**) 07-05-10

I mean by actually driving the car, what should or shouldnt happen and how would it feel, would there be for example a hesitation when you thottle it then suddenly get a responce?

I have exactly the same behavior on my 155. But, I suspect that something is wrong with the MAF or the throttle potentiometer. Has anybody experienced similar behavior?

Alfa155 TS · #6 (**Post Link**) 07-05-10

I'm gonna start an investigation as to why after a recent RR my flywheel is at 148bhp but the wheels are only 116bhp. And I'd like to start with the sparks, probably the wrong place completely but it is an Alfa after all

Factory spec is 150 so not bad for a car with 153 thousand miles on it....

celadon · #7 (**Post Link**) 08-05-10

Originally Posted by Alfa155 TS

I'm gonna start an investigation as to why after a recent RR my flywheel is at 148bhp but the wheels are only 116bhp. And I'd like to start with the sparks, probably the wrong place completely but it is an Alfa after all

Factory spec is 150 so not bad for a car with 153 thousand miles on it....

factory spec of 150 is the calculated flywheel power.
the loss is through gearbox diff and driveshafts

thats AFAIK

Alfa155 TS · #8 (**Post Link**) 08-05-10

What would be the standard amount of power loss to be expected? surely its not more than 30bhp?

Alfa155 TS · #9 (**Post Link**) 09-05-10

Well celadon you were right about the plug wells. 3 of them had a fair bit of oil and dirt so thoroughly cleaned it out but the plugs look like they need to be changed as hesitation is still there. What plugs would you recommend? I'm not looking for best of the best or anything just standard good ones.

celadon · #10 (**Post Link**) 14-05-10

Hmm, what to recommend ?

Depends on how long you aim to keep the car, if for about 65,000, then buy the iridium, cost about £120 for the set of 8. A lot I know, but last for a LONG time.

Thats what I have in mine, and have no problems, and wouldn't know what others to recommend.

Alfa155 TS · #11 (**Post Link**) 16-05-10

What brand did you get? While investigating the plugs and trying to figure out why there was so much dirt and water and oil getting in there I discovered somebody had removed the block and resealed it but the sealant wasnt applied/done right so am gonna have to do that properly me thinks. There are some small gaps in the seal between head and gasket.

celadon · #12 (**Post Link**) 17-05-10

I'm pretty sure the plugs I purchased were NGKs, I'll take a look later.

kungla · #13 (**Post Link**) 18-05-10

Oil in the plug well, definitely a source of problem in my case? Time will show if this was the only problem?

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