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Old 31-01-2018   #1
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Question No firing on no. 1 cylinder (cambelt end?)

Hi, I'm not certain how bad my Stilo has been running generally, it's not been perfect but I'd not really thought I had a major issue.
Yesterday on a long journey it started getting lumpier and lumpier, especially low speed and idle. Nothing was showing on OBD2 (Torque app).
Eventually it felt like it was running on 3 cylinders, I limped home and slept on it.

So today I've been testing things a bit. Unplugging the coil-packs one by one showed #1 was doing nothing to help the engine (or maybe say 5% difference but too close to nothing to not dismiss the idea it was an illusion).
I was thinking (hoping) bad coil-pack, but replacing it didn't help matters. I also have a cheap laptop-based oscilloscope and amp clamp and this was showing pretty much the correct current waveform entering the coil-pack. I also tried swap testing the coil-packs from 2 and 1 cylinder and the issue remained with #1 .

I checked the spark plug (irridiums) and swapped 1 and 2 and the issue remained with #1 cylinder.

I ran the engine briefly (2 seconds?) with the spark plug out thinking if it was getting fuel I'd see some kind of mist exiting the plug hole, I didn't see any, but am not sure this is a valid test?

The plug wasn't bone dry each time I removed it, but it looked more like a dampness of slightly oily carbon rather than petrol. I couldn't smell any obvious petrol (though the plugs obviously smelled "engine-ey" ), and the plug was definitely not wet.

Using the amp clamp on each of the wires in the 5-way connector to the injector rail gave a waveform on each that suggested to me that the signal was being sent by the ecu...and as it is an amp tester I suppose this means the circuit is ok and that the coil in the injector is being powered....but I've only just thought of this as I am typing, and I've only just read about testing the other side of the 5-way plug. I'll go Ohm test it now but wanted to get this question asked as soon as possible.

Are there other tests I can do injector-wise?

Can they be fixed...even temporarily?

Is it common for them to fail closed as a mechanical failure while the electrics all seems fine?

Should I be seeing an engine code?

cheers, Tim
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Old 31-01-2018   #2
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Re: No firing on no. 1 cylinder (cambelt end?)

Hi Tim.

Were the plugs of a similar colour?

Black..or bleached white could point to fuelling.

Are the coolant levels holding..?
Charlie
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Old 31-01-2018   #3
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Re: No firing on no. 1 cylinder (cambelt end?)

the bad cylinder plug (#1 ) was darker than the #2 plug. which seemed the correct tan colour. #1 plug was definitely discoloured but I guess I expected something due to it not firing properly for at least 30 miles, and maybe slightly bad for months.
Coolant is fairly stable (months between top-ups if that) though there is an issue of a film of oil that appears in the expansion tank. This, however, was there when I got the car 18 months ago. I've drained and cleaned the tank once, but the film re-appeared over some weeks. I don't really know what to make of that, but there's no mayonnaise building up (there was a bit in the oil filter tube and cap but I wouldn't say it builds up much, I've wiped the cap maybe twice in 18 months as there was a bit of build-up)
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Old 31-01-2018   #4
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Re: No firing on no. 1 cylinder (cambelt end?)

small update:

All four injectors measure 15.7 Ohms to 16.5 Ohms.

I suppose the injector could still be seized shut?

Is there a test other than remove the injector and watch it?
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Old 31-01-2018   #5
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Quote Originally Posted by Mytheroo View Post

I suppose the injector could still be seized shut?

Is there a test other than remove the injector and watch it?
Sooty dark plug points to fuel being present..but burning poorly.

Has the fuel economy been poor..??
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Old 31-01-2018   #6
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Re: No firing on no. 1 cylinder (cambelt end?)

hard to say. Was getting 22mpg when I first got it, am getting 25mpg average now, 26/7 on trip B. This is urban dual-carriageway with chicanes every kilometre (Milton Keynes )
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Old 31-01-2018   #7
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Re: No firing on no. 1 cylinder (cambelt end?)

would lack of fuel (less rather than none) cause a sooty plug do you think?
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Old 01-02-2018   #8
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Re: No firing on no. 1 cylinder (cambelt end?)

Too much to burn cleanly..

Do check valve clearances
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Old 02-02-2018   #9
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Re: No firing on no. 1 cylinder (cambelt end?)

update:

so at idle, removing the coil pack wiring makes little difference, but at higher revs it does make a difference.
I triggered each injector (in situ) with 12v and I can hear each clicking ok, obviously I haven't measured flow in any way.

I have a compression tester arriving tomorrow, and if that shows an issue I'll do a leakdown test to find the issue.

If you think it is fuelling too much, would running the engine with #1 spark plug removed not give me a fuel mist out of the spark plug hole?
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Old 02-02-2018   #10
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Re: No firing on no. 1 cylinder (cambelt end?)

Take the injector out of #1 and stick it in #2 .

If the problem stays on #1 , it could be the coil or the plug breaking down at high rpm... .

If the problem moves to #2 , then it's the injector.

Forget the plugs and what colour they are.. there's a problem on the cylinder so whatever the cause, the plug colour will be irrelevant. A plug with no fuel to burn won't be the same colour as a plug that's burning *something* (however well or badly, rich or weak etc.).

If the problem stays with #1 , even with a different injector fitted then try a different coil (new or second-hand) to see if it fixes the problem (or changes the symptoms in some way). You do have a 1.6 though, so it could be an ECU fault... but eliminate the cheaper to fix issues first.

If the problem moves to #2 then it's the injector. Just change it.


Ralf D.
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Old 02-02-2018   #11
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Re: No firing on no. 1 cylinder (cambelt end?)

thanks for that ralf, yes the injector swap-test is a step, though involves a lot more disassembly so have been leaving it till last.
The injectors measure ok on the ohm-meter, and all click with voltage applied.

Do you think a bad injector (mechanically) would cause less issue at higher revs (as my problem appears to act) or do you think idle should be better than higher revs?

I'll do compression test when Amazon arrives, and follow with leak-down if that test shows a problem.
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Old 03-02-2018   #12
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Re: No firing on no. 1 cylinder (cambelt end?)

update: 50psi compression on cylinder #1 , 160psi or so on cylinder #2

Will do a leakdown test next to figure out the job
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Old 05-02-2018   #13
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Re: No firing on no. 1 cylinder (cambelt end?)

Quote Originally Posted by Mytheroo View Post
thanks for that ralf, yes the injector swap-test is a step, though involves a lot more disassembly so have been leaving it till last.
The injectors measure ok on the ohm-meter, and all click with voltage applied.

Do you think a bad injector (mechanically) would cause less issue at higher revs (as my problem appears to act) or do you think idle should be better than higher revs?

I'll do compression test when Amazon arrives, and follow with leak-down if that test shows a problem.
I'd guess a bad injector would suffer more at higher RPM since it might be able to deliver enough fuel at lower RPM but not keep up with, or manage to supply a higher demand.

On the other hand.. looks like it's your no.1 cylinder, not the injector.

Have you put some oil in the cylinder to see whether the compression comes up? That would suggest rings, rather than anything more serious/expensive broken...


Ralf S.
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Last edited by Ralf S.; 05-02-2018 at 13:40.
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Old 05-02-2018   #14
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Quote Originally Posted by Mytheroo View Post
update: 50psi compression on cylinder #1 , 160psi or so on cylinder #2

Will do a leakdown test next to figure out the job
Test all 4 cylinders..with all plugs removed..

Then add a little oil down each plug hole..it should BRIEFLY improve the seal of worn rings.

But a blown gasket.or..nonsealing exhaust valve will still blow by.

At least you seem to have a clearer direction to search now..
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Last edited by varesecrazy; 05-02-2018 at 20:53.
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Old 06-02-2018   #15
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Re: No firing on no. 1 cylinder (cambelt end?)

the leakdown test will do all this in one (AFAIK). Put cylinder at TDC and apply air pressure to the spark plug hole. Then listen at dipstick, inlet, exhaust and expansion tank for the escaping air.
Haven't done it yet though...
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