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Old 02-09-2019   #46
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Re: 100hp mpg drop?

Quote Originally Posted by dac69er View Post
i am kinda suspecting a coil/coils. my only issue is that it drives really well, its simply the fuel consumption that seems off!

it is quite pricey to replace all 4 coils on a whim which is why i am a little reluctant to do it!

i know what you mean about the harness, it turns to dust once the mileage is up and the heat has got to it

from memory, i think the connectors are pretty straight forward to remove once you know the "knack" i would have to have a look and refresh my memory on that though!

did you get an engine warning light when one of the coils went? what mileage is your car currently?

it will be interesting to see what your fuel consumption is like now the coil is replaced. you did mention that yours was pretty crappy too
You could try one replacement and try it each cyclider/plug for a week see time see if it improves the mpg any?
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Old 02-09-2019   #47
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Re: 100hp mpg drop?

That's assuming it's only 1 coil at fault of course.

I guess I could try that. I'm still not sure how cost effective that is. Even the cheapest coils on eBay at around £20+ the relatively small reduction in mpg would take a while for me to recoup the expense if it does improve it.
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Old 04-09-2019   #48
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Re: 100hp mpg drop?

The performance and mpg have improved on mine with it's new stick coil. But doing mostly motorways and duals, it's unlikely to get above 40mpg.


It cost £43 from my friendly local parts shop so I'm hoping its the only one. On Shop4Parts they cost £45 plus VAT and delivery so very not cheap.

A basic test of failing coils means swapping them about and see if the cool exhaust stub "moves".
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Last edited by DaveMcT; 04-09-2019 at 10:45.
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Old 04-09-2019   #49
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Re: 100hp mpg drop?

Quote Originally Posted by DaveMcT View Post
The performance and mpg have improved on mine with it's new stick coil. But doing mostly motorways and duals, it's unlikely to get above 40mpg.


It cost £43 from my friendly local parts shop so I'm hoping its the only one. On Shop4Parts they cost £45 plus VAT and delivery so very not cheap.

A basic test of failing coils means swapping them about and see if the cool exhaust stub "moves".

i have found some substatially cheaper coils from some dubious sources, but these may be trash anyway!
im tempted to give them a try though


i cant see a coil that is only weak and not actually causing a misfire creating a noticeable decrease in the temp of one exhaust outlet port on the manifold without use of temperature probes in the runners.
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Old 05-09-2019   #50
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Re: 100hp mpg drop?

Quote Originally Posted by dac69er View Post
i have found some substatially cheaper coils from some dubious sources, but these may be trash anyway!
im tempted to give them a try though


i cant see a coil that is only weak and not actually causing a misfire creating a noticeable decrease in the temp of one exhaust outlet port on the manifold without use of temperature probes in the runners.
If you fully warm the engine the only way to get any information from the exhaust temperature would be via an IR thermometer. I used that method to set the throttle bodies on my bike.

My quick and dirty coil test runs the cold engine for less than 10 seconds. Enough to warm the exhaust runners. Any that feel cool are suspect. Swapping the coils around is long enough for the metal to cool back to ambient for a retest.

A cold engine tends to show weak coils more than a warm engine.
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Old 11-09-2019   #51
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Re: 100hp mpg drop?

well i managed to find some coils for £6.99 each

i have bought a full set so lets see how they go when they turn up.........
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Old 11-09-2019   #52
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Re: 100hp mpg drop?

Quote Originally Posted by dac69er View Post
well i managed to find some coils for £6.99 each

i have bought a full set so lets see how they go when they turn up.........
Wow!

That's little more than I paid for just one coil.
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Old 11-09-2019   #53
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Re: 100hp mpg drop?

Quote Originally Posted by DaveMcT View Post
Wow!

That's little more than I paid for just one coil.
May be false economy, but worth a try for fault finding sake.

I will take one for the team and share details if they are any good. They look good quality in the pictures!
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Old 17-09-2019   #54
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Re: 100hp mpg drop?

Well they work. Maybe a bit more pull at low rpm, but that may just be in my head.

They seem decent enough. Just need to test them long term.

Originals on the left, new ones on the right:
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Last edited by dac69er; 17-09-2019 at 19:26.
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Old 19-09-2019   #55
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Re: 100hp mpg drop?

I have one coil with damage to the flange where the cable connector clips on. But the coil which actually failed looks just fine.
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Old 21-09-2019   #56
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Re: 100hp mpg drop?

UPDATE:

Went on a good run today and got an average of 48mpg. Back to how she was. Midrange is also noticeably better too.
If I tried I could manage 50mpg without too much effort.

Definitely worth the sub £30 for the set.

These are what I bought: ebay item number 283538158008
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Old 14-11-2019   #57
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Re: 100hp mpg drop?

Bit of a thread revival. Would a failing coil/s or spark plug/s cause a slight hover in the revs when lifting off the accelerator when changing gears... Iím sitting with a combined average consumption of 7.1l/100km (38mpg if the conversion is to be believed) Iíve also noticed that when coasting in gear the consumption never drops below 2l/100km . When i did this with my Up! It would always be zero... would the coils be the cause or dirty throttle body?
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Old 14-11-2019   #58
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Re: 100hp mpg drop?

With the engine running, consumption can never be zero...

For the hovering, my money would be on the throttlebody.

gr J
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Last edited by A3jeroen; 14-11-2019 at 12:40.
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Old 14-11-2019   #59
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Re: 100hp mpg drop?

The computer never shows better than 99mpg (whatever that is in L/100km). It's wrong because coasting on a closed throttle uses zero fuel. However, my displayed average consumption figure is pretty close to brimming the tank and measuring against distance traveled.

The uneven revs could be many things from throttle body to accelerator pedal - it is drive by wire. I would say it is unlikely to be ignition coils but you never know. If you get a copy of www.multiecuscan.net you'll be able to datalog the engine parameters which should allow a diagnosis.
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Last edited by DaveMcT; 14-11-2019 at 13:31.
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Old 14-11-2019   #60
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Re: 100hp mpg drop?

Quote Originally Posted by A3jeroen View Post
With the engine running, consumption can never be zero...

For the hovering, my money would be on the throttlebody.

gr J


Coasting in gear? It does use fuel yes, but it shouldnít be that much should it? How much fuel is fed to keep the engine idling?

So a throttle body clean is in order? Ill
Search for a how to on the forum. Very new to fiat and their layouts but can do most of the work myself luckily...
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